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EDG Data Set Name	Granule Shortname
MODIS/Terra Net Primary Production Yearly L4 Global1km SIN Grid	MOD17A3

Version	Acquisition Range	Science Quality Status
V003	January 1, 2001 (2001001) - December 31, 2002 (2002365)	Beta

Data Set Characteristics
Area = ~ 10° x 10° lat/long
Image Dimension = 2 (1200x1200 row/column)
Average File Size = ~4 MB
Resolution = 1 kilometer
Projection = Integerized Sinusoidal
Data Type = 16-bit signed integer
Data Format = HDF-EOS
Science Data Sets = 2

kgC/m^2	Color
< 0.05	brown
0.05 - 0.10	light green
0.10 - 0.20	bright green
0.20 - 0.30	medium green
0.30 - 0.50	green
0.50 - 1.00	dark green

Product Description
The MOD17A3 approach to remote sensing estimates of Net Primary Production (NPP) is based on the concept of radiation use efficiency (RUE). Solar radiation in the wavelength band from 0.4 - 0.7 micrometers is potentially useful for photosynthesis, and radiation in this band is called photosynthetically active radiation (PAR). On average about 45% of the shortwave radiation reaching Earth's surface from the Sun is in the PAR spectral region. Some of this PAR is absorbed by plants (APAR), and some of this absorbed energy is used to fix CO₂ from the atmosphere as carbohydrate for growth and respiration. The amount of new growth that is produced from a given amount of APAR is a measure of the plant's RUE. It depends on the physiological characteristics of the plant, and also on the environmental conditions at any particular time. For example, a fast growing forb may have an intrinsically higher RUE than a slow-growing pine tree, but both plants might have a wide range of RUE depending on factors such as air temperature and the availability of water and essential nutrients in the soil.

Although the use of remote sensing data can provide global coverage on a frequent update cycle, the RUE approach to estimating NPP involves many simplifications and approximations, ignoring much of the ecophysiological complexity of the real terrestrial primary production processes. In order to capture some of that complexity in the simple remote sensing approach, we use results from a sophisticated ecosystem process model to set the parameter values for our simpler remote sensing algorithm.  The model is called Biome-BGC, a computer program that estimates biogeochemical cycles (BGC) represented by fluxes and storage of energy, water, carbon, and nitrogen for the vegetation and soil components of terrestrial ecosystems.  The model uses a daily time-step, which is composited to create an 8-Day Net Photosynthesis product (MOD17A2), and the annual Primary Production product, MOD17A3.

Further information:
*Monteith, J.L., 1972: Solar radiation and productivity in tropical ecosystems. J. Appl. Ecology, 9, 747-766

Running, S.W., P.E. Thornton, R.R. Nemani, J.M. Glassy. (2000) Global Terrestrial Gross and Net Primary Productivity from the Earth Observing System. In: Methods in Ecosystem Science, O.Sala, R. Jackson, and H.Mooney Eds. Springer-Verlag New York.

NOTE: These products are still experimental in nature upon their initial release. Investigations are underway to assess the scientific validity of these products.

SDS	Units	Data Type	Fill Value	Valid Range	Multiply by Scale Factor	Calibrated_nt
* MODIS Gridded 1KM Net Primary Productivity (NPP)	kgC/m^2	16-bit signed integer	32767	-30000 - 32700	0.0001	22
** NPP_QC_1KM	na	8-bit unsigned integer	255	0 - 254	na	na

Non-Terrestrial Value Index/Fill Value Index

Npp_1km
32767	Fill Value
32766	Landcover assigned as perennial salt or inland fresh water
32765	Landcover assigned as barren, sparse vegetation (rock, tundra, desert)
32764	Landcover assigned as perennial snow, ice
32763	Landcover assigned as permanent wetlands/inundated marshland
32762	Landcover assigned as urban/built-up
32761	Landcover assigned as unclassified/not able to determine

** Quality Control Bit Index

Npp_1km_QC 5 BITFIELDS IN 8-BITWORD
MODLAND_QC	START 0 END 1 VALIDS 4
00=0	Best Possible
01=1	OK, but not the best
10=2	Not produced, due to cloud
11=3	Not produced, due to other reasons
NOT ASSIGNED	START 2 END 5
SCF_QC	START 5 END 7 VALIDS 4
000=0	Pixel produced, best quality
001=1	Pixel produced, good quality, useable value
010=2	Pixel produced, poor quality due to geometry problems
011=3	Pixel produced, poor quality due to problems other than problems
100=4	Couldn't retrieve pixel
111=7	NOT PRODUCED AT ALL (non-terrestrial biome)

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MODIS/TERRA NET PRIMARY PRODUCTION YEARLY L4 GLOBAL 1KM ISIN GRID V003

EOS Data Gateway Search Tips

Data Center:	LPDAAC
Sensor:	MODIS
Dataset:	MODIS/Terra Net Primary Production Yearly L4 Global1km SIN Grid
Spatial:	HORIZONTALTILENUMBER Max/Min VERTICALTILENUMBER Max/Min
Geographic Extent:	Type Lat/Long Range or Draw on Map
Temporal Extent:	August 29, 2002 (2002241) - October 7, 2002 (2002280)

Product Information

Product Description (http://images.ntsg.umt.edu/productguide.php)

User Guide (http://modis-fire.umd.edu/documents/MODIS_Fire_Users_Guide_2_0__2.pdf)

Algorithm Theoretical Basis Document (ATBD) (http://modis.gsfc.nasa.gov/data/atbd/atbd_mod16.pdf)

MODIS Standard Data Products Catalog (http://modis.gsfc.nasa.gov/data/dataprod/index.php)

EOS Data Products Handbook Volume 1 (2000) (http://eospso.gsfc.nasa.gov/eos_homepage/for_scientists/data_products/vol1.php)

Contact Information

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Phone:	605-594-6116
Toll Free:	866-573-3222
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Fax:	605-594-6963
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