HR: 1340h
AN: AE33A-0185    [Abstracts]
TI: Meteorological Forcing of Lightning over the Gulf Stream
AU: Petersen, W A
EM: walt.petersen@msfc.nasa.gov
AF: University of Alabama-Huntsville, ESSC/NSSTC, Huntsville, AL 35899 United States
AU: * Rutledge, S A
EM: rutledge@atmos.colostate.edu
AF: Department of Atmospheric Science, Colorado State University, Ft. Collins, CO 80523 United States
AB: From the perspective of both the National Lightning Detection Network and the Lightning Imaging Sensor onboard TRMM, it is well known that there is a local lightning maximum located over the Gulf Stream region off the eastern coast of the U.S. Flash densities are roughly 10 flashes/km2/month, comprable to flash rates over the adjacent continental land mass to the west. TRMM Precipitation Radar data also indicate characteristically "continental" convective vertical structure and ice water paths, consistent with the lightning signature. The diurnal cycle of lightning (and precipitation) over the Gulf Stream exhibits an extended nocturnal and early morning peak, reaching a maximum near 12 UTC (7 AM local). NLDN lightning data suggest that systems forming over land the previous day may undergo an extended period of resurgence in intensity and thus their ability to generate lightning as they pass over the warm waters of the Gulf Stream (28 C). Analysis of climatological variables in active periods of Gulf Stream lightning indicate the presence of increased surface temperatures, increased surface and mid-level humidity and broad scale ascent. We suggest that the warmer, more moist conditions at the surface combined with favorable synoptic features lead to increased CAPE over the Gulf Stream, promoting stronger vertical motion and enhanced mixed-phase microphysics, leading to higher lightning flash rates relative to adjacent coastal waters.
DE: 3324 Lightning
DE: 3304 Atmospheric electricity
DE: 3314 Convective processes
SC: Atmospheric and Space Electricity [AE]
MN: 2004 AGU Fall Meeting