Adaptive Range Oversampling Processing for Nontraditional Radar-Variable Estimators

Christopher D. Curtis Cooperative Institute for Mesoscale Meteorological Studies, University of Oklahoma, and NOAA/OAR/National Severe Storms Laboratory, Norman, Oklahoma

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Sebastián M. Torres Cooperative Institute for Mesoscale Meteorological Studies, University of Oklahoma, and NOAA/OAR/National Severe Storms Laboratory, Norman, Oklahoma

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Abstract

Adaptive range oversampling processing can be used either to reduce the variance of radar-variable estimates without increasing scan times or to reduce scan times without increasing the variance of estimates. For example, an implementation of adaptive pseudowhitening on the National Weather Radar Testbed Phased-Array Radar (NWRT PAR) led to a twofold reduction in scan times. Conversely, a proposed implementation of adaptive pseudowhitening the U.S. Next Generation Weather Radar (NEXRAD) network would reduce the variance of dual-polarization estimates while keeping current scan times. However, the original version of adaptive pseudowhitening is not compatible with radar-variable estimators for which an explicit variance expression is not readily available. One such nontraditional estimator is the hybrid spectrum-width estimator, which is currently used in the NEXRAD network. In this paper, an extension of adaptive pseudowhitening is proposed that utilizes lookup tables (rather than analytical solutions based on explicit variance expressions) to obtain range oversampling transformations. After describing this lookup table (LUT) adaptive pseudowhitening technique, its performance is compared to that of the original version of adaptive pseudowhitening using traditional radar-variable estimators. LUT adaptive pseudowhitening is then applied to the hybrid spectrum-width estimator, and simulation results are confirmed with a qualitative analysis of radar data.

© 2017 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses).

Corresponding author: Christopher Curtis, chris.curtis@noaa.gov

Abstract

Adaptive range oversampling processing can be used either to reduce the variance of radar-variable estimates without increasing scan times or to reduce scan times without increasing the variance of estimates. For example, an implementation of adaptive pseudowhitening on the National Weather Radar Testbed Phased-Array Radar (NWRT PAR) led to a twofold reduction in scan times. Conversely, a proposed implementation of adaptive pseudowhitening the U.S. Next Generation Weather Radar (NEXRAD) network would reduce the variance of dual-polarization estimates while keeping current scan times. However, the original version of adaptive pseudowhitening is not compatible with radar-variable estimators for which an explicit variance expression is not readily available. One such nontraditional estimator is the hybrid spectrum-width estimator, which is currently used in the NEXRAD network. In this paper, an extension of adaptive pseudowhitening is proposed that utilizes lookup tables (rather than analytical solutions based on explicit variance expressions) to obtain range oversampling transformations. After describing this lookup table (LUT) adaptive pseudowhitening technique, its performance is compared to that of the original version of adaptive pseudowhitening using traditional radar-variable estimators. LUT adaptive pseudowhitening is then applied to the hybrid spectrum-width estimator, and simulation results are confirmed with a qualitative analysis of radar data.

© 2017 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses).

Corresponding author: Christopher Curtis, chris.curtis@noaa.gov
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  • Curtis, C., and S. Torres, 2011: Adaptive range oversampling to achieve faster scanning on the National Weather Radar Testbed phased-array radar. J. Atmos. Oceanic Technol., 28, 15811597, doi:10.1175/JTECH-D-10-05042.1.

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  • Curtis, C., and S. Torres, 2013: Real-time measurement of the range correlation for range oversampling processing. J. Atmos. Oceanic Technol., 30, 28852895, doi:10.1175/JTECH-D-13-00090.1.

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  • Curtis, C., and S. Torres, 2014: Adaptive range oversampling to improve estimates of polarimetric variables on weather radars. J. Atmos. Oceanic Technol., 31, 18531866, doi:10.1175/JTECH-D-13-00216.1.

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  • Torres, S. and D. Zrnić, 2003b: Whitening of signals in range to improve estimates of polarimetric variables. J. Atmos. Oceanic Technol., 20, 17761789, doi:10.1175/1520-0426(2003)020<1776:WOSIRT>2.0.CO;2.

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  • Torres, S., and C. Curtis, 2012: The impact of signal processing on the range weighting function for weather radars. J. Atmos. Oceanic Technol., 29, 796806, doi:10.1175/JTECH-D-11-00135.1.

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  • Torres, S., and C. Curtis, 2013: The importance of accurately measuring the range correlation for range oversampling processing. J. Atmos. Oceanic Technol., 30, 261273, doi:10.1175/JTECH-D-12-00085.1.

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  • Torres, S., C. Curtis, and J. R. Cruz, 2004: Pseudowhitening of weather radar signals to improve spectral moment and polarimetric variable estimates at low signal-to-noise ratios. IEEE Trans. Geosci. Remote Sens., 42, 941949, doi:10.1109/TGRS.2004.825579.

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