ABSTRACT
Long-term thunder data suggest that GFD has a relative standard deviation of 30%. Observations of optical transient density have been performed using satellites starting in 1995. ese
data have some of the same defects as thunder observations: cloud ºash and ground ºash activity is equally weighted and the observations are sporadic. However, statistical considerations as well as richly detailed observations of orographic terrain features now favor the use of optical transient density, reported by (Christian et al., 2003; NASA, 2006) over thunder observations to estimate ground ºash density.
