Analysis of frosty days in Gorgan synoptic station under climate change

Abstract
Background and objectives: According to the Fourth Intergovernmental Panel on Climate Change, Average global temperature in the 20th century has an increasing About 0.6 ° C and this increase for the 21st century is measured to be about 1.1 to 4.6. Cold and frost will be affected by these temperature changes. One of the major climatic factors that occur during most of the cold season in most parts of the country, The phenomenon is cold and freezing, It affects human life as well as construction activities and the growth and productivity of agricultural products and transportation, and many human activity. Accordingly, this research to compare and analyze the phenomenon of cold and frost using daily minimum temperature data downloads Gorgan Station with the climate change approach in the observation period (1961-2014) and projected future period (2015-2018) based on the output of the SDSM scale scaling model
Materials and methods: In this study, in order to analyze the ice days of the Gorgan station with a climate change approach, Daily Minimum Temperature Data of Gorgan Station, In the time period 2014_1961, it was received from the Golestan Province Meteorological Administration. Then, in the MATLAB software, the number of frosty days in the monthly and annual period in the observation and future period was calculated according to three new scenarios AR5 (RCPRCP_2.6, RCP_4.5 and RCP_8.5) in the 45-year period. The Intergovernmental Panel on Climate Change (ILO) has used the AR5's Fifth Assessment Report on new RCP scenarios as representatives of the various emission levels of greenhouse gases. In this research, SDSM software has been used to generate daily minimum temperature data in the upcoming period (2068-2015) from three scenarios of release RCP_2.6, RCP_4.5, RCP_8.5. In this study, Wilcoxon test was used because the data were not normal.
Result: After estimating the minimum temperature of the Gorgan station in the period of observations and the future based on three scenarios RCP_2.6, RCP_4.5 and RCP_8.5, it was determined that the minimum temperature in the future period has increased compared to the observation period. Which will reduce the freezing days in the future. For comparison of frosty days, observational data and data generated for the future are plotted in the chart. This chart shows a significant decrease in future frosty days. In the following , In SPSS software environment using Wilcoxon test the average of observational data has been compared with the three scenarios RCP_2.6 and RCP_4.5 and RCP_8.5. Meaningful meanings indicate that frost days will be reduced in the future. The results show that the minimum temperature in the future period has increased compared to the observation period. Which will reduce the freezing days in the future.
Conclusion: In this research, by specifying the number of frost days in the observation and future period and comparing them, they try to determine how to change the number of frosty days in the future and climate change. Comparison of the results in the observational and future period indicates a rise in the minimum temperature and a decrease in the number of freezing days, Based on the output of the used models, The average of frosty days from about 16 days in the observation period To about 8 days in the scenario RCP_2.6, about 7 days in the RCP_4.5 scenario and about 6 days in the scenario RCP_8.5 decreases, which is a logical consequence of climate change and global warming in the future.