Soil moisture, type, and evaporation
The moisture content of the soil is a key variable which has a strong influence on the partitioning of the available energy at the land surface. In case of sufficient water supply the evapotranspiration rate of the land surface is higher, while it is lower in case of low moisture content. As a consequence, soil moisture affects the energy exchange between the land surface and the atmosphere, which also affects the development of the atmospheric boundary layer.
Closely linked to the soil moisture is the soil type. The type of the upper soil layer influences substantially the soil moisture, run-off, and storage capacity.
Different satellite based methods have been developed to retrieve soil moisture information of the upper few centimeters of the soil from satellite data using active or passive microwave remote sensing methods. Satellite sensors used for this are the Advanced SCATterometer (ASCAT) aboard METOP and the Advanced Microwave Scanning Radiometer (AMSR-E) aboard the EOS-Satellites TERRA and AQUA. In 2009 the European Space Agency has launched a dedicated soil moisture satellite mission: Soil Moisture and Ocean Salinity (SMOS).
Here you can find information about soil type:
The topography of the Earth (on land and below the water line, i.e. the bathymetry) surface influences air flow and ocean currents, land hydrology (e.g. run-off) and glacier flow. In order to understand and correctly interpret climate-relevant processes, and in order to predict the impact potential future climate change may have, a global topography data set is important.
Here, we offer the topography data set: ETOPO1, with a spatial resolution of 1' (one arc minute = 1 nautical mile = 1.852 km); this is the successor of similar data sets with coarser spatial resolution: ETOPO2v2 and ETOPO5. The offered ETOPO1 data set is grid registered and over land shows the ice sheet surface (not the bedrock) (see NOAA-NGDC).
The ETOPO1 data set is a composite comprising a number of different data sources; information about these and the methods used to combine these is given in the ETOPO1 Development Report.
Access: (Attention: File size is 250 Mb - 400 Mb!) via
in the formats: geotiff, netCDF-GMT4, and netCDF-GDAL. The latter alternative is offered because of problems with GDAL reading the other, GMT4-based version (see readme-file).
ETOPO1 data have to be cited like this:
Amante C., and B. W. Eakins, 2009, ETOPO1 1 arc-minute global relief model: procedures, data sources and analysis, NOAA Technical Memorandum NESDIS NGDC 24, 19 pp., National Geophysical Data Center, Marine Geology and Geophysics Division, Boulder, Colorado.
More information is given under NOAA-NGDC.
For those of you who work with the Antarctic and require information about its topography, the location of observation stations, rock outcrops, etc., we recommend the latest issue of the Antarctic Digital Database (ADD) Version 6.0 hosted by BAS and SCAR.
Thanks to the work of the IBCAO a new bathymetric chart of the Arctic Ocean has been released recently. This Version 3.0 now comes with a grid resolution of 500 m x 500 m. More details you can find in Jakobsson et al. (2012).
For the investigations of the Earth gravity field, the derivation of MDT or SSH, and the derivation of sea ice and ice sheet thickness the geoid of the Earth needs to known. We offer two recent geoid models, one global and one which is limited to t he Arctic Ocean:
Occurrence and distribution of permafrost or frozen soil plays a fundamental role for the hydrological cycle and biochemical fluxes (like of CO2 or Methane) between soil and atmosphere. Spatial-temporal changes of permafrost distribution and layer thickness can be seen as indicator of climate change. Its amplification in Arctic and sub-Arctic regions seems to have initiated a reduction in permafrost distribution and vertical extent in some areas already.
We link here to a unique data set of permafrost distribution, vertical extent and other related parameters that has been compiled at the ETH-Zurich:
On the above-mentioned web site you can find versions of this data set as kml-file for Google Earth, in ArcGIS format and as raw binary file (3 GB!). The spatial resolution of this data set is 30 arcseconds (that is less than 1 km). It covers the area 60°S to 90°N and comprises 43200 x 18000 grid cells.
For further reading and citation of the data set the following reference is mandatory: Gruber, S. 2012: Derivation and analysis of a high-resolution estimate of global permafrost zonation, The Cryosphere, 6, 221-233. doi:10.5194/tc-6-221-2012.
Couple of users are interested in information about countries in a gridded format, e.g. to calculate a country mean temperature.
For those users we offer a netCDF-File with gridded country area information with the area each country occupies coded with a specific number on a 0.5° x 0.5° grid. The country associated with the respective number given in the netCDF file can be read in the corresponding table.
For users who need to know the land-water-distribution at fine spatial resolution we offer here the MOD44W data set. It is based on data of the SRTM shuttle mission and MODIS and provides the land-water-distribution at 250 m spatial resolution. More details are given here.