Impacts of tropical cyclones on the upper troposphere

Recent measurements from the Atmospheric Infrared Sounder (AIRS) on the Aqua satellite and Microwave Limb Sounder (MLS) on the Aura satellite are used to investigate the upper troposphere (UT) in the vicinity of tropical cyclones (TCs). We focus on UT water vapor distributions, since this is the most important greenhouse gas, but also include cloud properties in our analysis. We compare and contrast average UT conditions near TCs in all ocean basins around the world. The impacts on the water vapor and cloud distributions of the UT are generally greater for higher intensity cyclones, but are significant for all categories of cyclones. A simple water vapor budget estimate shows that TCs contribute a substantial amount to the global UT water vapor budget. Our analysis suggests that TCs play a significant role in the distribution of radiatively important trace gases in the tropical UT and thus that the cyclones are an important component of the climate system.