Wiebke Deierling - Determination and applications of the relationships of total lightning to microphysical and dynamical cloud parameters.
Total lightning measurements provide continuous temporal and broad spatial (hemispheric) sampling of attendant hazardous weather conditions (i.e., thunderstorms). This gives strong motivation for quantitatively defining useful physical relationships between lightning characteristics and storm behavior. Wiebke Deierling has previously investigated the relationship between total lightning amounts and ice mass, updraft characteristics and ice mass fluxes for thunderstorms in different climate regimes and of different storm type. She found a particularly strong relationship between the product of ice mass fluxes (downward precipitating and upward non-precipitating) and total lightning activity.
One aim of her research is the utilization of this relationship for meteorological applications such as improved numerical weather prediction. One of her current projects is to assimilate radar data into the Weather Research and Forecasting (WRF) modeling system using the Kalman ensemble filter technique and validate the model output with radar derived microphysics, 3D wind-field, the ice mass flux product etc.. In a second step it is planned to assimilate total lightning data making use of the flux product - total lightning relationship with the goal of improving storm scale model forecasts of thunderstorm evolution and quantative precipitation.
Another interest of Wiebke is to investigate the relationship between precipitation ice mass, rainfall and total lightning. Previous studies have demonstrated that total lightning activity is closely related to graupel and ice crystal mass in convection. It follows that it may be possible to use polarimetric radar data (and its ability to discriminate liquid from frozen condensate) in conjunction with total lightning data to estimate the fractions of liquid water content in convective rainfall that originates from both the cold and the warm rain process. To this end, the relationship between ice mass, liquid water mass, convective rainfall amounts, and total lightning activity for a number of storms that occurred in the High Plains of Kansas and Colorado, and in northern Alabama was investigated. Polarimetric radar data were used to compute rainfall amounts, and to partition ice and liquid water mass on storm scales. Total lightning data were available from ground based lightning mapping systems. The results show distinctly higher ratios of ice to liquid water content in rainfall occurring on the High Plains as compared to that of northern Alabama, consistent with studies performed using TRMM satellite data. These results suggest that it may be possible to use radar and total lightning data together to quantify the contributions to total convective rainfall of cold rain and warm rain processes. Such a quantification would be useful for climatological and microphysical studies that need information on the relative roles of warm and cold rain processes in the water cycle and precipitation development.
Figure 1. Relationship between IWM/LWM and mean total lightning is different for Northern Alabama (red) and High Plains (black).
|
ASP Spotlight January 2008
For more ASP spotlights click here http://www.asp.ucar.edu/spotlight/archive.jsp