SCIAMACHY CLOUD PRODUCT VALIDATION

摘要

Radiative scattering by clouds leads to errors in the retrievalrnof column densities and concentration prou0002lesrnof atmospheric trace gas species from satellites. ThernSCanning Imaging Absorption SpectroMeter for AtmosphericrnCHartographY (SCIAMACHY) instrument onrnthe Envisat satellite, principally designed to retrieve tracerngases in the atmosphere, is also capable of detectingrnclouds. Cloud fraction is retrieved using the OpticalrnCloud Recognition Algorithm (OCRA). In this paper, thisrnLevel 2 operational cloud product is compared to the resultsrnfrom other cloud algorithms such as FRESCO (FastrnRetrieval Scheme for Clouds from the Oxygen A-band).rnIt is shown that the retrieved cloud fractions correlate wellrnbetween OCRA and FRESCO since the 28th April 2004.rnFRESCO provides a consistent set of cloud products byrnretrieving simultaneously cloud fraction and cloud toprnpressure. Moreover, FRESCO retrievals are corroboratedrnwith cloud top pressure from MODIS. Other algorithmsrnsuch as HICRU (cloud fraction) and SACURA (cloudrntop pressure) are also available to validate independentlyrnthese cloud products.