A modified convective/stratiform partitioning algorithm

Abstract

Knowledge of the distribution of convective and rographics. stratiform rainfall in precipitating systems is important because of the differences in the diabetic heating profiles. Also, radar-derived estimates of rainfall could possibly be improved by using different radar reflectivity-rail-ate relationships. Several authors have developed their own convective-stratiform partitioning, but each had its limitations. An algorithm has been developed which partitions precipitating systems into their convective and stratiform components using radar reflectivity data. This was accomplished by combining the strengths of two previous methods and maximizing the use of cloud structure as determined by the radar reflectivity. The algorithm was tested using a large database of convective storms in southeast Texas, including squall lines, unorganized convection with little stratifying rain, and stratifying rain with embedded cores of convection. The results showed that the previous algorithm often misclassified the leading edge of squall lines as stratifying, in addition to missclassifying the enhanced radar echo to the rear as convective. The algorithm also left "rings'' of stratiform rain around the cores of isolated convective cells. The results from the new algorithm show a first order improvement to one of the previous partitioning algorithms. Roughly 20% of the total echo area and 15% of the total rain volume was reclassified using the new algorithm. The horizontal gradient of radar reflectivity and the bright-band faction (BBF) proved to be important parameters in the reclassification. Dual-Doppler data from the PRE-STORM dataset were used to validate both algorithms. In addition, the algorithm was applied to radar data from Darwin, Australia in order to test the transferability of the algorithm.