The Study of Sea Level Pressure Patterns and Wind aloft Features over the Middle East and the Persian Gulf Area during Spring Transition

The meteorological conditions during the period of spring transition over the Middle East and the Persian Gulf and adjacent land area is investigated. Monthly and seasonal variations of large-scale atmospheric patterns and wind aloft features at different levels were drawn from data collected from the National Centers for Environmental Prediction and National Center for Atmospheric Researches. The variations of atmospheric pressure patterns as indicated by monthly wind vectors of 1000، 850، 500 and 200 hPa and sea level pressure changes during summer، winter and spring months over the study area were analyzed. We found that the axis of the maximum wind at 500 and 200 hPa during the spring transition is moved northward from 27°N to 33°N; at 1000 hPa، the Omani Convergence Zone illustrated two closed adjacent cells، especially in April. Furthermore، sea level pressure variations during spring showed the expansion of pressure fall from Indian peninsula toward Pakistan and southeastern parts of Iran. When pressure fall reaches its abyth in May over India، Pakistan and also around the The Persian Gulf (about 7 hpa)، it is the sign of the onset of the Monsoon over the region. Interesting feature at 850 hPa is the strengthening of the wind speed during the transition over the northern part of the The Persian Gulf with a peak around 7.5 m/s.