Variations in Raindrop Size Distributions Associated with Diverse Storm Types and Structures

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Sunday, 2 February 2014
Hall C3 (The Georgia World Congress Center )
Anthony G. Viramontez, University of Louisiana, Monroe, LA; and L. J. Hopper Jr.

Heavy rainfall is produced by a variety of frontal and non-frontal storm types in northeast Louisiana, a subtropical region affected by midlatitude and tropical influences. These storm types produce a variety of raindrop size distributions (DSD) reflecting the different large scale influences impacting northeast Louisiana. Quantitative precipitation estimates derived from Z‐R algorithms that diagnose rain rates from radar reflectivity rely heavily on DSD relationships and may overestimate or underestimate observed rainfall totals if these algorithms do not accurately capture the underlying microphysical processes responsible for precipitation formation. Therefore, the primary objective of this study is to quantify microphysical variations in raindrop size distribution (DSD) associated with different storm types and structures using a laser-optical Parsivel-2 disdrometer.

Storms will be classified based on their large scale forcing (e.g., cold front, warm front, tropical cyclone, upper level disturbance, weakly forced, etc.) using surface and upper-air maps and radar and satellite imagery. In addition, precipitation structures will be classified utilizing horizontal and vertical cross sections and statistical distributions of radar reflectivity. Variations in DSDs will be analyzed using these storm classifications to determine how the DSDs vary by storm type. Collocated rain gauges and anemometers will also be used to determine the reliability of optical disdrometer measurements in various rainfall rates and wind conditions. If time permits, DSD anomalies observed by the Parsivel-2 disdrometer for each storm type will be compared to those observed by an (JW) RD-80 impact disdrometer located in southeast Texas, focusing on identifying and comparing cases without deep convection, including shallow convective and non-convective stratiform precipitation structures.