Abstract
The Terrestrial Gamma-ray Flashes (TGF) to lightning ratio, computed
over the 3 tropical chimneys, presents a paradox: African thunderstorms
produce the most lightning but yield the lowest fraction of TGF when
compared to American and Southeast Asian thunderclouds. To understand
the physical insights into this asymmetry, TRMM Precipitation Radar
measurements are used to depict the vertical precipitation structure of
the observed thunderstorms in the 3 regions and the thunderstorms during
TGF occurrences detected by AGILE, Fermi-GBM and RHESSI sensors. African
thunderstorms are taller, smaller and have higher concentration of dense
ice particles above the freezing level. TGF thunderstorms are taller and
less intense (0.5-2dBZ), besides presenting similar radar reflectivity
decay with height independent of the region. In addition, these storms
show thicker electrical charge layers separated by 4.7-5.2 km and also a
positive charge fraction reduction between -20 o C and -40 o C and
enhancement above -50 o C when compared to the overall thunderstorms.