ارزیابی بهترین دوره پایه انتخابی مدل‌های Gcm برای تعیین متغییرهای هواشناسی ایستگاه بیرجند در دوره‌های آتی

امروزه تعیین اثر تغییراقلیم برجنبه های مختلف زندگی بشریت کاملا مشهود است. در چنین شرایطی تعیین دوره پایه که تاثیرات تغییراقلیم نسبت به این دوره تعیین می شود بسیار حائز اهمیت می باشد. بدین منظور در این تحقیق، با استفاده از مدل های gcm، به ارزیابی دوره های پایه انتخابی برای ایستگاه سینوپتیک بیرجند پرداخته شد. برای انجام تحقیق، تعداد 27دوره پایه حاصل از 35مدل گزارش پنجم تغییراقلیم با دوره های مشابه حاصل از ایستگاه بیرجند مقایسه شدند. همچنین ماه هایی که بیشترین درصد اختلاف با نتایج مشاهداتی برای متغییر مورد نظر دارند مشخص شد. نتایج نشان داد که برای بارش دوره های طولانی مدت ولی برای دمای بیشینه وکمینه دوره هایی مانند 1980-1960 نتایج رضایتبخش ارائه می نمایند. با این حال در هر سه متغییر هواشناسی، دوره 1990-1960 و دوره های 31 ساله بهترین دوره ها از نظر تطابق با داده مشاهداتی می باشد. در بین ماه های سال نیز ماه های گرم جولای تا سپتامبر در مورد بارش و ماه های سرد دسامبر تا فوریه در مورد دمای کمینه و دمای بیشینه بیشترین درصد خطا نسبت به بقیه ماه ها را دارند.

Evaluation the best of selective base period of GCM models to determine meteorological variables of Birjand station in future periods

Evaluation the best of selective base period of GCM models to determine meteorological variables of Birjand station in future periods Abstract:Nowadays, determining the effect of a climate change in the various aspects of human life is quite evident. In such a situation, it is very important to determine the base period, which determines the effects of a climate change than in this period. Choosing a coursebased course plays an important role in choosing future courses to conduct research on the effects of climate change. Many researchers in the research use the LARSWG dynamic downscale method or the statistical method to measure the weather variables, which should be the same for the years of the base period and the upcoming period.This research was conducted to select the appropriate base course for estimating minimum temperature, maximum temperature and precipitation at the synoptic station in Birjand. The station is located at latitude 32 degrees and 53 degrees east and 59 degrees and 17 degrees north latitude. In order to evaluate and accuracy of the methods in this research, seven criteria for estimating root mean square error (RMSE) and mean absolute error (MAE), relative error (RD), mean relative error of the month of the year (MRDM), average relative error of the month in the year (RDMM), PBIAS and RSR. In this study, using GCM models, we assessed the selected base courses for the synoptic station in Birjand. To doing in the research, an amount of 27 base courses from 35 models of the fifth report of the change were compared with similar periods obtained from the station in Birjand.The results showed about precipitation that the duration of the base periods such as 19602005 and 19602000 is less of the RMSE and MAE errors than the rest of the courses, and the base period of 19651990 between periods less than 30 years and the period The 19901960s are also well suited to the precipitation data of the synoptic station. The maximum temperature of the 19601990, 19601985 and 19601995 is the lowest RMSE error. However, shortterm courses of 19801960 and 19651985 present satisfactory results.In the case of minimum temperatures, periods of 21 and 31 years 19601980, 19601985, 19601990 and 1965 1985 have a percentage error of RMSE and a lower percentage of PBIAS. Variable variation range can also be used to show the appropriate base course. The result showed that the periods 19602005 and 19702005 had a lower range of rainfall variation than the other variables and seems to be more suitable. However, courses such as 19902000, 19751995, and 19952005 have less certainty. The more courses that go into periods with shorter periods of time, the more modest and less certainty they will be. Also, if you look at changes in the 19752005 periods and the 19651995 periods, it will be clear how much each year towards the years closest to 2005 will be deducted from the precipitation daily average.The results also show that maximum temperature changes are better than precipitation, and all courses have less variation range. Nevertheless, the period of 19602005 has the highest degree of certainty and the period of 19752005 has the least degree of certainty compared to the rest of the courses. In contrast to precipitation, there are periods such as 19701990, which, if considered as the basis for research, provide more certainty than the longer period of 19652005 for maximum temperature. Also, what's most clear about the maximum temperature is the higher the period with years closer to 2005, the temperature increases, which will increase the temperature over time.The process of minimum temperature variations also indicates that in addition these changes are similar to the change in temperature, with the difference that the range of variations in the minimum temperature is somewhat higher than the maximum temperature. The period of 19602005 has the best degree of certainty and the period from 19752005 has the least degree of certainty than the rest of the courses. Although long periods of time are less certain than short periods, the result is that the longer the interval between periods increases, the more precise the results will be. The result is not entirely correct, 19752000 is less certainty than the 19652000 period and has better results in minimum temperatures. Therefore, the evaluation of selected periods of GCM models with similar periods from observations of Birjand station shows that for rainfall variables, periods with a number of years yield more satisfactory results, but for two variables the minimum temperature and maximum temperature of the periods, not long or short periods, provide less risk of RMSE and PBIAS than long periods.Keywords: climate change, GCM model, base period, meteorological variable, emotion scenario