Operational Weather Radar in the United States: Progress and Opportunity

Serafin, Robert; Wilson, James W.

doi:10.1175/1520-0477(2000)081<0501:owritu>2.3.co;2

Cited by 98 publications

(60 citation statements)

References 34 publications

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“…The United States operational WSR-88D Doppler radar network (NEXRAD) is a vital tool for the real-time detection and warning of hazardous weather (Crum and Albert, 1993;Crum et al, 1998;Serafin and Wilson, 2000). It is also an essential observing system for initializing non-hydrostatic, storm-resolving (i.e., horizontal grid spacing on the order of 1 km) numerical weather prediction (NWP) models (e.g., Lilly, 1990;Droegemeier, 1990Droegemeier, , 1997.…”

Section: Introductionmentioning

confidence: 99%

Variation of radio refractivity with respect to moisture and temperature and influence on radar ray path

2008

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In this study, the variation of radio refractivity with respect to temperature and moisture is analyzed. Also, the effects of vertical gradients in temperature and moisture on the propagation paths of electromagnetic waves of weather radar are examined for several sites across the United States using several years of sounding data from the National Weather Service. The ray path is important for identifying storm characteristics and for properly using the radar data in initializing numerical weather prediction models. It is found that during the warm season the radio refractivity gradient is more sensitive to moisture gradients than to temperature gradients. Ray paths from the commonly accepted vertical ray path model are compared to a ray path computed from a stepwise ray tracing algorithm using data from actual soundings. For the sample of about 16 000 soundings examined, we find that only a small fraction of the ray paths diverge significantly from those calculated using a ray path model based on the US Standard Atmosphere. While the problem of ray ducting in the presence of a temperature inversion is fairly well known, we identify the presence of a strong vertical moisture gradient as the culprit in the majority of the cases where significant deviations occurred.Key words: radio refractivity, radar ray path Citation: Gao, J. D., K. Brewster, and M. Xue, 2008: Variation of radio refractivity with respect to moisture and temperature and influence on radar ray path.

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Section: Introductionmentioning

confidence: 99%

Variation of radio refractivity with respect to moisture and temperature and influence on radar ray path

2008

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“…The MIT Lincoln Laboratory (Weber et al, 2005) have recently begun exploratory research on the capabilities and technology issues related to the use of multi-function phased array radar (MPAR) as a possible replacement approach for the 10-cm wavelength NEXRAD or WSR88-D (Serafin and Wilson, 2000) national-scale weather radar network. This is managed jointly by the NWS, the Federal Aviation Administration (FAA), and the Department of Defense (DoD).…”

Section: Dual Polarization Scanning X-band Cloud Radar (Dps-x)mentioning

confidence: 99%

The Status of the ACRF Millimeter Wave Cloud Radars (MMCRs), the Path Forward for Future MMCR Upgrades, the Concept of 3D Volume Imaging Radar and the UAV Radar

Kollias¹,

Miller²,

Widener³

et al. 2005

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Executive SummaryThe United States (U.S.) Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility (ACRF) operates millimeter wavelength cloud radars (MMCRs) in several climatological regimes. The MMCRs, are the primary observing tool for quantifying the properties of nearly all radiatively important clouds over the ACRF sites. The first MMCR was installed at the ACRF Southern Great Plains (SGP) site nine years ago and its original design can be traced to the early 90s. Since then, several MMCRs have been deployed at the ACRF sites, while no significant hardware upgrades have been performed. Recently, a two-stage upgrade (first C-40 Digital Signal Processors [DSP]-based, and later the PC-Integrated Radar AcQuisition System [PIRAQ-III] digital receiver) of the MMCR signal-processing units was completed.Our future MMCR related goals are: 1) to have a cloud radar system that continues to have high reliability and uptime and 2) to suggest potential improvements that will address increased sensitivity needs, superior sampling and low cost maintenance of the MMCRs. The Traveling Wave Tube (TWT) technology, the frequency (35-GHz), the radio frequency (RF) layout, antenna, the calibration and radar control procedure and the environmental enclosure of the MMCR remain assets for our ability to detect the profile of hydrometeors at all heights in the troposphere at the ACRF sites.In the near-term (0-2 years), the ACRF should proceed with the upgrade of the remaining MMCR with the PIRAQ-III digital receiver. The upgrade (completed in early 2007) will bring commonality among the 5 operational MMCR at the ACRF sites, reduce the maintenance costs, and provide uniform temporal resolution and radar operational modes in all the ACRF sites. Each signal processing unit upgrade is estimated to ~$30K per MMCR.In the long term (2-5 years) the ACRF should pursue the development of a high-performance digital data processor and timing controller implemented in field-programmable gate arrays (FPGA) that will replace the existing intermediate frequency (IF) hardware/software and timing MMCR components. The digital radar transceiver will replace the analog radar waveform generator that generates the pulse compression (frequency modulation of the transmitted waveform technique that results to higher sensitivity) with a direct digital synthesis (DDS) PC-based card. Furthermore, the current IF section of the MMCR will be replaced with an FPGA-based digital receiver that will offer higher flexibility, direct control of the radar waveform through the DDS, and higher overall MMCR performance. This development can be the focus of DOE's Small Business Innovation Research (SBIR) (proposed in 2006, completed in 2008), with an objective to develop a digital radar transceiver and timing unit suitable for ground-based cloud and precipitation profiling radars that utilizes chirp pulse waveforms and fast Fourier transform (FFT) processing for superior performance and multi-functionality. This development should be the ...

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“…Diverses voies ont été proposées sans qu'aucune ne parvienne à convaincre suffisamment pour être transférée à l'opérationnel : on pourra lire à ce sujet l'article de synthèse de Joss et Waldvogel (1990) ou celui de Sauvageot (1994a). Cependant, au cours des dernières années, les méthodes dérivées de la mesure polarimétrique semblent avoir ouvert de réelles possibilités et il est envisagé de mettre en oeuvre certains algorithmes polarimétriques sur le réseau Nexrad (Serafin et Wilson, 1999).…”

Section: Les Bandes De Fréquence Utilisées En Météorologie Radarunclassified

Le radar polarimétrique, une nouvelle approche pour l'observation des champs de précipitations

Sauvageot¹

2000

Météorologie

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Pour l'observation des champs de précipitations instantanés, on utilise des réseaux de radars. Cependant, les algorithmes de restitution des intensités de précipitations à partir de la réflectivité radar ne permettent pas d'obtenir une précision satisfaisante. Parmi les diverses voies explorées ou proposées pour améliorer la qualité des résultats, les méthodes polarimé-triques sont les plus prometteuses. Dans cet article, après avoir rappelé pourquoi et comment les radars « voient » les précipitations, les principaux concepts qui sous-tendent les méthodes polarimétriques sont présentés et les solutions proposées sont discutées de façon comparative. Les premiers algorithmes polarimétriques n'ont pas apporté d'amélioration décisive, en raison de leur sensibilité aux erreurs dues à l'atténuation et à l'étalonnage. Les algorithmes de polarimétrie différentielle récemment proposés semblent capables de surmonter la plupart des problèmes puisqu'ils ne sont pas, ou peu, affectés par l'atténuation, par les variations de la distribution de taille des gouttes, par les occultations de faisceau, par les échos de sol, par la grêle. Ils peuvent être utilisés pour détecter les propagations anormales et ils sont indépendants de l'étalonnage du radar. Cependant, leur validation en conditions opérationnelles reste à faire. Polarimetric radar: a new approach for rain-field observationA meteorological radar network is indispensable for instantaneous precipitation field observation. However, the usual rain-rate retrieval algorithms do not have sufficient accuracy. Polarimetric methods are the most promising of the various ways investigated, or proposed, to increase the effectiveness of radar estimation of rainfall. This paper first reminds why and how radars "see" precipitation, then presents the main concepts underlying the polarimetric methods and finally compares the solutions proposed. The early polarimetric algorithms did not bring any decisive improvement because of their sensitivity to attenuation and calibration error. The differential polarimetric algorithms recently proposed seem able to overcome most of the problems since they are not, or are only weakly, affected by attenuation, variations in drop-size distribution, beam occultation, ground clutter or hail. They also enable the detection of anomalous propagation and are independent of the radar calibration. However polarimetric methods have yet to be validated in operational conditions.

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Operational Weather Radar in the United States: Progress and Opportunity

Cited by 98 publications

References 34 publications

Variation of radio refractivity with respect to moisture and temperature and influence on radar ray path

Variation of radio refractivity with respect to moisture and temperature and influence on radar ray path

The Status of the ACRF Millimeter Wave Cloud Radars (MMCRs), the Path Forward for Future MMCR Upgrades, the Concept of 3D Volume Imaging Radar and the UAV Radar

Le radar polarimétrique, une nouvelle approche pour l'observation des champs de précipitations

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