Variation of Radar Reflectivity in Lower Troposphere at the West Coast of India During Pre‐Monsoon and Monsoon Seasons Using Ground Based Observations

The present study investigates the statistical distribution of slopes in radar reflectivity [S-Ze] in the lower troposphere at the west coast of India using the C-band radar during pre- monsoon months to monsoon months, which spans the different meteorological conditions, including from a drier atmosphere to moist atmosphere. To investigate the S-Ze, we calculated the difference in Ze between 4 to 2 km altitudes in the lower troposphere. For positive [negative] S-Ze, the Ze decreases [increases] towards the surface. The differences in S-Ze in the lower troposphere during pre-monsoon, monsoon onset and monsoon months reveals the precipitation variability. Among all the months, a higher fraction of +ve S-Ze are observed during March and April months compared to other months, and showed that in drier atmosphere the for most of the time Ze tends to decrease towards the surface. However, the average S-Ze shows the highest -ve average -ve S-Ze, during March and April months near the coastal boundaries and associates with the lesser number of profiles. May and June months have a higher fraction of -ve S-Ze [>60%] is observed over the northern latitudes of the study periods, whereas southern AS has a higher fraction of +ve S-Ze. August has the highest fraction of -ve S-Ze, over land and topographic features. September has the highest fraction of +ve S-Ze at the southern latitudes, and at the same time, the study regions are characterized by the drier atmosphere with less updraft. During the pre-monsoon months thermodynamic conditions are more important, where in the drier atmosphere Ze tends to decrease towards the surface. During the monsoon months the dynamics of convective and stratiform precipitation, and either evaporation during the stratiform precipitation along with the convective outburst may increase the lower level RH. Monsoonal months have the less increase or decrease in the hydrometeors size compared to pre-monsoon months, whereas precipitation is more of a convective nature. The results presented here would be an extension of the study from the satellite based observations, and reveals the extension climatology of inclusion of stratiform precipitation.