The Ecmwf Surface Analysis: Use of Active and Passive Microwave Data for Soil Moisture Analysis

This paper presents the European Centre for Medium-Range Weather Forecasts (ECMWF) soil moisture (SM) analysis system and its recent developments which enables the assimilation of active and passive microwave data. The current operational SM analysis used in the Integrated Forecast System (IFS), is based on an Optimal Interpolation (OI) scheme using proxy observations (2 m air temperature and relative humidity). The new SM analysis scheme is based on a point-wise ExtendedKalman Filter (EKF) for the global land surface [1]. It will be operationally implemented for Numerical Weather Prediction (NWP) in 2009. The EKF system is presented and operational issues are addressed. The new EKF surface analysis system opens a range of further development possibilities, exploiting new satellite surface data and products, for initialization of the land surface in NWP. Results of active microwave data assimilation are presented, using ASCAT (Advanced SCATTerometer) [2]. Developments for passive microwave data assimilation are also presented in the context of the preparation of SMOS (Soil Moisture and Ocean Salinity) [3].