Inter-decadal and long-term variations in the summer temperatures over the Middle East
Abstract
The variations in the 850 hPa temperatures over the Eastern Mediterranean (EM) in July-August for 1948-2001 were analyzed, using NCEP-NCAR reanalysis data. The variables examined contain the seasonal averages, seasonal extremes, seasonal standard deviations and the frequency and duration of "hot" and "cool" spells. "Hot" and "cool" days were defined as days whose individual daily average temperature deviated by more than 1 STD from the July-August average. The seasonal averages, together with the "hot" and "cool" spells, indicate the existence of three warm periods, one in the fifties, one in the late seventies and early to mid eighties, and the third, the warmest, beginning in the mid-nineties. An average warming trend, being 0.013^oKy-1, and an increase in extremity were found, in agreement with surface observations (Ben-Gai, 1999). This trend was found also in both seasonal maximum and minimum temperatures. The increasing trend of extremity is manifested in three forms. One is an increase in the seasonal standard deviation of the daily temperatures at a rate of 7% for 50 years. Second is an increase in the frequency and length of both "hot" and "cool" spells. Third is a trend of increase in the seasonal absolute maximum temperature, at a rate of 0.015^oKy-1, 3 times larger than the increase in the minimum temperature.
- Publication:
-
EGS - AGU - EUG Joint Assembly
- Pub Date:
- April 2003
- Bibcode:
- 2003EAEJA.....1266S