Validation of Hail Identification Algorithm for GPM DPR (version 7)

<p>Validation of Hail Identification Algorithm for GPM DPR (version 7)</p><p> </p><ul><li>Chandrasekar <sup>1, 2</sup> and Minda Le <sup>1</sup></li> </ul><p>Colorado State University</p><p>Finnish Meteorological Institute</p><p>Extreme precipitation such as hail has raised interest due to its huge impact to human activities. In the new version of GPM DPR algorithm (version 7), a new Boolean hail product is developed to identify hail along a vertical profile. The  main feature of this  algorithm is for the first time, offers the potential of retrieving a uniform and homogeneous hail dataset on the global scale from radar sensors. The algorithm is built upon the precipitation type index (PTI). PTI is a value calculated for each dual-frequency profile with precipitation observed by GPM DPR.   The dual-frequency ratio slope with respect to height, the maximum of reflectivity and storm top height are three key ingredients composing PTI value.</p><p>PTI has been  shown  to be effective in separating various precipitation types such as snow, graupel and hail profiles [1][2][3]. In this research, we focus on validation of hail identification algorithm by analyzing and cross-validating hail observations from various sources including individual hailstorm and on a global scale. Our algorithm will be validating with hailstorms observed by ground validation radar NEXRAD, GMI based hail identification and multiple scattering effect from Trigger module output of DPR level-2 algorithm. The global scale analysis is essential for satellite-based products. We validation this hail product with various global hail maps using radar, radiometer-based algorithms and reports.  </p><p>[1] Le, M and V. Chandrasekar, Graupel and Hail Identification Algorithm for the Dual-frequency Precipitation Radar (DPR) on the GPM Core Satellite. J. Meteor. Soc. Japan, Vol. 99, 2021.</p><p>[2] Le, M. and V. Chandrasekar, Ground Validation of Surface Snowfall Algorithm in GPM Dual-Frequency Precipitation Radar. J. Atmos. Oceanic Technol., no 36, pp. 607–619, 2019.</p><p>[3] Le, M. and V. Chandrasekar, A New Hail Product for GPM DPR Algorithm. IGARSS’, 2021, Jul 12th ~ 16th, Brussels.</p><p> </p>