DESCRIPTION: SM-DAS-3
Soil Wetness Index in the roots region by ERS/SCAT and Metop ASCAT-A scatterometer assimilation in a Land Data Assimilation System (H27 - Offline product)


H27 map for parameter 40 (soil layer 1) on 15 June 2014.

H27 is a root zone soil moisture product retrieved from scatterometer Surface Soil Moisture (SSM) observations. The H27 production chain uses an offline sequential based on a Land Data Assimilation System (LDAS) based on an Extended Kalman Filter (EKF) approach that follows the approach of de Rosnay et al. (2013). The EKF constitutes the central component of the H27 production chain. The H-TESSEL Land Surface Model is used to propagate in time and space the soil moisture information through the root zone, accounting for physiographic information (soil texture, orography), meteorological conditions and land surface processes such as for example soil evaporation and vegetation transpiration (van den Hurk et al. 2000, van den Hurk and Viterbo 2003, Balsamo et al. 2009). Essentially the H27 production suite retrieves root zone soil moisture from ERS1/2 Active Microwave Instruments and ASCAT-A surface soil moisture for the period from 1992 to 2014. The H27 production chain also uses screen level parameters close to the surface (2-meters temperature and relative humidity) to ensure consistency of the retrieved Scatterometer root zone and the near surface observed weather conditions. The system is driven by ERA-Interim atmospheric fields (Dee et al., 2011).

Product Format:

The product is provided on a reduced Gaussian grid at a resolution of T1279 (i.e. N640 corresponding to ~16km). The reduced Gaussian grid has a quasi-regular grid spacing in distance at each latitude. The grid is symmetrical at the equator with no latitude raw at either pole or at the Equator, for more details see documentation.

Product Documentation:

For more information, see Product User Manual (PUM), Algorithm Theoretical Baseline Document (ATBD) and Product Validation Report (PVR) available at “User Document” page.