An Analysis of long-term monthly changes in lethal temperatures above 50°C in the Northern Hemisphere

This paper intends to identify and statistically analyze monthly changes in the lethal temperature above 50 degrees Celsius (TU50c) in the Northern Hemisphere. For this purpose, the reanalyzed data related to the maximum temperature up to two meters of the earth's surface was used during the period of 73 years from 1948 to 2020, and after adjustment, analyzed on a monthly basis. Descriptive statistics analysis methods, linear trend analysis and non-parametric Mann-Kendall test are used for evaluating the frequency of such occurrences. During the 73-year study period, 9553 days with minimum temperature of 50 degrees Celsius were identified and their coordinates were extracted. Examining the daily frequency of TU50c in the Northern Hemisphere showed that the months of May and January have had the highest frequency, respectively. Also, the highest increasing trend in the number of fatal temperatures was observed in the months of March, April, July and August. In terms of location, the region that could record the highest frequency and the most intense TU50c was related to Africa especially Sudan, West Asia (between Iraq, Southwest of Iran, Kuwait and Saudi Arabia) and India in the Indian subcontinent. Moreover, these temperatures are not rare in America either; but TU50c has not been reported in Europe and East Asia. The highest and most intense temperatures occurred in the fifth decade, between 1988 and 1998.