As the primary source of energy for all life on earth, solar radiation profoundly affects the atmosphere, water cycles and ecosystems. This is especially true on the Qinghai-Tibet plateau, where thinner, cleaner air and lower water vapor levels allow it to absorb more solar radiation, which is the most important part of the surface energy budget and profoundly affects the cryosphere.
Research shows that since the 1950s, solar radiation in most parts of the world has been on a downward trend, a phenomenon known as global dimming. The phenomenon lasted for decades but ended after 1990 and became increasingly bright (m. Wild et al. 2005). Such a torsion process is not found on the Qinghai-Tibet plateau. On the contrary, it shows a continuous trend of "dimming" (W. Tang et al. 2011).
What causes solar radiation to "darken" or "brighten"? At present, there is no consistent and widely accepted explanation in the academic circle, but basically it can be locked in the atmosphere, that is, without taking into account the influence of solar activity, changes in the earth's orbit and so on. So, what is the dominant change in cloud, water vapor, ozone, or aerosol content? Further answers remain to be acquired.
Deliang Chen, a distinguished professor of Qinghai-Tibet plateau research institute, Chinese academy of sciences, and the earth science department of the University of Gothenburg, Sweden, in cooperation with the national climate center, put forward a new perspective to explore the cause of "dimming" of solar radiation. In the past researches, more analysis of solar total radiation and the article, the authors believed that combining a simulated solar direct and scattering model and related long-term (direct solar radiation and scattering) observation could reveal solar radiation in the atmosphere extinction process (by absorption and scattering), and more specific dominant factors that result in the change of solar radiation. Specifically, this study analyzes the radiation coefficient (direct and scattering coefficient) used to simulate the direct and scattering of the sun. This coefficient was calibrated by comparing the observation with the simulation of a Solar Analyst. Despite failing to answer quantitatively the effects of changes in cloud cover, the study results showed that the plateau atmospheric wet (heating) in glomus and explain about 18% and 5% respectively of solar radiation in Lhasa dimmed, content and basic rule out the aerosol change - this was because the aerosol extinction effect of solar radiation on the plateau mainly by scattering effect, which would lead to the earth's surface receives the increase in the number of direct solar radiation parts to reduce and scattering, and observed the two parts of solar radiation are presented to reduce the trend.
In addition, the study also provided a basis for high-resolution solar radiation estimation in the Qinghai-Tibet plateau region: considering the complex terrain of the plateau, it was obviously better to interpolate the sparse number distribution radiation observation of the plateau directly into the high-resolution grid, and the radiation coefficient unaffected by the terrain would be better.
The research results were published in the International Journal of Climatology by Changgui Lin (postdoctoral fellow) as the first author and professor Deliang Chen as the corresponding author. This research was founded by the Chinese Academy of Sciences (Class A) Pilot Science and Technology Project: Pan-third pole environmental change and the construction of green silk road (XDA20060401), China Scholarship Council, Meteorological industry research special, Sweden VR, STINT, BECC and MERGE.
paper link:https://doi.org/10.1002/joc.5807