Temporal-Spatial Of Sunshine Duration In Anhui Province In Recent 45 Years And Optimization Of Solar Radiation Simulation

Sunshine duration is an important factor in the climate change and formation,and daily solar radiation is the source of surface energy.Because of few daily solar radiation weather stations and the stable ratio between the sunshine duration and the total solar radiation,it is very meaningful to study the change in sunshine duration and simulation of total solar radiation.This paper utilized daily sunshine duration and daily solar radiation data from 23 meteorological stations in Anhui Province during 1971-2015,analyzed the seasonal and interannual variations of sunshine duration and daily solar radiation in Anhui Province in the past 45 years by using linear regression,correlation analysis,mutation testing,wavelet analysis,error analysis,and total solar radiation simulation.This paper utilized spatial interpolation method to analyze the Spatial distribution of Sunshine Hours in Anhui Province,and compared the calculation accuracy of six kinds of solar daily solar radiation models such as Zuo Dakang,Cao Wen,Weng Duming,Tong Hongliang,Prescoff and FAO56 correction model.This paper built models by using least squares analysis at different time scales to analyze the spatial variation of daily solar radiation and further optimize models for reducing errors.Conclusion as below:?1?By analyzing the accuracy of three kinds of spatial interpolation techniques for the interpolation of sunshine hours in Anhui Province,it is shown that the inverse distance weighting?IDW?method can more accurately reflect the spatial distribution characteristics of sunshine hours in Anhui Province.The sunshine hours in Anhui show a spatial trend of decreasing from north to South and decreasing gradually from north to south.The sunshine hours in the south and southeast of Anhui Province are relatively low.The sunshine hours in the south of Anhui Province in spring are less than usual,and the sunshine hours in the northern and central north regions are relatively high.The regions with more sunshine hours in summer are mainly distributed in Huainan and northern Jiangnan regions.The sunshine hours in the southeastern and northwestern parts of Anhui Province in autumn were relatively low,while the sunshine hours in the Dangshan and Bozhou areas in the northern part of Anhui Province were relatively high.The sunshine hours in Anhui Province in winter showed a gradual increase from south to north.?2?The annual sunshine hours in Anhui province have changed greatly in the last 45years,the average annual sunshine hours is 1931.4h,and the annual sunshine hours show a significant decrease trend,with a change rate of-66.94 h/10a.The sunshine hours in Anhui Province in spring showed a weak upward trend in spring.The sunshine hours in summer,autumn and winter showed a decreasing trend,among which summer sunshine hours had the largest amplitude changes,and the rate of change was-30.48 h/10a.The sunshine hours of 23 weather stations all showed a downward trend,the declining trend of sunshine hours in Fuyang and Dangshan regions is the most obvious,and the declining trend of sunshine hours in Bengbu region is the slowest.?3?There is a 2-3a significant cycle of sunshine hours in recent 45 years in Anhui Province,and there is a 4-5a significant cycle during 1977-1985.There is a significant period of about 6-9a in spring,and a significant period of 2a during 1971-1980,1988-1995,and 2007-2014.There is a significant period of 2a and 3-5a in sunshine hours during 1971-2015 in summer.There is a significant period of 2-5a in autumn,and a significant period of6-9a during 1971-1980.There is a significant period of 3-7a in the winter during 1984-2015,and a significant period of 2a during 1971-1980 and 2005-2015.The annual sunshine hours have a significant mutation during 1989-1993,and the trend of reduction has been significant since 1990s.The sunshine hours in spring changed abrupt around 2001,but the mutation was not significant.The sunshine hours in summer have a significant change around 1997 and 1999.The sunshine hours in autumn and winter were abrupt in2005 and 1983 respectively,but the mutation was not significant.?4?The total solar radiation has shown a slight upward trend in the past 45 years in Anhui Province.The amount of solar radiation is less from the middle of 1970s to the beginning of 1980s.At the end of the 1980s,there was a significant upward trend of the total solar radiation in the early 1990s the total solar radiation had risen to a high point and then declined,after that it showed an upward trend again.The total solar radiation has a significant variation period about 2 to 5 years during 1971-2007,and a significant variation period about 6 to 11 years during 1980-1996.The total amount of solar radiation is the highest in summer,then in spring and lowest in winter.The total solar radiation in spring,summer and autumn showed an upward trend,with the upward trend in spring and the downward trend in winter.The total amount of solar radiation has increased significantly since the late 1980s,and has produced mutations in 2000.According to the Pearson correlation analysis,there is a significant positive correlation between the daily sunshine hours in Anhui and the daily solar radiation,and the daily solar radiation increases?decreases?with the increase?decrease?of sunshine hours.?5?The revised FAO56 model has the best result in the simulation of daily solar radiation in Anhui Province,and it can simulate the solar radiation value of the region more accurately.Under different weather conditions with or without sunshine and with or without precipitation,the FAO56 modified model had the smallest error in simulated values in the presence of sunlight and no precipitation.The Prescoff model has the smallest analog error in the absence of sunlight.Tong Hongliang model has the smallest error in simulated values in the presence of precipitation.?6?The annual and seasonal changes in sunshine hours and total solar radiation are relatively large in Anhui Province.The results of model simulation are different under different time scales.In order to further improve the accuracy of the model,the least squares method was used to fit the models in different seasons and different time scales in45 years,respectively.The results of the model fitting are as follows:Spring:R=R_L0?.171+.0677S₀?,Summer:R=R_L0?.209+.0584S₀?,Autumn:R=R_L?.0192+.0635S₀?,Winter:R=R_L0?.187+.0668S₀?,Year:R=R_L0?.189+0.642S₀?.The effect of fitting the model is better,which can further reduce the error of the simulation value and improve the accuracy of the simulation model.?7?The optimized daily solar radiation model was used to simulate the total solar radiation at 23 meteorological stations in 2015.The analysis shows that the total solar radiation over the region is higher in the north and lower in the south,and the overall trend is decreased from north to south.The total solar radiation is high in the northern Bozhou,Dangshan,and Bengbu regions,and the southern Tongling region.