Informal seminar: Optical Properties of Ice Clouds and Tropical Tropopause Layer Cirrus and their Impacts on Temperature and Troposphere-stratosphere Transport
The optical properties of ice clouds developed by Fu (1996) and Fu et al. (1998) have been used in the ECMWF models for more than 20 years. In the first part of my talk, I will discuss the optical properties of ice clouds, focusing on a known unknown parameter in determining the asymmetry factor of non-spherical ice particles, which needs to be considered in the next generation of the optical properties parameterizations of ice clouds for the use in weather and climate models. Tropical Tropopause Layer (TTL) Cirrus clouds are missing in modern reanalyses including ERA5 and MERRA 2. In the second part of my talk, I will show the impacts of TTL cirrus clouds on temperature and troposphere-stratosphere transport. I will then present temperature control of the TTL cirrus clouds. I will also discuss the interannual variability of TTL cirrus clouds and its relation to the large-scale circulations including El Niño–Southern Oscillation, quasi-biennial oscillation, and Brewer-Dobson circulation.