Evaluation of the FAME-C Cloud Climatology for the Years 2007-2009 in the Frame of the ESA Climate Change Initiative
Carbajal Henken, Cintia1; Lindstrot, Rasmus1; Preusker, Rene1; Fischer, Jürgen1; Stengel, Martin2; Hollmann, Rainer2
1Freie Universität Berlin, GERMANY; 2Deutscher Wetterdienst, GERMANY
In the frame of the ESA Climate Change Initiative Cloud, a synergistic daytime FAME-C (FUB AATSR-MERIS Cloud Retrieval) algorithm is developed for the Advanced Along-Track Scanning Radiometer (AATSR) and the MEdium Resolution Imaging Spectrometer (MERIS), both mounted on the polar orbiting satellite ENVISAT. The algorithm uses an optimal estimation scheme to retrieve a pixel-based error estimate for each retrieved cloud property.
FAME-C consists of two main steps. In the first step, for pixels identified as cloudy by a synergistic cloud mask algorithm, AATSR measurements in the visible are used to derive daytime micro-physical cloud properties such as cloud optical thickness, effective radius, and liquid water path/ice water path. The micro-physical cloud properties are used as input in the second step, which is the cloud height retrieval. The cloud top height can be determined from both thermal emission of the cloud using AATSR measurements in the infrared as well as from the average photon path length using MERIS measurements within and near the Oxygen-A absorption band. In cloudy situations this average photon path length is mainly determined by the cloud top pressure.
Within the first phase of the ESA Cloud CCI project a time series of the cloud properties for the years 2007-2009 is being generated. These level-2 products are evaluated using measurements from several ground-based instruments at ARM-sites, such as radar and microwave radiometer. Also, measurements from the active instruments on CALIPSO and CloudSat will be used. From the level-2 products monthly averages are produced. This Level-3 product is compared to a number of other Level-3 cloud property data sets from instruments such as MODIS, MSG, AMSR-E, and AVHRR. Differences are evaluated and discussed.
In light of the extension of the cloud climatology data set to the full ENIVSAT period 2002-2012 as well as the follow-up mission Sentinel-3, first results of the use of the 2007-2009 cloud climatology for the purpose of climate studies will be presented.