Rising occurrence of compound droughts and heatwaves in the Arabian Peninsula linked to large-scale atmospheric circulations

Abstract

Compound droughts and heatwaves (CDHWs) have emerged as a critical threat to global populations, with serious implications for water resources, agriculture, and ecosystems. Despite their significance, the occurrence and drivers of CDHW events remain inadequately understood, particularly in arid regions such as the Arabian Peninsula (AP). Using fifth-generation ECMWF reanalysis (ERA5) data, we analyze the spatiotemporal dynamics and variability of CDHW events over the AP from 1980 to 2023. Our results reveal a substantial increase in the frequency and intensity of CDHW events over this period, with a fourfold increase in the affected area since 1998. The northern parts of the AP are particularly vulnerable to CDHW events, due to the strong synchronization of heatwaves and droughts, derived by dominant role of temperature. We identify a robust linkage between CDHWs and large-scale circulation indices, notably the positive phase of Atlantic Multidecadal Oscillation (AMO) and the negative phase of Pacific Decadal Oscillation (PDO) have favored pronounced CDHWs over the past two decades. The AMO variability primary influences the mid-tropospheric pressure system leading to substantial temperature variations in the AP. However, the PDO largely impacts upper-level zonal winds, which modulate the strength of the subtropical westerly jet and subsequently changes the AP precipitation. Our findings highlight the urgent need for adaptive strategies and resilient measures to mitigate the adverse effects of CDHWs in a rapidly changing climate.