نوع مقاله : مقاله پژوهشی
1 گروه مهندسی عمران آب، دانشگاه آزاد اسلامی واحد علوم و تحقیقات تهران
2 فارغ التحصیل کارشناسی ارشد، رشته مهندسی و مدیریت منابع آب، موسسه آموزش عالی آل طاها
3 پژوهشکده مطالعات و تحقیقات منابع آب، موسسه تحقیقات آب، وزارت نیرو
4 دانشکده فنی و مهندسی، گروه مهندسی عمران، دانشگاه ولیعصر (عج) رفسنجان.
عنوان مقاله [English]
Today, the effects of large-scale atmospheric signals on the local weather in different parts of the world have been proven. Understanding the climate processes enables managers to evaluate in their policy and plan the damages cost that these phenomena can impose on the communities. This paper aims at evaluating the effect of large-scale atmospheric signals on the Iran's rainfall. To investigate precipitation variation, SOI, AO, NAO, and MJO indices were. The rainfall in 21 stations over the country was studied in the 40-year period from 1975 to 2014, and it was determined that the ENSO had the greatest impact on the rainfall in most of the study areas. In addition, Average Mutual Information (AMI) showed that there was no lag time between the occurrence of El-niño in the pacific and its effect on atmospheric changes in the stations. Following the detection of El-Niño and La-Niña episodes, the average rainfalls were calculated during these episodes and compared with that of the normal episode. According to the results, rainfall in Mashhad station with 39.5% increase took the greatest impact from El-Niño. The precipitation of Tehran also increased by an average of 10% under the influence of El-niño, and its maximum increase was taken place by 30.3% in 1982. In general, the El-niño in Iran causes increasing in rainfall amount and the La-Niña decreases rainfall.