بررسي روند تغييرات بارش، دما و رطوبت نسبي در 26 ايستگاه سينوپتيك كشور

Survey of precipitation, temperature and relative humidity trend in 26 synoptic weather stations of Iran

Climatic changes as one of the major global challenges has made interested in itself researchers, scientists, planners and politicians. Since the climate is one of the important parts of ecosystem, a little change on it, can affect other parts of the ecosystem in different severity. So the survey of climate changes, reasons and the effects of it on ecosystems and the human life are the cases that have special priority in natural recourse and land unit management such as ecosystem, field or watershed. To survey climatic changes in Iran, monthly and yearly changes trend of five parameters (minimum temperature, maximum temperature, mean temperature, relative humidity and the precipitation) at 26 synoptic stations (Babolsar, Bam, Bandaranzali, Esfahan, Kerman, Kermanshah, Khorram Abad, Mashhad, Ramsar, Rasht, Shahrood, Shiraz, Tabriz, Tehran Mehra bad, Yazd, Zahedan, Iranshahr, Khoy, Zanjan, Shahrekord, Sanandaj, Oroomieh, Hamedan, Birjand, Gorgan and Sabzevar) at 55 years duration have been surveyed by using y=a +bx function and t Kendall test. The results show the changes in temperature at the most stations which are in central, east and north of the country. Most of stations at Zagros have no significant changes at temperature. Precipitation parameter in the summer has significant descendant at most stations. Most stations at center and east of Iran have descendant relative humidity trend, while this condition isnʹt spreading in Zagros and north part of country. Also, results showed that the steepness and effect of minimum temperature in increasing in mean temperature, at stations that have temperature ascending trend, is more than maximum temperature. This subject can be the result of increasing in green house gases and reflection of received thermal energies from land at night. Temperature ascendant and relative humidity descendent can increase evaporation of received precipitation. At whole according to the surveyed station, climate changes trend at central and east and to some extent north part of country is observed.