Water Vapor
Contact: Chiara Cagnazzo (chiara.cagnazzo@cmcc.it)
Summary: Water vapor and ice are known to exert a key influence on the radiative and dynamical balance of the upper troposphere and lower stratosphere (UTLS). Recent research has demonstrated that observed variations of the global water vapor into the lower stratosphere are an important driver of decadal global surface climate change [Solomon et al. 2010]. Therefore, variations of the water vapor into the lower stratosphere can provide a source of decadal variability for the climate system. However, there is still a need to assess UTLS water vapor distribution and its variations in climate model such as those used in CMIP5 and SHFP. This DynVar Research Group aims to use long-term climate simulations performed with high-top models to assess the representation of water vapor distribution and variability in the UTLS. Specific topics tackled by the Research Group may include: The evaluation of the influence of improved vertical resolution and improved representation of tropical stratopheric dynamics on the modeled UTLS water vapor distribution and its interannual to decadal variability, the representation of the cold-point tropopause temperature and its variations, the representation of tropical clouds and their impact on the tropical tropospheric variability. The possible role of water vapor long-term variability in the upper troposphere and lower stratosphere on the decadal potential predictability of the climate system can also be addressed.