Model:GNE

GNE

Model:	Global NEWS / GNE
Contact person:	Sybil Seitzinger
Institute:	Rutgers - Institute of Marine & Coastal Sciences
City:	New Brunswick, NJ
Country:	USA
Email:	sybil@marine.rutgers.edu
2nd person involved:	Emilio Mayorga (Developer)
3rd person involved:	John Harrison (Developer)

Model type:	Single model for the terrestrial and coastal domain.
Description:	A multi-element (N, P, Si, C), multi-form (particulate, dissolved, organic, inorganic) set of biogeochemical sub-models that predicts annual river exports to the coast as a function of basin-aggregated natural and human impact characteristics; GNE is a generic framework used to run the basin models.

Supported platforms:	Linux, Windows
Programming language:	Python
Model was developed started from:	2002 and development still takes place
To what degree will the model become available:	As code, as teaching tool
Current license type:	--
Memory requirements:	minimal
Typical run time:	less than 1 minute after preprocessing

Input parameters:	Source inputs consist of global, spatially distributed (GIS) raster datasets: hydrological properties (river basin systems, runoff, reservoirs, irrigation, rainfall), topographic slope, land use, agricultural N & P inputs (fertilizer, manure), atmospheric N deposition, sewage, N fixation, etc.
Input format:	ASCII, Binary
Output parameters:	Primary outputs: N, P, Si, and C yields and loads by river basin and nutrient form. Secondary outputs: Source attribution by nutrient form and main natural and anthropogenic inputs to watersheds. Total Suspended Solids are also predicted.
Output format:	ASCII
Post-processing software (if needed):	no
Visualization software (if needed):	yes, out_ESRI, IDL, Matlab, Most GIS software

Processes represented by model:	Natural, agricultural, atmospheric, and direct human (sewage and P detergents) inputs; effect of hydrological functioning; generalized loss of nutrients in soils and groundwater; loss in rivers, reservoirs, and through consumptive water withdrawals (irrigation).
Key physical parameters & equations:	Net N & P land surface balance (from inputs, incl. atm. deposition) modulated with calibrated runoff relationships to estimate exports to streams; point sources calculated from socioecon. and sewage treatment information; reservoir and consumptive water withdrawal loss using physical relationships.
Length scale & resolution constraints:	Limited by resolutn of input & river systems data; basins < 20,000 km2 currently poorly represented
Time scale & resolution constraints:	Operates at annual scale; monthly-seasonal time steps are being explored.
Numerical limitations and issues :	Concerns about extrapolations beyond range of data used for model calibration and parameterization.

Available calibration data sets:	Calibration data consist of compilations of river N, P, Si and C annual yields by form.
Available test data sets:	Global (GEMS-GLORI), regional, national and literature compilations. A subset used for validation.
Ideal data for testing:	Robust river nutrient fluxes near the mouth representative of annual, contemporary conditions.

Currently or plans for collaborating with:	Model is the result of an international collaboration that is a UNESCO-IOC workgroup (Global NEWS).

Key papers of the model:	Papers published in Global Biogeochem. Cycles listed on Global NEWS website; code not published yet.
Is there a manual available:	yes
Model website if any:	http://www.marine.rutgers.edu/globalnews/

Comments:	Particulates model is regression-based, while dissolved model is more conceptual-mechanistic. Conceptual framework and data sets in development since 2002. Integrated modeling code framework (GNE) developed in 2007; currently tested on Windows only, but can be easily adapted to other platforms.