Dual-Polarization rainfall retrievals at long range over Missouri

This work investigates dual-polarization radar quantitative precipitation estimates (QPE) for significant rainfall events occurring in 2014 over the state of Missouri. Much of the state suffers from poor radar coverage and so QPE have to be found at long ranges from the nearest radar. This study looks at a range of retrieval methods using a dual-polarization parameters from National Weather Service radars. Data for this area, acquired from the St. Louis, MO (LSX), Kansas City, MO (EAX), Springfield, MO (SGF), and Paducah, KY (PAH) National Weather Service radars, was compared to a number of raingauges operated by the Missouri Climate Center and University of Missouri Agricultural Experiment Station which record rainfall at 5 minute intervals. The rainfall retrieval algorithms tested include those presented by Ryzhkov et al. (2005) and Giangrande & Ryzhkov (2008), including that based on the echo classification scheme, as well as the standard R(Z) relationships. Results suggest that although it is possible to retrieve accurate rainfall rates at long ranges when there is deep convection in some cases large errors are introduced with the use of some methods. In particular, the echo classification method is seen to overestimate the rainfall rate in situations where it erroneously identifies solid targets and adjusts the rainrate upward.