Abstract
Saudi Arabian subtropical high pressure is a major system affecting general circulation of the atmosphere of west Asia. Its annual relocation affects the relocation of other systems in the area, such as Mediterranean cyclones, Sudanese low pressure areas, and west wind waves. This system is known to relocate to the south and north in response to outward solar relocation, but the reasons behind its eastern and western relocation have not been studied thoroughly. The present study examined 1000 and 850 HPa levels over the course of 66 years (1948-2015) to determine a pattern of latitudinal and longitudinal relocation of the system using synoptic maps. The research showed that, after 2008, high pressure latitudinal and longitudinal swings were larger than in previous years and the annual high pressure relocation was not in concord with the apparent motion of the sun. At the onset of autumnal moderation, the high pressure core was positioned to the north of Saudi Arabia (22° - 30° north latitude and 42° - 50° south longitude). Southern movement continued until the end of March, when the core again relocated to the north. These relocations first occurred slowly, but the northern relocation occurred very quickly from May to June, such that the core moved northward 22° to 30°. After June, the core did not relocate much until the end of September. After September, it relocated strongly south in all time periods. It was noted that high pressure over Saudi Arabia had two cores from June to September in some years; in others the high pressure core was in southwestern Iran and Iraq. In still others, a southwest to northeast high pressure tab entered Iran from the southwest (Khuzestan) and continued northward with a core forming in the northern Caspian Sea.
Highlights
In the recent past and according to recent studies, subtropical high pressure, especially that over Saudi Arabia, is considered to be a factor that intensifies drought, dryness, and stability of the weather of Iran
It was noted that high pressure over Saudi Arabia had two cores from June to September in some years; in others the high pressure core was in southwestern Iran and Iraq
The subtropical high pressure over the Azores in the northeastern Atlantic Ocean is in the lower level; the high pressure in northwest Africa and Saudi Arabia is in the middle level; the high pressure of Tibet is in the upper level of the troposphere; these are independent centers
Summary
In the recent past and according to recent studies, subtropical high pressure, especially that over Saudi Arabia, is considered to be a factor that intensifies drought, dryness, and stability of the weather of Iran. When the Saudi Arabian anticyclone turns toward the east under specific circumstances and resides over the warm Arabian Sea, Sea of Oman, and the Indian Ocean, it operates very differently from the time it turns west and resides over the Arabian Peninsula and the Red Sea. Iran falls into a dry climate belt and features a dry and semiarid climate in response to its geographical location and topography and relative position in the general movement of the atmosphere. Saudi Arabian high pressure forms as a major subtropical high pressure cell on the Arabian Peninsula and moves upward and downward in latitude according to the apparent motion of the sun. This cell is dominant in Iran during the hot period of the year; its long term persistence causes hot and dry summers. The center of high pressure in Iran lies in both the middle and upper levels [2]
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