Forecasting temperature and precipitation parameters of Ahvaz synoptic station using MPI-EMS1-2-HR general circulation model and SDSM6.1 statistical downscaling model

Climate is considered one of the fundamental elements of human life and with the progress and development in the world, its protection becomes more important day by day. Humans are considered the main cause of these changes by ignoring the laws governing nature and not knowing the environmental issues related to it. The biggest cause of climate change is the increase of greenhouse gases and the most important greenhouse gas is carbon dioxide. In recent decades, the concentration of carbon dioxide greenhouse gas has increased at a very high speed and it seems that this trend will continue. Perhaps this is the reason why many recent researches have been devoted to the impact of various factors on the emission of carbon dioxide gas.

Ahvaz city, the capital of Khuzestan province, with an area of 4864 square kilometers, is located at 31 degrees and 20 minutes north latitude and 48 minutes east longitude. The average height of the city is 31 meters above sea level and the height of Ahvaz city is 18 meters above sea level. First, the basic data of the Ahvaz station from 1979 to 2014 were received from the General Meteorological Department of Khuzestan province, then using the statistical microdistribution model (SDSM) and by modeling the data of the projected socio-economic scenarios (SSP, temperature and precipitation of this The station was predicted based on the MPI-EMS1-2-HR coupled model of the Max Planck Institute from 2020 to 2050. The common socio-economic paths (SSP) are the projected socio-economic scenarios until 2100. From them to extract Greenhouse gas emission scenarios are used with different climate policies. 

CMIP6 is a project coordinated by the Working Group on Coupled Modeling (WGCM) as part of the World Climate Research Program (WCRP). Phase 6 builds on previous phases implemented under the leadership of the Climate Model Diagnostic and Intercomparison Program. ) (PCMDI is implemented. This model is provided by the Max Planck Institute with a higher resolution. The mentioned model is the latest version of the atmospheric general circulation models (GCM) and presented in the latest IPCC report. In addition to the previous models, which are based on the coupled models of the ocean, atmosphere and the interaction of the two and the large-scale system of the general circulation of the atmosphere, this model includes two other coupled models, including the land-vegetation model and the continent-ocean interaction model and It incorporates the carbon cycle, so it is currently one of the most complete statistical models. In most scenarios, the minimum temperature shows an increasing trend in most months. But in the ssp126 scenario, the minimum temperature will decrease in the months of January, May, September and December. Checking the monthly minimum temperature, observations show that the average minimum temperature in Ahvaz station has not reached below 6.5 degrees Celsius in any of the months of the year. But in all scenarios, the minimum temperature has increased to between 0.5 and 3.5 degrees Celsius, which indicates the temperature growth in the future. The highest average temperature growth is in ssp585, so that the long-term average monthly temperature has reached from 18.8 degrees to 20.9 degrees in this scenario, which shows an increase of 1.2 degrees compared to the base year. The lowest increase in minimum temperature is also 19.5 degrees long-term average in the ssp126 scenario, which shows an increase of 0.7 degrees compared to the base year. 

In this research work, SDSM statistical microscale method and to evaluate climate changes, the general circulation model and climate output models of the 6th series (CMIP6) which are updated RCP2.6, RCP4.5, RCP6.5 and RCP8.5 scenarios used. The results of the monthly minimum temperature survey for the years 2020 to 2050 showed that in the future the minimum temperature will increase between 0.5 and 3.5 degrees Celsius and it will be warmer, which indicates the temperature growth in the future. Also, the monthly average maximum temperature in the four investigated scenarios (2020 to 2050) for Ahvaz station shows that the monthly maximum temperature will increase between 0.8 and 2.3 degrees Celsius in all months and the air temperature will be warmer. The results of the analysis of the monthly rainfall data of the base period with predictive scenarios during (2020-2050) show that the rainfall based on most of the reviewed scenarios for all months wil