Trend analysis of widespread heat days in the Middle East and North Africa region between 1871 and 2012.

One of the greatest challenges facing the world today is global warming. Long‐term analysis of spatiotemporal variations in widespread heat days (WHDs) is one approach to monitoring this phenomenon, rather than focusing on the temperature trend. The objective of this study was to reconstruct the temporal and spatial variation of WHDs in the Middle East and North Africa (MENA) using the long‐term NOAA/CIRES/DOE 20th Century Reanalysis (V2) (20CRv2) reanalysis data between 1871 and 2012. Based on a 90% probability of occurrence, the temperature threshold for detecting WHDs was defined to be different for each grid point. Then, most WHDs of each month (142 samples) were identified based on the connected component labelling method. The results showed that most WHDs for each month occurred mainly after 2000. In general, the western parts of Iran, Syria, southern Turkey, Saudi Arabia, Kuwait, Egypt and northern Sudan had the highest density of WHDs. In the second period (1941–2012), the extent of WHDs increased compared to the first period (1871–1941). The spatial relationship between WHDs density in the first and second periods showed no statistical relationship, indicating that WHDs were completely different in the two periods. The results of this study contribute to a better understanding of the effects of global warming by using the relatively longest data sets. The comparison between the two periods shows that the WHDs in MENA have changed in extent (instead of variability). [ABSTRACT FROM AUTHOR]