Global Model Reference Data, 0.5 x 0.5 degree grid-cell

The Global Model Reference Collection contains 3 datasets that have been used extensively in various biogeochemical process models, in addition to some basic data layers used in analyzing and aggregating model estimates.

Model simulations of ecosystem processes require information about the landscape in addition to model-specific parameters based on vegetation characteristics and soil properties. The data included in the Global Model Reference Data collection are basic data layers.

The Geography Dataset:

The Geography dataset contains variables for continent code and grid-cell area that can be used when aggregating other data layers into regions (such as by continents). Area-weighted estimates using on grid-cell area are important to calculate because gridded data based on atitude/longitude boundaries vary in area depending on their location on the globe. Area-weighted estimates are used to determine how much land area is impacted by various environmental changes. The elevation data layer is used in models to determine high-elevation snow cover, or may be used to determine landscape properties or the direction of overland runoff.

Landcover Dataset:

The Landcover dataset contains the variable "potential vegetation", which is a classification of each grid cell as a natural vegetation type. This data layer does not contain any type of crop, pasture, urban, or other non-natural vegetation types. This data layer has been used to estimate the upper range of net primary production and other ecosystem processes in the absence of human intervention.

The Soils Dataset:

The Soils dataset contains a soil texture variable used to determine many water-related plant processes, including the depth of the root layer and the water-holding capacity of the soil. Because wetland ecosystems function very differently from dry-land ecosystems, we have included a wetland designation data layer to be used along with the potential vegetation data layer: in some models, such as TEM, wetland areas are not included in global or regional model runs.