Over The Last Decade The Increase In Stratospheric Aerosol Concentrations Cause Of A Preliminary Study

This paper contained the following two major contents:First, using NCEP reanalysis monthly mean data provided by NOAA, we calculated the global temperatures at different latitudes to the regional average during 1998 to 2008, and analyzed the long-term trend of the temperature on different stratospheric heights within the scope of different latitudes. Similarly, we used the satellite datum provided by MLS instrument, which is on the Aura satellite of NASA, to calculate concentrations of global stratospheric SO₂ to the regional average during 2004 to 2008, computed the variations on stratospheric SO₂ concentrations in these 5 years. Trends of stratospheric water vapor over the past decade were also investigated by literature review.Second, by means of Aerosol Chemistry and Microphysics Model (ACMM), we simulated the processes of stratospheric aerosol formation and development. By doing sensitivity tests on temperature, water vapor concentration, sulfuric acid gas concentration, and the initial aerosol concentration, the correlations between the rise of stratospheric SO₂ concentration and stratospheric environment variables mentioned above were revealed. Then they were used to explore possible factors that contributed to stratospheric SO₂ concentration increase.Some main conclusions were as follows:By analyzing relevant data, it could be found that there was a slow decrease of stratospheric temperature in recent ten years, and the decrease rate was below 1 K per year. However, there is an upward trend in stratospheric SO₂ concentration. Besides, according to literatures, water vapor concentration has decreased by about 10% since 2000.Simulations did by ACMM indicated that drop on temperature or water vapor concentration had little influence on stratospheric aerosol concentration and size distributions, while increase on sulfuric acid gas concentration in tropopause of tropics would bring a significant rise on the number concentration of aerosol and change the size distribution of stratospheric aerosol.At the height of 10 mb in tropics and 45°N area and at the height of 30mb in 45°N area, increase of the initial aerosol concentration could make the simulated aerosol concentration increase significantly.