Spatio-temporal characteristics of aerosol distribution over Tibetan Plateau and numerical simulation of radiative forcing and climate response

In this paper we have analyzed aerosol distribution over the Tibetan Plateau by using the global monthly mean satellite data of Stratospheric Aerosol and Gas Experiment II (SAGE II). The results are as follows: (1) Stratospheric aerosol optical depth can oscillate in the four seasons. It means that the aerosol optical depth is the thickest in winter and a little thinner in spring and the thinnest in summer and then a little thicker in autumn. We have found that the oscillation is caused by the oscillation of tropopause in different seasons. (2) Stratospheric aerosol comes mainly from sprays of volcano. After eruption of Mount Pinatubo aerosol optical depth in stratosphere over the Tibetan Plateau increases 10 times compared with before. (3) The characteristic of aerosol vertical distribution over the Tibetan Plateau is that there is an extremely high value at the altitude of 70 hPa. The most interesting thing is that the extremely high value can oscillate between 50 hPa and 100 hPa. We have verified that the oscillation is a unique characteristic over the Tibetan Plateau by comparing it with South China and North China. Then the radiative forcing and regional climate response over the Tibetan Plateau of aerosol are investigated. We have discovered such things as followed by: (1) The radiative forcing is positive because the parameterized aerosol optical depth is less than 0.14 which is the optical depth of the uniform background boundary aerosol layer. It is 0–3 W/m² in January and 0–4 W/m² in April and less than 3 W/m² in July and 3–6 W/m² in October. (2) Ground temperature rises 0.1–0.2 K in October which is the biggest increasing magnitude, and 0.01–0.02 in July which is the smallest one. It rises about 0.05-0.01 K in January and April. (3) Air temperature near the earth’s surface and the one at the altitude of 500 hPa rise too, but the increasing magnitude is less than the former one.