The following MODIS 250 m derived GPP/NPP products are available:

modis-250-gpp: MODIS 250 8-day GPP 2001-2017
modis-250-npp: MODIS 250 annual NPP 2001-2017

Data are also available on Google Earth Engine
modis-250-gpp: https://developers.google.com/earth-engine/datasets/catalog/UMT_NTSG_v2_MODIS_GPP
modis-250-npp: https://developers.google.com/earth-engine/datasets/catalog/UMT_NTSG_v2_MODIS_NPP

Data are scaled by 10,000. The table below describes the QC band values; please
see the paper for more detailed descriptions.

+---------------+-------------+-----------------------------------+
|    Dataset    | Pixel Value |            Description            |
+---------------+-------------+-----------------------------------+
| MODIS 250 GPP | 0           | Original NDVI value used          |
|               | 1           | Smoothed NDVI value used          |
| MODIS 250 NPP | 0 - 100     | Percent of NDVI values gap filled |
+---------------+-------------+-----------------------------------+

The table below describes input differences from NASA MOD17.

+----------------+--------------------+------------------------+----------------------------+----------------------------+
|                |                    | NASA MOD17             | MODIS 250                  | Landsat                    |
+----------------+--------------------+------------------------+----------------------------+----------------------------+
| Input Variable | Units              | Source    | Resolution | Source        | Resolution | Source        | Resolution |
+----------------+--------------------+-----------+------------+---------------+------------+---------------+------------+
| VPD            | Pa                 | GMAO/NASA | 0.5°       | Idaho Metdata | 4 km       | Idaho Metdata | 4 km       |
+----------------+--------------------+-----------+------------+---------------+------------+---------------+------------+
| SWrad          | w m-2              | GMAO/NASA | 0.5°       | Idaho Metdata | 4 km       | Idaho Metdata | 4 km       |
+----------------+--------------------+-----------+------------+---------------+------------+---------------+------------+
| Tavg           | °C                 | GMAO/NASA | 0.5°       | Idaho Metdata | 4 km       | Idaho Metdata | 4 km       |
+----------------+--------------------+-----------+------------+---------------+------------+---------------+------------+
| Tmin           | °C                 | GMAO/NASA | 0.5°       | Idaho Metdata | 4 km       | Idaho Metdata | 4 km       |
+----------------+--------------------+-----------+------------+---------------+------------+---------------+------------+
| Land Cover     | na                 | MOD12Q1   | 500 m      | NLCD          | 30 m       | NLCD          | 30 m       |
+----------------+--------------------+-----------+------------+---------------+------------+---------------+------------+
| FPAR           | na                 | MOD15A2   | 500 m      | MOD09Q1       | 250 m      | Landsat SR    | 30 m       |
+----------------+--------------------+-----------+------------+---------------+------------+---------------+------------+
| LAI            | m2 leaf m-2 ground | MOD15A2   | 500 m      | MOD09Q1       | 250 m      | Landsat SR    | 30 m       |
+----------------+--------------------+-----------+------------+---------------+------------+---------------+------------+

Robinson, N.P., B.W. Allred, W.K. Smith, M.O. Jones, A. Moreno, T.A. Erickson,
D.E. Naugle, and S.W. Running. 2018. Terrestrial primary production for the
conterminous United States derived from Landsat 30 m and MODIS 250 m. Remote
Sensing in Ecology and Conservation. https://dx.doi.org/10.1002/rse2.74

Contact: Brady Allred allredbw@gmail.com

Changelog
=========
2018-03-02 Provisional data release, version 0.2.0