Spatiotemporal climatology of the Arabian Subtropical Anticyclone

The Arabian Subtropical Anticyclone (ASA) plays an essential role in regulating weather systems over the Arabian Peninsula (Arabia) and adjacent areas. A need exists to document specific details of the spatial and temporal climatology of the ASA. In order to identify the monthly ASA position/center, the local maximum geopotential height (gph) should be located at different vertical levels. The common automated method did not work for the ASA in the warm season and an approach involving wind flow patterns was needed. The ASA was better defined in the lower troposphere in the cool season and in the mid- to upper-troposphere during the warm season. The near surface ASA begins in Aug over northern Arabia and migrates southeast until it reaches the Arabian Sea in Feb. Apr is the onset of the middle-troposphere ASA. From May to Aug, this anticyclone moves to the north with increasing height. The upper-level ASA is located over northeast Arabia in May and goes north in Jun and Jul. Seasonal changes in energy fluxes and atmospheric circulation patterns linked with the Asian Monsoon are identified as possible drivers of the temporal changes in the ASA.