Indian summer monsoon onset signatures on the tropical tropopause layer

Abstract

Over the Indian region, changes in the tropopause parameters during pre‐monsoon to monsoon seasons have been reported. However, no study exists to date dealing with the Indian summer monsoon (ISM) onset signatures on the tropopause parameters. In the present study, the climatological structure of the tropical tropopause layer during the onset phase of ISM is delineated by using long‐term (2006–2017) radiosonde observations over Gadanki (13.5°N, 79.2°E). A prominent transition in the tropopause parameters from pre‐monsoon to monsoon is noticed and the transition is initiated from the day of ISM onset. Continuous decrease (increase) of tropopause altitude (temperature) is perceived after the ISM onset. The ozonesonde observations clearly show the strong enhancement in the ozone mixing ratio in the lower stratosphere (~16–20 km) after the ISM onset. This clearly demonstrates the instantaneous warming of the tropopause region after the ISM onset in addition to the latent heat release due to the precipitation. Transitions from pre‐monsoon to monsoon in the tropopause parameters are influenced strongly by onset of ISM which was attributed as seasonal changes earlier. These results provide strong evidence on the ISM onset signatures on the tropical tropopause parameters.