2017-04-13: Surface reflectivity climatologies from UV to NIR determined from observations by GOME-2 and SCIA

The primary goal of this paper is to introduce two new surface reflectivity climatologies. The two databases contain the Lambertian-equivalent reflectivity (LER) of the Earth’s surface, and they are meant to support satellite retrieval of trace gases and of cloud and aerosol information. The surface LER databases are derived from the Global Ozone Monitoring Experiment (GOME)-2 and Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) instruments and can be considered as improved and extended descendants of earlier surface LER climatologies based on the Total Ozone Mapping Spectrometer (TOMS), GOME-1, and Ozone Monitoring Instrument (OMI) instruments.

The GOME-2 surface LER database consists of 21 wavelength bands that span the wavelength range from 335 to 772 nm. The SCIAMACHY surface LER database covers the wavelength range between 335 and 1670 nm in 29 wavelength bands. The two databases are made for each month of the year, and their spatial resolution is 1 degree × 1 degree. In this paper we present the methods that are used to derive the surface LER; we analyze the spatial and temporal behavior of the surface LER fields and study the amount of residual cloud contamination in the databases. For several surface types we analyze the spectral surface albedo and the seasonal variation. When compared to the existing surface LER databases, both databases are found to perform well. As an example of possible application of the databases we study the performance of the Fast Retrieval Scheme for Clouds from the Oxygen A-band (FRESCO) cloud information retrieval when it is equipped with the new surface albedo databases. We find considerable improvements. The databases introduced here can not only improve retrievals from GOME-2 and SCIAMACHY but also support those from other instruments, such as TROPOspheric Monitoring Instrument (TROPOMI), to be launched in 2017.

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Global maps of the surface LER retrieved by GOME-2 at 380, 440, 555, and 772 nm for the month of February. The surface LER type presented here is the MODE-LER.
Surface LER spectra, based on the SCIAMACHY surface LER database, calculated for various surface type regions, and presented for the months February (red), May (brown), August (green), and November (blue). The additional gray spectra represent the standard deviation in the surface LER spectra contained in the surface type regions. For ``Antarctica'' and ``Greenland'' only the retrieved spectra for two of the four months are displayed, as explained in the paper. The surface LER type presented here is the MODE-LER.