1956-2008年辽宁省日照时数变化特征

Characteristic on Sunshine Duration in Liaoning Province during the Period from 1956 to 2008

根据辽宁省7市1县8个气象站近53年(1956-2008年)逐月日照时数资料,建立辽宁省月、年日照时数时间序列,运用复值Morlet小波分析、5年滑动、气候倾向率和Mann-Kendall趋势检验法,分析辽宁省近53年的日照时数变化特征。结果表明:年日照时数呈显著减少趋势,倾向率为-57.61h/10a,M(标准化变量)值为-6.49,且存在25年和16年左右的周期性变化;春、夏、秋、冬四季的日照时数均表现为下降趋势,夏季下降趋势最明显,冬季表现最微弱,倾向率分别为-18.345h/10a和-7.615h/10a;年代际的变化趋势是,2000年以后日照时数的下降趋势很显著,M值为-2.59,而日照时数高值区和低值区的范围都有所减小。

In recent years,air pollution becomes more and more serious,and the concentrations of greenhouse gases are increased due to the impacts of natural factors and human activities. As a result,climate change is accelerated. Climate change results in the change of both physical and chemical structures of air. The variation of sunshine duration is one of the climate change factors in a region. The research on variation and distribution of sunshine duration is of great significance to agricultural production,urban construction planning,tourism resources development and solar power plant design. Liaoning is a main industrial and agricultural province,and its agricultural productivity is dominant in China. The Liaohe River Plain is located in central Liaoning Province,and it is an important agricultural production base. Nowadays,people all over the world pay more and more attention to global warming and its affecting factors,and Liaoning Province is also in its sphere. Since the 1980s,temperature has been gradually increased,but precipitation decreased in Liaoning,thus the agricultural production is impacted. Af-ter analyzing the change of sunshine duration indices,in this paper the factors resulting in climate change in this region are researched. This will be of great referential significance to agriculture. The decadal,annual,seasonal and monthly change of sunshine durations at 8 meteorological stations in Liaoning Province in recent 53 years （ 1956 -2008） is lucubrated using the Morlet wavelet analysis,climatic linear trend,Mann-Kendall trend methods and GIS spatial analysis,and the time series of annual,seasonal and monthly sunshine durations are developed. The results show that the annual sunshine durations is notably decreased with a climatic liner trend of -57. 61 h/10 a,M value of -6. 49,and 25-year and 16-year periodic fluctuations. There was an obvious 10-year fluctuation of sunshine duration before the 1970s but an obvious 5-year one after the 1970s. Seasonal sunshine duration was also in a decrease trend. In order to demonstrate the sunshine duration reduction,the distribution of sunshine duration in the 1990s is compared with that after 2000. The holistic trend reveals that the sunshine duration decreased from the coastal area to the inland due to the effect of precipitation and cloud cover. The comparison of sunshine duration between these two decades reveals that both the ranges of high and low values became lower. The decrease of sunshine duration is analyzed from three aspects of relative humidity,wind velocity and precipitation. The fitted results of relative humidity and precipitation are not so ideal. Therefore,it can be concluded that the reduction of wind ve-locity was the main factor resulting in the decrease of sunshine duration. Among the selected 8 meteorological stations,the sunshine duration increased （ 36. 626 h/10 a） in Benxi City only. The reasons of this special case need to be further studied.