Local climate and trends in air mass-based weather types over the Arabian Peninsula

Although previous research on climate change in the Arabian Peninsula (AP) has studied changes in individual meteorological variables, an analysis of changes in the overall weather conditions based on multiple meteorological variables is limited. Based on an air mass-based classification system, this research explored the local climate (1979–2023) of daily surface weather conditions (i.e., air masses) and associated changes over the Peninsula. For this purpose, the gridded weather typing classification (GWTC-2), an approach to classify multivariate surface weather situations relative to the average local climate, was utilized as it demonstrated outstanding performance in capturing daily weather characteristics in the Peninsula. Cold air mass (C), days with low temperature and near average humidity, was the most common cool weather type, with notable occurrences from Nov to Feb. Warm air mass (W), hot days with near average humidity, was the most common warm weather condition and maintained a marked presence throughout the year, with notable occurrences in summer. Coastal regions showed higher presences of humid warm (HW) and humid (H) days, whereas the central parts demonstrated higher occurrences of air masses of below-average humidity (dry [D], dry cold [DC], and dry warm [DW]). Much of the Peninsula showed high intra-annual variability in cool, warm, humid, and dry air masses. Findings from trend analysis reinforce findings from previous studies related to ongoing warming over the Peninsula, as cool weather types (DC, C, and HC) are becoming less frequent, while warm weather types (W, DW, and HW) are becoming more frequent. This analysis further detected decreases in the average weather conditions along with reduced duration of C-type and increases in the length of warm weather types, further aggravating thermal stress across the AP.