Observed changes in minimum and maximum temperatures in Nile Delta : Egypt in the 20th Century

الملخص EN

This study examines changes in annual mean minimum and maximum temperatures (AMMIT and AMMXT) variations in Nile Delta (Egypt) during the 20th century.

The analyses focus on two time series records (1900-1947 and 1957-2010) at the Alexandria, Port Said and Cairo Meteorological Stations.

The climate trend coefficient, Rxt, value compared with t-test table and represent that there is no significant linear climate trend in all annual time series for all stations under investigations.

The occurrence of abrupt changes and trends were examined using cumulative sum charts (CUSUM) and bootstrapping and the Mann-Kendall rank test.

Statistically significant abrupt changes and trends have been detected.

Major change points in the AMMIT and AMMXTT occurred in different years with different significant levels during the two periods.

The significant warming trend slope between; (1900-1947), AMMIT has increased by rate of (0.031, 0.021 and 0.027 °C/year) and during the period between ; (1957-2010), AMMIT has increased by rate of (0.014, 0.021 and 0.034 °C/year) for Alexandria, Port Said and Cairo respectively.

The significant warming trend slope between ; (1900-1947), AMMXT has increased by rate of (0.011, 0.023 and 0.057 °C/year).

The significant warming trend slope between; (1957-2010) for Cairo, AMMXT has increased by rate of 0.008 °C/year, while significant cooling slope trend for Alexandra and Port Said by rate of -0.004 and -0.007 °C/year respectively.

Negative diurnal temperature range (DTR) trend in Alexandria (1901-1947) was mainly due to night temperature increasing faster than during the day.

Positive DTR trends in Port Said and Cairo (1900-1947) caused by opposite minimum and maximum temperature situation than in Alexandria.

Negative DTR results for the three stations during (1957-2010) mainly due to high urbanization development inside the three cities.