Changes in extreme temperature and precipitation in the Arab region: long‐term trends and variability related to ENSO and NAO

Abstract

A workshop was held in Casablanca, Morocco, in March 2012, to enhance knowledge of climate extremes and their changes in the Arab region. This workshop initiated intensive data compilation activities of daily observational weather station data from the Arab region. After conducting careful control processes to ensure the quality and homogeneity of the data, climate indices for extreme temperatures and precipitation were calculated. This study examines the temporal changes in climate extremes in the Arab region with regard to long-term trends and natural variability related to ENSO and NAO. We find consistent warming trends since the middle of the 20th Century across the region. This is evident in the increased frequencies of warm days and warm nights, higher extreme temperature values, fewer cold days and cold nights and shorter cold spell durations. The warming trends seem to be particularly strong since the early 1970s. Changes in precipitation are generally less consistent and characterised by a higher spatial and temporal variability; the trends are generally less significant. However, in the western part of the Arab region, there is a tendency towards wetter conditions. In contrast, in the eastern part, there are more drying trends, although, these are of low significance. We also find some relationships between climate extremes in the Arab region and certain prominent modes of variability, in particular El Niño-Southern Oscillation (ENSO) and North Atlantic Oscillation (NAO). The relationships of the climate extremes with NAO are stronger, in general, than those with ENSO, and are particularly strong in the western part of the Arab region (closer to the Atlantic Ocean). The relationships with ENSO are found to be more significant towards the eastern part of the area of study.

Recent warming trend in the coastal region of Qatar

“…Similar trends have been observed in many parts of the world , including the Arabian region (Donat et al 2013). The warming trends in the percentile-based indices for Qatar are greater than the corresponding averages for the Arabian Peninsula, as mentioned before.…”

“…7, the increases in the number of warm days/nights occurred gradually during the 1980s, except for a sharp rise in the 1990s for both indices. Region-wide averaged results reported by Zhang et al (2005) and Donat et al (2013) have shown similar trends to the single-station results illustrated in Figs. 7 and 8.…”

“…Several stations within the region also reported this unexpected heating (AlSarmi and Washington 2011; Donat et al 2013). There were also reports (e.g., Webster et al 1999;Yu et al 1999) of anomalous rises of the sea surface temperature in the Indian Ocean, which could have been related to the El Niño effect.…”

“…This test is applied when a reference station is available, as in this case. A homogeneous reference station from Bahrain (Donat et al 2013; AlSarmi and Washington 2011) was selected as the reference station to check the homogeneity of the data series from DIA.…”

“…Extreme climate indices were analyzed for some countries in the Arabian Peninsula by AlSarmi and Washington (2014). Recently, a comprehensive analysis of climate extremes, based on the 27 Expert Team on Climate Change Detection and Indices (ETCCDI) for the entire Arabian region, indicated a consistent warming trend with an increase in the occurrence of warm days and nights, fewer cold days and nights, shorter cold spells, and higher extreme temperature values (Donat et al 2013). In a recent analysis, Lelieveld et al (2012) concluded that the heating across the region of the eastern Mediterranean to the Arabian Peninsula is more prominent.…”