Wintertime surface temperature in Egypt in relation to the associated atmospheric circulation

Mean wintertime temperatures (December, January, February) recorded during the period 1905-2000 at 18 weather stations distributed across Egypt were analysed to reveal spatial and temporal patterns of long-term trends. The relationship between winter atmospheric circulation indices and winter temperature in Egypt is examined using correlation analysis. The atmospheric circulation is represented by four indices: the well-known El Nino-southern oscillation (ENSO), North Atlantic oscillation (NAO) index, East Atlantic-West Russia (EAWR) index, and East Atlantic (EA) index. Surface temperature is a stable climatic element whose coefficient of variation (COV) is lower during winter. A statistically significant relation between COV and latitude indicates that stations in the south, Upper Egypt, are more variable than stations in the north, Lower Egypt. Increasing and decreasing winter surface temperature trends were found. In general, wintertime temperature has increased (warming) at most stations. Decreasing trends (cooling) are observed mainly over Upper Egypt. The upward trends in mean winter temperature during the 1910s-30s, mid 1970s, and early 1980s-2000 and the downward trends during the 1940s and 1960s are prominent features of the temporal distributions. The warming period that occurred early in the century may be explained by changes in circulation. Striking upward trends are most remarkable during the last 20 years. This Could be attributed not only to human activities, but also to atmospheric circulation changes. No detectable connection between Egypt temperature and either ENSO or EA index was found during winter. A statistically significant negative relationship between winter temperature and winter NAO index can be observed. The NAO index is more dominant in determining winter temperature than ENSO circulation. A significantly stronger negative relationship between temperature over Egypt and the winter EAWR index values is detected. Copyright (C) 2004 Royal Meteorological Society.