| Solar radiation, the main driving factor of plant photosynthesis and transpiration, is themost important energy source of the Earth-atmosphere system. It is also the primaryagricultural climate resources. Northeast China is an important Commodity Grain Base. Solarradiation (especially the growing season radiation) is the important energy for the crop growth.Therefore, the spatio-temporal variation characteristics of solar radiation during growingseason are useful for learning the climate change regular over Northeast region. Besides, itcan help to instruct the agricultural activity and provide the guideline for the sustainabledevelopment for the economy over Northeast China.This study firstly filtered and processed the solar radiation data of13meteorologicalstations and sunshine durations of90meteorological stations observed in Northeast China.These data were divided into6control groups to analyze using the MATLAB tool. The6control groups include the entire sequence, precipitation days, and non-precipitation days bothduring the growing season and year-round. This paper will select a high precision model toestimate and validate the solar radiation Northeast China. Then, this paper showed the changepattern of solar radiation, including the spatio-temporal trend, cycle and mutation of solarradiation over Northeast China. In summary, the main conclusions are as following:(1) Estimating the growing season solar radiation over Northeast China using the sunshinedurations of the6control groups based on the A-P model. The performance of the model istested by RMSE，MBE，MPE，t statistical. The results show that the A-P model for estimatingdaily global solar radiation on a horizontal surface for all of the13stations using the entiresequence data in May–September performs best. The entire measured data from all of the13sites were then combined and analyzed to obtain a model for estimating the daily global solarradiation during growing season in all Northeastern China meteorological stations.(2) We can get a conclusion by applying a polynomial fitting for the solar radiation ingrowing season over Northeast China: The average solar radiation in growing season is2818.23MJ/m~2during1962-2010. The highest value is2979.49MJ/m~2in1965, whereas thelowest is2653.81MJ/m~2in2003. The significant decrease trend of the solar radiation in thegrowing season is-21.55MJ/m~2during1960-2010over Northeast China.(3) Another conclusion can be getting by applying wavelet analysis to investigate the cycleof the solar radiation in growing season: There are three main oscillation cycles for solarradiation in the region. In the low frequency time scale (more than30a), the average sunshineduration in the researching region has obvious period of oscillation. In the time scale of15years, the cycle oscillation of solar radiation changes strongly in growing season. There arefive "on the high side period" and four "on the low side period" appearing alternately. In thetime scale of3years, the change of cycle oscillation of solar radiation in growing season ismuch more complex and the turn points are also much more.(4) Get another conclusion by applying the Mann-Kendall mutation analysis to investigatethe average solar radiation: In the1960s and1970s, the solar radiation in growing seasonchanged slightly. In1980, the average solar radiation in growing season over Northeast Chinahad an abrupt change. After1980s, the average solar radiation in growing season is decrease and the negative trend is significant after1985.(5) The last conclusion is getting by analyzing the spatial distribution of the average solarradiation in growing season. The trend of the solar radiation in growing season is decreaseduring the latest50years. Sanchahe station had the most decrease amplitude, locating in thenorth of Jilin. Areas with increase solar radiation are less than those with decrease trend,which mainly locate in Xiao Hinggan Mountains and parts of Sanjiang Plain. |
PDF Full Text Request