Empirical conversion of the vertical profile of reflectivity from Ku-band to S-band frequency

Authors

  • Qing Cao,

    1. Advanced Radar Research Center, University of Oklahoma, Norman, Oklahoma, USA
    2. Hydrometeorology and Remote Sensing Laboratory, National Weather Center, Norman, Oklahoma, USA
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  • Yang Hong,

    Corresponding author
    1. Advanced Radar Research Center, University of Oklahoma, Norman, Oklahoma, USA
    2. Hydrometeorology and Remote Sensing Laboratory, National Weather Center, Norman, Oklahoma, USA
    3. School of Civil Engineering and Environmental Sciences, University of Oklahoma, Norman, Oklahoma, USA
    • Corresponding author: Y. Hong, Hydrometeorology and Remote Sensing Laboratory and Advanced Radar Research Center, Suite 4610, 120 David L. Boren Blvd., Norman, OK 73072, USA. (yanghong@ou.edu)

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  • Youcun Qi,

    1. NOAA/National Severe Storms Laboratory, Norman, Oklahoma, USA
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  • Yixin Wen,

    1. Advanced Radar Research Center, University of Oklahoma, Norman, Oklahoma, USA
    2. Hydrometeorology and Remote Sensing Laboratory, National Weather Center, Norman, Oklahoma, USA
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  • Jian Zhang,

    1. NOAA/National Severe Storms Laboratory, Norman, Oklahoma, USA
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  • Jonathan J. Gourley,

    1. NOAA/National Severe Storms Laboratory, Norman, Oklahoma, USA
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  • Liang Liao

    1. Goddard Earth Sciences Technology and Research/Morgan State University, Greenbelt, Maryland, USA
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ABSTRACT

[1] This paper presents an empirical method for converting reflectivity from Ku-band (13.8 GHz) to S-band (2.8 GHz) for several hydrometeor species, which facilitates the incorporation of Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) measurements into quantitative precipitation estimation (QPE) products from the U.S. Next-Generation Radar (NEXRAD). The development of empirical dual-frequency relations is based on theoretical simulations, which have assumed appropriate scattering and microphysical models for liquid and solid hydrometeors (raindrops, snow, and ice/hail). Particle phase, shape, orientation, and density (especially for snow particles) have been considered in applying the T-matrix method to compute the scattering amplitudes. Gamma particle size distribution (PSD) is utilized to model the microphysical properties in the ice region, melting layer, and raining region of precipitating clouds. The variability of PSD parameters is considered to study the characteristics of dual-frequency reflectivity, especially the variations in radar dual-frequency ratio (DFR). The empirical relations between DFR and Ku-band reflectivity have been derived for particles in different regions within the vertical structure of precipitating clouds. The reflectivity conversion using the proposed empirical relations has been tested using real data collected by TRMM-PR and a prototype polarimetric WSR-88D (Weather Surveillance Radar 88 Doppler) radar, KOUN. The processing and analysis of collocated data demonstrate the validity of the proposed empirical relations and substantiate their practical significance for reflectivity conversion, which is essential to the TRMM-based vertical profile of reflectivity correction approach in improving NEXRAD-based QPE.

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