FRESCO+: an improved O 2 A-band cloud retrieval algorithm for tropospheric trace gas retrievals
By Ping Wang, Piet Stammes, G. Pinardi, Michel Van Roozendael. 2008
256 citations recorded by the source corpus.
The FRESCO (Fast Retrieval Scheme for Clouds from the Oxygen A-band) algorithm has been used to retrieve cloud information from measurements of the O 2 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 O 3 and NO 2 . To improve the cloud pressure retrieval for partly cloudy scenes, single Rayleigh scattering has been included in an improved version of the algorithm, called FRESCO+. We compared FRESCO+ and FRESCO effective cloud fractions and cloud pressures using simulated spectra and one month of GOME measured spectra. As expected, FRESCO+ gives more reliable cloud pressures over partly cloudy pixels. Simulations and comparisons with ground-based radar/lidar measurements of clouds show that the FRESCO+ cloud pressure is about the optical midlevel of the cloud. Globally averaged, the FRESCO+ cloud pressure is about 50 hPa higher than the FRESCO cloud pressure, while the FRESCO+ effective cloud fraction is about 0.01 larger. The effect of FRESCO+ cloud parameters on O 3 and NO 2 vertical column density (VCD) retrievals is studied using SCIAMACHY data and ground-based DOAS measurements. We find that the FRESCO+ algorithm has a significant effect on tropospheric NO 2 retrievals but a minor effect on total O 3 retrievals. The retrieved SCIAMACHY tropospheric NO 2 VCDs using FRESCO+ cloud parameters (v1.1) are lower than the tropospheric NO 2 VCDs which used FRESCO cloud parameters (v1.04), in particular over heavily polluted areas with low clouds. The difference between SCIAMACHY tropospheric NO 2 VCDs v1.1 and ground-based MAXDOAS measurements performed in Cabauw, The Netherlands, during the DANDELIONS campaign is about −2.12×10 14 molec cm −2 .
Subfields: Atmospheric Science, Global and Planetary Change
View Paper: https://www.semanticscholar.org/paper/4c904b063e87e0e9017a267d49f5cf593b63883b
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Citations in the corpus
- The operational cloud retrieval algorithms from TROPOMI on board Sentinel-5 Precursor (2017, methodology): “The FRESCO algorithm, also developed for GOME, is based on the calculation of transmittances (later, single-scattering radiances), and it retrieves effective cloud fraction and cloud top pressure, assuming a fixed cloud albedo of 0.8.”
- The GOME-2 instrument on the Metop series of satellites: instrument design, calibration, and level 1 data processing – an overview (2015, methodology): “An effective cloud fraction and cloud top pressure are retrieved for each GOME-2 ground pixel using the Fast Retrieval Scheme for Clouds from the Oxygen A band (FRESCO+) developed by KNMI (Wang et al., 2008).”