10 years of SCIAMACHY Cloud and Radiation Time Series Derived from FRESCO O2 A Band Algorithm
Wang, Ping; van der A, Ronald; Stammes, Piet
Royal Netherlands Meteorological Institute (KNMI), NETHERLANDS

In general clouds strongly affect trace gas retrievals. They cause shielding, albedo enhancement and in-cloud absorption. To correct for these cloud effects, the cloud fraction and cloud altitude are two important parameters. The FRESCO (Fast Retrieval Scheme for Clouds from the Oxygen A band) algorithm has been used to retrieve cloud information from measurements of the O2 A band around 760 nm by GOME, SCIAMACHY and GOME-2. The cloud parameters retrieved by FRESCO are the effective cloud fraction and cloud pressure, which are used for cloud correction in the retrieval of trace gases like O3 and NO2.

The FRESCO cloud product is not limited to cloud correction or cloud masking. The FRESCO level-3 global monthly mean cloud products have been used to study the cloud trend and variations globally and regionally. The FRESCO level-3 monthly mean product clearly shows the large scale cloud patterns especially for low clouds. One application is the use in the radiative forcing calculations. The aerosol radiative forcing climatology generated from the TM-5 model using FRESCO cloud product for full-sky scenes shows promising results compared to other aerosol climatologies.

Clouds have a strong influence on surface solar radiation. The effective cloud fraction is anti-correlated with the broadband surface solar irradiance (SSI). Therefore, a FRESCO SSI product has been developed and validated since 2010. The FRESCO SSI has good agreement with ground-based BSRN measurements, although the standard deviation of the difference is relatively large. However, the monthly mean SSI product has very good agreement with the ISCCP surface radiation product.

In the presentation we will show the SCIAMACHY FRESCO cloud and radiation time series and demonstrate some applications of the products.