Indian summer monsoon precipitating clouds: role of microphysical process rates

Abstract

the formation of cloud ice as revealed by the observation. Freezing rates at upper level and snow accretion at middle level may have effect on latent heating release. Further it can modulate the north-south temperature gradient which can influence the large-scale monsoon dynamics. The rain water evaporation is also considered as a key aspect for controlling the low level moisture convergence (source of water vapor) in ISM. This study has highlighted the importance of detailed microphysical production rates for warm and mixed-phase cloud processes, which is a major source of uncertainty in the climate models. Better understanding of these processes will definitely add value to the present generation climate models. Therefore the hypothesis/pathway emerged from the present study may be helpful for the future model development research.

Effect of cloud microphysics on Indian summer monsoon precipitating clouds: A coupled climate modeling study

“…Rainfall is a result of complex multiscale process, ranging from the large-scale moisture convergence to the microphysical processes of raindrop formation (e.g., autoconversion, rain accretion, snow accretion, and melting) [Zhao and Carr, 1997;Sundqvist et al, 1989;Tao and Moncrieff, 2009;Hazra et al, 2015Hazra et al, , 2016a. Satellite observation indicates that over the Indian summer monsoon region, about 40-50% of rainfall events originate from melting of ice [Field and Heymsfield, 2015], indicating the greater role of ice processes.…”

Contrast in monsoon precipitation over oceanic region of north Bay of Bengal and east equatorial Indian Ocean

“…There is no way of direct measurement of the detailed microphysical tendency rates; hence, we have used MEERA reanalysis, which is basically the output of GEOS5 model. The GEOS5 model consists of Relaxed Arakawa‐Schubert (RAS) cumulus and Zhao and Carr microphysical parameterization (Hazra et al ., ). Previously, a large number of studies had also used MERRA data for characterizing cloud properties (e.g.…”

“…Auto‐conversion has the largest contribution in terms of rainfall production during monsoon season (Hazra et al ., ), wherein CLW is developed into embryonic raindrops (Liu et al ., ). This is also clear by the huge dominance of auto‐conversion process (∼7–8 mm day −1 ) over nBoB region (Figure (a)).…”

“…The cloud microphysics defines the characteristics of deep convective clouds and their associated anvil clouds producing stratiform precipitation (Hazra et al ., , ), which is further controlled by cloud hydrometeors and the rate of microphysical tendencies (e.g. deposition, freezing auto‐conversion, rain and snow accretion).…”

“…() have pointed out that in cloud scale, the presence of ice and liquid phase (which depends on the vertical profile of cloud hydrometeors) significantly modifies the large‐scale circulation through the combined effect of latent and radiative heating. Previous studies have shown the important role played by atmospheric profile of cloud and its hydrometeors for distribution and variability of ISMR (Hazra et al ., , ; Rajeevan et al ., ; Chaudhari et al ., ). Furthermore, modelling studies have also corroborated that inclusion of microphysical processes (in particular ice processes) simulates realistic stratiform rain (SR) region over the mesoscale convective systems (e.g.…”