بررسي سينوپتيك الگوهاي سطح 500 هكتوپاسكال در خاورميانه در دوره 1961 - 1990

Spatial Variations of 500 hPa Level in the Middle East During 1961-90

In this study the monthly heights of the 500 hPa level at grid points with 5 degrees spacing for the 1961-90 period within the window of 20°N to 50°N and 0°E to 70°E were utilized. The temporal variations of the height patterns were studied using lag-correlations. The results showed no significant temporal or spatial changes in the 500 hPa height patterns. There was always a long wave trough over the Mediterranean during the cold period of the year. Its axis is usually situated over 30°E. During the warmer months, the westerlies move back to the northern latitudes and subtropical high pressure expands over the area.