Seasonal extreme rainfall variability over India and its association with surface air temperature

In recent decades, a significant rise in extreme rainfall events has been reported across India, accompanied by large-scale flood/drought-like conditions and catastrophic loss of life. Large-scale climate variability modes like the El Ni (n) over tildeo-Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) tend to influence the surface air temperature and rainfall variability over India. In what follows, the complete and independent influences of ENSO using Ni (n) over tilde o3.4, Ni (n) over tilde o3, and Ni (n) over tilde o4 indices, and IOD using Dipole Mode Index (DMI) on seasonal mean and extreme surface air temperature and rainfall over India are examined. A non-stationary generalized extreme value (GEV) distribution is implemented to analyze the seasonal extremes over the period 1979-2019. Ni (n) over tilde o3.4 induces deficit rainfall over regions such as the Gangetic plains, the entire Deccan plateau, and western India in boreal summer In autumn, strong positive seasonal mean rainfall responses are evident in peninsular India and eastern parts of Madhya Pradesh (MP). A dipole pattern evident in north India during summer reverses its polarity by autumn. Yet, Ni (n) over tilde o3 significantly reduces the intensity of rainfall over large parts of MP in summer. Contrarily, Ni (n) over tilde o4 strengthens the rainfall in similar regions, thereby significantly impacting the rainfall variability over India. Likewise, positive (negative) phases of the IOD lead to wet (dry) conditions over northwestern India in summers and central India in autumn. Overall, a coherent inverse relationship between rainfall and daily maximum temperature is observed. For Nino3.4 independent of IOD (Ni (n) over tilde o3.41 vertical bar(IO)(D)), a weaker intensity in rainfall is found in northern India compared to the original Nino3.4 response. However, the IOD independent of Ni (n) over tilde o3.4 (IOD vertical bar(Ni)((n) over tilde o3.4)) rainfall response is weaker in northern India and stronger in central India compared to original IOD responses. Importantly, a composite analysis of rainfall and temperature anomalies during different phase combinations of ENSO and IOD also shows that the IOD mitigates the influence of ENSO in boreal summer and fall whenever such events occur in-phase.