Trend Analysis Blocking system in the north of Himesepher

Blocking is one of the most protruding flow patterns and has received attention during the last decades due to its effect on seasonal weather characteristics. Moreover, finding show that Most of the blocking systems in the northern hemisphere are in all seasons and their continuity in the Atlantic and Pacific. The results of the Mann-Kandal test at the 95% confidence level of the percentage of frequency of blocking systems showed that the northern hemisphere blocking systems have been increasing in most parts of Asia-Pacific, Europe and Iran, and the trend is decreasing on the Atlantic Ocean and the American continental. Of course, these trends only increased significantly on parts of Central Asia and Central Pacific. In the monthly, the Eastern and Central Atlantic segregated from May to September and December the decreasing trend that decreasing only in June, September and December in some areas of the trend, in October, November January, February and March is an increasing, and only in October and March this trend is significant.In the Pacific, except in March, there has been an increasing trend in all months in July, August, October and September. In the Americas, except in May and August, there has been a significant decrease in the other months. In Europe, except for the months of August, September and December, in other month has an increasing trend, which has not been significant. In Asia and in the region of Iran, although it is more or less an increasing trend, it is not significant