در مطالعه حاضر، همبستگی، میزان و روند تغییرات عناصر دما و بارش ایستگاه شیراز طی دوره آماری 2005- 1951 در مقاطع سالانه و فصلی با استفاده از روشهای رگرسیون سریهای زمانی، شاخص استاندارد زی اسکور و روش میانگینهای متحرک، آزمونهای استقلال و همگنی، بتا( β ) و مان ـ کندال بررسی شده است. بررسی عنصر دما نشان میدهد که متوسط دمای سالانه دارای روند افزایشی به میزان9/1 درجه سانتیگراد در طی دوره مورد مطالعه است و این افزایش تقریباً در هر چهار فصل نیز قابل مشاهده است، اما متوسط بارش سالانه بر عکس متوسط دمای سالانه در کل یک روند کاهشی از خود نشان میدهد و از نظر فصول سال نیز این روند کاهشی به غیر از فصل زمستان در سایر فصول مشاهده میشود. با توجه به ضریب همبستگی رتبهای مان ـ کندال روند مشخصی در آماره بارش سالانه ایستگاه همدید شیراز یافت نشد.
عنوان مقاله [English]
Analysis of Temperature and Precipitation changes of Shiraz during the Period of 1951-2005
Â Analysis of Temperature and Precipitation changes of Shiraz during the Period of 1951-2005 Â Â Â A. Asadi. ( * ),Â PhD student of climatology, University of Isfahan, Isfahan, Iran Â email: firstname.lastname@example.org Â Â Â A. Heydari.Â Â Assistant Professor of Geography and Urban Planning, University of Yasuj, Yasuj, IranÂ Received: 6 July 2009 / Accepted: 17 August 2010, 39-42 P Â Â Â Extended Abstract Â 1- Introduction Â Climate change nowadays is considered as one of squabbles scientific and even political âsocial prevalent, indeed isnât new squabble. On basis climatic models forecast anticipated that increased precipitation measure in world, but not possible sound precipitation trend forecast in different regions. Likely monthly precipitation increased in latitudes high however whatever occurred in mid and tropical latitude depend to special climatic models and produce and dispersion matter pollution viewpoints. Â Â 2- Methodology Â The moving mean, time seriesÂ regression, correlation coefficient Pearson, Î² test, Mann-kendall, s test were used to analyze temperature and precipitation changes of Shiraz station.According to the normal distribution of temperature, linear regression coud use for analysis of temperature trend. But to determin existence or nonexistence trend and its direction must be use Î² test. Since some climatic series like precipitation doesnât subordinate normal distribution, thus for trend analysis could use Mann-Kendall test .This test examined hypothesizes in below: Â H0: Observations without increasing and decreasing trends. Â H1: Steady trend in time length. Â In this paper for temperature studying, have been used linear regression test and Î² test and for precipitation analyzing were applied linear regression test and Mann-Kendall test. Â Â Â Â 3- Discussion Â Changes temperature analyses do annually and seasonally. Â In Shiraz synoptic station is mean annually temperature 17.75o centigrade in term of 1951-2005.With linear regression test it trend has increase with correlation coefficient 0.64 and rate 1.9oC in term of discussion. Î² test in confidence level 95% do in this station and show that increased temperature in this term. Ho confirm in this parameter. Changes analysis mean seasonally temperature show increasing trend in 4 season .But temperature increasing is obviously in spring and summer. Â For exact survey, variation trend of precipitation using fitting polynomial regression line to 5 year moving mean utilized time was categorized to two periods. The first period be 1951 until 1982 and second period be from 1983 until 2005.The first period has show decreasing trend and second period shown increasing trend .In the first period rankly correlation level of time-precipitation (Mann-Kendall test) is -0.048. Therefore confirm H1 and series time data has show decreasing trend. In second period rankly correlation level of time-precipitation (Mann-Kendall test) is +0.162. Therefore confirm H1 and series time data has show increasing trend . Â In the winter rankly correlation level of time-precipitation (Mann-Kendall test) is +0.094. Therefore confirm H1 and series time data has show increasing trend. In spring rankly is correlation -0.147 and series time data has decreasing trend. Summer has rankly correlation +0.012 and series time data has increasing trend. In autumn season is rankly correlation +0.001 and series time data has low increasing trend. Â Â 4- Conclusion Â In this paper, changes of rate and trend of temperature and precipitation was studied with utilized time series regression, Z. Score, moving mean, independent and homogeneity tests, Beta test and Mann-Kendall ,s test techniques of shiraz during 55 year periods between 1951 to 2005. The results were obtained the temperature during this period shows an increasing trend and it observed in four seasons. The annual precipitation average shown a decrease trend and the seasonal precipitation average observed in all season exception winter. Â In this station, precipitation and temperature annual increasing trend followed a inverse trend, it means is that with incrasing temperature precipitation was decreasing. Exception of winter season, this inverse trend was observing in other seasons. Â Keywords : Time series regression, Z. Score, Independent and Homogeneity tests, Beta test, Mann-Kendall, s test. 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