Statistical comparisons of RHESSI Terrestrial Gamma-ray Flashes and WWLLN-detected lightning

We use the RHESSI database of terrestrial gamma-ray flashes (TGFs) and the WWLLN database of radio atmospherics from lightning in the years 2003-2008 to study the relation between TGFs and nearby thunderstorms, expanding upon work presented at the 2005 CEDAR workshop by one of us (EHL). We compare TGF detection times with the detection times of lightning from nearby storms to constrain the phase of storm development in which TGFs occur. We search for systematic displacements in the East/West and North/South directions between TGFs and the nearby thunderstorms. North/South asymmetry might arise if TGF electrons are produced at high enough altitudes that they are beamed along the magnetic field. Using all nearby lightning detected within minutes of the TGF allows us to use the full database of hundreds of RHESSI TGFs, rather than just the small number that are matched with a specific WWLLN atmospheric.