spatiotemporal analysis of carbon dixoid impact on seasonal rainfall oscillation in iran

climate change disturbs the distribution of precipitation patterns and affects water resources. a lot of evidences imply that the increased atmospheric concentration of greenhouse gasses in turn increases the precipitation changes around the world. thus, since iran is located in an arid zone of the earth, identifying the effects of co2 concentrations on iran precipitation rate is highly important in planning the projects for water resources. statistical data from 31 selected synoptic stations between 1975-2010 have been used. also data for co2 (ppm) were taken from the website of noaa and then were analyzed by pearson correlation coefficient (pcc). our results indicate that co2 had a positive (incaresing) effect on the spring precipitation in the northern areas of iran and a negative (decreasing) effect in the southern parts of the country. there is not a specific pattern for the distribution of precipitation in the summer; the related data were not much reliable. in the fall, co2 had an increasing effect on the precipitation rate in the eastern parts and, conversly, a decreasing effect observed in the northern parts (particularly in the southwestern coast lines of the caspian sea). finally, in the winter, precipitation rate showed an increasing pattern and, in some western and northeastern parts of the country, a decreasing pattern was observed.