title: Trends of the sunshine duration and diffuse radiation percentage on sunny days in urban agglomerations of China during 1960-2005.
abstract: The long-term observational data of sunshine duration (SD) and diffuse radiation percentage (defined as diffuse solar radiation/total solar radiation, DRP) on sunny days during 1960-2005 were analyzed in 7 urban agglomerations and the whole of China. The results show that the sunny sunshine duration (SSD) has decreased significantly except at a few stations over northwestern China in the past 46 years. An obvious decrease of the SSD is found in eastern China, with the trend coefficients lower than -0.8. Accompanied by the SSD decline, the sunny diffuse radiation percentage (SDRP) in most stations shows obvious increasing trends during the 46 years. The averaged SDRP over China has increased 2.33% per decade, while the averaged SSD shows a decrease of -0.13 hr/day per decade. The correlation coefficient between SDRP and SSD is -0.88. SSD decreased over urban agglomerations (small to large city clusters) in the past 46 years, especially in large cities and medium cities, due to the strong anthropogenic activities and air pollution represented by aerosol option depth (AOD) and tropospheric column NO2 (TroNO2). On the regional scale, SSD has an opposite trend from SDRP during 1960 to 2005, and the variation trends of regional mean values of SSD and SDRP in southeastern China are more pronounced than those in northwestern China.
authors.affiliation: Hainan Meteorological Observatory, Haikou 570203, China; Key Laboratory of Regional Climate-Environment Research for Temperate East Asia, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China; Key Laboratory of South China Sea Meteorological Disaster Prevention and Mitigation of Hainan Province, Haikou 570203, China. Electronic address: hnfuchuanbo@163.com.
authors.forename: Chuanbo
authors.initials: C
authors.lastname: Fu
authors.affiliation: Key Laboratory of Regional Climate-Environment Research for Temperate East Asia, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China. Electronic address: danli@tea.ac.cn.
authors.forename: Li
authors.initials: L
authors.lastname: Dan
authors.affiliation: Hainan Meteorological Observatory, Haikou 570203, China; Key Laboratory of South China Sea Meteorological Disaster Prevention and Mitigation of Hainan Province, Haikou 570203, China.
authors.forename: Youlong
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Hainan Meteorological Observatory, Haikou 570203, China; Key Laboratory of South China Sea Meteorological Disaster Prevention and Mitigation of Hainan Province, Haikou 570203, China.
authors.forename: Jiaxiang
authors.initials: J
authors.lastname: Tang
mesh_terms: D000336:Aerosols / Q000032:analysis*; D000393:Air Pollutants / Q000032:analysis*; D000397:Air Pollution / Q000032:analysis*; D002681:China; D002947:Cities; D004784:Environmental Monitoring; D052638:Particulate Matter / Q000032:analysis*; D012621:Seasons; D013472:Sunlight
chemical_list: D000336:Aerosols; D000393:Air Pollutants; D052638:Particulate Matter
keywords: Annual change; Diffuse radiation percentage; Sunny sunshine duration