Abstract
In characterizing the patterns of climate change across Saudi Arabia, several extreme indices are calculated from station values daily maximum and minimum temperature data. The trend analyses are performed on 13 annual extreme indices for Saudi Arabia, using observations from 27 surface stations with high-quality data for the period 1981-2010. RClimDex is used to calculate the indices, and simple regression methods are employed for the trend analysis. The analyses of extreme temperature indices detected a significant increase in the majority of the stations, which further indicates that the country has experienced a warming trend. The findings show that 92/89% of the stations displayed a significant increase in the annual occurrence of warm days/nights and 96/93% revealed a significant decrease for the occurrence of cool days/nights. Time-series analysis has also shown an important feature of the climate change signal. When the dataset is divided into two sub-periods, the analysis reveals a distinctive long-term trend that clearly distinguishes the two periods. It was found that the temperature extremes (hot and cold) in Saudi Arabia have increased significantly with greater magnitude in the recent-past (1996-2010) compared to the previous period (1981-1995). The most telling evidence for this is the heat- and cold-waves, where indices of both have occurred more frequently in the second part of the two sub-periods.