Document Type : Original Article
Master student of Climatology, Golestan University
Associate Professor of Climatology, Department of Geography, Golestan University, Gorgan
Researchers in various fields have given particular attention to the variability of temperature and precipitation components and the role of climate change as well as the effect of large-scale climate indicators in recent years. The North Caspian Sea (NCP) index is one of the most important regional-scale indicators that operates well in the East Atlantic with the NAO index. This study used three categories of data, including temperature and precipitation components, and reanalyzed geopotential altitude data of 500 hPa and geopotential altitude data of 500 hPa based on 14 climatic models. In the first stage, the NCP index was identified for future periods of development and generalization and then its positive and negative phases for the two scenarios RCP4.5 and RCP8.5. As well as maximum and minimum temperatures, precipitation rates, and number of precipitation days were displayed for future downscaling periods. Based on the forecasts for the positive and negative phases of this index, it was determined that for the next period 2060-2041, both the maximum and minimum temperatures will increase. Furthermore, the rate and number of rainy days in the future period will be more irregular than the temperature component compared to the base period. In the RCP4.5 scenario in both phases, it was found that the average number of rainy days will decline and, in both phases, rainfall rates will increase in stations that are near the Caspian Sea. In the RCP8.5 scenario, the average number of rainy days in the study area will decrease by about 5 days in the positive phase and increase by 4 days in the negative phase compared to the base period.