|
| EDG Data Set Name |
Granule Shortname |
| MODIS/Aqua Net Photosynthesis 8-Day L4 Global 1km SIN Grid |
MYD17A2 |
| Version |
Acquisition Range |
Science Quality Status |
| V004 |
July 4 2002 (2002185) |
Provisional
|
Data Set Characteristics
Area = ~ 10° x 10° lat/long
Image Dimensions = 1200 X 1200 rows/columns
File Size = ~4 MB
Resolution = 1 kilometer
Projection = Sinusoidal
Data Type = 16-bit signed integer
Data Format = HDF-EOS
Science Data Sets (SDSs) = 2 |
 |
|
MYD17A2 - 8-day gross primary vegetation productivity across
the Strait of Gibraltar from January 25 - February 1, 2004. Values
range from zero (black) to 0.02 kgC/m^2 (light green). |
Product Description
The MYD17 Net Photosynthesis (PSN) and Net Primary Production (NPP) products are Level 4, 1km global data collections used in calculating terrestrial energy, carbon, water cycle processes, and biogeochemistry of vegetation.
The rate at which light energy is converted to plant biomass is termed primary productivity. The sum total of the converted energy is called gross primary productivity (GPP). The MYD17A2 false-color image shown is an 8-day composite of GPP, expressed as the mass of Carbon per square meter, over North America.
MYD17A2 is produced based on the original work of Monteith* (1972) which relates
PSN and NPP to the amount of Absorbed Photosynthetically Active Radiation (APAR).
The algorithm uses input from MODIS LAI/FPAR (MYD15A2),
land cover, and biome-specific climatology data from NASA's Data Assimilation
Office (DAO). The 8-day PSN will be integrated over a year to produce MYD17A3,
an annual NPP product. Both have theoretical applications towards defining the
seasonal dynamic flux of terrestrial surface carbon dioxide for climate modeling.
Further information:
1. *Monteith, J.L., 1972: Solar radiation and productivity in tropical ecosystems. J. Appl. Ecology, 9, 747-766
2. 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-bit |
FILL VALUE |
VALID RANGE |
Multiply by
SCALE FACTOR |
Calibrated_nt |
| * MODIS Gridded 1KM 8-day Composite GPP |
kgC/m^2 |
16-bit signed integer |
32767 |
0, 30000 |
0.0001 |
22 |
| * MODIS Gridded 1KM 8-day Composite (GPP minus maint resp) as PsnNet |
kgC/m^2 |
16-bit signed integer |
32767 |
-30000, 30000 |
0.0001 |
22 |
| ** PSN QC 1KM |
na |
8-bit unsigned integer |
255 |
0, 254 |
na |
na |
* Non-Terrestrial Value Index/Fill Value Index
Gpp_1km and PsnNet_1km
| Value |
Description |
| 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 (Valid only for V004 MYD17A2 )
Psn_QC_1km 5 BITFIELDS IN 8-BITWORD
| Index |
Bit Value |
Description |
| MYDLAND_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 |
| |
|
|
| DEADDETECTOR |
START 2 END 2 VALIDS 2 |
|
| |
0 |
Detectors apparently fine for up to 50% of channels 1,2 |
| |
1 |
Dead detectors caused >50% adjacent detector retrieval |
| |
|
|
| CLOUDSTATE |
START3 END 4 VALIDS 4 |
|
| |
00=0 |
Significant clouds NOT present (clear) |
| |
01=1 |
Significant clouds WERE present |
| |
10=2 |
Mixed cloud present on pixel |
| |
11=3 |
cloud state not defined,assumed clear |
| |
|
|
| SCF_QC |
START 5 END 7 VALIDS 4 |
|
| |
000=0 |
Pixel produced, best quality |
| |
001=1 |
Pixel produced, good quality – saturation in FPAR/LAI algorithm |
| |
010=2 |
Pixel produced, poor quality due to geometry problems |
| |
011=3 |
Pixelproduced, poor quality due to problems other than geometry |
| |
100=4 |
Couldn't retrieve pixel |
| |
111=7 |
NOT PRODUCED AT ALL (non-terrestrial biome) |
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EOS Data Gateway Search Tips
| Source: |
Aqua |
| Sensor: |
MODIS |
| Dataset: |
MODIS/Aqua Net Photosynthesis 8-Day L4 Global 1km SIN Grid |
| Spatial: |
HORIZONTALTILENUMBER Max/Min VERTICALTILENUMBER Max/Min |
| Geographic Extent: |
Type Lat/Long Range or Draw on Map |
| Temporal Extent: |
2002-07-04 to present |
Product Information
Contact Information
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