ارزیابی عملکرد مدل های cmip6 در پیش نگری تغییرات دما و بارش در محدوده چاه نیمه های استان سیستان و بلوچستان

دما و بارش به دلیل تغییرات قابل ملاحظه زمانی و مکانی از مهمترین متغیرهای اقلیمی در بررسی تغییرات اقلیمی هستند و پیش نگری تغییرات آن‌ها در برنامه‌ریزی‌ها و مخاطرات محیطی از اهمیت زیادی برخوردار است. لذا در این پژوهش به پیش نگری آینده تغییرات دما و بارش در محدوده چاه نیمه‌های استان سیستان و بلوچستان پرداخته شد. بدین منظور، 8 مدل گردش کلی جو (gcm) از cmip6 با کاربست روش اصلاح اریبی مقیاس خطی (lsbc) با استفاده از سنجه‌های r2، mse، rmse و mae مورد ارزیابی قرار گرفت. سپس تغییرات دما و بارش در دوره آینده (2050-2021) نسبت به دوره پایه (2014-1995) با استفاده از بهترین مدل تحت سه سناریوی ssp1 2.6، ssp3 7.0 و ssp5 8.5مورد بررسی و پیش‌نگری قرار گرفت. جهت آشکارسازی روند تغییرات دما و بارش در دوره پایه (2014-1995) نیز آزمون ناپارامتری من کندال و تخمین‌گر شیب سن در مقیاس سالانه مورد بررسی قرار گرفت. نتایج نشان داد که بارش در منطقه مورد مطالعه دارای روند کاهشی و دما دارای روند افزایشی بوده است. نتایج حاصل از ارزیابی مدل‌های cmip6 نشان داد که مدل‌های bcc_csm2_mr و fgoals g3 به ترتیب با rmse برابر با 0.94 و 5.6، بهترین و ضعیف‌ترین عملکرد را جهت شبیه‌سازی بارش در منطقه مورد مطالعه دارند. ارزیابی عملکرد مدل‌های مورد بررسی در شبیه‌سازی متوسط دما نیز نشان داد که مدل‌ mri esm2 0 با rmse برابر با 0.23 بهترین عملکرد و مدل canesm5 با rmse برابر با 0.33 ضعیف ترین عملکرد را دارند. نتایج حاصل از پیش‌نگری دما و بارش در منطقه مورد مطالعه نیز نشان داد که بارش در دوره آینده به طور متوسط به میزان 4.1 درصد نسبت به دوره مشاهداتی کاهش و دما به میزان 1.4 درجه سلسیوس افزایش پیدا خواهد کرد. همچنین سناریوهای ssp5 8.5 و ssp1 2.6 به ترتیب بیشترین و کمترین تغییرات دما و بارش را در منطقه مورد مطالعه نشان می دهند.نتایج حاصل از این پژوهش می تواند در مدیریت منابع آب چاه نیمه ها موثر باشد

performance analysis of cmip6 models in projection of temperature and precipitation changes in the chahnimeh area of sistan and baluchistan province

changes in temperature and precipitation are one of the most important debates in the field of environmental sciences. this phenomenon is very important because of its scientific and practical dimensions, because human systems dependent on climate elements such as water, agriculture, industries and the like are designed and operate on the basis of climate stability. therefore, predicting and knowing about temperature and precipitation changes in the coming years can be a solution to problems such as drought, sudden floods, high evaporation and environmental destruction. the civilization of several thousand years of sistan has been completely dependent on the flow of water in the sistan river. currently, the only source of water supply in the region is the flow of water in the hirmand river and the water storage sources of chahnimeh. considering the dry climate of the region and the rainfall of about 50 mm per year and the presence of 120 day dry winds in sistan and the lack of suitable underground water resources in the region, the hirmand river and the chahnimeh are the only source of water supply in the region. as a result, investigating climate changes and predicting changes in temperature and precipitation within the limits of these devices is very important to save sistan. in this research, 8 gcm models from cmip6 were evaluated according to their high resolution and available meteorological data, and after correcting the bias using the lsbc method, the performance of these models was evaluated in simulating the relevant parameters. the study was conducted in the basic period of these models (1990 2014). after receiving the data, the observational and historical parameter values for each of the studied stations were extracted by preparing a in the matlab environment using the closest gcms grid in the base period (1995 2014). then the bias correction method was used to correct the data. in the following, the difference between the values of observational and historical parameters was evaluated using different indices. after validating and evaluating the accuracy of different gcm models, using the best model, temperature and precipitation changes in the future periods were predicted under three different scenarios and its changes in the future period compared to the historical period (1995 2014) was investigated. in order to reveal the trend of changes in temperature and precipitation, non parametric mann kendall test and sen,s slope estimator were also investigated.the results showed that the rainfall in zabul and zahak stations had a decreasing trend and this decreasing trend was not significant in any of the mentioned stations. based on this, the decreasing trend of precipitation in the studied area is the type of short term fluctuations of water and it is aerial. the highest decrease in precipitation is related to zabul station with a gradient of 2.4. the trend of temperature also shows an increasing trend in both meteorological stations and this increasing trend is significant at the level of 5% in zabul station. examining the slope of temperature changes also shows that the highest slope of temperature changes is related to zabul station with a slope of 0.07. after bias correction, the performance and accuracy of the models were evaluated in the simulation of the studied parameters using various indicators at the zabul syndication station as the selected station of the region. the results showed that based on the rmse index, bcc_csm2_mr model and then mpi esm1 2 lr have higher accuracy than other models for simulating precipitation.