ECHAM activities – Ulrike Lohmann’s group • SylvaineFerrachat: Maintainance of ECHAM6-HAM and previously developed aspects (entrainment, PBL clouds, shallow convection) • Philipp Reutter/Betty Croft: aerosol processing and scavenging of aerosols • Ana Sesartic: bioaersols and their possible importance as ice nuclei (IN) • VivekSant: drizzle and giant CCN • Miriam Kübbeler: heterogeneous vs. homogeneous freezing in cirrus clouds • Sebastian Bretl: possible influence of aerosols on tropical cyclones VivekSant Group Meeting February 1, 2011 1
Impact of wet scavenging on global aerosol and cloud properties in ECHAM5 (Philipp Reutter) Reference scavenging ratios changed following a study in the Arctic study by Bourgeious and Bey (2011).
Less cloud droplet number burden and less soluble nucleation and Aitken mode particles when scavenging ratios are reduced • Mechanism: • Initially more aerosol particles. • Nucleation of new particles impeded, more condensation of SO4 and organics on pre-existing particles. • Coagulation and less new particle formation lead to a reduction of the number mixing ratio of smallest modes.
IACETH Institute for Atmospheric and Climate Science Bacteria and fungal spores in ECHAM (Ana Sesartic) • Impact on clouds & radiation • small global impact • regional impact suspected • Possible future research • models with dynamic vegetation • regional modelling • observations & lab studies
Introducing a drizzle class in ECHAM5 (VivekSant) today Bretherton et al., 2001 future Courtesy of R. Posselt Vivek Sant Group Meeting February 1, 2011 5
Impact of aerosols on cirrus clouds (Miriam Kübbeler) Kärcher et al., JGR, 2006