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The National Aeronautics and Space Administration (NASA) and National Oceanic and Atmospheric Administration (NOAA) have a long and successful history of weather radar research. The NOAA ground-based radars—WSR-88D network—provide nationwide precipitation observations and estimates with advanced polarimetric capability. As a counterpart, the NASA–JAXA spaceborne radar—the Global Precipitation Measurement Dual-Frequency Precipitation Radar (GPM DPR)—has global coverage and higher vertical resolution than ground-based radars. While significant advances from both NOAA's WSR-88D network and NASA–JAXA's spaceborne radar DPR have been made, no systematic comparisons between the WSR-88D network and the DPR have been done. This study for the first time generates nationwide comprehensive comparisons at 136 WSR-88D radar sites from 2014 to 2020. Systematic differences in reflectivity are found, with ground radar reflectivity on average 2.4 dB smaller than that of the DPR (DPR version 6). This research found the discrepancies between WSR-88D and DPR arise from different calibration standards, signal attenuation correction, and differences in the ground and spaceborne scattering volumes. The recently updated DPR version 7 product improves rain detection and attenuation corrections, effectively reducing the overall average WSR-88D and DPR reflectivity differences to 1.0 dB. The goal of this study is to examine the systematic differences of radar reflectivity between the NOAA WSR-88D network and the NASA–JAXA DPR and to draw attention to radar-application users in recognizing their differences. Further investigation into understanding and alleviating the systematic bias between the two platforms is needed. [ABSTRACT FROM AUTHOR]

The scientific community has expressed interest in the potential of phased array radars (PARs) to observe the atmosphere with finer spatial and temporal scales. Although convergence has occurred between the meteorological and engineering communities, the need exists to increase access of PAR to meteorologists. Here, we facilitate these interdisciplinary efforts in the field of ground-based PARs for atmospheric studies. We cover high-level technical concepts and terminology for PARs as applied to studies of the atmosphere. A historical perspective is provided as context along with an overview of PAR system architectures, technical challenges, and opportunities. Envisioned scan strategies are summarized because they are distinct from traditional mechanically scanned radars and are the most advantageous for high-resolution studies of the atmosphere. Open access to PAR data is emphasized as a mechanism to educate the future generation of atmospheric scientists. Finally, a vision for the future of operational networks, research facilities, and expansion into complementary radar wavelengths is provided. [ABSTRACT FROM AUTHOR]

For nearly three decades, satellite nadir altimeters have provided essential information to understand primarily ocean but also inland water dynamics. A variety of parameters can be inferred via altimeter measurements, including sea surface height, sea surface wind speeds, significant wave heights, and topography of land, sea ice, and ice sheets. Taking advantage of these parameters with the long record of altimeter data spanning multiple decades has allowed a diverse range of societal applications. As the constellation of altimeter satellites grows, the proven value of the missions to a diverse user community can now be demonstrated by highlighting a selection of verifiable success stories. In this paper, we review selected altimeter success stories that incorporate altimetry data, alone or in conjunction with numerical models or other Earth observations, to solve a key societal problem. First, we define the problem or the key challenge of each use case, and then we articulate the uptake of the successful altimeter-based solution. Our review revealed steady progress by scientific and stakeholder communities in bridging the gap between data availability and their actual uptake to address a variety of applications. Highlighting these altimeter-based success stories can serve to further promote the widespread adoption of future satellite missions such as the Surface Water and Ocean Topography (SWOT) mission scheduled for launch in 2022. Knowledge of the breadth of current utility of altimeter observations can help the scientific community to demonstrate the value in continuing radar altimeter and similar missions, particularly those with expanded capabilities, such as SWOT. [ABSTRACT FROM AUTHOR]

With significant upgrades over the last decade, the Department of Energy's Atmospheric Radiation Measurement (ARM) radar network now features multiple scanning dual-polarization Doppler radars to exploit polarimetric, multifrequency, and multi-Doppler [...]

ABSTRACT The Tokyo Metropolitan Area Convection Study for Extreme Weather Resilient Cities (TOMACS) began as a Japanese domestic research project in 2010 and aimed to elucidate the mechanisms behind local [...]

The Flexible Array of Radars and Mesonets (FARM) Facility is an extensive mobile/quickly deployable (MQD) multiple-Doppler radar and in situ instrumentation network. The FARM includes four radars: two 3-cm dual polarization, dual frequency (DPDF), Doppler on Wheels (DOW6/DOW7), the Rapid-Scan DOW (RSDOW), and a quickly deployable (QD) DPDF 5-cm C band on Wheels (COW). The FARM includes three mobile mesonet (MM) vehicles with 3.5-m masts, an array of rugged QD weather stations (PODNET), QD weather stations deployed on infrastructure such as light/power poles (POLENET), four disdrometers, six MQD upper-air sounding systems and a Mobile Operations and Repair Center (MORC). The FARM serves a wide variety of research/educational uses. Components have deployed to >30 projects during 1995–2020 in the United States, Europe, and South America, obtaining pioneering observations of a myriad of small spatial- and temporal-scale phenomena including tornadoes, hurricanes, lake-effect snow storms, aircraft-affecting turbulence, convection initiation, microbursts, intense precipitation, boundary layer structures and evolution, airborne hazardous substances, coastal storms, wildfires and wildfire suppression efforts, weather modification effects, and mountain/alpine winds and precipitation. The radars and other FARM systems support innovative educational efforts, deploying >40 times to universities/colleges, providing hands-on access to cutting-edge instrumentation for their students. The FARM provides integrated multiple radar, mesonet, sounding, and related capabilities enabling diverse and robust coordinated sampling of three-dimensional vector winds, precipitation, and thermodynamics increasingly central to a wide range of mesoscale research. Planned innovations include S-band on Wheels Network (SOWNET) and Bistatic Adaptable Radar Network (BARN), offering more qualitative improvements to the field project observational paradigm, providing broad, flexible, and inexpensive 10-cm radar coverage and vector wind field measurements. [ABSTRACT FROM AUTHOR]

This article summarizes research and risk reduction that will inform acquisition decisions regarding NOAA's future national operational weather radar network. A key alternative being evaluated is polarimetric phased-array radar (PAR). Research indicates PAR can plausibly achieve fast, adaptive volumetric scanning, with associated benefits for severe-weather warning performance. We assess these benefits using storm observations and analyses, observing system simulation experiments, and real radar-data assimilation studies. Changes in the number and/or locations of radars in the future network could improve coverage at low altitude. Analysis of benefits that might be so realized indicates the possibility for additional improvement in severe-weather and flash-flood warning performance, with associated reduction in casualties. Simulations are used to evaluate techniques for rapid volumetric scanning and assess data quality characteristics of PAR. Finally, we describe progress in developing methods to compensate for polarimetric variable estimate biases introduced by electronic beam-steering. A research-to-operations (R2O) strategy for the PAR alternative for the WSR-88D replacement network is presented. [ABSTRACT FROM AUTHOR]

Did you know that aircraft can cause lightning? Researchers began investigating aircraft-triggered lightning after several cases were observed of aircraft receiving lightning strikes from lightning-inactive clouds. The phenomenon of aircraft-triggered [...]

Crowdsourcing is an observational method that has gained increasing popularity in recent years. In hail research, crowdsourced reports bridge the gap between heuristically defined radar hail algorithms, which are automatic [...]

ABSTRACT In recent years, hail accumulations from thunderstorms have occurred frequently enough to catch the attention of the National Weather Service, the general public, and news agencies. Despite the extreme [...]

Improving our ability to predict future weather and climate conditions is strongly linked to achieving significant advancements in our understanding of cloud and precipitation processes. Observations are critical to making these advancements because they both improve our understanding of these processes and provide constraints on numerical models. Historically, instruments for observing cloud properties have limited cloud–aerosol investigations to a small subset of cloud-process interactions. To address these challenges, the last decade has seen the U.S. DOE ARM facility significantly upgrade and expand its surveillance radar capabilities toward providing holistic and multiscale observations of clouds and precipitation. These upgrades include radars that operate at four frequency bands covering a wide range of scattering regimes, improving upon the information contained in earlier ARM observations. The traditional ARM emphasis on the vertical column is maintained, providing more comprehensive, calibrated, and multiparametric measurements of clouds and precipitation. In addition, the ARM radar network now features multiple scanning dual-polarization Doppler radars to exploit polarimetric and multi-Doppler capabilities that provide a wealth of information on storm microphysics and dynamics under a wide range of conditions. Although the diversity in wavelengths and detection capabilities are unprecedented, there is still considerable work ahead before the full potential of these radar advancements is realized. This includes synergy with other observations, improved forward and inverse modeling methods, and well-designed data–model integration methods. The overarching goal is to provide a comprehensive characterization of a complete volume of the cloudy atmosphere and to act as a natural laboratory for the study of cloud processes. [ABSTRACT FROM AUTHOR]

Descriptions of the experimental design and research highlights obtained from a series of four multiagency field projects held near Cape Canaveral, Florida, are presented. The experiments featured a 3 MW, dual-polarization, C-band Doppler radar that serves in a dual capacity as both a precipitation and cloud radar. This duality stems from a combination of the radar's high sensitivity and extremely small-resolution volumes produced by the narrow 0.22° beamwidth and the 0.543 m along-range resolution. Experimental highlights focus on the radar's real-time aircraft tracking capability as well as the finescale reflectivity and eddy structure of a thin nonprecipitating stratus layer. Examples of precipitating storm systems focus on the analysis of the distinctive and nearly linear radar reflectivity signatures (referred to as "streaks") that are caused as individual hydrometeors traverse the narrow radar beam. Each streak leaves a unique radar reflectivity signature that is analyzed with regard to estimating the underlying particle properties such as size, fall speed, and oscillation characteristics. The observed along-streak reflectivity oscillations are complex and discussed in terms of diameter-dependent drop dynamics (oscillation frequency and viscous damping time scales) as well as radar-dependent factors governing the near-field Fresnel radiation pattern and inferred drop–drop interference. [ABSTRACT FROM AUTHOR]

Motor vehicle crashes remain a leading cause of accidental death in the United States, and weather is frequently cited as a contributing factor in fatal crashes. Previous studies have investigated the link between these crashes and precipitation typically using station-based observations that, while providing a good estimate of the prevailing conditions on a given day or hour, often fail to capture the conditions present at the actual time and location of a crash. Using a multiyear, high-resolution radar reanalysis and information on 125,012 fatal crashes spanning the entire continental United States over a 6-yr period, we find that the overall risk of a fatal crash increases by approximately 34% during active precipitation. The risk is significant in all regions of the continental United States, and it is highest during the morning rush hour and during the winter months. [ABSTRACT FROM AUTHOR]

PyTroll (http://pytroll.org) is a suite of open-source easy-to-use Python packages to facilitate processing and efficient sharing of Earth Observation (EO) satellite data. The PyTroll software is intended for both 24/7 real-time operations as well as research and development. PyTroll grew out of the need to provide a resilient and agile platform that can respond quickly to new user needs and new data sources. PyTroll, being open source, stimulates international collaboration, which is vital with the rapid increase of satellite information availability. The PyTroll software development is strongly user driven and has grown over the past eight years from a collaborative effort between the Danish and Swedish national meteorological services to encompass a worldwide community with active contributors. PyTroll is being used at least operationally in the national meteorological services of Denmark, Norway, Sweden, Finland, Germany, Switzerland, Italy, Estonia, and Latvia. However, given its simplicity, minimal demand on user resources, and community-driven approach, it also encourages and facilitates usage of EO data for individual applications. While PyTroll was originally developed to cater to the needs of the atmospheric remote sensing community, it could be equally useful for land and ocean applications and within hydrology. This article provides an overview of PyTroll, with examples showing the capability of some of the core packages. [ABSTRACT FROM AUTHOR]

The article presents a study on tropical cyclone (TC)–associated enhanced Fujita 3 (EF3) tornado in China. Topics discussed include the relationship between the condensation funnel, damage swath, and radar observations; TC tornadoes tend to be spawned from minisupercells in the right-front from their parent TC; and discusses the visual observations such as number of urban traffic surveillance videos of strong winds, and publicly available photographs.

Roughly speaking, a tornado consists of an inner core that rotates as a solid body surrounded by an outer flow where the circulation is constant. Generally Doppler radar does not [...]

The article reports on the Multi-Radar Multi-Sensor (MRMS) system that was developed at the National Severe Storms Laboratory and the University of Oklahoma. It mentions that the MRMS system is being used at the U.S. National Centers for Environmental Prediction (NCEP). It also highlights the MRMS-Severe/Aviation system that is motivated for desire to enable forecasters to easily integrate data from multiple sources.

A National Science Foundation sponsored educational deployment of a Doppler on Wheels radar called the Hawaiian Educational Radar Opportunity (HERO) was conducted on Oahu from 21 October to 13 November 2013. This was the first-ever deployment of a polarimetric X-band (3 cm) research radar in Hawaii. A unique fine-resolution radar and radiosonde dataset was collected during 16 intensive observing periods through a collaborative effort between University of Hawai'i at Manoa undergraduate and graduate students and the National Weather Service's Weather Forecast Office in Honolulu. HERO was the field component of MET 628 "Radar Meteorology," with 12 enrolled graduate students who collected and analyzed the data as part of the course. Extensive community outreach was conducted, including participation in a School of Ocean and Earth Science and Technology open house event with over 7,500 visitors from local K-12 schools and the public. An overview of the HERO project and highlights of some interesting tropical rain and cloud observations are described. Phenomena observed by the radar include cumulus clouds, trade wind showers, deep convective thunderstorms, and a widespread heavy rain event associated with a cold frontal passage. Detailed cloud and precipitation structures and their interactions with O'ahu terrain, unique dual-polarization signatures, and the implications for the dynamics and microphys-ics of tropical convection are presented. [ABSTRACT FROM AUTHOR]

With funding provided by the 2012 Disaster Relief Act (Sandy Supplemental), NOAA's Earth System Research Laboratory Physical Sciences Division has installed three Doppler wind-profiling radars and surface meteorology towers along the U.S. Gulf and southeast coasts to help detect and monitor land falling tropical storms and other high-impact weather events. This same combination of instruments has been used to monitor landfalling atmospheric rivers on the U.S. West Coast. For this reason, we refer to the whole collection of instruments at each site as an Atmospheric River Observatory (ARO). These three new AROs supported by the Sandy Supplemental complement a fourth ARO deployed in coastal North Carolina as part of NOAA's Hydrometeorology Testbed Southeast Pilot Study. These four AROs were installed in time to capture the 2014 hurricane season and will be operated through the 2015 hurricane season. [ABSTRACT FROM AUTHOR]

Roddy Rhodes Rogers, professor emeritus of atmospheric science, passed away on February 20, 2019, at the age of 85. Rogers devoted his career to atmospheric remote sensing using Doppler radar, [...]

The operational weather radar network in Europe covers more than 30 countries and contains more than 200 weather radars. The radar network is heterogeneous in hardware, signal processing, transmit/receive frequency, and scanning strategy, thus making it fundamentally different than the Next Generation Weather Radar (NEXRAD) network. Another difference is that the density of the European weather radar network is roughly twice that of the NEXRAD network. Within the European National Meteorological Services (EUMETNET), a grouping of services, the Operational Program for Exchange of Weather Radar Information (OPERA) has been working since 1999 on improving the harmonization of radars and their measurements. In addition, OPERA has facilitated and stimulated the exchange of radar data between its members, among others, by the development of a radar data information model and jointly agreed data formats. Since 2011, a radar data center ('Odyssey') has been in operation, producing network-wide radar mosaics from volumetric data. An essential part of the OPERA work is the documentation of the members' best practices in radar operation and data production and the making of joint recommendations: for example, on the interferences caused by other microwave sources and the disturbances caused by wind turbines. Hence, the expertise of the most experienced members is made available to all members supporting the development of the network as a whole. Recent work has produced reports on best practices for production of radar data, on quality indicators, and on experiences with the use of polarimetric radars. All of these reports and recommendations are publicly available on the OPERA website, for use by the wider meteorological community. [ABSTRACT FROM AUTHOR]

With the unusually violent tornado season of 2011, there has been a renewed national interest, through such programs as NOAA's Weather Ready Nation initiative, to reevaluate and improve our tornado warning process. This literature review provides an interdisciplinary, end-to-end examination of the tornado warning process. Following the steps outlined by the Integrated Warning System, current research in tornado prediction and detection, the warning decision process, warning dissemination, and public response are reviewed, and some of the major challenges for improving each stage are highlighted. The progress and challenges in multi-day to short-term tornado prediction are discussed, followed by an examination of tornado detection, focused primarily upon the contributions made by weather radar and storm spotters. Next is a review of the warning decision process and the challenges associated with dissemination of the warning, followed by a discussion of the complexities associated with understanding public response. Finally, several research opportunities are considered, with emphases on understanding acceptable risk, greater community and personal preparation, and personalization of the hazard risk. [ABSTRACT FROM AUTHOR]

In 2008, the Canadian Space Agency sponsored the Radarsat Hurricane Applications Project (RHAP), for researching new developments in the application of Radarsat-1 synthetic aperture radar (SAR) data and innovative mapping approaches to better understand the dynamics of tropical cyclone genesis, morphology, and movement. Although tropical cyclones can be detected by many remote sensors, SAR can yield high-resolution (subkilometer) and low-level storm information that cannot be seen below the clouds by other sensors. In addition to the wind field and tropical cyclone eye information, structures associated with atmospheric processes can also be detected by SAR. We have acquired 161 Radarsat-1 SAR images through RHAP between 2001 and 2007. Among these, 73 images show clear tropical cyclone eye structure. In addition, we also acquired 10 images from the European Space Agency's Envisat SAR between 2004 and 2010. Both Atlantic hurricanes and Pacific typhoons are included. In this study, we analyze these 83 (73 Radarsat-1 and 10 Envisat) images with tropical cyclone eye information along with ancillary tropical cyclone intensity information from the archive to generate tropical cyclone morphology statistics. Histograms of wave-number asymmetry and intensity are presented. The statistics show that when the storm has higher intensity, the tropical cyclone eye tends to become more symmetric, and the area of the tropical cyclone eye, defined by the minimum wind area, tends to be smaller. Examples of finescale structures within the tropical cyclone (i.e., eye/eyewall mesovortices, arc clouds, double eyewalls, and abnormally high wind or rain within eyes) are presented and discussed. [ABSTRACT FROM AUTHOR]

The second Verification of the Origins of Rotation in Tornadoes Experiment (VORTEX2), which had its field phases in May and June of 2009 and 2010, was designed to " explore i) the physical processes of tornadogenesis, maintenance, and demise; ii) the relationships among tornadoes, tornadic storms, and the larger-scale environment; iii) numerical weather prediction and forecasting of supercell thunderstorms and tornadoes; and iv) the wind field near the ground in tornadoes. VORTEX2 is by far the largest and most ambitious observational and modeling study of tornadoes and tornadic storms ever undertaken. It employed 13 mobile mesonet-instrumented vehicles, 11 ground-based mobile radars (several of which had dual-polarization capability and two of which were phased-array rapid scan), a mobile Doppler lidar, four mobile balloon sounding systems, 42 deployable in situ observational weather stations, an unmanned aerial system, video and photogrammetric teams, damage survey teams, deployable disdrometers, and other experimental instrumentation as well as extensive modeling studies of tornadic storms. Participants were drawn from more than 15 universities and laboratories and at least five nations, with over 80 students participating in field activities. The VORTEX2 field phases spanned 2 yr in order to increase the probability of intercepting significant tornadoes, which are rare events. The field phase of VORTEX2 collected data in over three dozen tornadic and nontornadic supercell thunderstorms with unprecedented detail and diversity of measurements. Some preliminary data and analyses from the ongoing analysis phase of VORTEX2 are shown. [ABSTRACT FROM AUTHOR]

Advancements in radar technology since the deployment of the Weather Surveillance Radar-1988 Doppler (WSR-88D) network have prompted consideration of radar replacement technologies. In order for the outcomes of advanced radar research and development to be the most beneficial to users, an understanding of user needs must be established early in the process and considered throughout. As an important early step in addressing this need, this study explored the strengths and limitations of current radar systems for nine participants from two key stakeholder groups: NOAA's NWS and broadcast meteorologists. Critical incident interviews revealed the role of each stakeholder group and attained stories that exemplified radar strengths and limitations in their respective roles. NWS forecasters emphasized using radar as an essential tool to assess the current weather situation and communicate hazards to key stakeholder groups. TV broadcasters emphasized adding meaning and value to NWS information and using radar to effectively communicate weather information to viewers. The stories told by our participants vividly illustrated the advancing nature of weather detection with radar, and why there are still issues with weather radar and radar-derived information. Analysis of the stories, which ranged from accounts of severe weather to winter weather, revealed four underlying radar needs: 1) clean, accurate data without intervention, 2) higher spatial- and temporal-resolution data than that provided by the WSR-88D, 3) consistent and low-altitude information, and 4) more accurate information on precipitation type, size, intensity, and distribution. A supplement to this article is available online: [ABSTRACT FROM AUTHOR]

The article focuses on capabilities of weather radar in the measurement of rainfall. It discusses the possible impact of the errors in rain gauge measurements of rainfall and sampling uncertainties. It explores operational utility of radar rainfall estimation and promoted its use in flash flood forecasting.

Information about several papers discussed at a symposium on the development of radar technology for weather surveillance is presented. Topics include the efforts key to a successful multifunction phased array radar (MPAR) risk-reduction plan, the future Federal Aviation Administration challenges, and the mission requirements for aircraft detection. The symposium featured several leaders from different agencies including Mary Glackin, Victoria Cox and Randel Zeller.

The article focuses on the implementation of dual-polarization radar in the validation process of Global Precipitation Measurement (GPM) mission, currently a prototype which measure precipitation accurately. GPM is a science mission designed to provide detailed information on global water/energy cycle variability and to improve meteorological predictions. Its GPM core satellite is equipped with a dual-frequency precipitation radar (DPR) which will gather precipitation measurement that needs to be validated. It says that the dual-polarization weather radar can be used as a validation tool that could be applied to GPM to provide data related to hydrometeor phase/type information and droplet size distribution properties.

The article provides information about the Collaborative Radar Acquisition Field Test (CRAFT) Project. The benefits of the CRAFT methodology include utilization of open source software, and networking technology. The NWS adopted the project for its implementation across the contiguous United States (CONUS) and select DOD radars wherein CRAFT demonstrated that Weather Surveillance Radar-1988 Doppler (WSR-88D) level II data could be virtually transferred to any user without lossing its content and at low cost using software and telecommunications infrastructures for radar sites. Moreover, NWS's operational data distribution system's architecture offers future inclusion of other radars such as the National Weather Radar Testbed Phased Array Radar, and others

The instruments on the Tropical Rainfall Measuring Mission (TRMM) satellite have been observing storms as well as rainfall since December 1997. This paper shows the results of a systematic search through seven full years of the TRMM database to find indicators of uncommonly intense storms. These include strong (> 40 dBZ) radar echoes extending to great heights, high lightning flash rates, and very low brightness temperatures at 37 and 85 GHz. These are used as proxy variables, indicating powerful convective updrafts. The main physical principles supporting this assertion involve the effects of such updrafts in producing and lofting large ice particles high into the storm, where TRMM's radar easily detects them near storm top. TRMM's passive microwave radiometer detects the large integrated ice water path as very low brightness temperatures, while high lightning flash rates are a physically related but instrumentally independent indicator. The geographical locations of these very intense convective storms demonstrate strong regional preferences for certain land areas while they are extremely rare over tropical oceans. Favored locations include the south-central United States, southeast South America, and equatorial Africa. Other regions have extreme storms mainly in specific seasons, such as the Sahel, the Indian subcontinent, and northern Australia. Because intense storms are distributed quite differently from rainfall, these maps provide some new metrics for global models, if they are to simulate the type of convection as a component of our climate system. [ABSTRACT FROM AUTHOR]

The steeply rising coastal terrain of southeast Alaska can produce a wide variety of terrain-induced flows such as barrier jets, gap flows, and downslope wind storms. This study uses a combination of satellite remote sensing, field observations, and modeling to improve our understanding of the dynamics of these flows. After examining several thousand synthetic aperture radar (SAR) high-resolution wind speed images over the Gulf of Alaska, several subclasses of barrier jets were identified that do not fit the current conceptual model of barrier jet development. This conceptual model consists of an acceleration and turning of the ambient cross-barrier flow into the along-barrier direction when the ambient low-level flow is blocked by terrain; however, the SAR imagery showed many barrier jet cases with significant flow variability in the along-coast direction as well as evidence for the influence of cold, dry continental air exiting the gaps in coastal terrain. A subclass of jets has been observed where the transition from the coastal to the offshore flow is abrupt. The results from these climatological studies have motivated modeling studies of selected events as well as field observations from the Southeast Alaska Regional Jets (SARJET) experiment field campaign in the Gulf of Alaska during fall of 2004. This paper will highlight preliminary results obtained during SARJET, which collected in situ measurements of barrier jets and gap flows using the University of Wyoming's King Air research aircraft. [ABSTRACT FROM AUTHOR]