Climate change impact on annual precipitation and temperature of Zanjan province with uncertainties investigation

In this paper climate change impact on annual precipitation and temperature series for Zanjan province was assessed and uncertainties were investigated. Spatial average of annual time series of precipitation and temperature for Zanjan province were calculated and then were modelled using ARMA model and 100 annual precipitation and temperature series of length 30 years were generated for spatial average of Zanjan province. Using the models, future scenarios of 6 GCMs under 3 emission scenarios were downscaled and 100 annual precipitation and temperature series of length 30 years were generated for each of the scenarios. 90% bounds of the variable statistics for the current condition were compared with the 90% bounds of the corresponding values for the all of the future scenarios and the uncertainties were investigated in the results. Model validation showed that the models are adequate for generation of the annual temperature and precipitation series. In confidence level of 90%, it is expected that average temperature of Zanjan province will increase from 0.6 to 3.2 ºC and average precipitation change from -25% to % in 2035-64 period. So, the uncertainty due to the GCMs Structure and the emission scenarios are considerable and should be considered.