Measurements and simulations of orographic mixed-phase clouds in Switzerland
Aerosol-cloud interactions constitute the highest uncertainties in radiation forcing estimates. Uncertainties due to the phase and longevity of mixed-phase clouds (MPCs) influence the radiative balance and the hydrological cycle. Due to Wegener-Bergeron-Findeisen-process (WBF) which describes the glaciation of MPC due to the lower saturation vapor pressure over ice than over water, the MPCs are mostly expected to be short-lived. In contrast, in-situ measurements have shown that MPCs can persist over longer time.
Because of the limitation of the in-situ information, i.e. point measurements and missing measurements of vertical velocities at JFJ, the mechanism of the long persistence of MPCs at JFJ cannot be fully understood. Therefore, in addition to measurements we investigate the JFJ region with a regional model study with a new version of the non-hydrostatic model COSMO that includes the online coupled Aerosol reactive trace gases model (ART) and the aerosol module M7. The combination of kilometer-scale simulations with measurements allows to systematically study the effect of vertical velocity and temperatures on MPCs at JFJ, the synoptic conditions, origins of air masses and aerosol concentration.
|Speaker:||Professor Ulrike Lohmann, ETH Zurich|
|Time:||27 May 2015, 11.00|
|Venue:||Yet to be assigned|