Relationship between horizontal wind velocity and normalized surface cross section using data from the HIWRAP dual-frequency airborne radar

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  • 1 NASA Goddard Space Flight Center, Code 612, Greenbelt, MD
  • 2 Goddard Earth Science Technology and Research, Morgan State University, Baltimore, MD
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Abstract

The HIWRAP dual-frequency conically-scanning airborne radar provides estimates of the range-profiled mean Doppler and backscattered power from the precipitation and surface. A VAD (velocity azimuth display) analysis yields near-surface estimates of the mean horizontal wind vector, vh, in cases where precipitation is present throughout the scan. From the surface return, the normalized radar cross section (NRCS) is obtained which, by a method previously described, can be corrected for path attenuation.

Comparisons between vh and the attenuation-corrected NRCS are used to derive transfer functions that provide estimates of the wind vector from the NRCS data under both rain and rain-free conditions. A reasonably robust transfer function is found by using the mean NRCS, 〈NRCS〉, over the scan along with a filtering of the data based on a Fourier series analysis of vh and the NRCS.

The approach gives good correlation coefficients between vh and 〈NRCS〉 at Ku-band at incidence angles of 300 and 400. The correlation degrades if the Ka-band data are used rather that the Ku-band.

Denotes content that is immediately available upon publication as open access.

Corresponding author: Robert Meneghini, robert.meneghini-1@nasa.gov

Abstract

The HIWRAP dual-frequency conically-scanning airborne radar provides estimates of the range-profiled mean Doppler and backscattered power from the precipitation and surface. A VAD (velocity azimuth display) analysis yields near-surface estimates of the mean horizontal wind vector, vh, in cases where precipitation is present throughout the scan. From the surface return, the normalized radar cross section (NRCS) is obtained which, by a method previously described, can be corrected for path attenuation.

Comparisons between vh and the attenuation-corrected NRCS are used to derive transfer functions that provide estimates of the wind vector from the NRCS data under both rain and rain-free conditions. A reasonably robust transfer function is found by using the mean NRCS, 〈NRCS〉, over the scan along with a filtering of the data based on a Fourier series analysis of vh and the NRCS.

The approach gives good correlation coefficients between vh and 〈NRCS〉 at Ku-band at incidence angles of 300 and 400. The correlation degrades if the Ka-band data are used rather that the Ku-band.

Denotes content that is immediately available upon publication as open access.

Corresponding author: Robert Meneghini, robert.meneghini-1@nasa.gov
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