The time series of SAIs for both the temperature and rainfall are
depicted in Figs. 2 and 3, respectively. Successive above-normal
departures of nighttime and daytime temperatures are striking
since around the mid-1980s, with the warming of climate more
pronounced during the nighttime than the daytime. However, the
rate of the increasing trend in the maximum temperature over the
period of study is slightly stronger (0.25 C decade1; a < 0.001)
than the corresponding rate for the minimum (0.21 C decade1;
a < 0.001). Accordingly, the mean temperature series has a rate of
0.23 C decade1, significant at a < 0.001. Results by Elagib and
Elhag (2011) show for El Gedaref: (1) that the rate of increasing
maximum temperature anomalies is the highest in the country and
(2) that the anomalies of the temperature variables are significantly,
but negatively, related to the rainfall anomalies for the
period 1971e2008, indicating concurrent warmth and dryness.