This data set is only available for a restricted user group, please contact us if you want to access these data.
RESTRICTED only accessable in ZMAW net or via CliSAP login What does that mean?
Remark: Only the annual NPP data are available directly from the file system. The 8-daily GPP data are stored separately for performance reasons and are provided on request.
This data set comprises the (8-) daily gross primary production (GPP) and the annual net primary production (NPP) together with various quality and confidence flags derived from MODIS collection 6 radiance and reflectance observations.
Derivation of the NPP is rooted on i) plant NPP is directly related to the absorbed solar energy; ii) NDVI and EVI as observed, e.g. by MODIS, are connected with the solar energy absorbed by the plants, and iii) biophysical reasons determine the ratio between actual and potential efficiency of conversion of solar energy by the plants.
Based on this concept, and expressed very simple, the fraction of absorbed photosynthetically active radiation (FAPAR) can be linked via the efficiency of the plants to convert solar radiation into their growth, to estimate primary production. This conversion efficiency depends on biome type, LAI, and evapotranspiration & respiration conditions. Hence derivation of the two primary production parameters GPP and NPP offered here requires data about land cover, LAI, FAPAR, soil and atmospheric conditions as input as described in the User Guide.
The data sets (MODIS collection 6) offered here (NPP: MOD17A3H and GPP: MOD17AH2) have 8-daily (GPP) and annual (NPP) temporal resolution.
The data sets were included into the ICDC data holding on: November 25, 2016
Period and temporal resolution:
Coverage and spatial resolution:
This data set roots on re-calibrated MODIS observations of collection 6. Long-term inconsistencies caused by problematic calibration of particularly MODIS TERRA have been solved (Lyapustin et al., 2014). The innovative elements in collection 6 are, e.g., usage of Collection 5 vegetation cover and other auxiliary land surface data based on MODIS and usage of the Collection 6 cloud mask.
The data set offered here contains 2 different flags: one quality flag and one confidence flag.
The quality flag comes in two groups of values < 100 and values > 100, the latter indicating "good quality" according to the MODLAND criteria. Subdivisions give information about MODIS sensor detector reliability and cloud cover.
The confidence flags are 0: very best possible; 1: good, very usable, but not the best (FPAR/LAI saturation occurred); 2: substandard due to geometry problems, use with caution; 3: substandard due to other than geometry problems, use with caution; 4: Could not retrieve pixel, not produced, non-terrestrial biome.
An important note: NPP Data from 2000 show artificial jumps in NPP values for a number of tiles due to sub-optimal aggregation of the GPP values. Also, the two flags are mostly constant for every tile in the NPP data set. These are both known issues and production team is working on an improvement.
LP DAAC User Services
Prof. Steven Running
Upon using this data please cite as follows:
For Net Primary Production (NPP):
S. Running, Q. M., M.Zhao. (2015). MOD17A3H MODIS/Terra Net Primary Productivity Yearly L4 Global 500m SIN Grid V006. NASA EOSDIS Land Processes DAAC. doi.org/10.5067/MODIS/MOD17A3H.006 obtained from the Land Processes Distributed Active Archive Center (LP DAAC), located at the U.S. Geological Survey (USGS) Earth Resources Observation and Science (EROS) Center (lpdaac.usgs.gov), modified and converted into netCDF file format at the Integrated Climate Data Center (ICDC, icdc.cen.uni-hamburg.de), University of Hamburg, Germany
and for Gross Primary Production (GPP):
S. Running, Q. M., M.Zhao. (2015). MOD17A2H MODIS/Terra Gross Primary Productivity 8-Day L4 Global 500m SIN Grid V006. NASA EOSDIS Land Processes DAAC. doi.org/10.5067/MODIS/MOD17A2H.006 obtained from the Land Processes Distributed Active Archive Center (LP DAAC), located at the U.S. Geological Survey (USGS) Earth Resources Observation and Science (EROS) Center (lpdaac.usgs.gov), modified and converted into netCDF file format at the Integrated Climate Data Center (ICDC, icdc.cen.uni-hamburg.de), University of Hamburg, Germany