Thermodynamic and stability features of the atmospheric boundary layer over Kochi during different monsoon seasons based on radiosonde profiles

Abstract

The characteristics of thermodynamic parameters at different pressure levels have been studied using radiosonde data for the period 1989–2019 during different seasons incorporating sea-land breeze circulation influences over Kochi, in western peninsular India. It is also observed that the variation in lower tropospheric stability of (LTS) is found to be influenced by other thermodynamic parameters, such as temperature, mixing ratio, potential temperature, equivalent potential temperature, CAPE, and CINE at various pressure levels. The average value of temperature, potential temperature, mixing ratio, and equivalent potential temperature was maximum during the pre-monsoon season. At 700 hPa level, the average value of the mixing ratio was high during the sea breeze circulation of pre-monsoon season. The average value of equivalent potential temperature at 700 hPa level was maximum for the southwest monsoon season. A decreasing trend was observed in lower tropospheric stability (LTS) over the region in all seasons except for the winter season during the sea breeze circulation. The positive trend of LTS was observed during the sea breeze circulation time during the winter season, and it has a strong correlation with the positive trend in temperature and potential temperature at the 700 hPa level. Moreover, the southwest monsoon season exhibited a substantial decrease in LTS, potentially associated with an increasing trend in temperature, potential temperature, mixing ratio, and equivalent potential temperature at the surface level. CAPE has a significant increasing trend only for the sea breeze circulation period during the monsoon season. Additionally, CINE displayed an increasing trend across all seasons, with higher values observed during the winter and post-monsoon seasons.