A SurveyTrend and Slope Trend Sum-Month of Heating Degree Day of Iran

Climate change and increase the temperature of the environmental importance of human behavior that is considered In recent years many studies have been devoted. Objective of this study is to investigate trend and slope Trend monthly of HDD with temperature threshold of 18. Mean daily temperature of weather during the statistical period of 44 years (1962-2005) was provided from Asfe zary dataset. Then trend and slope trend of HDD was calculated for each cell by nonparametric Kendall test. Data included a matrix with dimensions of (7187*44) in which lines show place (cell) and columns show time (year). Results indicate positive CDD trend in North Kordestan and Zanjan، Western half of Shahrekord، Macue and Westrern Bojnoord lower temperature، indicating that the spring and Fall. HDD negative trends for the Plain inter، the Zagros range north and south and rang mountain Kerman and khorasan appear increase in temperature indicates that this region. The maximum range of spatial need heating in month jan h with 54 percent of the extent of Iran''s. Maximum slope of negative trends requires heating block Lute and Tehran of the 2 - to 4 - degree days per year.