Moisture Sources for Precipitation Variability over the Arabian Peninsula

Abstract

We apply the Lagrangian-based moisture back trajectory method to two reanalysis datasets to determine the moisture sources for wet season precipitation over the Arabian Peninsula, defined as land on the Asian Continent to the south of the Turkish border and west of Iran. For this purpose, we make use of the evaporative source region between 65°W–120°E and 30°S–60°N, which is divided into twelve sub-regions. Our results indicate north-to-south spatiotemporal heterogeneity in the characteristics of dominant moisture sources. In the north, moisture for precipitation is mainly sourced from midlatitude land and water bodies, such as the Mediterranean and Caspian Seas. Areas further south are dependent on moisture transport from the Western Indian Ocean and parts of the African continent. The El Niño Southern Oscillation (ENSO) cycle exhibits an overall positive but sub-seasonally varying influence on the precipitation variability over the region, with noticeable moisture anomalies from all major source regions. A significant drying trend exists over parts of the Peninsula, which both reanalyses partially attribute to anomalies in the moisture advection from the Congo Basin and South Atlantic Ocean. However, considerable uncertainty in evaporation trends over the terrestrial evaporative sources in observations warrants additional modeling studies to further our understanding of key processes contributing to the negative trends.

Precipitation teleconnections during 1950-2021 over the Arabian Peninsula

“…The AP is defined following Horan et al (2022) analyses is based on a two-tailed Student's t-test with N-2 degrees of freedom at the 90% confidence level.…”

“…The most well-known and widely studied phenomenon with influence over the AP is the El Niño-Southern Oscillation (ENSO). Studies show that the positive (negative) phase of ENSO is related to an increase (decrease) in precipitation over most of the AP (Almazroui et al, 2013;Donat et al, 2014;Kang et al, 2015;Atif et al, 2020;Horan et al, 2022;Abid et al, 2016Abid et al, , 2020. Kang et al (2015) additionally noted the strengthening of ENSO influence on AP precipitation in recent decades.…”

“…With limited freshwater resources and a rapidly warming regional climate that regularly reaches manuscript submitted to Journal of Geophysical Research -Atmospheres extreme temperatures due to the background environmental conditions, knowing the changes in the likelihood of anomalously wet and dry years is critical for the region. Trends since 1980 indicate drying patterns with decreasing precipitation reaching statistical significance over the central AP (Kwarteng et al, 2009;Almazroui et al, 2012;Alsaaran & Alghamdi, 2022;Syed et al, 2022;Horan et al, 2022).…”

“…The precipitation distribution exhibits spatial heterogeneity, with higher magnitudes limited to the northern AP, central Saudi Arabia, and the coastal areas through Oman. The exception is the areas bordering the Red Sea that are influenced by topographic-induced convection and receive noticeable precipitation (~30 %) outside the wet season (Horan et al, 2022). Several studies project that a continuously warming climate may lead to more commonplace occurrences of extreme precipitation and prolonged droughts across the AP region Donat et al, 2014).…”

“…Likewise, robust knowledge of the influences exerted by the internal modes of variability in the Northern Hemisphere is also lacking. The North Atlantic Oscillation (NAO) -the most prominent mode of variability in the Northern Hemisphere during winter -has been shown to have a generally negative, though statistically insignificant correlation with precipitation over most of the AP (Saeed & Almazroui, 2019;Ehsan et al, 2017;Atif et al, 2020;Donat et al, 2014;Horan et al, 2022). However, several other frequently occurring Northern Hemisphere atmospheric patterns (Barnston & Livezey 1987), such as East Atlantic Mode (EAM), East Atlantic West Russia Pattern (EAWR), and Siberian High (SH), may manuscript submitted to Journal of Geophysical Research -Atmospheres also impact AP precipitation through the modulation of extratropical storm tracks, which warrants thorough investigation.…”