Characterization of Deep Convective Cells during the onset of the Indian
summer monsoon using C-band polarimetric Doppler Weather Radar
observations over Thumba (8.50 N, 770 E)
Abstract
The vertical structure and dynamics of deep convective clouds plays an
important role during the Indian summer monsoon period. The
characteristics of deep convective cells (DCC) and their microphysics
remain unclear, especially during the onset phase of the monsoon.
Further, the intensity of convection is an important element, which
plays a key role in the progression of the monsoon. Thus the present
study focuses on characterizing DCC over a coastal location Thumba (8.50
N, 770E) during the onset of the Indian summer monsoon periods of 2017,
2018 and 2019 using C-band polarimetric Doppler Weather Radar (DWR)
measurements in terms of their intensity, vertical extent, top heights
and their microphysical properties. A method is devised to identify the
DCC from the DWR observed reflectivity cross-sections. The results
showed that the occurrence of reflectivities in the range of 30-40 dBZ
dominates below 6 km and the reflectivities in the range of 10-20 dBZ
dominates above 6 km. The diurnal evolution of DCC also been
investigated and it is found that these systems peak at three local time
intervals viz., 5-7, 11-14 and 16-19 hrs during the study period. The
present results provide a quantitative assessment of DCC including their
diurnal evolution during the onset of Indian summer monsoon season over
Thumba using DWR observations for the first time.