DOCSLIB.ORG

The Detection of Mesoscale Convective Systems by the GPM Ku-Band Spaceborne Radar

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Detection of Mesoscale Convective Systems by the GPM Ku-Band Spaceborne Radar For Peer Review The Detection of Mesoscale Convective Systems by the GPM Ku-band Spaceborne Radar Journal: Journal of the Meteorological Society of Japan Manuscript ID JMSJ-2019-0034.R1 Manuscript Type: Articles Date Submitted by the n/a Author: Complete List of Authors: wang, jingyu; Pacific Northwest National Laboratory, Atmospheric Sciences & Global Change Houze, Robert ; University of Washington, Department of Atmospheric Sciences; Pacific Northwest National Laboratory, Atmospheric Sciences and Global Change Division Fan, Jiwen; Pacific Northwest National Laboratory, Atmospheric Sciences and Global Change Division Brodzik, Stacy; University of Washington, Department of Atmospheric Sciences Feng, Zhe; Pacific Northwest National Laboratory, Atmospheric Sciences and Global Change Division Hardin, Joseph; Pacific Northwest National Laboratory, Atmospheric Sciences and Global Change Division GPM evaluation, 3D reflectivity structure, Mesoscale Convective System Keywords: tracking, MCS feature, Global MCS distribution, Intense convection Page 1 of 100 For Peer Review 1 The Detection of Mesoscale Convective Systems by the 2 GPM Ku-band Spaceborne Radar 3 4 Jingyu Wang 5 Pacific Northwest National Laboratory, 6 Richland, Washington, USA 1 7 Robert. A. Houze, Jr 8 University of Washington, 9 Seattle, Washington, USA 10 Pacific Northwest National Laboratory, 11 Richland, Washington, USA 12 Jiwen Fan 13 Pacific Northwest National Laboratory, 14 Richland, Washington, USA 15 Stacy. R. Brodzik 16 University of Washington, 17 Seattle, Washington, USA 18 Zhe Feng 19 Pacific Northwest National Laboratory, 20 Richland, Washington, USA 21 and 22 Joseph C. Hardin 23 Pacific Northwest National Laboratory, 24 Richland, Washington, USA 25 26 27 March 31, 2019 28 ------------------------------------ 29 1) Corresponding author: Robert Houze, University of Washington, Seattle, Washington, 30 USA. Email: [email protected] For Peer Review Page 2 of 100 31 Abstract 32 33 The Global Precipitation Measurement (GPM) core observatory satellite launched in 34 2014 features more extended latitudinal coverage (65S-65N) than its predecessor 35 Tropical Rainfall Measuring Mission (TRMM, 35S-35N). The Ku-band radar onboard of 36 the GPM is known to be capable of characterizing the 3D structure of deep convection 37 globally. In this study, GPM’s capability for detecting mesoscale convective systems 38 (MCSs) is evaluated. Extreme convective echoes seen by GPM are compared against an 39 MCS database that tracks convective entities over the contiguous US. The tracking is 40 based on geostationary satellite and ground-based Next Generation Radar (NEXRAD) 41 network data obtained during the 2014-2016 warm seasons. Results show that more than 42 70% of the GPM-detected Deep-Wide Convective Core (DWC) and Wide Convective Core 43 (WCC) objects are part of NEXRAD identified MCSs, indicating that GPM-classified DWCs 44 and WCCs correlate well with typical MCSs containing large convective features. By 45 applying this method to the rest of the world, a global view of MCS distribution is obtained. 46 This work reveals GPM’s potential in MCS detection at the global scale, particularly over 47 remote regions without dense observation network. 48 49 Keywords GPM evaluation; 3D reflectivity structure; Mesoscale Convective System 50 tracking; MCS features; Intense convection; Global MCS distribution 1 Page 3 of 100 For Peer Review 51 1. Introduction 52 As a collaborative effort between the National Aeronautics and Space Administration 53 (NASA) and the Japan Aerospace Exploration Agency (JAXA), the Tropical Rainfall 54 Measuring Mission (TRMM) satellite was equipped with a Ku-band (13.8 GHz) quantitative 55 precipitation radar, together with a variety of sensors including passive microwave, visible, 56 infrared, and lightning (Kummerow et al., 1998; Schumacher et al. 2004; Zipser et al. 57 2006; Houze et al. 2015). Launched in 2014 as the successor of TRMM, the Global 58 Precipitation Measurement (GPM) core observatory satellite carries the first space-borne 59 Dual-frequency Precipitation Radar (DPR) operating at both Ku (13.6 GHz) and Ka (35.5 60 GHz) bands. Compared to TRMM, the DPR system helps improve the accuracy of 61 precipitation measurement and upgrade the detectability of weak rain as low as 0.5 mm hr- 62 1. Another key advancement of GPM is its extended coverage to higher latitudes (65S to 63 65N compared to 35S to 35N for TRMM), providing a near-global view of 3D cloud and 64 precipitation structure every 2-3 hours. 65 Mesoscale Convective Systems (MCSs) are of great importance because of their large 66 area (at least one hundred kilometers in one direction) and intense, long-lasting (up to 24 67 hours) precipitation (Houze 2004, 2018). In midlatitudes, MCSs strongly impact local 68 climate through their precipitation, severe weather, and redistribution of heat and moisture, 69 which further impact the regional to global hydrological cycle and large-scale circulations 70 (Houze et al. 1990; Feng et al. 2016, 2018; Futyan and Del Genio, 2007). Based on the 2 For Peer Review Page 4 of 100 71 detailed 3D radar reflectivity field observed by spaceborne precipitation radar, Houze et al. 72 (2007, 2015) developed a convective echo classification algorithm based on the horizontal 73 and vertical dimensions of echoes of a given intensity. The most intense of such 3D 74 convective echo objects are assumed to be strongly associated with MCSs (Houze et al. 75 2015, 2019). However, direct comparison to other independent MCS data sets is needed 76 to support this argument. Identification of MCSs has been traditionally carried out by 77 tracking convective elements in geosynchronous satellite or ground-based radar data, 78 which provide temporally continuous spatial data. For example, satellite imagery that 79 provides cloud radiative properties such as brightness temperature at high temporal 80 resolution has been used to track deep convective clouds at regional to global scale 81 (Schmetz et al. 1993; Machado et al. 1998; Morel and Senesi 2002; Héas and Mémin 82 2008; Escrig et al. 2013; Roca et al. 2014). However, the incapacity of visible and infrared 83 satellite data to show the structure of the clouds in the lower troposphere leaves large 84 uncertainties in satellite-based MCS tracking. Ground-based radar measurements provide 85 3D structure of precipitating deep convection that can complement satellite imagery to 86 more accurately detect MCSs. A recently developed tracking algorithm called FLEXible 87 object TRacKeR (FLEXTRKR, Feng et al. 2018) jointly uses the geostationary satellite 88 brightness temperature and NEXRAD 3D radar reflectivity structure to identify and track 89 MCSs. A comprehensive 13-year (2004-2016) MCS tracking database east of the Rocky 90 Mountains has been developed using FLEXTRKR (Feng et al. 2019). This database is 3 Page 5 of 100 For Peer Review 91 considered here as ground-truth to evaluate the MCS objects detected by GPM. 92 To determine GPM’s capability of MCS detection, we organize this study as follows. In 93 Section 2, the data sets of GPM Ku-band reflectivity, NEXRAD observations, as well as 94 their corresponding MCS detecting/tracking algorithms are introduced. In Section 3, the 95 quantitative comparison of 3D radar reflectivity fields is performed between the two data 96 sets. This comparison is essential to determine whether the GPM and NEXRAD radar 97 systems detect the 3D radar reflectivity fields in a consistent way. After the consistency 98 between the two data sets is established, the GPM’s snapshots of intense convective echo 99 objects are compared to the NEXRAD MCS tracking database over the Continental United 100 States (CONUS) to quantify GPM’s MCS detection capability. Then, the regionally 101 validated GPM’s MCS detection algorithm is applied elsewhere around the world, 102 presenting a global view of MCS distribution. Finally, conclusions and discussions are 103 provided in Section 4. 104 2. Data and methodology 105 2.1 GPM Data and convective object classification 106 As a major component of the GPM DPR system, the onboard Ku-band precipitation 107 radar features a swath width of 245 km. The horizontal resolution is 0.05, or 108 approximately 5 km. The vertical resolution is 125 m, provided in 176 levels. In this study, 109 the GPM Ku band radar reflectivity data were downloaded from the University of 110 Washington GPM-Ku Data Set located at http://gpm.atmos.washington.edu, which 4 For Peer Review Page 6 of 100 111 geolocates and interpolates the DPR Level 2A Ku band version 5B data (Iguchi et al. 112 2017) from “radar coordinates” to a Cartesian grid with the aforementioned resolutions. 113 Detailed methodology regarding the geolocation correction and interpolation can be found 114 in Houze et al. (2007). 115 NASA and JAXA divide the GPM Ku-band radar echoes into convective, stratiform, and 116 other categories. In this study, the echo-object classification scheme developed by Houze 117 et al. (2007, 2015) is applied to the convective echoes. The analysis for evaluating GPM 118 3D radar reflectivity and GPM’s MCS detection capability is conducted in the CONUS 119 region for the warm seasons (April-September) of 2014-2016. The classification scheme 120 defines convective echoes as deep, wide, or deep and wide depending on radar reflectivity 121 intensity thresholds, and criteria for convective echo object height and area. Both strong 122 and moderate criteria (as defined by Houze et al. 2015) are used in this study to examine 123 the sensitivity of the results to the criteria. Strong/moderate deep convective core (DCC) 124 objects contain echoes that are greater than or equal to 40 dBZ/30 dBZ (everywhere in the 125 column) in intensity and have a maximum altitude of at least 10 km/8 km. Strong/moderate 126 wide convective core (WCC) objects contain echoes that are greater than or equal to 40 127 dBZ/30 dBZ and have a maximum horizontal extent of at least 1000 km2/800 km2.
Load more

Recommended publications
  • Atmospheric Circulation Newsletter of the University of Washington Atmospheric Sciences Department
    Autumn 2017 Atmospheric Circulation Newsletter of the University of Washington Atmospheric Sciences Department Studying the effects of Southern African biomass burning on clouds and climate: The ORACLES mission by Professor Robert Wood, Michael Diamond, & Sarah Doherty iny aerosol particles, emitted by Fires, mainly associated with dry season Teverything from tailpipes to trees, float agricultural burning on African savannas, above us reflecting sunlight, seeding clouds and generate smoke, a chemical soup that absorbing solar heat. How exactly this happens includes a large quantity of tiny aerosol – and how it might change in the future particles. This smoke rises high in – is one of the biggest uncertainties the atmosphere driven by strong in how humans are influencing surface heating and then is climate. blown west off the coast; it In September 2016, three then subsides down toward University of Washington the cloud layer over the scientists took part in a southeastern Atlantic large NASA field campaign, Ocean. The interaction Observations of Aerosols between air moisture and Above Clouds and their smoke pollution is complex Interactions, or ORACLES, and not well understood. that is flying research planes Southern Africa produces around clouds off the west coast almost a third of the Earth’s of southern Africa to see how smoke biomass burning aerosol particles, particles and clouds interact. yet the fate of these particles and their ORACLES is a five year program, with influence on regional and global climate is three month-long aircraft field studies, and is poorly represented in climate models. led by Dr. Jens Redemann from NASA Ames The ORACLES experiment is providing Research Center in California.
    [Show full text]
  • AMMA-Weather
    Multi-scale Observations and Modeling of West African Tropical Rainfall Systems: AMMA-Weather Principal Investigators: Chris D. Thorncroft SUNY at Albany Chris Davis NCAR Robert A. Houze University of Washington Richard H. Johnson Colorado State University Steven A. Rutledge Colorado State University Bradley F. Smull University of Washington PROJECT OVERVIEW Executive Summary AMMA-Weather is designed to improve both fundamental understanding and weather prediction in the area of the West African monsoon through deployment of U.S. surface and upper-air observing systems in July and August 2006. These systems will be closely coordinated with International AMMA. The project will focus on the interactions between African easterly waves (AEWs) and embedded Mesoscale Convective Systems (MCSs) including the key role played by microphysics and how this is impacted by aerosol. The pronounced zonal symmetry, ubiquitous synoptic and mesoscale systems combined with the close proximity of the Saharan aerosol make the WAM an ideal natural laboratory in which to carry out these investigations. The observations will provide an important testbed for improving models used for weather and climate prediction in West Africa and the downstream breeding ground for hurricanes in the tropical Atlantic. The international AMMA program consists of scientists from more than 20 countries in Africa, Europe, and the US. Owing to the efforts of European countries, a strong infrastructure is being installed providing a unique opportunity for US participation. Support in excess of twenty million Euros has already been secured by Europeans for AMMA including the 2006 field campaign. Significantly for AMMA-Weather, this will include support for the U.S.
    [Show full text]
  • Leading and Trailing Anvil Clouds of West African Squall Lines
    1114 JOURNAL OF THE ATMOSPHERIC SCIENCES VOLUME 68 Leading and Trailing Anvil Clouds of West African Squall Lines JASMINE CETRONE AND ROBERT A. HOUZE JR. Department of Atmospheric Sciences, University of Washington, Seattle, Washington (Manuscript received 10 June 2010, in final form 5 January 2011) ABSTRACT The anvil clouds of tropical squall-line systems over West Africa have been examined using cloud radar data and divided into those that appear ahead of the leading convective line and those on the trailing side of the system. The leading anvils are generally higher in altitude than the trailing anvil, likely because the hydrometeors in the leading anvil are directly connected to the convective updraft, while the trailing anvil generally extends out of the lower-topped stratiform precipitation region. When the anvils are subdivided into thick, medium, and thin portions, the thick leading anvil is seen to have systematically higher reflectivity than the thick trailing anvil, suggesting that the leading anvil contains numerous larger ice particles owing to its direct connection to the convective region. As the leading anvil ages and thins, it retains its top. The leading anvil appears to add hydrometeors at the highest altitudes, while the trailing anvil is able to moisten a deep layer of the atmosphere. 1. Introduction layer ascent (Zipser 1969, 1977; Houze 1977; Houze et al. 1989). We take advantage of a set of data collected at Satellite data show that a large portion of upper-level- Niamey, Niger, as part of the African Monsoon Multi- cloud ice clouds in the tropics originate as anvil clouds disciplinary Analyses (AMMA) field program of summer associated with precipitating deep convection (Luo and 2006 (see Redelsperger et al.
    [Show full text]
  • The Olympic Mountains Experiment (Olympex)
    THE OLYMPIC MOUNTAINS EXPERIMENT (OLYMPEX) ROBERT A. HOUZE JR., LYNN A. MCMURDIE, WALTER A. PETERSEN, MATHEW R. SCHWAllER, WIllIAM BACCUS, JESSICA D. LUNDQUIST, CLIFFORD F. MASS, BART NIJSSEN, STEVEN A. RUTLEDGE, DAVID R. HUDAK, SIMONE TANEllI, GERALD G. MACE, MICHAEL R. POEllOT, DENNIS P. LETTENMAIER, JOSEph P. ZAGRODNIK, ANGELA K. ROWE, JENNIFER C. DEHART, LUKE E. MADAUS, AND HANNAH C. BARNES OLYMPEX is a comprehensive field campaign to study how precipitation in Pacific storms is modified by passage over coastal mountains. hen frontal systems pass over midlatitude the lee sides. Snow deposited at high elevations by mountain ranges, precipitation is modified, these storms is an important form of water storage Woften with substantial enhancement on the around the globe. However, precipitation over and windward slopes and reduced accumulations on near Earth’s mountain ranges has long been very difficult to measure. As a result, the physical and dynamical mechanisms of enhancement and reduc- AFFILIATIONS: HOUZE, MCMURDIE, LUNDQUIST, MASS, NIJSSEN, tion of precipitation accompanying storm passage ZAGRODNIK, ROWE, AND DEHART—University of Washington, over mountains remain only partially understood. Seattle, Washington; PETERSON—NASA Marshall Space Flight Center, Huntsville, Alabama; SCHWAllER—NASA Goddard Space The launch of the Global Precipitation Measurement Flight Center, Greenbelt, Maryland; HOUZE AND BARNES—Pa- (GPM) satellite in February 2014 by the U.S. National cific Northwest National Laboratory, Richland, Washington; Aeronautics and Space Administration (NASA) and BACCUS—Olympic National Park, Port Angeles, Washington; the Japan Aerospace Exploration Agency (Hou et al. RUTLEDGE—Colorado State University, Fort Collins, Colorado; 2014) fosters exploration of precipitation processes HUDAK—Environment and Climate Change Canada, King City, over most of Earth’s mountain ranges.
    [Show full text]
  • Atmospheric Circulation Newsletter of the University of Washington Atmospheric Sciences Department
    Autumn 2012 Atmospheric Circulation Newsletter of the University of Washington Atmospheric Sciences Department The Weather Challenge by Lynn McMurdie he UW Atmospheric Sciences spring Tforecast contest has been an annual tradition in the department for many years. It’s a time when faculty and students alike agonize over whether there will be a marine push or a convergence zone wrecking their forecast for maximum temperature and precipitation probability at SeaTac. The winner earns department-wide recognition with their name engraved on a trophy, and the respect (or envy!) of their fellow forecasters. Now imagine forecasting for a wide-variety of cities across the United States and competing against thousands of other contestants from many other universities and institutions across the country. That’s just what a group of intrepid undergraduate and graduate students did this past year. For the first time, University of Washington entered a team in the national WxChallenge. The WxChallenge contest was developed A few of this year’s participants. From left: Xiaojuan Liu, Jack Neukirchen, Hannah Barnes, by the University of Oklahoma and officially started in 2006 when it replaced the National Jen DeHart, Elizabeth Maroon, Lynn McMurdie, Magdalena Szabo and Ken Dixon. Collegiate Weather Forecast contest. The goal of challenges. Often impromptu discussions would slipped into 3rd place. Aaron Hill, a recent 2012 the WxChallenge is to make the best forecast of erupt in the computer lab or someone’s office grad, had the top score in the nation for wind the next day’s maximum temperature, minimum when tricky forecasts were looming overhead at Riverton, WY.
    [Show full text]
  • Atmospheric Circulation Newsletter of the University of Washington Atmospheric Sciences Department
    Autumn 2016 Atmospheric Circulation Newsletter of the University of Washington Atmospheric Sciences Department OLYMPEX: Testing a NASA Satellite on the Olympic Peninsula by Dr. Lynn McMurdie and Professor Robert A. Houze, Jr. It’s early October 2015, and NASA is project to test a new precipitation measuring satellite, and scientists from the Departments of Atmospheric Sciences and Civil and Environmental Engineering are leading this massive adventure. There is no need for earplugs to protect your ears from the roar of rockets or a countdown: the Olympic Mountains Experiment (OLYMPEX) is being launched by a mule train. mountains and nearby ocean. Highly specialized radars were set up at several locations on both sides of the mountains. For over three years, Houze and Center, McMurdie worked with NASA were planned and colleagues, wrote plans, explored directed. Often 2-3 air craft were in the air at instruments in remote areas, radars on the coast and inland, and locations for aircraft patterns. McMurdie directed a staging. Two aircraft stationed at McChord team of graduate student forecasters, who Mules carry OLYMPEX instruments through wilderness to the high terrain of the Olympic Mts. were crucial for deciding the exact times to the storms with cloud instruments to measure launch the aircraft, operate radars and launch OLYMPEX occurred last fall and winter and the sizes and types of rain and snow particles. soundings. The lead graduate student forecaster was led by Prof. Houze and Dr. McMurdie of To realize this plan, McMurdie and Houze was Jennifer DeHart of the Department of the Department of Atmospheric Sciences.
    [Show full text]
  • Atmospheric Circulation Newsletter of the University of Washington Atmospheric Sciences Department
    Autumn 2011 Atmospheric Circulation Newsletter of the University of Washington Atmospheric Sciences Department Making of the YouTube Can Crushing Video by Kelly McCusker he Department of Atmospheric Sciences and boiled down to the essential information, all brief departure to smooth jazz while the Safety TOutreach group has recently ventured while remaining within the story arc and incor- Chicken shared his safety message. into a bold new frontier: YouTube. Composed porating some humor. “Due to recent advances The rest of the crew for this video included: of faculty, staff, and students, our group has in de-cylindrification theory, the power to crush Bryce Harrop, Brian Smoliak, Jack Scheff, and been volunteering time for over 20 years, shar- cans without undue physical exertion is now in yours truly, with new additions for upcoming ing science with youth on visits to the depart- the power of everyday citizens like yourself!” videos. The process was exceptionally fun, but ment, demonstrating concepts relevant to the Pure genius! We had lots of fun coming up with we did run across some pitfalls, many of which atmosphere, and generally illustrating the won- everyone’s lines. Can you pick out the lines that the group has since corrected. In order to cre- ders of our field. ate high definition video, we now utilize an reference an early 90’s song? In early 2009, the outreach group was HD video camera from the UW Student Tech Step three: filming. We used the department approached by UW’s Joint Institute for the Fee equipment office. We also now focus on Study of the Atmosphere and Ocean (JISAO) to video camera, providing us the flexibility to maintaining consistent audio throughout (care- participate in their Science in 180 initiative.
    [Show full text]
  • Variability of Vertical Structure of Precipitation with Sea Surface Temperature Over the 2 Arabian Sea and the Bay of Bengal As Inferred by TRMM PR Measurements
    1 1 Variability of vertical structure of precipitation with sea surface temperature over the 2 Arabian Sea and the Bay of Bengal as inferred by TRMM PR measurements 3 Kadiri Saikranthi1, Basivi Radhakrishna2, Thota Narayana Rao2 and 4 Sreedharan Krishnakumari Satheesh3 5 1 Department of Earth and Climate Science, Indian Institute of Science Education and 6 Research (IISER), Tirupati, India. 7 2 National Atmospheric Research Laboratory, Department of Space, Govt. of India, Gadanki 8 - 517112, India. 9 3 Divecha Centre for Climate Change, Centre for Atmospheric and Oceanic Sciences, Indian 10 Institute of Science, Bangalore - 560012, India. 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 Address of the corresponding author 31 Dr. K. Saikranthi, 32 Department of Earth and Climate Science, 33 Indian Institute of Science Education and Research (IISER), 34 Tirupati, 35 Andhra Pradesh, India. 36 Email: [email protected] 2 37 Abstract 38 Tropical rainfall measuring mission precipitation radar measurements are used to 39 examine the variation of vertical structure of precipitation with sea surface temperature (SST) 40 over the Arabian Sea (AS) and Bay of Bengal (BOB). The variation of reflectivity and 41 precipitation echo top with SST is remarkable over the AS but small over the BOB. The 42 reflectivity increases with SST (from 26°C to 31°C) by ~1 dBZ and 4 dBZ above and below 43 6 km, respectively, over the AS while, its variation is < 0.5 dBZ over the BOB. The 44 transition from shallow storms at lower SSTs (≤ 27°C) to deeper storms at higher SSTs is 45 strongly associated with the decrease in stability and mid-tropospheric wind shear over the 46 AS.
    [Show full text]
  • Diurnally Modulated Cumulus Moistening in the Preonset Stage of the Madden–Julian Oscillation During DYNAMO*
    1622 JOURNAL OF THE ATMOSPHERIC SCIENCES VOLUME 72 Diurnally Modulated Cumulus Moistening in the Preonset Stage of the Madden–Julian Oscillation during DYNAMO* JAMES H. RUPPERT JR. AND RICHARD H. JOHNSON Department of Atmospheric Science, Colorado State University, Fort Collins, Colorado (Manuscript received 28 July 2014, in final form 28 November 2014) ABSTRACT Atmospheric soundings, radar, and air–sea flux measurements collected during Dynamics of the Madden–Julian Oscillation (DYNAMO) are employed to study MJO convective onset (i.e., the transition from shallow to deep convection) in the tropical Indian Ocean. The findings indicate that moistening of the low–midtroposphere during the preonset stage of the MJO is achieved by simultaneous changes in the convective cloud population and large-scale circulation. Namely, cumuliform clouds deepen and grow in areal coverage as the drying by large-scale subsidence and horizontal (westerly) advection wane. The reduction of large-scale subsidence is tied to the reduction of column radiative cooling during the preonset stage, which ultimately links back to the evolving cloud population. While net column moistening in the preonset stage is tied to large-scale circulation changes, a new finding of this study is the high degree to which the locally driven diurnal cycle invigorates convective clouds and cumulus moistening each day. This diurnal cycle is manifest in a daytime growth of cumulus clouds (in both depth and areal coverage) in response to oceanic diurnal warm layers, which drive a daytime increase of the air–sea fluxes of heat and moisture. This diurnally modulated convective cloud field exhibits prominent mesoscale organization in the form of open cells and horizontal convective rolls.
    [Show full text]
  • Morphology, Intensity, and Rainfall Production of MJO Convection: Observations from DYNAMO Shipborne Radar and TRMM
    FEBRUARY 2015 X U A N D R U T L E D G E 623 Morphology, Intensity, and Rainfall Production of MJO Convection: Observations from DYNAMO Shipborne Radar and TRMM WEIXIN XU AND STEVEN A. RUTLEDGE Department of Atmospheric Science, Colorado State University, Fort Collins, Colorado (Manuscript received 1 May 2014, in final form 16 September 2014) ABSTRACT This study uses Dynamics of the Madden–Julian Oscillation (DYNAMO) shipborne [Research Vessel (R/V) Roger Revelle] radar and Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) datasets to investigate MJO-associated convective systems in specific organizational modes [mesoscale convective system (MCS) versus sub-MCS and linear versus nonlinear]. The Revelle radar sampled many ‘‘climatological’’ aspects of MJO convection as indicated by comparison with the long-term TRMM PR statistics, including areal-mean 2 rainfall (6–7 mm day 1), convective intensity, rainfall contributions from different morphologies, and their variations with MJO phase. Nonlinear sub-MCSs were present 70% of the time but contributed just around 20% of the total rainfall. In contrast, linear and nonlinear MCSs were present 10% of the time but contributed 20% and 50%, respectively. These distributions vary with MJO phase, with the largest sub-MCS rainfall fraction in suppressed phases (phases 5–7) and maximum MCS precipitation in active phases (phases 2 and 3). Similarly, convective–stratiform rainfall fractions also varied significantly with MJO phase, with the highest convective fractions (70%–80%) in suppressed phases and the largest stratiform fraction (40%–50%) in active phases. However, there are also discrepancies between the Revelle radar and TRMM PR.
    [Show full text]
  • 1 October-31 December 2003 Volume 18, Number 4
    Issue #25 and Volume 18, Number 4 1 October−31 December 2003 Editorial Researchers could also use the time between events to What to Do When the Pacific Is “pacific” update the various El Niño-related impacts maps for their regions, or for the entire globe. The public and media in We have recently emerged from a relatively weak El Niño different locations around the world take these maps (2002−03), and speculation and “guesstimates” by various seriously, viewing them as authoritative. These maps researchers have suggested that there would be a shift should be updated at regular intervals − say between El toward La Niña. This shift has not yet happened. For El Niño events, as researchers gather new insights with each Niño impacts researchers, this is rather boring. While the new warm event. Between El Niño, such as the present Pacific Ocean is “pacific,” it is difficult to write about time, researchers could compare societal responses to the something that seems to be boring in an exciting way. recent El Niño forecast (2002−03) with those for the 1997−98 event. Researchers have shown that together El Niño events and La Niña events occur about 55% of the time. This means that the sea surface temperatures in the equatorial Pacific are in a so-called “neutral” phase 45% of the time. That seems to be the phase of the El Niño-Southern Oscillation (ENSO) cycle at the present time. So, what are forecasters to do? What might impacts researchers do? What can the media write or discuss about El Niño or La Niña? Not much, apparently.
    [Show full text]
  • Miami, Florida AOML Science Program Assessed During
    Miami,Miami, FloridaFlorida AOMLAOMLKeynotes March-April 2008 Atlantic Oceanographic and Meteorological Laboratory Volume 12, Number 2 The contributions of the following individuals AOML Science Program Assessed during Quadrennial Review were instrumental to the success of AOML’s February and March were busy months at AOML as the Laboratory prepared for a quadrennial science review: critical assessment of its science program. On March 18-20th, five reviewers and several invited guests including Drs. Richard Spinrad and Alexander MacDonald of NOAA’s Climate Research Presentations: •Molly Baringer–Meridional Overturning Office of Oceanic and Atmospheric Research (OAR) visited AOML to participate in the Circulation Laboratory’s quadrennial science review. AOML Director Dr. Robert Atlas began the proceedings by presenting an organiza- •David Enfield–Large Scale Climate Dynamics tional overview of the Laboratory, followed by an overview of AOML’s three science divisions presented by Drs. Silvia •Chunzai Wang–Climate and Atlantic Garzoli, Frank Marks, and John Hurricane Activity Proni. •Gustavo Goni–Global Ocean Variability Reviewers were tasked with and Trends evaluating AOML’s science •Rick Lumpkin–Upper Ocean Dynamics program based upon three research themes derived from the mission Ecosystem Research Presentations: •Rik Wanninkhof–The AOML Ocean Carbon goals of NOAA’s Strategic Plan: Program oceans and climate, coastal ecosystems, and hurricanes. •James Hendee–Integrating Near Real-Time Data for Coral Reef Ecosystem Forecasting Science presentations for each theme (see shaded box to the left) Photo courtesy of Robert Houze •Christopher Kelble–The NOAA/AOML South were tailored to address a series Florida Ecosystem Restoration Program AOML Director Dr. Robert Atlas (left), invited guests, of key questions aimed at reviewers, and staff converge in the first-floor conference •Jia-Zhong Zhang–Nutrient Dynamics in the demonstrating the quality of the room during the three-day evaluation of AOML’s science Ocean research performed, its relevance program.
    [Show full text]