A decadal climatology of cloud vertical structure over the Indo-Gangetic Plain using radiosonde and radar observations

Abstract

The cloud vertical structure (CVS) over any place significantly impacts the boundary layer dynamics and horizontal/vertical temperature gradient at local scale, whereas on the synoptic scale it plays a crucial role in determining the atmospheric circulation and hydrological cycle. There is a notable lack of long-term comprehensive studies on CVS over Indian subcontinent. Here, we have done a comprehensive study of CVS over the Indo-Gangetic plain (IGP), in which we have studied the statistics of CVS over various urban agglomerations (UAs) lying within the IGP (using radiosonde data) coupled with CVS of the entire IGP (EIGP) which majorly includes rural and suburban areas (using CloudSat profiling radar data) from 2006 to 2017. Seasonal analysis shows that CVS is much different in monsoon season as compared to other seasons over both EIGP and UAs. The frequency of single layer clouds is ~91%, 87%, 76% and 91% over EIGP and ~ 81%, 80%, 58% and 82% over UAs in winter, pre-monsoon, monsoon and post-monsoon seasons, respectively. In the monsoon season, both data show significant increase in multi-layer clouds frequency, however, the frequency of multi-layer clouds is significantly higher over UAs (>40%) compared to that over EIGP (<26%). The average depth of single-layer clouds over EIGP (2.3–5 km) is higher than that over UAs (1.8–2.7 km). The average cloud top height of single layer clouds is slightly lower over UAs (6.4–7.8 km) as compared to EIGP (7.3–11.2 km), except in pre-monsoon. We infer that though the aerosol induced warming inhibits the convective cloud formation over UAs; aerosols tend to invigorate the convective clouds whenever sufficient moisture is present for cloud formation. The analysis of present study would be helpful in many applications related to radiation budget and climate studies.