Temperatures trends analysis in context of climate change using mann-kendall and semi-average tests: A Case study of Imam Turki bin abdullah royal nature reserve (Itba, Saudi Arabia)

Temperatures trend analysis, on different spatial and temporal scales, has been used by the scientific community during the past century as the indicate of global climate change. According to some recent studies, the Nature Reserve (ITBA) has been suffering a Temperatures increase, especially in the second half of the studied period (1993-2018). The aim of the present study is to analyze the Temperatures trends using the time series of 41 years in Qaysumah, Rafha and Al Jawf and 39 in Ha’il stations surrounding the Nature Reserve of (ITBA) that extended on area of about 91500 km2 in the Northeast of Saudi Arabia. This study applied the Mann-Kendall test and the Semi-averages method to determine the temperatures trends using the recorded data. So, the main results obtained revealed the highest temperatures at Qaysumah and the lowest temperatures at Ha’il and Al Jawf. The variance, Chi square test shows that the variance of the maximum daily temperatures was significant in Qaysumah and Ha’il, the variance of the mean daily temperature was significant in only Qaysumah, and the variance of the minimum daily temperature was significant in all studied stations. The Fmax-ratio shows the variance of the maximum daily temperatures is not homogeneous in the total of studied stations, and the variance of the mean daily temperature is not homogeneous in Al Jawf and Rafha. While the variance of the minimu daily temperature is not homogeneous in only Qaysumah. As for the trends analysis, the T-student and Mann-Kendall tests show the significant increased trends of the maximum daily temperatures at only Ha’il and Al Jawf, the significant increased trends of the mean daily temperatures in all of the studied stations at 5% level of significance and 39 and 37 degree of freedom, respectively.