Solar energy on the Tibetan Plateau: Atmospheric influences

Solar energy utilization is expected to be increasingly important in order to meet future energy needs and limit CO2 emissions to the atmosphere. To quantify the solar energy potential on the Tibetan Plateau, we have analyzed global horizontal irradiance (GHI) measurements for a three-year period at four sites with different aerosol and cloud conditions. The measurements indicate a very large solar energy potential on the Tibetan Plateau, with a small portion of GHI values even exceeding the corresponding top-of-the-atmosphere (TOA) value. Compared to a hypothetical sky condition without aerosols and clouds all year, aerosols were found to reduce the annual irradiation by about 3-6%, and the combined reduction by aerosols and clouds was found to be at most 23%. This reduction is very low compared to that at other sites around the world. For example, the west coast of Norway has a cloud/aerosol reduction effect of almost 50%, and Beijing has an estimated aerosol reduction effect of 35%. In Lhasa, Tibet the annual irradiation was found to be 7.6 GJ m(-2), which is 85% of the corresponding annual irradiation at the TOA.