Climatological Study of Atmospheric Stability overSaudi Arabia

Abstract. The atmospheric stability in midseason months (January,April, July and October) over the Kingdom of Saudi Arabia (KSA)has been studied using the average global data for the period 1960-2002. Generally, it was found that the areas of low static stability aresituated in the areas of cyclones or troughs and in the area of largestfrequency of disturbances occurrence. In the transitional seasons(springs and autumns), the area of Arabian Peninsula and south westRed Sea shows significant low static stability throughout thetroposphere up to 500 hPa. In the lowest layer (surface – 850 hPa). Itis associated with large baroclinicity with maximum heating, whatseems to be a favorable condition for cyclonic disturbances anddevelopment in the western Arabian Gulf. The appearance of very lowstatic stability over central and south west Red Sea at the same periods(April – October) in the lower layers, seems to be a cause of thesimultaneous amplification of the easterly Sudan monsoon wave. Thisleads to the conclusion that the development over the ArabianPeninsula and Gulf area is due to the interaction between the tropicaland extratropical disturbances. The low static stability is a veryessential factor especially for development of the small scale systems,such as the desert depressions and the formation of convective clouds