On-Shore and Off-Shore Storm Characteristic Results Over East Central Florida

Natural cloud-to-ground lightning characteristics may vary depending on the characteristics of the attachment mediums, including the peak current (inferred from radiation fields) and the number of ground strike locations per flash. Existing literature has raised questions over the years on these characteristics of lightning over oceans, and the behaviors are not yet well understood. To investigate this we are obtaining both identical electric field observations and peak current measurements over adjacent land and ocean regions during both clear air and thunderstorm periods, beginning in February 2014. Oceanic observations are obtained using a 3-meter NOAA buoy moored 20NM off the Kennedy Space Center Coast. The buoy has been instrumented with a Campbell Scientific electric field mill and New Mexico Tech's slow antenna, to measure the electric fields. Peak-current (Ip) measurements are obtained using Vaisala's National Lightning Detection Network. Measurements from this system have been compared to the existing on-shore electric field mill suite of 31 sensors. To date, the first storms have shown higher static E-fields over ocean during both high reflectivity and active lightning as compared to on-shore E-fields using the same criteria. The largest Ip's have occurred over the ocean. This on-going project will demonstrate the value of off-shore electric field measurements for safety-related decision making at KSC, may improve our understanding of relative lightning risk to objects on the ground vs. ocean, and may illustrate fundamental differences in lighting characteristics over land and ocean.