Advances in Geosciences www.adv-geosci.net 1680-7340 1680-7359 23 10th EGU Plinius Conference on Mediterranean Storms (2008) 2010 10.5194/adgeo-23-11-2010 http://www.adv-geosci.net/23/11/2010/ http://www.adv-geosci.net/23/11/2010/adgeo-23-11-2010.html http://www.adv-geosci.net/23/11/2010/adgeo-23-11-2010.pdf 11 16 2010-02-17 Prediction of lightning flash density with the WRF model B. Lynn yoavya@openu.ac.il Y. Yair The Hebrew University of Jerusalem, Jerusalem, Israel Weather-It-Is, Efrat, Israel The Open University of Israel, Ra'anana, Israel The Lightning Potential Index (LPI) is a measure of the potential for charge generation and separation that leads to lightning flashes in convective thunderstorms. It is calculated from model simulated updraft and microphysical fields. It was designed to predict the potential of lightning occurrence in operational weather forecasting models, but could possibly be used to improve short-range forecasts of heavy rain. The index is modified here to be model grid-scale transparent between 1 and 4 km (the approximate upper limit of explicit microphysical weather forecasts). Two case studies show that the modification appears to work quite well, and that LPI can be calculated on both an extremely high resolution research-grid (i.e., 1.33 km) and high resolution (i.e., 4 km) operationally compatible forecast grid. Analytical expressions are presented to use the LPI to predict the hourly lightning flash density. Altaratz, O., Levin, Z., Yair, Y., and Ziv, B.: Lightning Activity over Land and Sea on the Eastern Coast of the Mediterranean, Mon. Weather Rev., 131, 2060–2070, 2003. Deierling, W., Petersen, W. A., Latham, J., Ellis, S., and Christian, H. J.: The relationship between lightning activity and ice fluxes in thunderstorms, J. Geophys. Res., 113, D15210, doi:10.1029/2007JD009700, 2003. Deierling, W. and Petersen, W. A.: Total lightning activity as an indicator of updraft characteristics, J. Geophys. Res., 113, D16210, doi:10.1029/2007JD009598, 2008. Dudhia, J., Hong, S.-Y., and Lim, K.-S.: A new method for representing mixed-phase particle fall speeds in bulk microphysics parameterizations, J. Meteorol. Soc. Jpn., 86, 33–44, 2008. Kotroni, V. and Lagouvardos, K.: Lightning occurrence in relation with elevation, terrain slope and vegetation cover over the Mediterranean, J. Geophys. Res.-Atmos., 113, D21118, doi:10.1029/2008JD010605, 2008. Lagouvardos, K., Kotroni, V., Betz, H.-D., and Schmidt, K.: A comparison of lightning data provided by ZEUS and LINET networks over Western Europe, Nat. Hazards Earth Syst. Sci., 9, 1713–1717, 2009. Lynn, B. H. and Yair, Y.: Lightning Potential Index: A new tool for predicting the lightning density and the potential for extreme rainfall. Geophysical Research Abstracts, EGU General Assembly, Vienna, Vol 10, EGU2008-A-01571, SRef-ID:~1607-7962/gra/EGU2008-A-01571, 2008. MacGorman, D. R. and Rust, W. D.: The Electrical Nature of Storms, Oxford Univ Press, 422~pp., 1998. MacGorman, D. R., Cohen, A., Mansell, T., and Ziegler, C.: Flash rate, electrical, microphysical, and dynamical relationships across a simulated storm spectrum, Eos Trans. AGU, 89(53), Fall Meet. Suppl., Abstract~AE24A-06, 2008. Petersen, W. A. and Rutledge, S. A.: On the relationship between cloud-to-ground lightning and convective rainfall, J. Geophys. Res., 103, 14025–14040, 1998. Saunders C. P. R. : Charge separation mechnisms in clouds, Space Sci. Rev., 137(1–4), 335–354, doi:10.1007/s11214-008-09345-0, 2008. Sherwood, S. C., Phillips, V. T. J., and Wettlhaufer, J. S.: Small ice crystals and the climatology of lightning, Geophys. Res. Lett., 33, L05804, doi:10.1029/2005GL025242, 2006. Skamarock, W. C., Klemp, J. B., Dudhia, J., Gill, D. O., Barker, D. M., Wang, W., and Powers, J. G.: A description of the advanced research WRF version~2, NCAR Technical Note 468+STR, June~2005, revised, January, 2007. Thompson, G., Rasmussen, R. M., and Manning, K.: Explicit forecasts of winter precipitation using an improved bulk microphysics scheme, Part~I: Description and sensitivity analysis, Mon. Weather Rev., 132, 519–542, 2004. Wiens, K. C.: Summary of Colorado State University's LMA-Related Observations from STEPS, Eos Trans. AGU, 89(53), Fall Meet. Suppl., Abstract AE24A-07, 2008. Yair, Y., Lynn, B., Price, C., Kotroni, V., Lagouvardos, K., Morin, E., Mugnai, A., and Llasat, M. C.: Predicting lightning density in Mediterranean storms based on the WRF~model dynamic and microphysical fields, J. Geophys. Res., in press, 2010.