Conducted over the Tiwi Islands of Northern Australia, MCTEX provided a daily opportunity to study tropical thunderstorms on a intimate level during the transition between dry and monsoon seasons. A C-band polarimetric Doppler radar provided a means to investigate the relationship between electrical activity, as measured by an Advanced Lightning Detection Network (installed by NASA-Marshall Space Flight Center), and radar derived quantities, such as rain mass flux, graupel mass aloft, and liquid water content. Using a combination of horizontal reflectivity, specific differential phase and differential reflectivity, rain mass flux was estimated over the entire lifecycle of the storm for two days during MCTEX.
A significant rise in rain mass flux occurs as scattered late morning warm-rain showers (below the freezing level) merge along a sea breeze front and spark second order storms with tops exceeding 16 km AGL. Coincident with the initial RMF increase is a rapid proliferation of CG flashes, which peaks 30-60 minutes before the RMF peak. More in tune with the CG flash rate are the estimates of total graupel mass aloft in the mixed phase region. The behavior of this variable, (estimated with horizontal reflectivity and specific differential phase), suggests a coupling between the lofting and subsequent freezing of supercooled rain drops to form graupel and subsequent storm electrification. Consistent with NIC theory, the major increases in CG flash rate are preceded 10-20 minutes by surges in estimated graupel mass in the mixed phase region