Climatology of the areal precipitation in Amman/Jordan

Data of the rainy seasons from 1956/1957 to 2005/2006 for 11 stations distributed over Amman area were analyzed. They were used to estimate the areal rainfall amount in Amman area; the annual data have a normal distribution with an average of 283.7 mm. The areal rainfall amounts varied from year to year, with a standard deviation (SD) of 72.9 mm and with a variation coefficient of 26%. The analysis of the areal rainfall over a 50-year period shows a decreasing trend (-0.4 mm/year), but with no statistical significance. The running means show two wet periods (1962/1963-1973/1974 and 1987/1988-1993/1994) and two dry periods that occurred in the beginning and the end of the study period. The amounts of water fall over Amman area ranged from 300 mm(3) to 870 mm(3). Despite these amounts, Amman suffers from water shortage which needs to be solved. Copyright (C) 2010 Royal Meteorological Society