Predicting and Validating the Tracking of a Volcanic Ash Cloud during the 2006 Eruption of Mt. Augustine Volcano

BY P. W. WEBLEY, D. ATKINSON, R. L. COLLINS, K. DEAN, J. FOCHESATTO, K. SASSEN, C. F. CAHILL, A. PRATA, C.J. FLYNN, AND K. MIZUTANI

FIG. I. Map of Alaska showing key locations. (Map background courtesy of Google Earth.) (a) State of Alaska and (b) the Cook Inlet region. Places named include: Barrow (7I°I8'N, I56°47'W), Fairbanks (64°5I'N, I47°43'W), Chatanika (65°7'N, I47°28'W), Anchorage (6I°I3*N, I49°54'W), Kodiak City (57°47'N, I52°24,W), Augus- AFFILIATIONS: WEBLEY—Arctic Region Super Computing tine Volcano (59°22'N, I53°26'W), Redoubt Volcano Center, Geophysical Institute, and Alaska Volcano Observatory, (60°29'N, 152°44'W), Homer (59°39'N, I5I°33'W), Cook University of Alaska Fairbanks, Fairbanks, Alaska; ATKINSON— Inlet, Prince William Sound, and the Kenai Peninsula. International Arctic Research Center, University of Alaska Fairbanks, Fairbanks, Alaska; COLLINS, FOCHESATTO, SASSEN, AND CAHILL—Geophysical Institute, University of Alaska Fairbanks, n 11 January 2006, Mt. Augustine (59.36°N, Fairbanks, Alaska; DEAN—Geophysical Institute, and Alaska 153.43°W) Volcano in southern Alaska (Fig. 1) Volcano Observatory, University of Alaska Fairbanks, Fairbanks, 0 began erupting after a 20-year repose. There Alaska; PRATA—Norwegian Institute for Air Research, Kjeller, Norway; FLYNN—Pacific Northwest National Laboratory, Rich- were 13 explosive eruptions in 20 days, with a period mond, Washington; MIZUTANI—National Institute of Information of continuous activity from 28 January until 2 Feb- and Communications Technology, Kogenai, Tokyo, Japan ruary. From 11 to 28 January, the volcano was in an CORRESPONDING AUTHOR: Peter W. Webley, Arctic Region explosive phase, and by 28 January, it changed to a Super Computing Center, University of Alaska Fairbanks, 909 more continuous phase (Table 1). This phase began Koyukuk Drive, Fairbanks, AK 99775 at 2331 UTC on 28 January (1431 Alaskan Standard E-mail: [email protected] Time, AKST) after four strong explosions that had DOI: 10.1175/2008BAMS2579.1 generated ash plumes to heights of 9 km above sea

©2008 American Meteorological Society level. Figure 2 shows the ash plume over the volcano on the afternoon of 30 January. The Anchorage Fore-

AMERICAN METEOROLOGICAL SOCIETY NOVEMBER 2008 BAI1S" | 1647 Unauthenticated | Downloaded 10/10/21 04:18 PM UTC TABLE I. Volcanic eruption parameters for Mt. Augustine's eruption on 28 January 2006, as used by the Puff model. Date Start time (UTC) End time (UTC) Plume height

05:24:00 05:33:00 30,000 ft 28 January 2006 (1/27 20:24:00 AKST) (1/27 20:33:00 AKST) 9 km)

08:37:21 08:38:45 < 10,000 ft 28 January 2006 (1/28 22:37:21 AKST) (1/27 22:38:45 AKST) (< 3 km)

11:04:13 11:06:40 26,000 ft 28 January 2006 (02:04:13 AKST) (02:06:40 AKST) (~ 8 km)

16:42:00 16:45:00 25,000 ft 28 January 2006 (07:42:00 AKST) (07:45:00 AKST) (~ 7.6 km)

28 January 2006 23:31:00 * 10—14,000 ft 1 February 2006 (continuous period) (14:31:00 AKST) (~ 3-4.3 km)

*Note: Discrete events to 30k ft, I km = 3,280 ft. All heights above mean sea level.

cast Office of the National Weather Service (NWS) tration (FAA)—to alert aircraft to the presence of issued an advisory at 0555 UTC 28 January (2055 potentially hazardous volcanic ash clouds. The need AKST 27 January) warning residents of Kodiak City for such a monitoring program was highlighted dur- (Fig. 1) to remain indoors and avoid exposure to the ing the December 1989 eruption of Redoubt Volcano ash (Fig. 3a). At 0506 UTC 31 January (2006 AKST when a Boeing 747 flew into the Redoubt ash cloud. 30 January), Alaska Airlines cancelled all flights to Intake of ash into the four jet engines caused all and from Anchorage (Fig. 3b) after the Anchorage four engines to stall. The engines were restarted 1-2 Forecast Office had issued a series of volcanic ash ad- min before impact, with no loss of life. Damage to visories for Kodiak Island, Kenai Peninsula, Western the aircraft was estimated at $80 million. Since that Prince William Sound, and Anchorage (Fig. 1). time, UAF-GI at AVO has developed an ash disper- The Augustine eruption was reported by the Alaska Volcano Observatory (AVO), which was established in 1988 as a joint program of the United States Geological Survey (USGS), the Geo- physical Institute (GI) of the University of Alaska Fairbanks (UAF), and the State of Alaska Division of Geological and Geophysical Surveys (ADGGS). AVO is responsible for monitoring the 100 active volcanoes in the Northern Pacific and issues reports—in conjunc- tion with the Anchorage Volcanic Ash Advisory Cen- ter (VAAC) of the NWS and FIG. 2. Volcanic eruption cloud from Augustine Volcano at 2200 UTC 30 Janu- Federal Aviation Adminis- ary 2006 (1300 AKST), courtesy of Game McGimsey (AVO/USGS).

1648 | BAPIS- NOVEMBER 2008 Unauthenticated | Downloaded 10/10/21 04:18 PM UTC WWAK71 PAFC 280557 sion model, called "Puff," that allows NPWAER forecasters to predict the movement of URGENT - WEATHER MESSAGE NATIONAL WEATHER SERVICE ANCHORAGE AK volcanic ash clouds and warn aircraft 855 PH AST FRI JAN 27 2006 of potential hazards. AK2171-281800- KODIAK ISLAND- Validation of volcanic ash disper- INCLUDING. ..KODIAK CITY sion and transport models such as 855 PH AST FRI JAN 27 2006 (a) ...ASHFALL ADVISORY IN EFFECT UNTIL 8 AM AST SATURDAY MORNING OVER KODIAK ISLAND...

Puff is not trivial. Ash clouds can be THE ALASKA VOLCANO OBSERVATORY HAS REPORTED THAT AUGUSTINE VOLCANO ERUPTED AROUND 830 difficult to detect and are dynamic, PH AST THIS EVENING. AN ASH CLOUD HAS BEEN DETECTED BY THE NATIONAL WEATHER SERVICE DOPPLER RADAR. ASH IS rapidly dispersed, and dangerous EXPECTED TO MOVE OVER KODIAK ISLAND TONIGHT AND REMAIN IN THE AREA THROUGH EARLY to sample. Satellite data are used as SATURDAY MORNING. A LIGHT ASH FALL HAY OCCUR. RESIDENTS SHOULD REMAIN AT HOME OR INDOORS AND REDUCE OUTSIDE ACTIVITY. KEEP WINDOWS the primary "truth" but have some AND DOORS CLOSED. DO NOT EXERCISE OUTDOORS. limitations because they only detect high concentrations of particles usu- ally near their sources, are obscured Alaska Airlines Cancels Anchorage Flights As Result Of Mt. Augustine Volcanic Ash by weather clouds, and can possess 1/30/2006 8:06 p.m. limited coverage frequency. The detec- ANCHORAGE, ALASKA - Alaska Airlines announced it has canceled all flights tion of ash clouds relies heavily on the to and from Anchorage. Alaska, tonight and early Tuesday morning. The (b) flights were canceled as a safety precaution related to the pattern of ash at "split window" differencing technique, altitude created by the Mt. Augustine volcano. as discussed by Prata in a 1989 article. As of 6 p.m. Alaska time, 36 flights were canceled. The airline is monitoring the pattern of ash at altitude on a continuous basis and anticipates resuming In Alaska, ash clouds often drift to Anchorage flights on Tuesday, the southeast over the Pacific Ocean, where there are few sampling instru- ments and ash deposits are lost in the FIG. 3. (a) NWS Ash Advisory: 27 January 2006 at 2055 AKST and (b) ocean. During the continuous phase Alaska Airlines announces flight cancellations (www.alaskasworld. of the eruption of Augustine Volcano, com/Newsroom/ASNews/ASstories/AS 20060130 200557.asp). the local winds first transported the ash to the south-southeast and then by 1-2 February "L," Fig. 4). During 27-31 January, the low and trough northward across interior Alaska to the Arctic Ocean. remained largely unchanged. Weak surface flow from The cloud was detected by a variety of ground-based the east-northeast was evident across the southern- and satellite-borne instruments both in the neighbor- central part of the state. At upper levels (250-300 hood of Mt. Augustine Volcano and across Alaska mb), steering was weak, with the jet axis well south up to 1500 km north. In this paper, we examine the of the eruption site. At the beginning of the continu- prevailing flow, the Puff model predictions, and mea- ous eruption period, a closed low at 500 mb (Fig. 5a) surements of the ash cloud taken by aerosol samplers, was situated over the Kenai Peninsula. This feature laser radar (or lidar) systems, and satellites obtained moved slowly westward over the next several days during the continuous period of eruption (29 Janu- (Figs. 5b,c). Examination of the wind flow pattern in ary-2 February 2006). These measurements are criti- Fig. 5 suggests that material injected into the 5-km cal in assessing the potential hazard associated with level (approximately 500 mb) would initially move the airborne ash cloud and defining satellite detection toward the south-southeast and then curve tightly limits and dispersion model accuracies. back around to end up west of the volcano. Figure 6 shows how this affected the Puff model predictions. MOVEMENT OF ASH CLOUD IN THE By 30 January (Fig. 5c), the initial trajectory was NEIGBORHOOD OF MT. AUGUSTINE. By away from the volcano and was weakly to the north- 2330 UTC on 28 January (1430 AKST), the Augustine northwest. This pattern was also evident at the 3-km Volcano began a state of continuous eruption with (700-mb) level. steady ash emission, small pyroclastic flows, and In response to the continuous phase of the erup- elevated seismic activity. The prevailing synoptic tion, AVO assigned the volcano an aviation color situation near the surface during the continuous code of "red" [i.e., major explosive eruption expected phase was dominated by a weak but persistent low- within 24 h, large ash plume(s) expected to reach at pressure center positioned over the Kenai Peninsula least 25,000 ft above sea level, or an explosive eruption with an accompanying trough (emphasized as a red may be in progress]. The satellite monitoring group

AMERICAN METEOROLOGICAL SOCIETY NOVEMBER 2008 BASIS' I 1649 Unauthenticated | Downloaded 10/10/21 04:18 PM UTC in AVO at UAF-GI initiated automated, ongoing runs of the Puff model to predict the location and movement of the ash cloud and warn of possible aircraft hazards. Initialization parameters for the continuous phase of the eruption were for a 5-km ASL ash plume using forecast wind fields from the North American Mesoscale Model. The model was run for an initial 24-h period (starting at 2320 UTC, 28 January) and then rerun for successive 24-h periods at 2320 UTC, FIG. 4. Surface analysis at 0000 UTC 31 January 2006. This surface pattern continuing until 2 February. was typical of the period of eruption. Note a weak but persistent low-pressure Each rerun used the Puff center positioned over the Kenai Peninsula (emphasized with red "L"). model output from the end

FIG. 5. 500-mb heights and wind vectors at 1200 UTC for (a) 28 January; (b) 29 January; (c) 30 January; (d) 31 January; (e) I February; and (f) 2 February 2006. Calibration [10 m s 1 (~20 knots)] in upper right corner.

1650 | BAPIS- NOVEMBER 2008 Unauthenticated | Downloaded 10/10/21 04:18 PM UTC FIG. 6. Puff model predictions of volcanic ash cloud, as airborne ash concentrations and airborne ash color- coded by altitude, on (a) 0200 UTC 29 Jan (1700 AKST 28 Jan); (b) 0200 UTC 30 Jan (1700 AKST 29 Jan); and (c) 0200 UTC I Feb (1700 AKST 31 Jan). These are all taken from the 24-h predictions. Within each part of the figure, ash concentration is in top left and airborne ash color-coded by altitude (km) on the right.

of the previous prediction period, so by 2 February there was a continuous 6-day prediction. The reruns every 24 h allowed the Puff model predictions to use the most up-to-date numerical weather prediction wind fields. window method. The ash cloud movement is initially As expected from the meteorological analyses, toward the south or southeasterly direction (Fig., 7a) the Puff prediction showed that the ash would ini- moving to a more southerly direction (Fig. 7b). Then tially circle the volcano before heading northward there is a backing to an easterly direction (Fig. 7c), and across Alaska. The initial Puff prediction showed an finally the transport assumes a northeasterly direc- ash cloud moving to the southeast toward Kodiak tion, supporting the Puff-based predictions (Fig. 6). Island (Fig. 6a). This was an important component As the cloud spread further from the volcano, the in the decision to release an ash advisory for the af- airborne ash concentrations decreased, receding to fected area. The trajectory had a subsequent gradual levels below the detection limits of the satellite-borne backing in direction to the northeast and across the instruments. Satellites could not track the ash cloud Kenai Peninsula by the following day (Fig. 6b). By beyond Cook Inlet. The Puff forecast model on 30 the third day, this circulation had given way to a January (Fig. 8) was used to alert the UAF-GI lidar direct northeasterly trajectory, up Cook Inlet toward researchers and showed that the ash cloud would Anchorage (Fig. 6c). Model-predicted ash concentra- spread northward over Alaska, reaching Fairbanks tions were greatest near Mt. Augustine, with pro- after about 20 h (-1900 UTC 31 January) and con- gressively lower concentrations over the mainland. tinuing northward to the Arctic Ocean (0400 UTC The ashfall in the Cook Inlet area was recorded by 1 February UTC). an 8-stage DRUM aerosol impactor operating at Homer. Samples indicated the presence of ash with MOVEMENT OF ASH CLOUD ACROSS higher iron-to-calcium ratios than associated with ALASKA. From 31 January to 2 February, the ambient (nonvolcanic) aerosols. 500-mb closed low (Fig. 5 d-f) began to deepen, Satellite observations depicted the distribution of and by 1 February merged with a larger center ap- the ash cloud in the Cook Inlet area. Figure 7 shows proaching from the northwest. This led to a steady the daily composites of the detected volcanic ash on southwesterly flow, moving at approximately 40-45 28-31 January, showing the ash detected by the split- knots (20-25 m s_1), as seen in the wind vectors

AMERICAN METEOROLOGICAL SOCIETY NOVEMBER 2008 BASIS' I 1651 Unauthenticated | Downloaded 10/10/21 04:18 PM UTC FIG. 7. Moderate Resolution Infrared Spectrometer (MODIS) and Advanced Very High-Resolution Radiometer data (AVHRR) ash detection daily composites for (a) 28; (b) 29; (c) 30; and (d) 31 January 2006. Black arrows indicate general direction of ash cloud movement.

in Fig. 5. The Puff operational prediction for this model. Observational confirmation of the ash trajec- period is shown in Figs. 9a and 9b. The prediction tory was available from several sources. suggests that from 1 to 2 February, the trajectory of There were three lidar facilities in operation during the ash cloud was curved, to flow over the interior this event that were able to confirm the presence of of Alaska. The model predicts the presence of ash ash at various times and locations along its northward over Fairbanks up to altitudes of 4 km, with ash at trajectory: 1) at Chatanika, a Multi-Wavelength Lidar higher altitudes passing to the east of Fairbanks. The (MWL) operated by UAF and the National Institute nature and persistence of this flow pattern would for Information and Communications Technology; further place aerosol, initially entrained at the 500- 2) at Fairbanks, a Cloud Polarizing Lidar (CPL) oper- mb level over the Augustine Volcano, in the vicinity ated by the Arctic Facility for Atmospheric Research of Barrow, consistent with the prediction by the Puff in Fairbanks; and 3) at Barrow, a Micro-Pulse Lidar

1652 | BAfft NOVEMBER 2008 Unauthenticated | Downloaded 10/10/21 04:18 PM UTC We interpret the lidar data as precipitating cloud particles (large backscatter, large depolarization, and wetter) that lie below 4.4 km, a layer of cirrus clouds (large backscatter in narrow layers, higher depolar- ization, and drier) that lies between 4.4 and 5.0 km, and volcanic ash (low backscatter, lower depolariza- tion, and drier) that lies between 5.0 and 6.0 km. The volcanic ash is undoubtedly present at lower altitudes but masked by the presence of the clouds. Similar observations, where desert dust and cirrus clouds are present, have also been reported by lidar observations at Fairbanks. The Puff model at 0400 UTC 1 February (Fig. 8) predicts the presence of ash over Chatanika up to altitudes of 6 km. A 3-stage DRUM aerosol impactor located in Fairbanks collected aerosols for 24 h from 0400 UTC 1 February. The impactor detected ash with iron-to-calcium ratios similar to those measured at Homer throughout this 24-h period. The lidar observations at Barrow, from 1100 to 1200 UTC on 2 February in Fig. 10c, were also FIG. 8. Puff operational prediction of location of volca- nic ash across Alaska for 0400 UTC I February 2006 made under scattered clouds. Two distinct layers (2000 AKST 31 January) as (top left) airborne ash are observed: one above 5 km (~ 5.2-5.8 km), and concentrations and (lower right) airborne ash color- one below 5 km (~ 1.4-5 km). Puff predictions coded by altitude. (Fig. 9a) suggest the ash plume has moved west- ward along the north coast of Alaska with ash over Barrow up to altitudes of 6 km. Finally, the Polarization System (MPL-PS) at the Atmospheric lidar observations at Fairbanks were made under Radiation Measurement (ARM) site. Each of these clear sky conditions from 2110 to 2230 2 February instruments returns scattering information of various UTC, Fig. lOd. Enhanced scattering is observed in polarities and wavelengths. The lidars were able to the 1.8-3.8-km region, but there is no evidence of establish the presence of ash at various times, loca- aerosol layers above this altitude. The CPL aero- tions, and altitudes (Table 2), despite the presence of sol measurements also yielded measurements of clouds at Chatanika and Barrow. the depolarization ratio that are similar to those The first lidar measurements were made with the measured by the MWL over Chatanika. The Puff MWL from 0307 to 0445 UTC, 1 February. The lidar operational prediction (Fig. 9b) indicates that the observations were collected under scattered clouds, trajectory of the ash cloud showed ash below 4 km and the relative lidar signal is shown in Fig. 10a. The passing over Fairbanks and ash at higher altitudes signals due to clouds and aerosol are clearly visible up passing to the east of Fairbanks. to 6 km, where the lidar signal is enhanced relative to Additional remote-sensing data were available the expected signal from a cloud-free atmosphere. There from sulfur dioxide (S02) concentrations of the vol- are three types of echoes observed in the profiles: There canic ash cloud, determined by the Atmospheric In- are weak enhancements between 5 and 6.2 km, stronger frared Sounder (AIRS) instrument (Fig. 11). The high- layered enhancements between 4.4 and 5 km, and broad est total column tropospheric S02 is situated in the enhancements below 4.4 km. The echoes above 4.4 km neighborhood of Augustine Volcano. There are lower stay at the same altitude during the observation period, levels, approximately one-third of the maximum, seen while the other echoes move downward during the across the Alaska interior and the northern coastal observation period. The echoes above 5 km have a low regions of the state. The locations of these S02 clouds depolarization ratio, -20% (Fig. 10b), while the echoes correspond well to the Puff-predicted volcanic ash from 4.4 to 5 km have a higher depolarization ratio clouds during 1-2 February (Figs. 8 and 9). These (-70%). The Raman lidar signal recorded with the Lidars data show the usefulness of infrared detection of S02 indicates the presence of water vapor to 4.4 km. clouds for volcanic cloud tracking and highlights its

AMERICAN METEOROLOGICAL SOCIETY NOVEMBER 2008 BASIS' I 1653 Unauthenticated | Downloaded 10/10/21 04:18 PM UTC TABLE 2. Evolution, detection, and validation of Mt. Augustine ash clouds. Puff timing Measurement Timing Measured signal (UTC) Prediction

Ash at surface with high Movement of ash cloud over Sampler at Homer 30 Jan 0200 30 Jan iron to calcium ratio. Homer

IR signature of ash cloud 0200 29 Jan- Movement of ash in Satellite 29 Jan-1 Feb over southern Alaska 0200 1 Feb Mt Augustine neighborhood

0307-0445 Lidar at Chatanika Echo profile up to 6 km 0400 1 Feb Ash over Chatanika up to 6 km 1 Feb UTC

Ash at surface with high 0400 1 Feb- Movement of ash over Sampler at Fairbanks 1-2 Feb iron to calcium ratio. 2200 2 Feb. Fairbanks neighborhood

1100-1200 Lidar at Barrow Echo profile up to 6 km 1130 2 Feb Ash over Barrow up to 5 km 2 Feb UTC

2110-2230 Lidar at Fairbanks Echo profile up to 4km 2200 2 Feb Ash over Fairbanks up to 4 km 2 Feb UTC

Sulfur dioxide 0400 1 Feb- Satellite 28 Jan-2 Feb Movement of ash across Alaska distribution over Alaska 2200 2 Feb

FIG. 9. Puff predictions of volcanic ash location at (a) 1130 and (b) 2200 UTC 2 February 2006 (0230 and 1300 AKST, respectively). The inset figures show airborne ash concentrations, while the larger figures show airborne ash color-coded by altitude.

1654 | BAPIS- NOVEMBER 2008 Unauthenticated | Downloaded 10/10/21 04:18 PM UTC FIG. 10. (a) Relative lidar echo signal plotted as a function of altitude at Chatanika (green solid) integrated over the observation period. Signal is normalized to unity over 7-8 km. The expected Rayleigh scattered signal is plotted for comparison (blue dash), (b) Depolarization ratio plotted as a function of altitude (green). Parallel and perpendicular polarization signal profiles were smoothed with 0.25-km running average, (c) Relative lidar echo signal plotted as a function of altitude at Fairbanks (green solid), (d) Relative lidar echo signal plotted as a function of altitude at Barrow (green solid).

use in high-latitude winters, where other ultraviolet satellite-borne sensing platforms. The AVO Remote (UV) sensors, such as the Ozone Mapping Instrument Sensing group at UAF-GI provided Puff model pre- (OMI), would not be able to detect the clouds. dictions of the ash cloud trajectory that were validated by these remote-sensing and sampling measurements. SUMMARY AND CONCLUSIONS. The 2006 A summary of the observations and associated pre- eruption of the Augustine Volcano provided a unique dictions is presented in Table 2. We note that the lidar opportunity to validate the ash cloud dispersion mod- measurements at two sites (Chatanika and Fairbanks) els being used operationally to provide guidance to were collected in response to the 29 January forecast aircraft operations. During 28 January-2 February, an by the Puff model. Samplers detected the presence of ash cloud from Mt. Augustine Volcano traveled over aerosols at the surface, which had characteristics of several lidar facilities and aerosol samplers in Alaska. volcanic aerosols, at sites where Puff had predicted the Ash and sulfur dipxide clouds were also detected by ash clouds would be. Satellite data showed the evolu-

AMERICAN METEOROLOGICAL SOCIETY NOVEMBER 2008 BAFft | 1655 Unauthenticated | Downloaded 10/10/21 04:18 PM UTC data showed the dispersion of an S02 cloud further from the volcano, where the ash cloud was too thin to be observed directly using the split-window method for detecting ash from remote-sensing data. The AIRS data showed S02 where ash was very difficult to observe and, in that the eruption occurred during a high-latitude winter, the OMI and other UV sensors were unable to detect the signal. Lidars verified the presence of volcanic aerosol with consistent spectral/polarization characteristics over Alaska. The lidar signals were capable of detecting the aerosol, even in the presence of water vapor clouds, where the ash cloud is too thin or dispersed to be detected by remote-sensing satellite data. The lidar measurements revealed the different tra- jectories of lower- and upper-level ash consistent with the Puff predictions. Using this suite of observational FIG. 11. AIRS sulfur dioxide (S02) retrieval for 28 Janu- support, the utility of the Puff model to accurately ary-February 2006. 15 AIRS granules have been used forecast the path of a volcano ash cloud across Alaska in the composite and the S02 has been accumulated from Augustine Volcano to Barrow (-1300 km) has in 0.1 ° lat x 0.1° long bins and smoothed. been verified. Dispersion models provide a forecast of volcanic ash movement in both proximal and distal tion and movement of the ash cloud in the neighbor- areas that might be undetectable but still represent a hood of Mt. Augustine Volcano. In addition, satellite potential hazard to aircraft. Validation of the predic- tions from Puff is key to assessing the accuracy of any future predictions. The study highlights the use of multiple and complementary observations in detecting the trajectory of an ash cloud, both at the surface and aloft within the atmosphere.

ACKNOWLEDGMENTS. The authors wish to thank the staff at AVO for their monitoring of the volcano, their efforts in alerting fellow researchers to the progress of the eruption, and their analysis of satellite data. The authors thank Game McGimsey (AVO/USGS) for the use of the photograph of the Augustine Volcano ash cloud and Peter Rinkleff (UAF-GI) for generating the composite satellite images of the ash clouds. AVO is a tripartite program sup- ported by USGS, UAF-GI, and ADGGS. The lidar, sample, and satellite measurements were supported by DOE, NASA, and NSF. The meteorological data were provided by the NWS, and the ashfall advisory was provided by Sam Albanese, NWS Alaska Region. The authors would also like to thank Tom Fahey, manager of meteorology at Northwest Airlines, and one anonymous reviewer for their comments and suggestions.

JOSS-WALDVOGEL Disdrometer FOR FURTHER READING by Distromet Ltd. Aoki T., K. Mizutani, S. Ishii, R. L. Collins, and J. Fochesatto, 2006: Multiwavelength and depolariza-

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Unauthenticated | Downloaded 10/10/21 04:18 PM UTC tion lidar measurements of clouds and aerosols. eruptions of Redoubt volcano: An introduction. /. 23rd International Laser Radar Conf., Nara, Japan, Volcanol. Geotherm. Res., 62, 1-10. 455-456. Power, J. A., and Coauthors, 2006: The reawakening Cahill, T. A., and P. Wakabayashi, 1993: Composi- of Alaska's Augustine volcano. EOS, Trans. Amer. tional analysis of size-segregated aerosol samples. Geophys. Union, 87, 373-377. Measurement Challenges in Atmospheric Chemis- Prata, A. J., 1989: Observations of volcanic ash clouds try, L. Newman, Ed., American Chemical Society, in the 10-12 ^m window using AVHRR/2 data. Int. 211-228. J. Remote Sens., 10, 751-761. Casadevall, T. J., 1994: The 1989-1990 eruption of Re- Raabe, O. G., D. A. Braaten, R. L. Axelbaum, S. V. doubt Volcano, Alaska: Impacts on aircraft opera- Teague, and T. A. Cahill, 1988: Calibration studies of tions. /. Volcanol. Geotherm. Res., 62, 301-316. the DRUM impactor. /. Aerosol Sci., 19, 183-195. Dean, K., J. Dehn, K. Engle, P. Izbekov, K. Papp, and M. Sassen, K, 2005: Polarization in lidar. Lidar: Range- Patrick, 2002: Operational satellite monitoring of Resolved Optical Remote Sensing of the Atmosphere, volcanoes at the Alaska Volcano Observatory. Adv. C. Weitkamp, Ed., Springer, 19-42. Environ. Monit. Model., 1, 3-35. , 2005: Dusty ice clouds over Alaska. Nature, 434, , , .K. R. Papp, S. Smith, P. Izbekov, R. Peterson, 456 doi: 10.1038/434456a C. Kearney, and A. Steffke, 2004: Integrated satellite , J. Zhu, P. Webley, K. Dean, and P. Cobb, 2007: observations of the 2001 eruption of Mt. Cleveland, Volcanic ash plume identification using polarization Alaska. J. Volcanol. Geotherm. Res., 135, 51-73. lidar: Augustine eruption, Alaska. Geophys. Res. Flynn, C. J., A. Menoza, Y. Zheng, and S. Mathur, 2007: Lett., 34, doi: 10.1029/2006GL027237 Novel polarization-sensitive micropulse lidar mea- Searcy, C., K. G. Dean, and W. Stringer, 1998: Puff: A surement technique. Opt. Express, 15, 2785-2790. volcanic ash tracking and prediction model. /. Vol- Miller, T. P., and B. A. Chouet, 1994: The 1989-1990 canol. Geotherm. Res., 80, 1-16. AN EYE ON POLICY TOWN HALL MEETING—TUESDAY, JANUARY 13th 12:OOPM "Integrated Solutions for Environment and Health: Your Research Can Inform Public Health Decisions'' A changing climate puts pressure on the shoulders of public health officials, who must stay ahead of the curve to prevent and to prepare the public for current and emerging diseases. Come join this For those scientists who would like to contribute to discussion to see how your research can benefit public health information for today and tomorrow. public policy by working on Capitol Hill, come learn how FOURTH SYMPOSIUM ON POLICY AND SOCIO-ECONOMIC RESEARCH the AMS/UCAR MONDAY: Sustainability and Growth: How Can a City Develop Sustainably When its Identity Congressional Science Fellowship allows you to is Based on Growth?, Adaptation and Vulnerability to Climate Change and Extremes , Policy spend a year working for a and Socio-Economic Research Poster Session, Climate and Policy: From Local to Global Member of Congress or a TUESDAY: Policy, Social and Economic Dimensions of Water, Water in the West, Societal congressional committee— Dimensions of Weather and Climate Hazards, Use of Forecasts and Communicating for more information plan Uncertainty, Into the Policy Fray: Bringing Science to the U.S. Congress to attend the panel WEDNESDAY: Societal Benefits of Research, Evaluation and Use of Decision-Support discussion: Systems, Developing a National Climate Service, Socio-Economic Research Methods and their Into the Policy Fray: Applications Bringing Science to the THURSDAY: State of the Field U.S. Congress (Tuesday) EIGHTH COMMUNICATION WORKSHOP MONDAY: Communication: Moving toward a better understanding of a complex process WEDNESDAY: The Role of the Media in the Communication Puzzle

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1658 | BAPIS- NOVEMBER 2008 Unauthenticated | Downloaded 10/10/21 04:18 PM UTC