Constructing a Climatology of Whistler Wave Energy from Lightning in Low Earth Orbit

摘要

Starting from OTD/LIS lightning data representing 1995-2005, a climatology is constructed with 1 deg x 1 deg latitude-longitude spatial resolution, averaged into 2 hour bins for each month of the year. Assuming a linear relationship between optical flash rate and VLF power flux, and that the VLF amplitude drops off as one over distance, a proxy for VLF power is developed. A typical lightning spectrum is then applied and the values are scaled by an appropriate transionospheric absorption for each time and place. These values are mapped up the geomagnetic field lines to low earth orbit altitudes and over to conjugate locations in order to compare them to E-field spectral densities measured by the DEMETER satellite between 2005 and 2009. An overview of the DEMETER survey mode data is presented which leads to a best scaling of the lightning VLF climatology. The final distribution's spatial and temporal variations are compared with the DEMETER data and some implications are discussed.