Summary and analysis of 216 GHz polarimetric measurements of in-situ rain

Abigail S. Hedden; David A. Wikner; Russell W. Bradley

doi:10.1117/12.2177805

19 May 2015 Summary and analysis of 216 GHz polarimetric measurements of in-situ rain

Abigail S. Hedden, David A. Wikner, Russell W. Bradley

Proceedings Volume 9462, Passive and Active Millimeter-Wave Imaging XVIII; 94620G (2015) https://doi.org/10.1117/12.2177805
Event: SPIE Defense + Security, 2015, Baltimore, MD, United States

Abstract

The Army Research Laboratory (ARL) has developed a polarimetric frequency-modulated continuous-wave (FMCW) instrumentation radar that has been used to study the polarization and backscatter properties of in-situ rain in the 220 GHz atmospheric window. A summary of the preliminary measurements is presented in this work including an analysis of the co-polarization backscatter and attenuation characteristics measured at 216 GHz. A marginal detection of the copolarization backscatter signature of rain was made during a series of fast-moving, heavy downpour thunderstorm events. A detection limit of -40±3 dB[m²/m³] was found for the VV-polarization cross section per unit volume for rain rates up to 150 mm/hr. Co-polarization (VV- and HH-polarization) attenuation characteristics measured at high rain rates (< 20 mm/hr) were well described by a Joss thunderstorm drop distribution in the high frequency limit, where drop size is much greater than the observation wavelength. Observations at 216 GHz suggest attenuation levels of 8-10 dB/km at rain rates above 20 mm/hr, strengthening previous evidence that attenuation through rain is independent of frequency under high rain rate conditions. Attenuation measurements at lower rain rates (< 20 mm/hr) were qualitatively consistent with both Laws and Parsons and Joss thunderstorm distributions.

Citation Download Citation

Abigail S. Hedden, David A. Wikner, and Russell W. Bradley "Summary and analysis of 216 GHz polarimetric measurements of in-situ rain", Proc. SPIE 9462, Passive and Active Millimeter-Wave Imaging XVIII, 94620G (19 May 2015); https://doi.org/10.1117/12.2177805

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