NOAA TECHNICAL MEMORANDUM NWS WR-253
INFERENCED OCEANIC KELVIN/ROSSBY WAVE INFLUENCE ON NORTH AMERICAN WEST COAST PRECIPITATION
Martin E. Lee Dudley Chelton National Weather Service College of Oceanic and Northwest River Forecast Center Atmospheric Sciences Portland, Oregon Oregon State University Corvallis, OR
April1998
U.S. DEPARTMENT National Oceanic and National Weather Atmospheric Administration Service OF COMMERCE 72 10554)
75 A Study of the Low Level Jet Stream of the San Joaquin Valley. Ronald A. Willis and Philip Williams, Jr., May 1972. {COM 72 10707) 76 Monthly Climatological Charts of the Behavior of Fog and Low Stratus at Los Angeles lntemaloonal Airport. Donald M. Gales, July 1972. {COM 7211140) 77 A Study of Radar Echo Distribution 1n Anzona During July and August. John E. Hales, Jr., July 1972. (COM 72 11136) NOAA TECHNICAL MEMORANDA 78 Forecasting Precopitaloon at Bakersfield, California, Using Pressure Gradient Vectors. Earl T. Riddiough. July 1972. (COM 7211146) National Weather Service, Western Region Subseries 79 Climate of Stockton. California. Robert C. Nelson, July 1972. (COM 72 10920) 80 Estimation of Number of Days Above or Below Selected Temperatures. Clarence M. Sakamoto, The National Weather Service (NWS) Western Region {WR) Subseries provodes an informal medoum for October 1972. (COM 72 10021) the documertatlon and qUJck dtsseminatton of results not appropriate, or not yet ready. for formal 81 An Aid for Forecastong Summer Maximum Temperatures at Seattle, Washington. Edgar G. oubilcation. The senes is used to report on work tn progress, to describe technical procedures and Johnson, November 1972. (COM 73 10150) oracttces. or to relate progress to a limited audience. These Techmcal Memoranda wtll report on investtga· 82 Flash Flood Forecasting and Warning Program in the Western Region. Philip Williams. Jr., Chester ttons devoted pnmarily to reg tonal and local problems of interest matnly to personnel. and hence will not L. Glenn, and Roland L. Raetz, December 1972, {Revosed March 1978). (COM 7310251) oe wtdely dtstributed. 83 A companson of Manual and Semoautomatoc Methods of Digitizing Analog Wind Records. Glenn E Rasch, March 1973. (COM 73 10669) Papers 1 to 25 are in the former senes, ESSA Technical Memoranda, Western Region Techmcal 86 Condoloonal Probabilities for Sequences of Wet Days at Phoenix, Arizona. Paul C. Kang1eser, June Memoranda {WRTM); papers 24 to 59 are 1n the former senes. ESSA Technocal Memoranda, Weather 1973. (COM 7311264) Bureau Technical Memoranda {WBTM) Beginnong with 60, the papers are part of the senes. NOAA 87 A Refinement of the Use of K-Values in Forecasting Thunderstorms in Washington and Oregon. Technocal Memoranda NWS. Out-of-print memoranda are not listed. Robert Y.G. Lee, June 1973. (COM 7311276) 89 Objective Forecast Precipitation Over the Western Region of the United States. Julia N. Paegle Papers 2 to 22, except for 5 {revised ediloon), are available from the National Weather Service Western and Larry P. Kierulff, September 1973. (COM 7311946/3AS) Regoon, Scoentific Servoces Division. 125 South State Street- Rm 1210, Salt Lake City, Utah 84138-1102. 91 Anzona "Eddy" Tornadoes. RobertS. Ingram, October 1973. (COM 73 10465) Paper 5 (revised edotoon), and all others beginning with 25 are avaolable from the Natoonal Technical 92 Smoke Management on the Willamette Valley. Earl M. Bates. May 1974. {COM 74 11277/AS) Information Servoce, U.S. Department of Commerce, Sills Building, 5285 Port Royal Road, Springfield, 93 An Operational Evaluation of 500-mb Type Regression Equations. Alexander E. MacDonald, June Vlrginoa 22161. Pnces vary for all paper copies; microfiche are $3.50. Order by accession numcer shown 1974. {COM 74 11407/AS) •n parentheses at end of each entry. 94 Condoloonal Probability of Visibility Less than One-Half Mile in Radiation Fog at Fresno, California. John D Thomas, August 1974. (COM 7411555/AS) ESSA Technical Memoranda (WRTM) 95 Climate of Flagstaff. Arizona. Paul W. Sorenson, and updated by Reginald W. Preston, January 1987. {PB87 143160/AS) Clomatologocal Precipitation Probabilities Compiled by Lucianne Miller, December 1965. 96 Map type Precipitation Probabilities for the Western Region. Glenn E. Rasch and Alexander E. Western Regoon Pre- and Post-FP-3 Program, December 1, 1965, to February 20. 1966. Edward MacDonald, February 1975. {COM 75 10428/AS) · D. Diemer. March 1966. 97 Eastern Pacifoc Cut-Off Low of April21-28. 1974. William J. Alder and George R. Miller, January Statoon Descnptoons of Local Effects on Synoptic Weather Patterns. Philip Williams, Jr., April 1966 1976. (PB 250 711/AS) (Revosed November 1967, October 1969). (PB-17800) 98 Study on a Sign~icant Precipitation Episode in Western United States. Ira S. Brenner, April1976 8 Interpreting the RAREP. Herbert P. Benner. May 1966 (Revosed January 1967). (COM 75 10719/AS) . 11 Some Electncal Processes in the Atmosphere. J. Latham. June 1966. 99 A Study of Flash Flood Susceptibility-A Basin in Southern Arizona. Gerald Williams August 1975 17 A Digitalized Summary of Radar Echoes within 100 Miles of Sacramento, Cal~omia. J. A. Youngberg (COM 75 11360/AS) ' . and L. B. Overaas. December 1966. 102 A Set of Rules for Forecasting Temperatures in Napa and Sonoma Counties. Wesley L. Tuft 21 An Objectove Aid for Forecasting the End of East Winds on the Columbia Gorge, July through October 1975. (PB 246 902/AS) ' October. D. John Coparanis, April1967. 103 Application of the National Weather Servoce Flash-Flood Program 1n the Western Region. Gerald 22 Derivation of Radar Horozons in Mountainous Terrain. Roger G. Pappas, April1967. Williams. January 1976. (PB 253 053/AS) 104 Objective Aids for Forecasting Minimum Temperatures at Reno, Nevada, During the Summer ESSA Technical Memoranda, Weather Bureau Technical Memoranda (WBTM) Months. Christopher D. Hill, January 1976. (PB 252 866/AS) 105 Forecasting the Mono Wind. Charles P Ruscha, Jr., February 1976 (PB 254 650) 25 Verification of Operation Probability of Precipitation Forecasts, April 1966-March 1967. W. W. 106 Use of MOS Forecast Parameters in Temperature Forecasting. John C. Plankinton Jr. March Dickey, October 1967. (PB-176240) 1976. (PB 254 649) ' . 26 A Study of Winds in the Lake Mead Recreation Area. R P. Augulis, January 1968. (PB-177830) 107 Map Types as Aids in Using MOS PoPs in Western United States. Ira S. Brenner August·1976 28 Weather Extremes. R. J. Schmidli, April1968 (Revosed March 1986). (PB86177672/AS). (Revised (PB 259 594) ' . October 1991- PB92-115062/AS) 108 Other Kinds of Wind Shear. Christopher D. Hill, August1976 (PB 260 437/AS) 29 Small-Scale Analysis and Prediction. Philip Williams, Jr., May 1968. (PB178425) 109 Forecasting North Winds 1n the Upper Sacramento Valley and Adjoining Forests. Chnstopher E. 30 Numencal Weather Prediction and SynoptiC Meteorology. CPT Thomas D. Murphy, USAF, May Fontana, September 1976. (PB 273 677/AS) 1968. {AD 673365) 110 Cool Inflow as a Weakening Influence on Eastern Pac~ic Tropical Cyclones. William J. Denney 31 Precipitation Detection Probabilities by Salt Lake ARTC Radars. Robert K. Belesky, July 1968. (PB November 1976. (PB 264 655/AS) ' 179084) 112 The MAN/MOS Program. Alexander E. MacDonald, February 1977. (PB 265 941/AS) 32 Probability Forecasting-A Problem Analysis with Reference to the Portland Fore Weather District. 113 Winter Season Monomum Temperature Formula for Bakersfield Californoa Usong Mulliple Harold S. Ayer, July 1968. (PB 179289) Regression. Michael J. Oard, February 1977. (PB 273 694/AS) ' ' 36 Temperature Trends in Sacramento-Another Heat Island. Anthony D. Lent1n1. February 1969. (PB 114 Tropical Cyclone Kathleen. James R. Fors, February 1977. (PB 273 676/AS) 183055) 116 A Study of Wind Gusts on Lake Mead. Bradley Colman. April1977. (PB 268 847) 37 Oosposal of Logging Residues Without Damage to Aor Quality. Owen P. Cramer, March 1969. (PB 117 The Relalove Frequency of Cumulonimbus Clouds at the Nevada Test Site as a Function of K 183057) Value. R.F. Quinng, April1977. (PB 272 831) 39 Upper-Air Lows Over Northwestern United States. A.L. Jacobson. Apri11969. PB 184296) 118 Moisture Distribution Mod~ication by Upward Vertical Motion. Ira S. Brenner Apri11977. (PB 268 40 The Man-Machine Mox in Applied Weather Forecastong 1n the 1970s. L. W. Snellman August1969. 740) ' (PB 185068) ' 119 Relative Frequency of Occurrence of Warm Season Echo Activity as a Functoon of Stability Indices 43 Forecasting Maxomum Temperatures at Helena. Montana. David E Olsen. October 1969. (PB Computed from the Yucca Flat. Nevada. Rawonsonde. Darryl Randerson June 1977. {PB 271 185762) 290/AS) . 44 Estimated Return Penods for Short-Duration Precipotallon in Arizona. Paul C. Kangieser, October 121 Climatological Prediction of Cumulonimbus Clouds in the Viconity of the Yucca Flat weather Statoon 1969. (PB 187763) R.F. Quiring, June 1977. (PB 271 704/AS) 46 Apphcatoons of the Net Radiometer to Short-Range Fog and Stratus Forecasting at Eugene, Oregon. 122 A Method for Transforming Temperature Distribution to Normality. Morns s. Webb Jr. June 1977 L Yee and E. Bates. December 1969 {PB 190476) (PB 271 742/AS) . ' 47 Staloslocal Analysis as a Flood Routing Tool. Robert J.C Burnash. December 1969. {PB 188744) 124 Statostocal Guidance for Prediction of Eastern North Pac1f1c Tropical Cyclone Moloon - Part 1 48 Tsunamo. Rochard P. Augulls, February 1970. {PB190157) Charles J. Neumann and Preston W. Leftwich. August1977. {PB 272 661) . 49 PrediCting Precipolatoon Type. Robert J.C. Burnash and Floyd E. Hug, March 1970. {PB 190962) 125 Statostocal Guidance on the PrediCtion of Eastern North Pacific Tropical Cyclone Mallon • Part 11 50 Statistocal Report on Aeroallergens {Pollens and Molds) Fort Huachuca, Arozona, 1969. Wayne S. Preston W. Leftwoch and Charles J Neumann. August1977 (PB 273 155/AS) · Jonnson. April1970 (PB 191743) 126 Climate of San Franc1sco. E. Jan Null, February 1978. (Revosed by George T. Pericht, April1988 51 Western Region Sea State and Surf Forecaster's Manual. Gordon C. Shields and Gerald B. and January 1995). (PBBB 208624/AS) Burdwell, July 1970. {PB 193102) 127 Development of a Probability Equation for Winter-Type Precipotatoon Patterns in Great Falls 52 Sacramento Weather Radar Climatology. R.G. Pappas and C. M Vehquette, July 1970. (PB Montana Kenneth B. Moelke, February 1978. {PB 261 367/AS) ' 193347) 128 Hand Calculator Program to Compute Parcel Thermal Dynamocs. Dan Gudgel April1978 {PB 283 54 A Refonement of the Vorticity Field to Delineate Areas of Significant Precipotatoon. Barry B. 080/AS) . Aronovitch. August 1970. 129 Fire whirls. David W Goens, May 1978. {PB 263 666/AS) 55 Application of the SSARR Model to a Bason Without Ooscharge Record. Vail Schermerhorn and Donal 130 Flash-Flood Procedure. Ralph C. Hatch and Gerald Williams. May 1978. (PB 286 014/ASI W. Kuehl, August 1970. (PB 194394) 131 Automated Fore-Weather Forecasts Mark A. Mollner and David E. Olsen September 1978 (PB 56 Areal Coverage of Precipitation 1n Northwestern Utah. Phihp Williams. Jr., and Wemer J. Heck, 289 916/AS) ' . i, September 1970 {PB194389) 132 Estimates of the Effects of Terrain Blocking on the Los Angeles WSR-74C Weather Radar R.G. 57 Preliminary Report on Agncultural Field Burnong vs. Atmosphenc Visibility 1n the Willamette Valley Pappas, R.Y. Lee, B.W. Finke, October 1978. (PB 269767/AS) of Oregon. Earl M. Bates and Oavod 0. Chilcote. September 1970. {PB 19471 OJ 133 Spectral Techniques in Ocean Wave Forecasting. John A. Jannuzzi October 1978 58 Aor Polluloon·by Jet Aorcraft at Seattle-Tacoma Airport. Wallace R. Donaldson, October 1970. {COM {PB291317/AS) ' . 71 00017) 134 Solar Radiation. John A. Jannuzzi, November 1978. (PB291195/AS) 59 Application of PE Model Forecast Parameters to Local-Area Forecasting. Leonard W Snellman, 135 Application of a Spectrum Analyzer In Forecastong Ocean Sv;ell in Southern California Coastal October 1970. {COM 71 00016) Waters. Lawrence P. Koerulff, January 1979. (PB292716/AS) 60 An Aid for Forecasting the Monomum Temperature at Medford. Oregon, Arthur W Fritz, October 1970. 136 Bas1c Hydrologoc Pnncoples. Thomas L. Dietrich, January 1979. (PB292247/AS) (COM 71 00120) 137 LFM 24-Hour Predoctoon of Eastern Pacific Cyclones Refoned by Satellite Images. John R. 63 700-mb Warm Air Advection as a Forecasting Tool for Montana and Northern Idaho. Norris E. Zommerman and Charles P. Ruscha. Jr., January 1979. (PB294324/AS) Woerner, February 1971. (COM 71 00349) 138 A Somple Analysos/Doagnosos System for Real Time Evaluatoon of Vertocal Motion. Scott Heflick and 64 Wind and Weather Regimes at Great Falls, Montana. Warren B Price, March 1971. James R. Fors. February 1979. (PB294216/AS) 65 Climate of Sacramento. Calofornia. Richard Henton and Tony Martini (Retored), August1996. (Fifth 139 Aids for Forecasting Minimum Temperature in the Wenatchee Frost District. Roberts. Robinson ReVISIOn) {PB89 207781/AS) . Aprll1979. (PB298339/AS) ' 66 A Prehm1nary Report on Correlation of ARTCC Radar Echoes and Precipitation. Wilbur K. Hall, June 140 Influence of Cloudiness on Summertime Temperatures in the Eastern Washington Fire weather 1971 {COM 71 00829) dostnct. .James Holcomb, April1979. (PB298674/AS) 69 Natoonal Weather Service Support to.Soanng Activities. Ellis Burton. August1971. (COM 71 00956) 141 Companson of LFM and MFM Precopitatoon Guidance for Ne~ada During Doreen Christopher Hill, 7 1 Western Regoon Synoptoc Analysis-Problems and Methods. Philip Williams, Jr., February 1972. April1979. {PB298613/AS) . {COM 72 10433) 142 The Usefulness of Data from Mountaintop Fire Lookout Stations 1n Determining Atmospheric 74 Thunderstorms and Hail Days Probabiht1es 1n Nevada. Clarence M. Sakamoto. April1972. (COM NOAA TECHNICAL MEMORANDUM NWS WR-253
INFERENCED OCEANIC KELVIN/ROSSBY WAVE INFLUENCE ON NORTH AMERICAN WEST COAST PRECIPITATION
Martin E. Lee Dudley Chelton National Weather Service College of Oceanic .and Northwest River Forecast Center Atmospheric Sciences Portland, Oregon Oregon State University Corvallis, OR
April1998
UNITED STATES National Oceanic and National Weather Service DEPARTMENT OF COMMERCE Atmospheric Administration John J. Kelly, Jr., Assistant William M. Daley, Secreta!)' D. James Baker, Under Administrator for Weather Services Secreta!)' and Administrator ( \ I
Thi~ publication has been reviewed and is approved for publication by Scientific Services Division, Western Region
Delain A. Edman, Chief Scientific Services Division Salt Lake City, Utah
111 TABLE OF CONTENTS
I. Introduction ...... 1
II. Significant 1994-1996 Trans-Pacific Ocean/Atmosphere Patterns ...... · .... 2
Ill. Oceanic Rossby Wave Observations and Theory ...... 5
IV. Tropical Air-Sea Interaction ...... 7
V. Proposed Ocean-Atmosphere Conceptual Model ...... 9
VI. Conclusion ...... II •••••• ·• ~ ••••• •• 11
VII. Acknowledgments ...... ; ...... ~ ...... 14
VIII. References ...... 15
IV lnferenced Oceanic Kelvin/Rossby Wave Influence on North American West Coast Precipitation
Martin E. Lee · •Dudley Chelton ··
Abstract
The complex interaction of coupled ocean-atmosphere processes is sti/1 far from being completely understood, and documented. This Technical Attachment documents a nonclassic, oceanic Kelvin/Rossby wave conceptual model to partially explain above normal 1994-1996 precipitation patterns along the North American west coast. The proposed conceptual model focuses on an eastern Pacific past-El Niflo heat transfer mechanism associated with oceanic Kelvin!Rossby waves that potentially affect preferential atmospheric forcing, resulting in selectively focused offshore storm track and moisture advection trajectories. Synergistic components of this model thereby have the potential to enhance (or reduce) U.S. west coast interannual precipitation.· The magnitude of U.S. west coast flood damages incurred during the winters of 94/95 and 95196 imply that analysis and assimilation of this proposed conceptual oceanic Kelvin!Rossby wave interaction may be worth considering in order to improve accuracy in forecast expectations for timing and placement of both above and below normal west coast annual .and interannual precipitation. Other implications resulting from this research also include: 1) the imminent necessity of incorporating a multidisciplinary, combined earth systems approach in west coast precipitation forecasting; and 2) a concluding argument regarding the continued necessity for in situ oceanic observation programs beyond tropical latitudes.
Introduction recognizing the economic and social value of accurate precipitation forecasts, Accurate prediction of local precipitation is dedicates significant resources to important for early flood warning and increase lead times of watches and reservoir management, especially· in warnings for flood and flash flood events mountainous areas of the western United (Olson et al. 1995). However, abrupt and States where severe flooding during vast data sparse upstream conditions heavy precipitation occurs in steep terrain commencing along a dominant land-sea and narrow valleys (Miller and Kim 1996). boundary, marked by the west coast of The National Weather Service (NWS), the United States and the Pacific Ocean,
·National Weather Service, Northwest River Forecast Center, Portland, Oregon. Corresponding author address: Martin E. Lee, NWS NWRFC, 5241 NE 122nd Ave., Portland, OR 97230. E-mail: [email protected].
**College of Oceanic and Atmospheric Sciences, Oregon State University, Corvallis, OR 97331; also a TOPEX/POSEIDON Science Working Team Principal Investigator. '
1 introduce pronounced complexity to considerations in this analysis can be precise forecasting of significant summarized bythefollowing questions: 1) precipitation. Upstream, air-sea interaction What are oceanic Rossby waves? 2) Did has the potential to modify both an interannual (1994-1996) heavy atmospheric temperature and wind fields precipitation pattern shift northward along that may then alter even global-scale the west coast of the United States in atmospheric and oceanic circulations (Min: association with a propagating oceanic wei and Dayong 1988). The ability to Rossby wave associated with a produce reliable forecasts in NWS pronounced but concl,uding ~I ~ina event, Western Regi.on .locations of the United trailing off with diminishing propagation States is thus . dependant on an speed at increasing.ly high latitudes? 3) appreciation and conceptual. What is the surface manifestation of understar)ding of significant upstream oceanic Rossby ,waves .as pertains to a,ir ocean-atmosphere interactions. sea interaction ·that may affect precipitation? 4) Are · sea ·· surface During the winter of 1994-'95, California temperature (SST) anomalies associ·ated received unusually. large amounts of . with oceanic Rossby waves significant precipitation, with th~ Russian River J?asin enough to alter preferred low-mid lat'itude being among the hardest hit areas in . moisture advection trajectories,. localized January 1995, reporting over an estimated ·atmospheric forcing, and resultant 800 million dollars in flood-related interannual west coast . precipitation damages from just three consecutive patterns? and 5) Is it cost-effective to strong storms between 7 anc;l 11 January even consider oceanic Rossby waves .as (Miller and Kim 1996). In the following ' a relevant factor in North Americar1,yyest winter (1995-96), western Oregon and coast operational forecasting? .and' 6) Washington were inundated with What are ·the short-long term implications numerous record-breaking winter floods. if the answer to question number 5 is II' I What substantive mechanism/s "yes"? contributed to this sequence of interannual events? In general terms, II Significant· 1994-1996' Tf~n~ variation in Pacific coast precipitation is Pacific Oc.ean/Atmosphere tne result of . "annual variation in the ·Patterns· interaction between the maritime westerlies from the .North Pacific and th~ The Spring of 1995 was marked by below~ mountains of the U.S, West Coast" (Chen normal. equatorial eastern Pacific SSTs; et al. 1996). and was followed by an active western Pacific Typhoon season in the fall of This Technical Memorandum considers 1995. This indicated that warm hypothetical "nonclassic" (Hobbs et al. equatorial surface water had shifted west 1996) upstream ocean-atmosphere of the date line. The spring and summer interactions responsible for producing of 1996 provided further confirmation of excessive winter (1994-95, and 1995-96) this in a disastro1,.1s manner. During this west coast precipitation. Although not period Typhoons Ann, Frankie, Gloria, necessarily in the respective order given and Herb produced severe damage in here, the dominant conceptual
2 Eastern Asia. For example, early-mid July 1996. However, this U.S. west coast 1996 severe, typhoon related weather and precipitation was minor in significance flooding in southern-central China was when compared to cumulative U.S. west responsible for approximately 1 , 108 coast winter 1994-95 and 1995-96 deaths, and an estimated $11.23 billion in precipitation. economic losses across Anhui, Guangxi, Guizhou, Hubei, Hunan, Jiangsu, Jiangxi, Halpert et al. (1996) note that abnormally and Zhejiang provinces. In these high 1994-95 winter season precipitation provinces, flooding was responsible for was observed in California and the damage to approximately 2.8 million southwestern United States. This pattern, homes and the collapse of another especially from December 1994 to 810,000 homes, leaving millions of people February 1995, was associated with an homeless, and also destroying over 5 eastward extension of a jet stream core million tons of grain (Reuters Limited, across the Pacific and into California. Beijing: July 25, 1996). Before moving During January 1995, the jet stream core into Eastern China, Typhoon Gloria was and storm track aimed at California was responsible for an estimated 50 deaths in displaced approximately 18 a of latitude the Philippines (Philippine News Agency, south of their typical location. Resulting Manila: July 29, 1996), and $21 million in significantly above-normal precipitation crop damages across southern Taiwan steered into California at that time, (Reuters Limited, Hong Kong: August 2, producing excessive flooding throughout 1996). Typhoon Herb then caused the state. During · January 1995, the another 39 deaths in the Philippines southern Cascades, the northern Sierra (Reuters Limited, Manila: July 29, 1996), Nevadas, and several central-coastal also before clipping Taiwan and moving California locations observed 950-1050 into Eastern China. mm of precipitation, and October-April totals in parts of southern California Remnant decaying tropical storms reached at least two times the normal advecting to higher latitudes then resulted seasonal total records (Fig. 2). According in 68 deaths and $246 mi[lion in flood to the Products and Services Division of damage across South Korea· (Reuters the National Climate Data Center, over Limited, Seoul: July 31, 1996). This 3.0 billion dollars in flood damage was included the loss of an estimated four tons assessed from January-March 1995 of ammunition (hand grenades, mortar flooding in California - including 27 and artillery shells, and land mines) swept deaths. away by flood waters. Another estimated 860 tons of ammunition stored near the In the following winter (1995-96), severe North Korean Border was buried by flood river flooding (especially west of the induced landslides. During this stormy Cascades) occurred in western season in the western Pacific, Typhoon Washington and northwestern Oregon, Bart typified a fully recurving storm (Fig. where 200-500 mm of heavy rain fell from 1), with its decaying remnants entraining November-December 1995 · (Fig. 3). into a trans-Pacific westerly jet stream, Enhanced warm, moist, southwesterly eventually resulting in U.S. west coast flow facilitated this excessive precipitation precipitation interception during May pattern anomaly. As noted above, March-
3 May 1995 marked the end of El Nino/ the equator. Sub~idiary clues are derived Southern Oscillation (ENSO) conditions from an .apparent northwestward shift of across the Pacific. For example, below eastern Pacific positive SST anomalies normal SSTs developed from the South along the U.S. west coast, from March American coast and the equatorial Pacific May 1995 to September-November .1995. to 120°W, where SSTs reached -1.0°C in This northern hemisphere, northwestward many areas (Fig. 4}. Central Pacific SST positive anomaly shift is puzzling in maximum positive SST anomalies ·had the context of first order eastern ·Pacific significantly diminished, and .central semi-permanent atmospheric and ocean equatorial Pacific atmospheric convection current circulatidn patterns. For example, returned to normal.. Near normal low-level clockwise circulation around semi .equatorial easterlies also reappeared, and permanent eastern Pacific high pressure western Pacific SST anomalies exceeded results in mean equatorward surface wind Q,5oC above normal between 120°E to components along the southwestern U.S. ·150°E. coast. Similarly,. eastern Pacific. mean ocean currents along the westerri U.S. El Nino processes, by classic definition, coast are characterized by equatorward were therefore relinquishing control of flow (Fig. 5). weather patterns over the eastern Pacific. Yet, according to the Products .and A direct correlation exists between the Services Division of the National .Climate organized eastern Pacific positive SST Data Center, .. February 1996 Oregon anomaly behavior described above and uninsured flood damage alone :reached positive Sea Surface Height , (SSH) 400 million dollars:· Over 300 million anomaly structure (Fig. 6)~ Additionally, dollars damage to Oregon ·highways and this 1995-1996 ocean/ system waterway .. infrastructures. was also phenomenon has symmetry .. rhatching reported. Overall flood damage to the strong November 1995 and February Pacific Northwest is now estimated to 1996 storm track~ - routed from near the approach $1 billion .,... including 14 Hawaiian Islands, along northward curving fatalities. Thus, one of the driving subtropical jet streams, often referred to questions becomes: · "What other as a "Pineapple Express." These mechanisms have we learned enough associations eventually resulted in the about to.explain.this above normal, non El formulation of a conceptual rnodel that Nino. wi_nter precipitation pattern over can explain the previously discussed western North America?" northwestward shift of SST anomalies. The positive, symmetric SSH an'omaly Surprising struCture and symmetry in structure in Fig. 6 correspond to positive eastern Pacific March-May 1996 positive SST anomalies (Bob Cheney 1996, SST anomalies (Fig. 4) provide potential personal communication) via a selective clues to answering the previously.raised redist~ibution of .heat energy (Dudley question., For example, a coupled, Chelton 1997, personal communication). northern and southern hemisphere, Both the positive SST and SSH offshore poleward "banana-shaped" positive SST anomalies are associated with oceanic anomaly structure is evident 6ver the Ross by waves.· In the following sections; eastern Pacific in Fig. 4, symmetric about this association is developed into a
4 conceptual model that can be used to A prec1s1on radar altimeter aboard the inferentially explain how and why oceanic TOP EX/ POSEIDON satellite provides the Kelvin and Rossby waves may be linked most accurate, currently available directly to: 1) poleward shifts of eastern altimeter data for studying general ocean Pacific positive SST anomalies; and 2) circulation and its variability (Fu et al. selectively focused precipitation patterns 1994; Fu and Cheney 1996). This is along the U.S. west coast. Concluding possible using altimetric measurement of sections of this text also explore the sea surface elevation, because low plausibility and ramifications of this frequency sea level variations (i.e., with proposed model, as well as subsidiary tidal variation removed) are indicative of planning, design, and management motions throughout much of the water issues. column - extending to the sea floor in certain instances (Pedlosky 1979). Ill Oceanic Rossby Wave TOPEX is the U.S. acronym for Ocean Observations and Theory Topography Experiment, a joint mission with France. POSEIDON, the mythical Technological advancement in Greek god of the sea, is the acronym for observation sampling capabilities has the French· contribution to this mission. made it possible to improve our The TOPEX/POSEIDON satellite is a und~rstanding of ocean circulations that modified Multimission Modular Spacecraft play critical roles in varying climate over a configured with the first spaceborne dual wide range of time scales: from seasonal frequency (5.3 and 13.6 GHz) radar to interannual (e.g., El Nino phenomenon) altimeter. The radar altimeter was to decades and even centuries - as designed and constructed by the Applied revealed in recent ice core analyses Physics Laboratory of the Johns Hopkins (Johnson et al. 1992). Our ability to University (APL!JHU), and the 2,500 kg identify ever smaller scale ocean satellite was launched into a highly stable circulation processes is also increasing. orbit on August 10, 1992, by an Ariane For example, the decline in intensity of the 42P rocket from the European Space eastward flowing Kuroshio Extension and Agency's Guiana Space Center in French its westward recirculation gyre has been Guiana (Fu et al. 1994). The launch linked to energy transfers from the mean vehicle was contributed to this project by current flow to an eddy field in a region the "Centre National d'Etudes Spatiales south of the Kuroshio Extension (Qiu (CNES)," or the National Center of Space "1995). In the quest to further understand Studies, France's equivalent of NASA. these increasingly evident complex ocean system processes, remote sensing has The TOPEX/POSEIDON satellite has a become the most practical approach to 66° inclination orbit- 1,336 km above the observe seasonal-to-interannual ocean Earth's surface (Fig. 7). Sea surface variability on global scales with adequate height is observed by a TOPEX radar space and time resolution; and recent signal reflected off the ocean's surfa9e. advancements in satellite observing The dual-frequency altimeter allows for a systems have significantly improved our correction for ionospheric effects on the 2- ability to monitor global ocean circulation. way travel time of radar pulses. The time calculated for a standard local sea level
~s radarreturn is compared to the measured L1 ·- 70 km, compared to the analogous return time. If the return signal takes Jess atmospheric Rossby length scale,, LA ·- time, the ocean surface is above its 1900 km. Conversely, th·e time scale for standard reference sea leveL Insertion L1- 60 days, while the time. scale forL;i'~ into orbit W9S so successful that sufficient 2 days (Stewart 1985). Local vertical, fuel .remains aboard the satellite to sustain latitudinal variation of the Earth's angular its mission significantly beyond the year rotation vector.:.... resulting .from curvature 2000 .. of the Earth's surface ,..;;. provides: the restoring force for oceanic Rossby waves Satellite altimetry, provided via projects (Pedlosky 1979). These · .waves are like the TOPEX/POSEIDON mission, is considered to play a key role in modern probably the only way that global oceanic large-scale ocean circulation theory. They circulations can be studied .relative to the are also considered an important sea surface as a reference level, because mechanism in the westward intensificatidh the geostrophic surface velocity can. be of large-scale circulation gyres.{Anderson determined from the ·. s.atellite derived and Gill 1975; Anderson et aL 1979) . .surface .height (F!-1 ;:md Smith· 1996). Oce.an swrface currents are initially forced Wind and thermal buoyancy forcing, at ·by momentum tranSfer from . the eastern ocean boundaries and. i11terior atmosphere. Yet,· once free from direct regions,~generate oceanic Rossbyw.aves; forcing · by the wind, . these nearly and El Nino events are also oceanic geostrophic currents tend to move slowly Rossby wave generators (Barnett. et aL and nearly frictionlessly under pressure 1991; Neelin et al.. 1994; Battisti aAd gradient a.nd Coriolis force influences. .Sarachik .1995) .. Eastward propag·ating Thus, sea surface height anomaly data oceanic equatorial Kelvin waves, forced-"in across these currents facilitates the. western Pacific by wind anomalies theoretical current velocity estimations. A associated with El Nino events, generate positive 1 em sea surface height change poleward propagating coastally trapped may generate an elevated slab containing Kelvin waves when they reach the eastern the equivalent of several millions·of cubic .boundary of the Pacific, resulting .'·in meters of water per second, a rate of positive sea surface height anomalies that discharge greater than all the rivers in the have been observed to propagate as fat world (from the JPL TOPEX/ POSEIDON north as the Gulf of Alaska .. These forced; Mission Hom·ePage, http//topex · positive. sea surface height anomalies www.jpLnasa.gov/). Although less.er in 9enerate westward propagating oceanic scope, significant responses also occur at Ross by waves along the west coast of the smaller than global-hemispheric scales, Americas ... :Model results suggest th.at where other quasigeostrophic processes these westward propagating waves may c;tre at work" Oceanic Rossby waves fall extend well into high latitudes, covering within this category. The theoretical the entire North. .Pacific,. remaining larg.ely oceanic Rossby wave length scale L1 ( undamped to 160 o W longitude,.·. and the Rossby deformation radius) is. equal to continuing into 'the western Pacific a the product of a characteristic buoyancy decade later (Jacobs et aL 1994). Jacobs frequency and its vertical. scale divided by et aL (1994) also note that El Nino the Coriolis parameter. At - 30° latitude, generated oceanic Ross by waves may be
6 linked with North Pacific mid latitude height and SST anomalies, with potential ocean circulation anomalies a decade 1994-1996 eastern Pacific and western later. They have hypothesized that these North American weather modification. transient ocean circulations may have a non-trivial impact on North American IV Tropical Air-Sea Interaction weather patterns. The simplistic theoretical impact these Rossby waves Bocheng and Qiyu ( 1988) remark that "the have on eastern Pacific meteorology is western tropical Pacific Ocean is the that they appear to facilitate a complex largest heat and moisture source on the exchange process. The 1-10 em sea earth .... " As a result, it has a significant surface height signatures of oceanic impact on Asian, as well as world climate. Rossby waves are associated with much Variations in western tropical Pacific greater thermocline depth variations (- 3 current systems are intimately linked to El. orders of magnitude, and opposite in Nino events. This air-sea interaction is sign). Thus, oceanic Ross by wave signals the subject of intensive research that has represent large thermal variations in the resulted in our increased appreciation of upper ocean. how both oceanic and atmospheric responses are inextricably dependent Initially, oceanic Rossby waves provide upon forGings and exchanges between tran~ient ocean circulation adjustment in these two complicated systems. For response to large-scale atmospheric example, Hendon and Salby (1996) note forcing. The resulting anomalous change that atmospheric frictional wave-CISK in ocean circulation may then be capable (conditional instability of the second kind)
\ / of influencing climate. Despite their explains eastward frequency selections in importance in time varying oceanic western Pacific tropical to subtropical processes, Rossby wave surface atmospheric circulation and anomalous signatures are difficult to detect, with convection interactions. In the western height variations of less than 10 em over Pacific this interaction is highly correlated wavelengths ranging from hundreds to with equatorial frictional convergence that thousands of kilometers. However, the shifts towards warm SST anomalies, and TOPEX/ POSEIDON altimeter is capable is associated with dynamical responses of continuous measurement accuracy of- involving forced Kelvin and Rossby wave 3 em since becoming fully operational in disturbances. Shifting toward positive October 1992, and amplitudes assmall as temperature anomalies results in a net - 1 em can be detected in large-scale sea tropical eddy available potential energy level signals over the entire woi"ld ocean, gain that facilitates amplification of after measurement error filtering is eastward convective components, and the . performed. The TOPEX/POSEIDON frequency of these eastward components altimeter is thus able to detect oceanic · is dominated by unstable tropical Kelvin Rossby waves unambiguously (Schlax wave structure in the atmosphere. and Chelton 1994; Parke et al. 1987; Fu However, frictional wave-CISK et al. 1994). The remainder of this correlations (assuming a zonal SST Technical Memorandum examines the variation) become insignificant in the associative correlations of these oceanic eastern Pacific - because typically colder Rossby waves, via their sea surface SSTs do not provide sufficient
7 climatological convection. This distinction Pacific may vary by only a 'few degrees C. of eastern Pacific tropical-subtropical Hansen (1988) categorized ~, 1 oc atmospheric processes, different from anomalies observed during 1. 986 in the those in the western Pacific, is another Pacific as "large." ·Various moist process manifestation of how important· it is to cycles, resulting in eastward .propagation understand air-sea interactions over the of convection toward the eastern Racific ·Pacific. (including El Nino/Southern 'Oscillation (ENSO) events) may . be attributed to ·TropicaiPacific Ocean SSTs are relatively these smaller warm . SST anomalies uniform, in·. that cold, dense water through their enhancement of unsfable characteristically lies below a thin, wind conditions conducive to sustained mixed layer (.;. 100 m , thick) of much atmospheric convection (Chan and Lau warmer water. The highly stratified region 1988). ·separating the we.akly stratified ·shallow and deep layer is called the thermocline This un~table air-sea interaction is largely (Stewart 1985). However, at the onset of driven by turbulent flux exchange across the 1986-1988 El Nino/Southern the ocean-atmosphere interfac~·. Oscillation (ENSO) episode, anomalous transforming SST anomalies into diabatic eastward transport· of warm surface mixE?d heating that results·· in forcing of We fre·e layer waterwas observed equatorward of atmosphere (Min wei and Dayong 1988). 10 a N latitude. In response to the In the tropics, significant positive and/or eastward export of surface mixed layer negative SST anomalies cari also be water away from the western Pacific, th~ frequently correlated with observed thermocline in the tropical western Pacific changes in atmospheric boundary layer essentially "shoaled," coinciding with wind regimes (Dayong et al. 1988);; In tine .observed decreases in dynamic height ;tropical eastward on-set of ,.an ·£LNitio over the· upper (300-400 m} . tropical event, positive SST anomalies directly western Pacific Ocean (Toole· et al. 1988). result in surface wind convergence. and Eastward export of warm surface layer associated precipitation fields (Barnett et water also resulted in colder temperatures al. 1991). Barnettet al. (1991) caveatthat .observed over the surface of the tropical .the direct effect of heat exchange from the western Pacific Ocean. ocean to the atmosphere is r~latively weak in forcing of the· main. troposphere. According to Chan and Lau (1988), SSTs However, the. air-sea temperature are one of the most significant factors in difference has a .very important indirect the genera~ion and maintenance of role in the thermodynamics . of tropical convective cloud· processes. atmospheric circulation:. the low-level These convective processes have been surface wind convergence associated with correlated with selective variance.around the positive SST forcing provides. critical tropical SSTs of 28 ac, and outgoing initiation of vertical mass and water vapor 2 longwave radiation values of~ .240 wm- . flux above the planetary boundary layer The ,SST relationships between a (PBL), thus determining where heat from cdnvectively active, . relatively. warm condensation in the troposphere occurs. western Pacific . versus a convectively Thi.s tropospheric heat of condensation is suppressed, relatively ; cooler eastern estimated to be four times greater than
8 sensible heat flux from the ocean into the V Proposed Ocean-Atmosphere lower PBL, but its positioning is tied to the Conceptual Model positive SST anomaly feedback. Fig. 6 is a global map of sea level Selective subtropical to global scale constructed from TOPEX/ POSEIDON temperature modifications result at the altimeter data acquired in April1996. The hemispheric scale from Hadley circulation positive SSH anomalies of 2 3 em over of net poleward energy flux, and the the eastern Pacific, in both the northern. Hadley circulation of this energy flux is and southern hemispheres, have a largely forced by the addition of low structure consistent with that expected for latitude surface latent heating (Palmen an oceanic Rossby wave crest: the and Newton 1969; Min wei and Dayong positive SSH anomaly gradually curves 1988). On the scale of tropical Kelvin from mid-high latitude far eastern Pacific wave processes in the eastern Pacific, coastal boundaries · towards western Hendon and Salby (1996) conclude that Pacific tropical latitudes. Positive SST convective disturbances "can be anomalies in Fig. 4 have similar structure understood as the propagating response to that of the positive SSH anomalies in to transient heating that is localized." Fig. 6. These two positive anomaly Using numerical simulations, Wendell structures are directly associated, and the (1988) also found that even midlatitude mechanism responsible for this correlated SST warming significantly impacted structure is the latitudinal variation of cyclogenisis in boundary layer interaction oceanic Rossby waves initiated nearly with cyclones, via increasing planetary · simultaneously along the eastern boundary layer (PBL) "convergence and boundary of the Pacific (Chelton and redistribution of surface heat to the Schlax 1996). These latitudiHally midtroposphere .... " Jacobs et al. (1994) dependent oceanic Rossby waves· are have observed high-latitude SST thought to be initiated by passage of anomalies across the North Pacific of the coastally trapped, poleward propagating same magnitude and temporal-spatial baroclinic oceanic Kelvin waves. Oceanic extent as those in equatorial latitudes Kelvin waves have been observed in during El Nino events. Despite relatively current meter and hydrographic data· minor magnitudes of positive SST along the west coast of South America anomalies (i.e., compared to magnitudes (Smith 1978; Huyer 1980), and Dorman of typical frontal inversions in the (1985) .has presented evidence of atmosphere), the microscale effects of 'trapped, internal oceanic Kelvin wave converging low-level moist air also existence along the coast of California. contribute to further destabilizing of the PBL (Stull 1988). Collectively, these low Coastally trapped, oceanic Kelvin waves, mid latitude dynamic processes thus have propagating poleward along the west the potential to re-define higher latitude coasts of North and South America, are storm tracks, primarily as a result of mean balanced directly along the coast by zonal temperature field modification (Lee pressure gradient and Coriolis forces and Mak 1996). (Dorman 1985). Allowing poleward propagating, trapped oceanic Kelvin waves originating off Central America to
9 reach the Gulf of Alaska, this relatively upstream precipitation along preferential undamped ageostrophic forc:;e balance is storm tracks have resulted in heavy; post directly analogous to trapped barrier jets El Nino west coast precipitation (Figs. 2-3, in the atmosphere. Trapped oceanic 8, and 10)? Kelvin waves decay exponentially offshore over . a · length scale. equivalent to the A simple simulation of trapped oceanic Rossby radius of deformation, The Kelvin and · Rossby wave pro·pagation initiation of a westward propagating along the North American west coast was .oceanic Rossby wave by ·a trapped, develop:ed to further study the plausibility poleward . propagating oceanic Kelvin of. this conceptual model. ·A .constant wave .is illustrated in Fig. 8. Because of phase speed of 50 cm/s was used, for the "~-effect" of latitudinal variation of the poleward propagating trapped, oceanic Corio lis parameter,. SSH ·. anomalies coastal Kelvin· .waves propagating associated with coastal· Kelvin wave.s poleward. along the west coast of Central propagate· westward. as oceanic Ross by and North America. Observed Patiflc waves. As time .elapses and·· trapped, oceanic Rossbywavephase speeds,-frbni oceanic. Kelvin waves continue to Chelton and Schlax (1996), were selectetl propagate poleward and oceanic Rossby for use in this simulation (Fig. 9). Results waves are initiated at increasing!~ higher from this simulation; using these latitudes. component oceanic Kelvin and Rossby wave properties, are illustrated in Fig. 11; The phase delay in the initiation of These simulation results reveal critical pceanic Rossby waves at higher latitudes details regarding the organized oceanic contributes to the increasing lag of more Rossby wave crests observed in nature. poleward Rossby wave initiation.· Also, For example, a localized· minimum in: .the the phase speed of oceanic Rossby Westward propagation distance (between waves decreases rapidly with increasing - 15°N, 102-121 oW) clearly appears latitude at midlatitudes (Fig. 9). These between 100-250 days after Kelvin waves two factors result in. wave crests. and propagate poleward of soN latitude. This troughs that are ·approximately symmetric is primarily a result of the orientation ·of about , the equator, as previously the Central American. coastline. This discussed in terms of the positive SST coastal effect results in Rossby waves at: and SSH anomaly symmetry .in Figs. 4 higher lat.itude later time-steps to actually and 6. The associations presented in the exceed the westward longitudinal position previous section suggest the. potential achieved by previously initiated lower atmospheric .forcing effects that this latitude Rossby waves. This simulation oceanic Rossby wave crest-front may result is extremely useful in explaining have on · eastern Pacific organized TOPEX/POSEIDON positive SSH precipitation processes: In summary, this anomaly patterns off the west coast 'Of ocean-atmosphere interacti.on is linked by Centrai.America in Fig. 12. . : geographically focused boundary layer latent heat flux that is selectively forced by Oceanic Rossby wave crests identified in the structured, positive SST patterns TOPEX/POSEIDON data, between April as.sociated, with oceanic Ross by waves. 1994-February 1995 and December 1994- Could this selective enhancement of May 1996, were tracked from - 14 oN to
10 30 oN (Fig. 11). These two dominant wave remains regarding these simulation crests coincided in time, respectively, with results, in conjunction with our increasing the abnormally wet 1994-1996 winter empirical knowledge of ocean science via seasons experienced in the Western U.S. observational data from sources such as The mean, estimated oceanic Kelvin wave the TOPEX/POSEIDON project. . For phase speeds for the 94/95 winter case example, if the conceptual model was - 38.3 cm/s (over a 294 day period), . proposed here is realized in nature, what while for the 95/96 winter case, it was are the implications regarding estimated to be - 51.0 cm/s (over a 392 precipitation/storm track re-adjustment 2-6 day period). The combined, mean . years following the demise of a significant oceanic Kelvin phase speed for both El Nino event in the eastern Pacific (for cases was - 44.6 cm/s (within 12% of the example, in the 800-2400 day Rossby assumed Kelvin phase speed of 50 cm/s, crest solutions in Fig. 11 )? Without the selected for use in the Fig. 11 simulation oceanic Kelvin-Rossby wave conceptual result). The estimated phase speed rnodel component described above (Figs.· differences may possibly be attributed to 8 and 11 ), it is difficult to make concise a change of the initial phasing of the two analytic inferences regarding the origins of analyzed oceanic Kelvin/Rossby wave observed sea surface anomaly patterns, events (an - 13 cm/s difference in 1994- and potentially our west coast heavy 1996 freely propagating oceanic Kelvin winter precipitation patterns, too. wave phase speed would require substantial changes in ocean density VI Conclusion \ structure). Regardless of the specific ) reason for the differences, this raises Our understanding of large to local scale critical questions concerning the seasonal coupled ocean-atmosphere processes is positioning of dominant oceanic Rossby far from complete, but knowledg'e is wave crests. accumulating, for example, from studies such as those conducted by the Climate Did more southeastward positioning of Diagnostic Center to examine the role of estimated 94/95 winter season dominant air-sea interactions in climate and climate oceanic Rossby wave front (the 350-400 change. Results from one of these day Ross by crest solution in Fig. 11) result studies illustrate the significant upper in selective aiming of more preferential, level ocean (surface to 400 m) thermal heavy precipitation storm tracks into structure interannual to decadal variability southern California? Similarly, in the that is known to occur in the central North following 95/96 winter season, did a more Pacific (Fig. 13). Westward propagating northwestward positioned dominant oceanic Rossby waves, capable of oceanic Rossby wave crest (the 500-600 significantly altering thermal properties in day Rossby crest solution in Fig. 11) this slab of surface layer water, have now provide sufficient forcing to result in more been observed throughout much of the westward positioned, transient "pineapple world's oceans (Schlax and Chelton express" storm tracks to intersect the 1994). The slow propagation speeds of North American west coast further north, midlatitude oceanic Rossby waves, in toward Oregon and Washington (Figs. 2- conjunction with associated SST 3, and 8)? A multitude of other questions anomalies, and previously discussed
11 inferences concerning possjble resultant locking with atmospheric processes, may atmospheric responses., suggest that a significantly improve medium .. l_ong range significant, and difficult to. forecast forecasting accuracy of heavy seasonal r:etationship between oceanic west coast precipitation interception, For Kelvin/Rossby waves and. North American example, .the. mean .1996 Pacific SSH west coast weather patterns may exist anomaly ·pattern (Fig. 14) has evtdent This relationship may be . a critical correlation with placement of significantly component leading to unusual interannual above normal· Decemb.er . · 199.6 west coast weather patterns. However, precipitation (Fig: 15). Conversely, the .. results of this ana.lysis are not . drought forecasts for the west coas,t may conclusive, and do not constitute absolute alsa. be improved - by anticipating ,the proof of the hypothesized links between development of prolonged high pressure oceanic. Ross by waves and atmospheric ridging over. Washington, Oregon,,, :and proc.esses. California. This drought scenario may . . result as the SST patterns associated with From preliminary inspection, oceanic oceanic Rosby waves steerabove-norrnal Rossby wave forcing of the atmosphere precipitation into British Columbia ;;and appears unable to produce continuous Alaska (refer to Fig, 11 wave crestand ·storm track modification, either trough locations after 800 days).. Or, intraseasonally (time scales of 10-1 00 perhaps west coast scenarios sug.gestive days) or interannually. Other dominant, of below-normal precipitation may also be larger scale synoptic-h~mispheric sca:le correlated .. with cold SST patterns processes often diminish the signal level associated with oceanic Rossby wave .of oceanic Rossby . wave forcing troughs (Fig. 16). Fat example, Fig·,, 17 (Trenberth . 1997). However, . if the places below-normal precipitation over associative links, suggested in this yYashington and northern Oregon, aligned Technical Memorandum (ie., significant, along the upstream orientation of .a positive SST anomalies with geographical dominant oceanic Rossby wave trough in patterns organized by oceanic Fig. 16. ..: Kelvin/Rossby wave processes -:- · intersecting upstream trans-Pacific jet Regarding the consideration of oceanic stream tracks) reach a critical fee.dback Rossby waves .in west. coast dro.ught threshold, then it maybe possible to make forecasting, mid, Pacific model results. the following .inferences. 1 Meridionally imply oceanic Rossby waves. of low skewed.- crests and troughs of dominant latitude origin in association with El Nino · warm core, eastern Pacific oceanic events influence the .. .location of 'the Ross by waves nec:tr the west .coast of. the Kuroshio Exte_nsion between 35--40? eN United States, particularly following El (Jacobs et al. 1994). However, the ro.le of Nino events transitioning into La Nina larger . scale ocean-:-atrnosp.here episodes, may be highly correlated with processes -,..., such as the eastward the geographical distribution and intensity extension of a warm northerly Kuroshio of above normal, west coast winter return current- may be more important to precipitation (Fig·. 8). Thus, recognition of North. American west coast. forecasting; this ocean system process, occasionally The cumulative potential west coast resulting in transient resonant, phase- meteorological and hydrologic scenario
12 results · postulated in the previous operations take prolonged precedence, paragraph nonetheless suggest that and/or relevant analysis data availability is consideration of pronounced eastern temporarily limited. ·· Observing the Pacific oceanic Rossby wave activity may presence of dominant oceanic Rossby . be warranted. Organized oceanic Rossby waves may entail a consistent, periodic wave thermal forcing of the atmosphere analysis of remotely sensed eastern ·appears to be more of a microscale Pacific SST and SSH anomalies, in influence, but over a sufficiently large and conjunction with possibly. correlated consistent subregion. Repetitive tracking DMSP microwave precipitation and of storms following northward along the preferential GOESS-9 water vapor eastern U.S. are often linked to the moisture advection tracks from low to mid baroclinic zone established along the latitudes. Drifting buoy data is another coast, defined by contrasting cold source of supplementary, in situ SST continental air over run by warmer, moist anomaly observations to correlate with marine air masses advected over the Gulf SSH data. Stream (Carlson 1991). Although not energetically capable of producing similar This integrated approach is probably the extreme contrasts, eastern Pacific oceanic only presently available operational Rossby waves may be instrumental in technique to use in conceptually establishing a much weaker yet still identifying the potential occurrence of analogous baroclinic atmospheric tracking pronounced oceanic Ross by wave activity zone. Using this conceptual model, at the field office level. Because of forecasters may be more able to make oceanic Rossby wave process subtleties, large-scale process inferences in sparse development of a working conceptual . and/or remote data sets (Figs. 14-17). · model that incorporates key evolution and What other existing, coupled conceptual structure details will be necessary before models do forecasters presently use to predictive skills can be evolved (McGinley explain the patterns in Figs. 14 - 17? 1986). Keeping in mind the billions of dollars in west coast flood damage between 1994- TOPEX/POSEIDON altimeter data 1996, it seems prudent to consider the capable ·of resolving oceanic potential association/s proposed in the Kelvin/Rossby waves has only been multifaceted conceptual model introduced available since October 1992 (Fu et al. above? 1994). This initial date of TOPEX/ POSEIDON data availability occurred in If this conceptual model is considered a the midst of the last prolonged El Nino potential mechanism to partially explain episode, extending over a 5 year period variations in heavy west coast between 1990-1994 (Halpert et al. 1995). precipitation patterns, how do we As a result, we still have much to learn systematically make the necessary about what this new type of data can tell associations suggested in this Technical us regarding ocean-atmosphere Memorandum? Slow oceanic Rossby interactions, both preceding and following wave propagation speeds (on the order of El Nino episodes. Many questions remain 10 cm/s) facilitate interrupted analysis and to be answered regarding the relevancy of tracking, for example, when other this forecast problem. For example, are
13 oceanic Kelvin/Rossby waves previously detected systematic satellite deterministic? Do the .effects of zonal observation data errors, that remote atmospheric Walker circulations oyer the sensing of subtle but critical ocean ·Pacific play a more critical role thai') atmosphere interactions will require oceanic Rosspy and . Kelvin waves in ground-truth calibration with, for example, selectively altering SSTs (Liu ·1997)? Yet, long term in situ buoy data. as Trenberth (1997) suggests, a key step in predicting interannual ENSO cycle VII Acknowledgments . onset and evolution entails antecedent identification of hoW oceanic Kelvin and Vital support inclUded numerous data sets Hossby waves redistribute warm, tropical made available via the Internet by: 1) the water, in concert with atmospheric wind Jet Propulsion La·botatory's forCing. TOPEX/POSEIDON Global Ocean"' Monitoring Mission;1 2) the NOAA/ERL Answers . to the plethora of rema1mng Climate Diagnostics Center (CDC);2 3) as questions will be discovered as we well as the U.S. Departmeht of cumulatively increase our understanding Commerce; NOAA; Climate Prediction over the full range of significant ocean Center (CPC); 3 and 4) the NOAA atmosphere feed..,back mechanisms Laboratory for Satellite Altimetry. The occurring across the Pacific Ocean, as CPC Internet posting of Halpert·· et al. well as over the global scale ocean (1996)4 proved to be extremely valuable atmosphere, system. Hopefully, · the throughout this project. Mr. Charles analysis discussed in this Technical Orwig, a NWS Northwest River Forecast Memorandum demonstrates that our Center (NWRFC) Senior Hydrologist, understanding of nonclassic., North provided much appreciated American west coast applied meteorology encouragement throughout this research can be advanced significantly via effort, and contributed to the final review forecaster's conceptual recognition, and and editing of this manuscript. Special reporting of potentially significant, thanks to Steven M. Taylor, frohi the U.S. coupled, upstream-offshore.·. feedback Naval Postgraduate School, for generating processes. Conversely, it is clear that the May 1996 Pacific Ocean surface identification. of these complex. earth system prd.cesses will necessitate an interdisciplinaryapproach, both in terms,of 1 At http://topex-www.jpl.nasa.gOv/ professional training (Mass 1996), and operational interaction. This type of 2 At approf]ch to improving North American http://www .cdc.noaa. gov: 8 0/~map/maprobm west coast forecasting will accelerate the /text/climat_produtts.shtml conceptual intersection, of valuable functional knowledge in, but by nomeans 3 At limited to, oceanography, geodetic and http://WJ:cc.sage. dri. edu/recent_climate.htmi: · thermographic remote sensing, terrestrial hydrologic implications, as well as the 4 At atmospheric sciences. However; in this http://nic.fb4.noaa.gov: 80/products/assessme endeavor, .it is also evident, from nts/assess 95
14 current plot. Regards to Ryan Smith, from VIII References NOAA's Global Drifter Center,5 for providing selected Pacific drifting buoy Anderson, D.L.T., K.Bryan, A.E. Gill, and data plots; and to Bob Cheney, Chief of C. Pacanowski, 1979: The Transient NOAA's Geosciences Laboratory Satellite Re.sponse of the North Atlantic: Some and Ocean Dynamics Branch, 6 for Model Studies. J. Geophys. Res., 84, answering numerous questions regarding 4795-4815. oceanic Rossby waves. The GMS image of Typhoon Bart was made available by Anderson, D.L.T., and A.E. Gill, 1975: Taikan Oki, from the Institute of Industrial Spin-up of a stratified ocean, with Science, University of Tokyo, Japan. The applications to upwelling. Deep-Sea author is grateful to the numerous other Res., 22, 583-595. unnamed individuals who contributed to this analysis (primarily via the Internet). Barnett, T.P., L. Latif, E. Kirk, and E. Critical feedback regarding this research Roeckner, 1991: On ENSO Physics. J. was obtained at the February 1997 Pacific Clim., 4, 487-515. Northwest Weather Workshop, and the August 1997 First Pacific Rim Battisti, D.S., and E.S. Sarachik, 1995: Hydroclimate Workshop; support essential Understanding and predicting ENSO. to attend these workshops was made Rev. Geophys., 33 (suppl.), 1367- possible by the efforts of Dr. Thomas 1376. Potter, Director, NWS Western Region Headquarters, Donald Laurine, NWRFC Bocheng L., and Q. Liao, 1988: The Developmental and Operations Variations in Current System[s] in the· Hydrologist, and Andy Edman, Scientific Western Tropical Pacific and Its Services Division, NWS Western Region Relations[hip] to the Wind Field. Headquarters. Invaluable reference Proceedings of US-PRC International materials supporting this research were TOGA Symposium, Beijing, China, 33- obtained from the NCAR Foothills 39. Laboratory Library, Boulder, Colorado, and the NOAA Central Library, Silver Carlson, T.N., 1991: Mid-Latitude Spring, Maryland (email Weather Systems. HarperCollins [email protected]). Academic, 507 pp.
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5 At Chen T-C., J-M. Chen, and C.K. Wikle, http://www.aoml.noaa. gov/phod/ dac/ dacdata 1996: lnterdecadal Variation in U.S. .html Pacific Coast Precipitation over the Past Four Decades. Bull. Amer. 6 At Meteor. Soc., 77 (6), 1197-1205. http://ibis. grdl.~oaa. gov/SAT /SAT .html
15 Dayong J., Y. Meiyu, and Min wei, 1988: Heburn, G.W., and R.C. Rhodes,:;1987: A GCM Study on the Response of the Numerical simulations of wind forced •Atmosphere :Surface Wind Fields tb seasonal and interannual variability'of Tropical SST Anomalies. Proceedings the transport through the Caribbean , of US-PRC International TOGA . Sea. Trans. Amer. Geophys: ·Union; . ·Symposium, Beijing, China, 433·A39. 68; 337 pp . 1,,1 Dorman, C.E., 1985: Evidence of Kelvin Hendon, H.H., and M.L Salby, 1996: Waves in California's Marine Layer Planetary-Scale Circulations Forced by and. Related Eddy .Generation .. M. lntraseasonal Variations of Obseri!ed · Weather Rev., 113 (5), 73-85. Convection, J. Afmos. Sci., 53, 1751- 1758: '' FuL-L., E.J. Christensen, C.A. Yamarone '>I •' Jr., M. Lefebvre, Y. Menard, M. Dorrer, Hobbs, P.V;·, J.D. Locatelli, and J.E. and P. ,.. Esc u die. r; · 1 ·9 9 4: Martin, 1996: A New Conceptual TOPEX/POSEIDON rnission overview. Model for Cyclones Generated in the J. Geophys. Res., 99, 24369-24381. Lee of the Rocky · Mountains. · Bull. l.:, Amer. Meteor. Soc., 77 (6), 1169-.-'' Fu L--L., and R.E. . Cheny, 1996: 1178. ' '' Application of satellite altimetry to ocean circulation studies: 1987--1994. Hogan T. F., and T.E. Rosmohd,' 1991: Rev. Geophys., 77 (suppl.), 213-223. The Description of the • Navy Operational Atmospheric PrediCtion· Fu L-L.·, and R.D. Smith, •1996: Global · System's Spectral F'orecast Mo'del. . , ...... I ·· Ocean Circulation from Satellite Mon. Wea. Rev., 119, 1786-1815. · Altimetry and High'-Resolution . \.. ~ '• ·.~ ' ' ' '' ' ' ' •. ··c' r Computer Simulation. Bull.· Ainer. Huyer, A., 1980: The offshore structt,.Jre · Meteor. So.c., 77 (11), 2625-2636. and subsurface expression of' sea level variations off Peru, 1976-1977. J. Halpert, M.S., G. D. Bell, V.E. Kousky, and · Phys. bceanogr;, 1_0, 1755-1768. C.F. Ropelewski, 1996: Climate Assessmeflt for 1995, Bull. Amer. Meteor. lngmanson, D.E., W.J. Wallace, 1979: Soc., 77 (5), S1-S44. Oceanography: An· 1htroduCtioh: Wadsworth Pub. Co., 357 pp. Hansen, D.V., 1988: Surface Current and Temp·erature. Patterns in the Western Jacobs, G.A. et al., 1994: Decade-scale Tropical Pacific. Proceedings of US · trans-Pacific propagation and warming PRC International TOGA Symposium, effects of an ELNino anomaly. Nature, Beijing, China, 121-127. 370, 360-370.
Johnson, S.J., and Coauthors, 19m~: Irregular glacial interstadials recorded in a new Greenland ice core. Nature, 359, 311-312.
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Liu, Z., 1996: Oceanic Regulation of the Parke, M.E., D.L. Stewart, D.L. Farless, Atmospheric Walker Circulation. Bull. and D.E. Cartwright, 1987: On the Amer. Meteor. Soc., 78 (3), 407-411. Choice of Orbits for an Altimetric Satellite to Study Ocean Circulation Mass, C.F., 1996: Are We Graduating and Tides. J. Geophys. Res., 92, Too Many Atmospheric Scientists?, 11693-11707. Bull. Amer. Meteor. Soc., 77 (6), 1255- 1267. Pedlosky, J., 1979: Geophysical Fluid Dynamics. Springer-Verlag, 624 pp. McGinley, J., 1986: Nowcasting Mesoscale Phenomena. Mesoscale Qiu, B., 1995: Variability and energetics of Meteorology and Forecasting, Edited the Kuroshio Extension and its by Ray, P.S., American Meteorological recirculation gyre from the first two Society, 793 pp. yearTOPEX data. J. Phys. Oceanogr., 25, 1827-1842. Min wei, and J. Dayong, 1988: The Characteristics of Solar Radiation and Schlax, M.G., and D.B. Chelton, 1994: Energy Fluxes over the Western Aliased tidal errors in Pacific Ocean: Observations of US TOPEX/POSEIDON sea surface PRC Cruises 2 and 4. ·Proceedings of height data, J. Geophys. Res., 99, US-PRC International TOGA 24761-24775. Symposium, Beijing, China, 237-250. Smith, R.L., 1978: Poleward propagating Neelin, J.D., M. Latif., and F.-F. Jin, 1994: perturbations in currents and sea Dynamics of Coupled Ocean levels along the Peru coast. J. Phys. Atmosphere Models: The Tropical Oceanogr., 83, 6083-6092. Problem, Rev. Fluid Mech., 26, 617- 659. Stewart, R.H., 1985: Methods of Satellite Oceanography. University of California Nuss, W., 1988: Boundary Layer Press, 360 pp. · Interaction in Oceanic Midlatitude Cyclones. The 7th Cont. On Ocean Stull, R.B., 1988: An Introduction to Atmos. Interaction, Anaheim, CA., Boundary Layer Meteorology. Kluwer Amer. Meteor. Soc., 216-217. Academic Publishers, 666 pp.
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17 Fig. 1. GMS image of Typhoon Bart recurving northeastward off the northeast coast of Luzon on May 15, 1996, with upper level storm outflow entraining into the mid-latitude westerlies (image courtesy of the Institute of Industrial Science, University of Tokyo, Japan). PEA:: EHT •JF ti:U=tf~·~ L PRECIPITI!I.TICJN 1994/199:5 L.mVet Season Cbko-.be·r ·i994 - ..4prif 1995
( I I "'-__)
Fig. 2. Concentration of 200% above normal Winter 1994-95 wet season precipitation anomalies focused over southern coastal California (from Halpert et al. 1996). r~ ( \
50N
45N -- ·
J5N -··················-·····""······
-.200 -150 -1.00 -75 -.50 -25 2.5 50 7.5 100 150 200
Fig. 3. November-December Winter 1995 ~ 100 mm precipitation anomalies over Northwestern Oregon and Western Washington, using departures from 1961-90 base period means (from Halpert et al. 1996). f!....1ARCH-MAY SEPTEMBER-NOVEMBER 1995 1995
-5 -<'I -J -2 -'I - I\.>1ARCH-MAY SEPTEMBER~NOVEMBER 1995 1995 1961-90 BASED PRECIPITATION PERCENTILES Fig. 4. Composite northern hemisphere SST and precipitation anomalies positionally correlated, and indicating the presence of a Spring-Fall 1995 west-northwest shifting positive anomaly structure in the eastern Pacific (from Halpert et ai. 1996). 9SOS2S/OOOO~OOO OCEAN CURRENTS KTS Fig. 5. The United States Navy Fleet Numerical Oceanographic Center (FNOC) has oceanographic programs dependent on the Navy Operational Global Atmospheric Prediction System (NOGAPS), and one of these programs provides ocean current predictions (Hogan and A osmond 1991; Heburn and Rhodes 1987). The plot displayed above is a NOGAPS surface Pacific Ocean currents analysis for May 1996 (courtesy of Steven M. Taylor, from the U.S. Naval Postgraduate School, Monterey, California). ( '~·· 96 I 04 I 22 cycle 132.33 -180 1 80 90 t .;. : r: - r ";_ .... , r~r~•T,; :, "i·''.'1} -~- ·. : ':"','f~;:;:::_._ --~·1'r '•_,1T :, !Yi,ij :~:·,;;,~,·~ ~~T···-: .. :' ~:·: ~ >':f ,t " ~~' '5' ':' '' ·::.;.r '" " :·: :•r-~: :;.~:·-~ r; ·,· 5 •• - ''., -.::;:;:;::t.:;; ,, ,, i:·,"'~C . '. It- - '-""'; :, :·:rJ:'·! ·. . ,' .·,·~: ",'' ., . ,:. :- -~,., •.. '.- ' I 90 -9olllllll•~ Sea surface variability Centimeters Fig. 6. Ten days of consecutive TOPEX/POSEIDON data are used to generate each of the sea surface height anomaly images included in this paper (images originally produced at the Jet Propulsion Laboratory (JRL) in Pasadena, California using software codeveloped with the University of Colorado, Boulder). Time shown at the top of this image, in a ''yy/mm/dd" format, represents the "center-time" of a 10 day observation blend periods. The center time of this image was April 22, 1996. The dominant, positive eastern Pacific SSH anomalies have axial symmetry similar to positive SST anomalies in Fig. 4. This symmetry reelected across the equator results from the intersection of individual dominant oceanic Rossby waves along an organized Rossby wave front. ( -- --- Fig. 7. TOPEX/POSEIDON satellite and orbit placement (originally a JPL image, modified to incorporate subsidiary information regarding functionality of the satellite). COn...... _."" ., FORCa:/ ...... ~ ___ " ______-~ Fig. 8. Proposed conceptual model. Several details are exaggerated to separate features for illustrative clarity. For example, oceanic Kelvin waves actually slope directly away from the west coast in a non-gausian manner. There is also more of a continuous transfer process than illustrated, as Kelvin waves dissipate offshore and transition directly to oceanic Rossby waves. Observed Oceanic Pacific RossbyWave Phase Speed, from Chelton and Schlax {1996) 50 45 40 35 15 10 5 0+------~------~------~------rl 8 10 14 32 50 Latitude (deg N) Fig. 9. Observed northern hemisphere Pacific oceanic Rossby wave phase speeds (cm/s), from Chelton and Schlax (1996). · 1ao 90W 9QE 180 EQ EQ -2 I 5 -2 -1.5 -1 -0.5 0 0D 5 1.5 2 2.5 Fig. 10. December 1995 mean tropospheric temperature anomalies. Positive temperature anomalies, derived from microwave sounding data, occur along a track similar to eastern Pacific oceanic Rossby wave fronts (from Halpert et al. 1996; original data contributed by the University of Alabama at Huntsville). ---·------··- ( ( \. \ -~) ~ .. ' MODELED NE PACIFIC OCEANIC ROSSBY WAVE PROGRESSION I I L~- I 4. 31 I I I I II I I I I . I I I I I I I 4= F ... J >ii TRAVEL 60. ~-· .4-< I I I I I I _.-r:L I I I i I I 1---t-- TIME w i:n--1 I I I I I I I I I ··-·1 --± I (IN DAYS) c '---7YEARS ::» 2400 2:200-- 6 YEARS t: 2000 1- · 1800--5 YEARS 1600 :s 40. 140o--4 YEARS :z: ~1200 1000--3 YEARS ~ 800--2 YEARS g ···\1:~ 400 350-- 1 YEAR Ia 20& 300 250 ~ 2()0 150-- .5 YEARS w 100 0" 50 25 0. 0 I 0 I -180.00 -160.00 -140.00 -120.00 -100.00 -80.00 DEGREES WEST LONGITUDE .. ______----~-· ·-·-·······--··------~------···----·------...---·------·------__ . _ · SIMULAnON =50.0 cm/s ~-~~YIN_ SET .. up SPEEDS: 94195 & 95196 MEAN OBSVD =44.6 cml~- ..94195 (294 days) ~ 38.3 cmls t · ... - ·----...... ·- ..··-·------.. ------··.,_95196 (392 days).,...._-~ - · Fig. 11. Oceanic Rossby/Kelvin wave propagation simulation results. -180 90~------ -90 -180 Sea surface variability -6 -3 0 Centimeters Fig. 12. Relative Pacific Ocean Rossby wave front speed minima off the coast of Central America evident in TOPEX/POSEIDON February 2, 1995 data (provided by JPL). (~ ~~) "'- '<'r ,Ip , 1 il r il i II :'ir r!; !>'.; j: J.·. '[: i;.f j'!:C'IIPII! ll,·•;~l:'i';[ ,! 1! ,!i ,·, !! ) I, IJ I : l ' l\~1 !, .!\ H t ·l: I,, I'' i 1 li J L \'1 r JY,, ,U Fig. 13. Upper ocean (suriace a 400 m) interannualadecadal SST anomaly variability observed in the eastern Pacific between 30N-42N, 176W-144W (courtesy of the National Climatic Data Center (NCDC)). T1P Sea Level Anotnaly )7 ear 96 -S -·7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 S 6 1 S H(em) Fig. 14. Mean SSH anomalies for 1996 indicating presence of organized oceanic Rossby wave fronts across the Pacific in the northern and southern hemispheres (provided by the NOAA laboratory for Satellite Altimetry). Percent ofNormal Precipitation, December, 1996 \ Percent ofNa:nnl Pred.pitaticn 100 150 200 250 300 350 400 Fig. 15. December 1996 winter west coast precipitation anomalies, with significant coincidence of oceanic Rossby wave front alignment in fig. 14 to the > 300 precent above normal precipitation track reaching into southwestern Montana (courtesy of NCDC). (\ I ' -90 -180 Sea surface variability -6 -3 0 3 Centiineters Fig. 16. 10 day mean TOPEX/POSEIDON SSH anomalies centered around January 15, 1993, during the 1992-93 winter season, with relative oceanic Rossby wave front trough evident in the eastern Pacific (image provided by JPL). ,, (' "! 0 /) / PRECIPITATION ANOMALIES (MM) BASE PERIOD 1951-1980 90N~------, B5N ~~-~·.D.--·-;-·~- 6~ ~~0-·~·-,·· 75111 ~;...oCJ- ~ t:;::7. ....--~ 7(:fr.l ~~ ~ BON {-!·· ..ifP- 551'11 -~ " ~ ~ } ' ~ ~ . !SCf.l 45111 4(:fr.l ::S5N :50N 251'11 2Cf.IJ- ~~· 0 Gr-ADS: COLA/LJ!oR::P wTmER 1992 Fig. 17. Winter 1992-93 precipitation anomalies, with generally below normal precipitation indicated over a majority of the Pacific Northwest (provided by NCDC). ,, (j \~ /) \, DRIFTER DATA ASSElvlBLY CENTER ···~ •.~,, t-~ r· ·-~ --~· !, DEC 30,1996 J\ A • b. !~. t/'~·\A A A A .• ~ F. ' ~ .... .~··II &, • •' # A ~ ' ' ' ,., • • • tt'. . .A., ·~,- .~•..,. At ' ..... , ""· 11. A,7.'. ,olllllo a- . 1:1,: 1. - ... '!'l'· A At\ 6 .... ~' A c/A •. • t ib. . -IIJ'-.l. I l\ .A" l:\ ,,.., {~. ~ -~- .6. 15(})~ 15 ·~~~ ~-- I ~·. C'~ • .. ·-- ••. ~--: J"t",·,.. . l ~. ---- , .... ,.. ·r· ·-i·!•/ :\-.--- '',1""':,{ .• ·.·_.•·' ~·. 1 -,.'·-·t·:'l'),.,.,&- .--J . r:;UL l- ~--....' '·-' ~~- _1/'\!·'--t;~l. L-!' ·.• •··· i· ~~-- · • ~I ==:] 1-;.. -3.0 L5 .3.0 ::~~ i -l.5 -0.5 0.5 c, f \' ~:·! •. l:i ·-· :-. .: .,· ';' __ ••• .:; ; .;: j •• :: :, ll h-..~.· .. l~~~:: (Ui··J ;.::'L .. UJ) -~---!' i Ui{)!X-::~> :·::• :: .. Fig. 18. December 30, 1996 SST anomaly data (courtesy of NOAA's Drifter [Buoy] Data Assembly Center). A sub-region of eastern Pacific 1.5 to 3.0 C SST anomalies is highlighted in yellow. ( go"N~~._~_.~~--._~~~~._~-+~~--~~_.~~--~~_.~~~~ so"N 30°N o" so"s 60°S 90 ° s ' I I I I I I I I I I I I I I I 1-- I I I I :; I I I I I I I I I I I I I I I 00 60°E 120°E 180° 120°"Vf 60aW oa SST 9/22/96-12/28/96 ·-- " -~ •r?Cl=!r~c--:Jc~--Jr-~--1~~---~r 1' --:r - J 2. 4. 6. a. 10. 12. 14. 16. 18. 20. 22. 24. 26. 2a. 20. 30. Fig. 19. Satellite derived SST anomaly satellite data for the period of September 22-28, 1996 (courtesy of NCDC). Inferred eastern Pacific oceanic Rossby wave fronts, north and south of the equator, along the dashed white lines. Stability. ·Jonathan W. Corey, Aprit1979. (P8298899/AS) . . . Roger L. Cross and Kenneth B. Mielke, September 1987. (PB88110895/AS) 201 An Inexpensive Solution for the Mass Distribution of Satellite Images. Glen W. 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(PB81 106494) 212 Preltminary Analysis of the San Francisco Rainfall Record: 1849-1990. Jan Null, May 19~ 156 The Effects of Terrain Distribution on Summer Thunderstorm Activity at Reno, Nevada. Christopher (PB91-208439) Dean Hill, July 1980. {P881 102501) 213 Idaho Zone Preformat. Temperature Guidance, and Verification. Mark A. Mollner, July 19' 157 An Operattonal Evaluation of the Scofteld/Oiiver Techntque for Estimating Precipitation Rates from (PB91-227405/AS) Satellite Imagery. Richard Ochoa, August 1980. (PB81 1 08227) 214 Emergency Operational Meteorological Considerations During an Accidental Release of Hazardo 158 Hydrology Practicum. Thomas Dielrtch, September 1980. (P881 134033) Chemicals. Peter Mueller and Jerry Galt, August 1991. (PB91-235424) 159 Troptcal Cyclone Effects on Califomta Arnold Court, October 1980. (P881 133779) 215 WeatherTools. Tom Egger, October 1991. (PB93-1B4950) 160 Eastern North Pacific Tropical Cyclone Occurrences Dunng lntraseasonal Periods. Preston W. 216 Creating MOS Equattons for RAWS Stations Using Digital Model Data. Dennis D. Gettm< Leftwich and Gait M. Brown, February 1981. (P881 205494) December 1991. (PB92-131473/AS) 161 Solar Radiation as a Sole Source of Energy for Photovoltatcs in Las Vegas, Nevada, for July and 217 Forecasting Heavy Snow Eve11ts in M1ssoula, Montana. Mike Richmond, May 19~ December. Darryl Randerson, April1981. (P881 224503) (PB92-196104) 162 A Systems Approach to Real-Time Runoff Analysis with a Determintstic Rainfall-Runoff Model. 216 NWS Winter Weather Workshop in Portland, Oregon. Venous Authors, Decamber 195 Robert J.C. Bumash and R. Larry Ferra!, Apri11981. (PB81 224495) (PB93-146785) 163 A Comparison ofTwo Methods for Forecasting Thunderstorms at Luke Air Force Base, Arizona. LTC 219 A Case Study of the Operational Usefulness of the Sharp Workstation in Forecasting Keith R. Cooley, April1981. (P881 225393) Mesocyclone-lnduced Cold SectorTomado Event in Caldomia John P. Monteverdi, 'March 1St 164 An Objective Aid for Forecasting Afternoon Relative Humidrty Along the Washington Cascade East (P893-176697) Slopes. RobertS. Robinson. Apri11981. (PB81 23078) 220 Climate of Pendleton, Oregon. Claudia Bell, August 1993. {PB93-227536) 165 Annual Data andVerdication TabulatiOn, Eastern North Pacific Tropical Storms and Hurricanes1980. 221 Utilization of the Bulk Richardson Number, Helicity and Sounding Modification in the Assessme Emil B. Gunther and Staff, May 1981. (P882 230336) of the Severe Convecttve Storms of 3 August 1992. Eric C. Evenson, September 19~ 166 Preliminary Estimates of Wind Power Potential at the Nevada Test Site. Howard G. Booth, June {PB94-131943) 1981. (P882 127036) 222 Convective and Rotational Parameters Associated wijh Three Tornado Episodes in Northern ac 167 ARAP Use(s Guide. Mark Mathewson, July 1981, Revised September 1981. (P882 196783) Central California. John P. Monteverdi and John Ouadros. September 1993. (PB94-131943) 168 Forecasting the Onset of Coastal Gales Off Washington-Oregon. John R. Zimmerman and William 223 Climate of San Luis Obispo, California. Gary Ryan, February 1994. (PB94-162062) D. Burton, August 1981. (P882127051) 224 Climate of Wenatchee, Washington. Michael W. McFarland, Roger G. Buckman, and Gregory· 169 A Statistical-Dynamical Model for Prediction ofTropical Cyclone Motion in the Eastern North Pacific Matzen, March 1994. (PB94-164308) Ocaan. Preston W. Leftwich, Jr.. October 1981. (P882195298) 225 Climate of Santa Barbara, California. Gary Ryan. December 1994. (PB95-173720) 170 An Enhanced Plotter for Surface Airways Observations. Andrew J. Spry and J~rey L. Anderson, 226 Climate of Yakima, Wiashington. Greg DeVoir, David Hogan, and Jay Neher, Decamber 199 October 1981 .. {P882 153883) (PB95-173688) 171 Verification of 72-Hour 500-MB Map.Type Predictions. R.F. Quiring, November 1981. 227 Climate of Kalispell, Montana. Chris Maier, December 1994. (P895-169488) (PB82-158098) 228 Forecasting Minimum Temperatures in the Santa Maria Agricultural Distnct. Wi~red Pi and Pet• 172 Forecasting Heavy· Snow at Wenatchee, Washington. James W. Holcomb, December 1981. Fetsch, December 1994. (P895-171088) (P882-177783) 229 The 10 February 1994 Oroville Tornado-A Case Study. Mike Staudenmaier, Jr., April 199 173 Central San Joaquin Valley Type Maps. Thomas R. Crossan, December 1981. (PB82196064) (PB95-241873) 174 ARAP Test ResuHs. Mark A. Mathewson. December 1981. (PB82 198103) 230 Santa Ana Winds and the Fire Outbreak of Fall1993. Ivory Small, June 1995. (PB95-241865) 176 Approximations to the Peak Surface Wind Gusts from Desert Thunderstorms. Darryl Randerson, 231 Washington State Tornadoes. Treste l;iuse. July 1995. (PBSS-107024) June 1982. (PB82 253089) . 232 Fog Climatology at Spokane. Washington. Paul Frisbie. July 1995. (PB96-106604) 177 Climate of Phoenix, Arizona. Robert J. Schmidli and Austin Jamison. April1969 (Revised July 1996). 233 Storm Relattve Isentropic Motion Associated with Cold Fronts in Northern Utah. Kevin B. Bake (PB96-191614) Kathleen A. Hadley. and Lawrance B. Dunn, July 1995. {PB96-106596) 178 Annual Data and Verdication Tabulation, Eastern North Pacific Tropical Storms and Hurricanes1962. 234 Some Climatological and Synoptic Aspects of Severe Wieather Development in the Northwestec E. B. Gunther, June 1983. (PB65106078) United States. Eric C. Evenson and Robert H. Johns. October 1995. (PB96-112958) 179 Stratified Maximum Temperature Relationships Between Sixteen Zone Stations in Arizona and 235 Climate of Las Vegas, Nevada. Paul H. Skrbac and Scott Cordero, December 199 Respective Key Stations. Ira S. Brenner, June 1963. (PB83 249904) (PB96-135553) 180 Standard Hydrologic Exchange Format (SHEF) Version I. Phillip A. Pasteris, Vernon C. Bisset, David 236 Climate of Astoria, Oregon. Mark A. Mcinerney. January 1996. G. Bennett. August 1983. (PB85106052) 237 The 6 July 1995 Severe Weather Events in the Northwestern Unrted States: Recent Examples ' 181 Quantitative and Spacial Distribution of Winter Precipijation along Utah's Wasatch Front. Lawrence SSWEs. Eric C. Evenson. April1996. B. Dunn, Augusi1983. (PB85 106912) 238 Signiftcant Wieather Patterns Affecting West Central Montana. Joe Lester. May 199E 182 500 Millibar Sign Frequency Teleconnection Charts -Winter. Lawrence B. Dunn, December 1983. (PB96-178751) (PB85 106276) 239 Chmate of Portland, Oregon. Cltnton C. D. Rockey, May 1996. (PB96-17603) 183 500 Millibar Sign Frequency Teleconnection Charts- Spring. Lawrence B. Dunn, January 1984. 240 Downslop Winds of Santa Barbara. CA. Gary Ryan, July 1996. (P896-191697) (PB85111367) 241 Operational Appltcations of the Real-ttme Nattonal Ltghtntng Detectton Network Data at the NWSC 184 Collectton and Use of Lightning Strike Data in the Western U.S. During Summer 1983. Glenn Rasch Tucson, ./>Z.. Darren McCollum, Davtd Bnght. Jtm Meyer. and John Glueck, September 199- and Mark Mathewson, February 1984. (PB85110534) (PB97-108450) 185 500 Millibar Sign Frequency Teleconnection Charts- Summer. Lawrence B. Dunn, March 1984. 242 Climate of Pocatello, Idaho. Joe Hetm. October 1996. (PB97-114540) (PB65111359) 243 Climate of Great Falls. Montana. Matt Jackson and D. C. Wilhamson, December 1996. (PB97 186 Annual Data and Verdication Tabulation eastern North Pacific Troptcal Storms and Hurricanes1983. 128694) E.B. Gunther, March 1984. (PB85 109635) 244 WSR-88D VAD Wind Proftle Data Influenced by B~d Mtgratton over the Southwest United States 187 500 Millibar Sign Frequency Teleconnection Charts - Fall. Lawrence B. Dunn, May 1984. Jesus A. Hare. January 1997. (PB97-135263) (PB85-110930) 245 Climatology of Cape for 'eastern Montana and Northam Wyomtng. Heath Hockenberry and Kett 188 The Use and Interpretation of lsentroptc Analyses. Jeffrey L. Anderson, October 1994. Meter. January 1997. (PB97-133425) (P885-132694) 246 A Western Region Guide to the Eta-29 Model. Mtke Staudenmaier, Jr.. Marcli 1997. (PB97 l, 189 Annual Data & Verdicatton Tabulatton Eastern North Pacdic Tropical Storms and Hurricanes 1984. 144075) . E.B. Gunther and R.L. Cross, April1985. (PB85 1878887AS) 247 The Northeast Nevada Climate Book. Edwin C. Clark. March 1997. (First Revision- January 199. 190 Great Salt Lake Effect Snowfall: Some Notes and An Example. David M. Carpenter, October 1965. -AndrewS. Gorelow and Edwin C. Clark - PB98-123250) (PB86 119153/AS) 248 Climate of Eugene. Oregon. Cltnton C. D. Rockey, April1997. (PB97-155303) 191 Large Scale Patterns Associated wrth Major Freeze Episodes in the Agrtcultural Southwest. Ronald 249 Climate ofTucson, AriZona. John R. Glueck, October 1997. S. Hamilton and. Glenn R. Lussky, December 1985. {PB86 144474AS) 250 Northwest Oregon Daily Extremes and Normans Cltnton C. D. Rockey, October 1997. 192 NWR Votce Synthesis Project: Phase I. Glen W. Sampson. January 1966. (PB86 145604/AS) 251 A Composite Study Examintng Five Heavy Snowfall Patterns for South-Central Montana. Jonathac 193 The MCC -An Overvtew and Case Study on Its Impact in the Western United States. Glenn R. D. VanAusdall and Thomas W. Humphrey. February 1998. (P898-125255) Lussky, MariCh 1986. {PB86 170651/AS) 252 Climate of Eureka, California. Alan H. Puffer. February 1998. (P898-130735) 194 Annual Data and Verdtcatton Tabulation Eastern North Pacific Tropical Storms and Hurricanes 1985. E.B. Gunther and R.L. Cross. March 1986. (PB86 170941/AS) 195 Radtd lnterpretatton Guidelines. Roger G. Pappas. March 1986. (PB86177680/AS) 196 A Mesoscale Convecttve Complex Type Storm over the Desert Southwest. Darryl Randerson, April 1986. {PB86 19099B/AS) 197 The Effects of Eastern North Pacific Tropical Cyclones on the Southwestern United States. Walter Smijh, August 1966. (PB87 106258AS) 198 Preliminary Lightntng Climatology Studies for Idaho. Christopher D. Hill, Carl J. Gorski, and Mtchael C. Conger, April1987. (PB87 180196/AS) 199 Heavy Rains and Flooding tn Montana: A Case for Slantwise Convection. Glenn R. Lussky, April 1987. (PB87 185229/AS) ' ~"" /200 Annual Data and Vemication Tabulation Eastern North Pacific Tropical Storms and Hurricanes 1986. NOAA SCIENTIFIC AND TECHNICAL PUBLICATIONS The National Oceanic and Atmospheric Administration was established as part of the Department of Commerce on October 3, 1970. The mission responsibilities of NOAA are to assess the socioeconomic impact of natural and technological changes in the environment and to monitor and predict the state of the solid Earth, the oceans and their living resources, the atmosphere, and the space environment of the Earth. The major components of NOAA regularly produce various types of scientific and technical information in the following kinds of publications. 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