DOI: 10.1594/pangaea.775959
title: Circumpolar surface soil moisture and freeze/thaw surface status remote sensing products (Version 2) with links to geotiff images and NetCDF files (2007-01 to 2010-09)

description: This dataset is part of the ESA Data User Element (DUE) Permafrost Full Product Set (doi:10.1594/PANGAEA.780111).MetOp ASCAT data have been used for both the near surface soil moisture (SSM) product and determination of freeze/thaw status at pan-boreal/arctic scale. Metop-A, launched in October 2006 by the European Organization for the Exploitation of Meteorological Satellites (EUMETSAT), is the first of three satellites within EUMETSAT's Polar System (EPS). Alternative global products exist from passive microwave sensors. In case of surface soil moisture, these datasets have been recently combined with ERS and ASCAT records within the ESA WACMOS project for a 30-year historic record. The DUE Permafrost service aims on regular updates and has been adjusted to high latitudes. This included the review of processing parameters and improved masking for frozen ground conditions. The initial freeze/thaw status flag has been implemented for the weekly averaged surface soil moisture service. It has been improved in cooperation with the ESA STSE ALANIS-Methane project in order to reflect daily conditions and also snowmelt conditions. It is referred to as the enhanced freeze/thaw detection method or surface state flag (SSF).The ASCAT Level 2 product including soil moisture data are produced by EUMETSAT in near-real time following the method developed and prototyped for EUMETSAT by the Institute for Photogrammetry and Remote Sensing of the Vienna University of Technology. ASCAT data are available via the EUMETCast system and are also accessible through the Unified Meteorological Archive and Retrieval Facility (UMARF) at EUMETSAT.The ASCAT Level 2 data are delivered in orbit geometry at two different grid spacings: 25 km and 12.5 km. The two products are derived directly and on the same grid as the equivalent ASCAT Level 1b product (normalized backscatter), hence the resolution of the soil moisture values is approximately 50 km/25~35 km respectively. For Permafrost project the high resolution product with 12.5 km grid spacing is used.For further processing, ASCAT data are resampled to a Discrete Global Grid (DGG). The DGG is an adapted sinusoidal grid using an ellipsoid based on the GEM6 model. The grid is defined such that the spacing is approximately 12.5 km. The Surface Soil Moisture parameter represents a relative measure of the soil moisture in the top layer of the soil, scaled between wilting level (0%) and field capacity (100%).The ASCAT SSM DUE Permafrost product is the result of an improved SSM retrieval algorithm developed at the Institute for Photogrammetry and Remote Sensing (IPF) of the Vienna University of Technology. The SSM Product is delivered with a weekly temporal resolution and 25 km spatial resolution. The soil moisture product also includes a quality flag which contains the number of used measurements. Data are masked for frozen ground conditions also based on MetOp ASCAT. The product is provided as weekly averaged images north of 50°N in GeoTIFF/NetCDF format and EASE Grid projection.Overview figures:- SST surface status in May 2008: hdl:10013/epic.39188.d003- SSM summer 2007 and summer 2008: hdl:10013/epic.39188.d002