Climate Change in the Middle East and the West Indian Subcontinent: Geographic Interconnections and the Modulation Roles of the Extreme Phases of the Atlantic Meridional Oscillation (AMO) and the Monsoon Cloudiness

In this study, the long-term (1961–2020) values of the summertime station-based surface air temperature (SAT) data at 151 qualified stations, alongside the corresponding ERA5 gridded data, were analyzed to investigate climate change over the Middle East and the west Indian subcontinent. Significant positive (negative) trends were observed at 134 (2) stations, while trends were insignificant at 15 stations. The positive (negative and insignificant) trends were mainly concentrated in the interior highlands (monsoon-dominated lowlands), where ERA5 exhibited from 10% to 70% overestimations (5% to 26% underestimations). These ERA5-related biases exhibited strong correlations with elevation. To assess the trends’ disparity reasons, we first showed that the outputs of SAT+AMO − SAT−AMO are highly positive (negative or near zero) over the overestimated (underestimated) regions. The study then demonstrated that cloudiness, atmospheric circulation, specific humidity, and convective activities above the monsoon-dominated areas differ between +AMO and −AMO. For these areas, the enhanced +AMO-related cloudiness suppresses positive SAT anomalies, while the increased −AMO-associated sunshine offsets negative SAT anomalies. Contrarily, for some areas such as northern Iran, the +AMO (−AMO)-associated cloudiness or clear sky can affect climate change by amplifying the warmness or coldness. In addition, +AMO (−AMO) has caused further convective activities over the Arabian Sea (Bengal Bay).