Xavier Ceamanos

AERUS‐GEO: A newly available satellite‐derived aerosol optical depth product over Europe and Africa

This article presents a new aerosol optical depth (AOD) product delivered in near real time by the ICARE Data and Services Center to the scientific community. The AERUS-GEO (Aerosol and surface albEdo Retrieval Using a directional Splitting method-application to GEOstationary data) product is derived from observations from the Meteosat Second Generation (MSG) geostationary satellite covering Europe, Africa, and part of Asia and South America. The retrieval method exploits the directional information contained in the series of 96 MSG observations per day of the Earths disk to derive a daily averaged AOD. The performances of this product are similar to those of other widely used satellite-derived AOD. This article illustrates the advantages of the spatial (3 km at best) and temporal (daily) resolution of the AERUS-GEO product to monitor particular aerosol activity (e.g., volcanic eruptions) or to study given phenomena (e.g., the impact of topography on aerosol loading).

Comparison of two methods for aerosol optical depth retrieval over North Africa from MSG/SEVIRI data

A comparison between the algorithm for Land Aerosol property and Bidirectional reflectance Inversion by Time Series technique (LABITS) and a daily estimation of aerosol optical depth (AOD) algorithm (AERUS-GEO) over land surface using MSG/SEVIRI data over North Africa is presented. To obtain indications about the quantitative performance of two AOD retrieval methods mentioned above, daily SEVIRI AOD values is considered with respect to those measured from the global aerosol-monitoring Aerosol Robotic Network (AERONET) data. The correlation coefficient (R2) between retrieved SEVIRI AOD at 650 nm from the AERUS-GEO algorithm and the AERONET Level 2.0 daily average AOD at 675 nm is 0.80 and root mean square error (RMSE) is 0.044, and R2 between retrieved AOD from the LABITS algorithm and AERONET AOD is 0.80 and RMSE is 0.037.

Analysis of snow-free vegetation and bare soil albedos and application to numerical weather prediction

Land surface albedo is considered to be a fundamental quantity for accurate assessment of the surface energy budget. Whereas satellite products usually provide total surface albedo, land surface models often require a separation of snow-free surface albedos of the vegetation canopy and the underlying bare soil. Visible and near infrared vegetation and bare soil albedos are here retrieved from a decade of MODIS data at global scale by using a Kalman-filter-based method. The retrieved quantities show good agreement with those derived in previous studies. The main advantage of the proposed method over other approaches is that it provides albedo components efficiently throughout the year, thus allowing the seasonal cycles to be captured. In a second step, the snow-free vegetation and bare soil albedos derived from the satellite surface albedo product are exploited to evaluate the value added of the use of satellite albedo in Numerical Weather Prediction (NWP) models.

Merged MSG and EPS land surface albedo products in the frame of the LSA SAF project: Method and validation over Europe

This study aims at presenting for the first time merged GEO (geostationary elevation orbit) MSG and LEO (low elevation orbit) EPS albedo products over Europe issued from an operational production center. The assets of the merging is to complete the high latitude coverage from existing GEO products with a resolution grid adapted. Spectral norms were applied for product matching and also standard atmospheric correction. Still aerosol removal need to be timely performed.

Downwelling shortwave surface flux from MSG geostationary satellite: Impact assessment on Land Surface Models and improvements on consideration of aerosol effects

Downwelling radiative fluxes at the surface level are estimated in near real time in the framework of the Satellite Application Facility on Land Surface Analysis (LSA SAF). This is achieved using data acquired by the geostationary Meteosat Second Generation satellite. The method for the retrieval for downwelling shortwave surface fluxes (DSSF) is based on a physical parameterization, which depends on the solar energy arriving to Earth, the cloud coverage, and the atmospheric transmittance, among other parameters. After many years of development and operational activities involving the DSSF product of the LSA SAF, a summary of the retrieval algorithm, some applications, and the recent improvements on the consideration of aerosol effects is presented here.