92nd American Meteorological Society Annual Meeting (January 22-26, 2012)

Monday, 23 January 2012: 5:15 PM
Improving Geostationary Satellite Rainfall Estimates Using Lightning Information: Underlying Statistical Relationships
Room 256 (New Orleans Convention Center )
Weixin Xu, ESSIC/UMD, College Park, MD; and R. Adler and N. Y. Wang
Manuscript (453.9 kB)

Many studies have reported close link between convective rainfall (or storm properties) and lightning, both for individual (or ensemble) storms and for large spatial domains. These relationships, if quantified and validated, could be very useful in improving rainfall estimation. One potential application is to constrain passive microwave or IR based rainfall retrievals on convective rain area and intensity. However, in-depth rainfall-lightning relationships and their variability in different regimes need to be further investigated.

This study first identifies particular rainfall regimes in terms of convective properties and structures, namely continental, oceanic, and monsoonal regimes. Ice-based processes associated with vigorous convection are thought to be much more important in the contribution of rainfall in the continental regime than in the maritime. Maritime rainfall likely has a more significant contribution from low-level warm-rain collision and coalescence processes. Monsoon rainfall in general is intermediate between continental convection and convection over the open ocean.

Preliminary results show that lightning-convective rainfall relationships on the storm scale vary greatly among different rainfall regimes. They have the strongest relation in continental regimes, a weaker relation in monsoon rains, and the weakest relation in oceanic regimes. Therefore, regime difference should be taken into consideration when lightning-convective rain relationships are parameterized. On the other hand, convective proxies related to ice-phase processes, especially graupel production, show strong and stable relationships with lightning frequency. Analysis of relationships of rainfall and storm properties with lightning is also examined on the smaller, convective scale too. Convective cells are defined based on convective pixels or certain values of radar reflectivity or brightness temperature from microwave radiometer. Correlations of lightning with areal structure, vertical structure, and intensity of convective cells will be quantified.

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