Land Surface Atmospheric Boundary Interaction Product (LANDMET)

Investigations of land-atmosphere interactions have usually tended to rely, in part, on a variety of models to describe either atmospheric conditions near the land surface (global or regional weather analyses or forecast models) or the variations of land surface properties forced by changing weather conditions (land surface models) because some aspects of the near-surface meteorology or land properties were not readily available from observations. In fact there is a rich variety of observations available from conventional surface-based and satellite sources, but these have generally been used in piecemeal comparisons to these models, not usually as an integrated set of information that encompasses the whole complex of land-atmosphere interactions. Earlier projects to pull together global, combined data products, namely the International Satellite Land Surface Climatology Project (ISLSCP I and II, Hall et al. 2006) and the Global Soil Wetness Project (GSWP, which used some of the ISLSCP product, Dirmeyer et al. 1999), were focused primarily on asseling a comprehensive set of the atmospheric forcing for land surface models (LSMs).

This new product is a multi-variate data compilation that reconciles the variation scales of these multiple measurements, merges and maps them into a comprehensive description of the near-surface atmospheric properties together with the land surface property variations on diurnal-to-decadal time scales. The land surface is represented by land fraction, land surface type, topography (mean and standard deviation), total effective and black sky spectral albedoes at solar wavelengths, thermal effective infrared and microwave emissivities, temporary flooding fraction, soil moisture, snow cover fraction and skin temperature. The atmosphere is represented by temperature and humidity profiles from the surface up to the 500 hPa level, surface windspeed, precipitation amount and type, low-level cloud types and amounts, net SW and LW radiative fluxes at the surface and at 680 hPa, and turbulent sensible and latent heat fluxes at the surface. Despite the increase of the number of available data products, their differences in space-time resolution preclude making a merged product at finer spatial intervals than about 100 km and finer time intervals than daily, but any product with finer time sampling is reported here at 3-hr intervals. The time period overlap among the products covers only 10 years, 1998-2007. In other words, available data still do not allow for much improvement over the first ISLSCP product in terms of space-time resolution and coverage. The LANDMET data product is comprised of a sequence of daily global files, where quantities are mapped into 1.0-degree-equivalent equal-area grid. The format is netCDF-4.

Many of these data products, especially those based on surface measurements, are spatially and/or temporally sparse or incomplete in coverage, so procedures were developed to fill missing values. These procedures are based on evaluations of the characteristic space-time scales of variability of each quantity. Because of the spatial heterogeneity of the land surface and larger-scale variations of the atmosphere, time interpolation at each location is the preferred filling method.

The LANDMET product is comprised of 4 Ancillary products that are fixed in time but vary with location, 3 Land Surface properties that vary at daily intervals and 7 Surface and Lower Atmospheric properties that vary at 3-hr intervals. The global maps are arranged in daily files with eight components for those quantities reported at 3-hr intervals.

To download the dataset in NETCDF 4 format click here.

To Download Documentation and the Ancillary datasets Click Here