Radar-derived microphysics related to 3D VHF lightning mapper data during EULINOX

The main objective of the two-year European Lightning Nitrogen Oxides (EULINOX) project from 1998 to 1999 was to quantify the amount of nitrogen fixation due to lightning discharges in central European thunderstorms. Among the various measuring platforms also a C-band polarimetric Doppler radar (POLDIRAD, operated by DLR) and a 3D interferometric VHF lightning mapper (ITF, operated by ONERA) were monitoring thunderstorms in the observation area around Oberpfaffenhofen near Munich in southern Germany.

Aside from determining the NOx production within thunderstorms, comparative observations of flash location and propagation within the storms and of radar-derived cloud-microphysics enabled a closer look at relevant cloud electrification mechanisms. For the main day of the EULINOX intensive observation period (21 July 1998) a supercell hailstorm showed a close link between lightning discharges and the graupel region of the thundercloud. Further, many negative leaders were observed near the freezing level, indicative of a strong positive lower positive charge center.

The results obtained for this storm will now be compared to those for other days of the EULINOX campaign. Thereby a variety of thunderstorm types is covered (single, multi, and supercell) and also different synoptic situations. It will be outlined which of the characteristics determined from the 21 July 1998 supercell also hold for other storms and so could become a basis for refined lightning parameterizations for mesoscale models.