HR: 08:00h
AN: A21E-01    [Abstracts]
TI: Global fields of aerosol properties from remote sensing: Preferred choices and associated direct radiative forcing
AU: * Kinne, S
EM: kinne@dkrz.de
AF: MPI Meteorology, Bundesstrasse 53, Hamburg, 20146 Germany
AB: Our understanding of the impact of anthropogenic aerosol on climate (usually quantified by radiative forcing) is largely based on simulations with global models. The accuracy of model results depends critically on simulated aerosol properties. These deviate often from observations, even on regional and seasonal scales. Alternatively, statistics from remote sensing data can be assembled to establish global fields for those aerosol optical properties that are needed in radiative transfer methods in order to calculate the associated aerosol radiative forcing: Preferred choices for global (and monthly) fields of aerosol optical depth, aerosol absorption and aerosol size are introduced, based on merged observational data. Differences to corresponding fields suggested in global modelling (exemplified by the median of 16 global models participating in the AeroCom model comparison) are illustrated to demonstrate deficiencies global modelling, most notably several regions with underestimates to aerosol optical depth and aerosol absorption. In addition, associated net-flux changes are compared at the top of the atmosphere (to capture the impact for the entire Earth-Atmosphere-System). With respect to all (natural and anthropogenic) aerosol at unrealistic cloud-free conditions there is general agreement for aerosol radiative forcing at about -5W/m2, with estimates form models slightly less negative than observation based estimates. More interesting, however, is the forcing attributed to anthropogenic aerosol under realistic all-sky conditions. For the satellite based approach this required external assumptions for the relative placement between aerosol and clouds and the aerosol anthropogenic forcing (which for consistency was borrowed from modelling). The anthropogenic aerosol direct radiative forcing, suggested by global modelling is near -0.2W/m2, whereas the satellite based approach suggest a cooling near -1.0W/m2. It is hoped to have answers on the discrepancy at the time of the conference.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0325 Evolution of the atmosphere (1610, 8125)
DE: 0345 Pollution: urban and regional (0305, 0478, 4251)
DE: 0360 Radiation: transmission and scattering
DE: 1637 Regional climate change
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005