Evolving thermodynamic convective environments over India: spatio-temporal variability, trends, and regime shifts

Convective environments over India are experiencing significant spatio-temporal evolution under the combined influence of monsoon dynamics, thermodynamic variability, and ongoing climate warming. Understanding how atmospheric instability, convective inhibition, and moisture–temperature coupling vary across regions, seasons, and decades is essential for assessing changes in thunderstorm activity and extreme rainfall risk. This study presents a comprehensive assessment of thermodynamic convective environments over India during 1981–2020 using ERA5 reanalysis data. Key instability diagnostics Convective Available Potential Energy (CAPE), Convective Inhibition (CIN), K Index (KI), Total Totals Index (TTI), and Net Convective Potential (NCP) are analysed to characterise climatological patterns, seasonal and interannual variability, long-term trends, relative variability, and regime shifts. Results reveal strong spatial heterogeneity in convective environments, with eastern, northeastern, and peninsular India consistently exhibiting higher instability due to persistent moisture transport and monsoon forcing, while western and northwestern regions remain comparatively inhibited. Seasonal analysis highlights a pronounced monsoon control, with pre-monsoon and monsoon periods displaying the most favourable thermodynamic conditions for deep convection. Trend and decadal analyses indicate widespread increases in moisture-driven instability, reflected by rising CAPE and KI and weak or declining CIN across large parts of India, whereas lapse-rate-driven instability (TTI) shows comparatively weak or negative trends. Relative variability analysis demonstrates that CAPE and KI exhibit high interannual variability over arid and semi-arid regions, indicating greater sensitivity to moisture fluctuations and boundary-layer processes. Spatial change-point detection reveals pronounced non-stationarity in convective environments, with coherent regime shifts occurring predominantly during the late 1990s and early 2000s, particularly during pre-monsoon and monsoon seasons. These findings indicate that convective environments over India are evolving through a combination of gradual thermodynamic amplification and abrupt regime shifts. Overall, the results suggest that increasing thunderstorm and extreme rainfall risk over India is primarily driven by moisture-related thermodynamic enhancement modulated by monsoon dynamics, rather than uniform large-scale destabilization, with important implications for convective predictability and climate adaptation in a warming monsoon system. • Thermodynamic convective environments over India exhibit strong spatio-temporal heterogeneity and non-stationarity. • Moisture-driven instability (CAPE and K Index) has increased across large parts of India since the 1980s. • Convective inhibition shows weak or declining trends, enhancing the likelihood of convective initiation. • Change-point detection reveals abrupt regime shifts in convective environments during the late 1990s–early 2000s. • Evolving convective environments imply increasing thunderstorm and extreme rainfall risk under a warming monsoon climate.