|Title||Aerosol analysis and forecast in the ECMWF Integrated Forecast System: Data assimilation.|
|Publication Type||Technical memorandum|
|Secondary Title||ECMWF Technical Memoranda|
|Authors||Benedetti, A, Morcrette, J-J, Boucher, O, Dethof, A, Engelen, R, Fisher, M, Flentjes, H, Huneeus, N, Jones, L, Kaiser, J, Kinne, S, Mangold, A, Razinger, M, Simmons, A, Suttie, M, team, theGEMS-AER|
This study presents the new aerosol assimilation system developed at the European Centre for Medium-Range Weather Forecasts for the Global and regional Earth-system Monitoring using Satellite and in-situ data (GEMS) project. The aerosol modelling and analysis system is fully integrated in the operational four-dimensional assimilation apparatus. Its purpose is to produce aerosol forecasts and reanalysis of aerosol fields using optical depth data from satellite sensors. This paper is the second of a series which describes the GEMS aerosol effort and focuses on the theoretical architecture and practical implementation of the aerosol assimilation system. It also provides a discussion of the background errors and observations errors for the aerosol fields, and presents a subset of results from the two-year reanalysis which has been run for 2003 and 2004 using data from the Moderate Resolution Imaging Spectroradiometer on the Aqua and Terra satellites. Independent datasets are used to show that, despite some compromises that have been made for feasibility reasons in regards to the choice of control variable and error characteristics, the analysis is very skilful in drawing to the observations and in improving the forecasts of aerosol optical depth.