Solar radiation trend across China in recent decades: a revisit with quality-controlled data W.-J. Tang1,2, K. Yang1, J. Qin1, C. C. K. Cheng3, and J. He1,2 1Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100085, China 2Graduate School of Chinese Academy of Sciences, Beijing 100049, China 3Department of Building and Construction, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China
Abstract. Solar radiation is one of the most important factors affecting climate and
environment, and its long-term variation is of much concern in climate
change studies. In the light of the limited number of radiation stations
with reliable long-term time series observations, this paper presents a new
evaluation of the long-term variation of surface solar radiation over China
by combining quality-controlled observed data and two radiation models. One
is the ANN-based (Artificial Neutral Network) model and the other is a
physical model. The two models produce radiation trends comparable to the
observed ones at a few validation stations possessing reliable and
continuous data. Then, the trend estimate is extended by the ANN-based model
to all 96 radiation stations and furthermore extended by the physical model
to all 716 China Meteorological Administration (CMA) routine stations. The
new trend estimate is different from previous ones in two aspects. First,
the magnitude of solar radiation over China decreased by about −0.23 W m−2 yr−1 between 1961 and 2000, which is greatly less in magnitude
than trend slopes estimated in previous studies (ranging over −0.41 ~ −0.52 W m−2 yr−1). Second, the "From Dimming to Brightening"
transition in China during the late 1980s ~ the early 1990s was
addressed in previous studies, but this study indicates the solar radiation
reached a stable level since the 1990s and the transition is not noticeable.
These differences indicate the importance of data-quality control and analysis approaches. Finally, an obvious transition from brightening to dimming
around 1978 is found over the Tibetan Plateau, where aerosol loads are very
low, indicating that the importance of cloud changes in altering solar
radiation may be comparable to that of the aerosol changes.
Citation: Tang, W.-J., Yang, K., Qin, J., Cheng, C. C. K., and He, J.: Solar radiation trend across China in recent decades: a revisit with quality-controlled data, Atmos. Chem. Phys., 11, 393-406, doi:10.5194/acp-11-393-2011, 2011.