1. Relationships between lightning flash rates over the tropics and subtropics and the vertical structures of precipitation radar reflectivity Chuntao Liu Department of Atmospheric sciences, University of Utah Contributors: Edward Zipser 1, Daniel Cecil 2 1. University of Utah 2. University of Alabama at Huntsville

2. Riming electric charge separation Takahashi and Miyawaki, 2002, JAS Keys : Graupel Temperature Super-cooled liquid water Why there is a relationship between radar reflectivity and lightning flash?

3. Define precipitation features using TRMM Precipitation Radar Radar Precipitation Features (RPFs) Contiguous area with rainfall Properties of precipitation features Flash rate Temperature at 20, 30, 40 dBZ echo tops Maximum reflectivity at temperatures Area of 20, 30, 40 dBZ at temperatures Volume of 20, 30 40 dBZ at -5 o C - -35 o C IWC of 20, 30 40 dBZ at -5 o C - -35 o C PR echo top height (km)

5. Population of RPFs and those with lightning 1998-2010 LandCoastOpen oceanAll 36S-36N RPF3.7 million6.4m million11.8 million22.2 million With flash 11.5%2.6%0.5%3%

6. Correlation between radar reflectivity vs. flash rate in precipitation features

7. Echo top temperature vs. Flash rate Correlation coefficient to flash rate in precipitation features OceanCoastLandAll 36S-36N Maximum 20 dBZ echo top Temperature -0.12-0.18-0.27-0.24 Maximum 30 dBZ echo top Temperature -0.30-0.36-0.40-0.38 Maximum 40 dBZ echo top Temperature -0.49-0.50-0.49-0.50

8. Correlation coefficient to flash rate in precipitation features area of reflectivity at temperatures vs. Flash rate Solid : land dotted: ocean

9. area of reflectivity at temperatures vs. Flash rate auto-correlation among different part of storms removed Solid : land dotted: ocean

10. Regional variation of correlations (I) Correlation coefficients

11. Regional variation of correlations (II) Slope of linear relationship

13. Summary Flash rate is best correlated with the volume of the high reflectivity (> 30 dBZ) in the mixed phase region, confirming the importance of the presence of large particles in the charging process. More flashes are generated over land than over ocean given the same volume of 30-35 dBZ in the mixed-phase region. There are large regional differences in the correlations between radar reflectivity properties vs. flash rate. Even with the similar radar reflectivity profiles to the oceanic systems, it is still easier to have lightning flashes over Amazon. Other factors must play important roles besides the graupel at mixed phase region in the lightning generation.

15. 2-D histogram of RPFs and probability with lightning Temperature of 20 dBZ echo top vs. Temperature of 30 dBZ echo top

16. Regional variation of lightning probability in precipitation systems

17. Correlation coefficient to flash rate in precipitation features maximum reflectivity at altitudes vs. Flash rate

18. Correlation coefficient to flash rate in precipitation features area of reflectivity at temperatures vs. Flash rate Solid : land dotted: ocean