Tropical cyclones impact on tropopause and the lower stratosphere vapour based on satellite data

As one of the deep convection systems, tropical cyclones (TCs) could significantly affect the thermodynamic structure and cloud microphysical processes near the tropopause, which may cause changes in troposphere and stratosphere water vapour activity, with important influences on global climate change. However, the effects of TCs on tropopause and the lower stratosphere water vapour remain unclear. Here, we use satellite data from year 2012 to 2016 to assess the effect of TCs on water vapour at the tropopause and in the lower stratosphere over the Northwest tropical Pacific Ocean. It is found that TCs could decrease the tropopause temperature and increase the process of water vapour deposition on cloud ice to a certain extent. This process can increase cloud ice mixing ratio and then dehydrate the tropopause. Part of the small cloud ice particles will be injected into the lower stratosphere, where they would be sublimated, hydrating the lower stratosphere. Compared to non-TC area, the average water vapours in TC area decrease about 1.04 ppmv near the tropopause, but increase by 0.75 ppmv in the lower stratosphere.