Satellite Observation of Aerosol and Cloud Properties
A contribution to ACCENT-TROPOSAT-2, Task Group 1
Wolfgang von Hoyningen-Huene
Institute of Environmental
Physics, University of Bremen, Otto-Hahn-Allee 1, D-28334 Bremen
Aerosols are a significant part of atmospheric turbidity and air pollution. Biomass burning, industrial pollution, desert dust transports, arctic haze are events connected with strong increased aerosol impacts. Aerosol impacts are of interest in multiple ways.
They affect the climate in direct way by increasing the scattering and absorption and modification of the radiative forcing.
They affect the climate in indirect way, contributing to cloud formation and cloud modification by the aerosol-cloud interaction.
They are part of heterogeneous chemical reaction chains.
They are significant air pollutants and have feedbacks on human health, traffic and others.
All these are reasons for the investigation of the magnitude of concentration, the regional and temporal behaviour of aerosols on regional and global scales. Thus climate research and environmental control require powerful observation tool from space-borne platforms, giving accurate enough information on the aerosol status in the troposphere and the atmospheric boundary layer.
Modern multi-spectral space-borne radiometers, like SeaWiFS, MERIS, MODIS, SCIAMACHY and others provide enough spectral and radiometric information for the determination of aerosol properties from space. Methods are in development, enabling such observations over land and ocean surfaces with the required accuracies. Together with this cloud investigations can be made and can combined together. These techniques enable a new integrated kind of earth observation.
At IUP the BAER (Bremen AErosol Retrieval) for the determination of the aerosol optical thickness has been developed. For the investigation of cloud properties the SACURA (Semi-Analytical CloUd Retrieval Algorithm) is developed. This enables the investigations of aerosol and cloud properties from satellite observations. The methods are adapted to work with data from SeaWIFS, MERIS, SCIAMACHY. Other satellite radiometers with similar data structures can be included by data interfaces. With these tools the following tasks will be undertaken:
Improvement of the retrieval methods for the space-borne determination of aerosol parameters, e.g. aerosol optical thickness and their spectral behaviour as preconditions for further investigations.
Application and extension of the retrieval methods to a wide range of surface and latitude conditions of the earth surface: ocean, land surfaces with different vegetation cover, desert regions, arctic regions.
Investigation of pollution events, like industrial and urban pollution, biomass burning, forest fires, desert dust transports.
Near simultaneous determination of cloud parameters from the same scenes, e.g. cloud optical thickness, effective radius, cloud top height and cloud phase.
Investigation of indications for aerosol-cloud interaction combining aerosol and cloud results.
Retrieval of spectral surface reflectance as by products of the aerosol retrieval.
Alexander Kokhanovsky IUP Bremen
Gerrit de Leeuw TNO, Den Haag, The Nederlands
Piet Stammes KNMI, De Bilt, The Nederlands