ISLSCP Initiative II

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IGBP NPP Model Intercomparison Data

Seventeen global models of terrestrial biogeochemistry were compared with respect to annual and seasonal fluxes of net primary productivity (NPP) for the land biosphere. The comparison, sponsored by IGBP-GAIM/DIS/GCTE, used standardized input variables wherever possible and was carried out through two international workshops and over the Internet. The models differed widely in complexity and original purpose, but could be grouped in three major categories: satellite-based models that use data from the NOAA/AVHRR sensor as their major input stream (CASA, GLO-PEM, SDBM, SIB2 and TURC), models that simulate carbon fluxes using a prescribed vegetation structure (BIOME-BGC, CARAIB 2.1, CENTURY 4.0, FBM 2.2, HRBM 3.0, KGBM, PLAI 0.2, SILVAN 2.2 and TEM 4.0), and models that simulate both vegetation structure and carbon fluxes (BIOME3, DOLY and HYBRID 3.0)
      This data set contains modeled annual net primary production (NPP) for the land biosphere from seventeen different global models. Annual NPP is defined as the net difference of annual carbon uptake (grams CO₂/m²/yr) from the atmosphere through photosynthesis by the land vegetation and that lost back to the atmosphere through autotrophic or maintenance respiration. NPP is also related to the Net Ecosystem Exchange (NEE) of carbon accumulated by or lost from the surface by its vegetation and soils. NPP is NEE plus heterotrophic (decomposition) respiration of the vegetation and soils. Only NPP values are included in this data set as some models did not estimate NEE.

Data Provider: Wolfgang Cramer

Data Files (ISLSCP II Disc #1)

Data Set Documentation

Image Viewing Tutorial

File Information

The file format consists of numerical fields of varying length, which are delimited by a single space and arranged in columns and rows. There are two resolutions to this data, one-degree (360 columns by 180 rows) and half-degree(720 columns by 360 rows). All values are written as real numbers. Missing values are assigned the value of -99.99. The files have been compressed using the PKZip program. There are 3 data files for each resolution:

One-degree Data
• modeled_npp_average_1d.asc
• modeled_npp_cv_1d.asc
• modeled_npp_stdev_1d.asc

  Half-degree Data

• modeled_npp_average_hd.asc
• modeled_npp_cv_hd.asc
• modeled_npp_stdev_hd.asc

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Revision Date: August 25, 2003