Climatology and Trends of Various Oceanic and Atmospheric Parameters in the Arabian Sea Over the Last 45 Years

Abstract

This study investigates the timescale variability of key atmospheric and oceanic variables in the Arabian Sea (AS) using 45 years (1979–2023) of data. Analyzing sea surface temperature (SST), wind components, precipitation, significant wave height, and peak wave period, notable regional and seasonal variations are identified. The northern AS experiences the highest surface warming at a rate of 0.15°C per decade. The westerlies have strengthened in the southwestern AS, while the northern AS displays a weakening trend. Along the northwest coast of India, the northerlies have intensified, but along the southwest coast of India, they have weakened. Precipitation trends have significant increases only along the southwest and northwest coasts of India. The significant wave height has increased across much of the AS, with a pronounced rise observed near the Somali coast (about 0.2 cm per year), and the peak period in the eastern AS has decreased, indicating a decline in long-period swells from the south. Even though this basin is strongly influenced by seasonal signals, the interannual variations in wave height anomalies are particularly significant in the central AS. Seasonal analysis reveals that the wave height in the central AS has a decreasing trend in June and August, despite being the peak monsoon months. This decrease corresponds with a similar decreasing trend in SST and westerlies, as well as an increase in the peak wave period. The study further explores the influence of dominant climate modes, such as the Indian Ocean Dipole (IOD) and El Niño-Southern Oscillation (ENSO), on the AS climate. Even though the phase agreement between IOD and ENSO is relatively good (r = 0.67) during the study period, the years 1997 and 2023 have notable differences in the meridional wind patterns, which in turn influence the significant wave height. These findings emphasise the need for adaptive strategies to address the impacts of climate variability and long-term trends on the marine environment of the AS.