July 2003
These MYD15A2 images are pseudo-colored to display the Fraction of Photosynthetically Active Radiation (FPAR) calculated over the northeast U.S. (tile h11v05).
October 2003
Between 8-day periods in July and October 2003, decreasing levels of green clearly indicate the progression of Summer to Fall.
The level-4 MODIS global Leaf Area Index (LAI) and Fraction of Photosynthetically Active Radiation (FPAR) product is composited every 8 days at 1-kilometer resolution on a Sinusoidal grid. Science Data Sets provided in the MYD15A2 include LAI, FPAR, a quality rating, and standard deviation for each variable.
The LAI variable defines the number of equivalent layers of leaves relative to a unit of ground area, whereas FPAR measures the proportion of available radiation in the photosynthetically active wavelengths that are absorbed by a canopy. Both variables are used as satellite-derived parameters for calculating surface photosynthesis, evapotranspiration, and net primary production, which in turn are used to calculate terrestrial energy, carbon, water cycle processes, and biogeochemistry of vegetation.
Version-5 MODIS/Aqua LAI products are Validated Stage 2, accuracy has been assessed over a widely distributed set of locations and time periods via several ground-truth and validation efforts. Version-5 MODIS/Aqua FPAR products are Validated Stage 1, meaning that accuracy has been estimated using a small number of independent measurements obtained from selected locations and time periods and ground-truth/field program efforts. Although there may be later improved versions, these data are ready for use in scientific publications.
Temporal Coverage | July 4, 2002 - |
Area | ~10 x 10 lat/long |
File Size | ~0.2 MB compressed |
Projection | Sinusoidal |
Data Format | HDF-EOS |
Dimensions | 1200 x 1200 rows/columns |
Resolution | 1 kilometer |
Science Data Sets (SDS HDF Layers) | 6 |
Science Data Sets for MODIS/Aqua Leaf Area Index/FPAR 8-Day L3 Global 1km SIN Grid V005 (MYD15A2):
Science Data Sets (HDF Layers) (6) |
UNITS |
BIT TYPE |
FILL |
VALID RANGE |
MULTIPLY BY SCALE FACTOR |
---|---|---|---|---|---|
Fpar_1km | Percent | 8-bit unsigned integer | 249–255 | 0–100 | 0.01 |
Lai_1km | m2plant/m2ground | 8-bit unsigned integer | 249–255 | 0–100 | 0.1 |
FparLai_QC | Class flag | 8-bit unsigned integer | 255 | 0–254 | na |
FparExtra_QC | Class flag | 8-bit unsigned integer | 255 | 0–254 | na |
FparStdDev_1km | Percent | 8-bit unsigned integer | 248–255 | 0–100 | 0.01 |
LaiStdDev_1km | m2plant/m2ground | 8-bit unsigned integer | 248–255 | 0–100 | 0.1 |
The QA information below is excerpted from an HDF-EOS file of the MODIS LAI/FPAR product MOD15A2.
There are two QC data sets for LAI/FPAR QC. Table 1 displays the bit legend for the general QC values found in the SDS “FparLai_QC,” while Table 2 shows the more detailed information included in “FparExtra.”
Table 1: MYD15A2.005 LAI/FPAR General QA (8-bit)
Bit No. |
Parameter Name |
Bit Comb. |
FparLai_QC |
---|---|---|---|
0 | MODLAND_QC bits | 0 | Good quality (main algorithm with or without saturation) |
1 | Other Quality (back-up algorithm or fill values) | ||
1 | Sensor | 0 | Terra |
1 | Aqua | ||
2 | DeadDetector | 0 | Detectors apparently fine for up to 50% of channels 1,2 |
1 | Dead detectors caused >50% adjacent detector retrieval | ||
3–4 | CloudState (inherited from Aggregate_QC bits {0,1} cloud state) | 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 | ||
5–7 | SCF_QC (five level confidence score) | 000 | 0, Main (RT) method used, best result possible (no saturation) |
001 | 1, Main (RT) method used with saturation. Good,very usable | ||
010 | 2, Main (RT) method failed due to bad geometry, empirical algorithm used | ||
011 | 3, Main (RT) method failed due to problems other than geometry, empirical algorithm used | ||
100 | 4, Pixel not produced at all, value coudn't be retrieved (possible reasons: bad L1B data, unusable MODAGAGG data) |
Table 2: MYD15A2.005 LAI/FPAR Detailed QA (8-bit)
Bit No. |
Parameter Name |
Bit Comb. |
FparExtra_QC |
---|---|---|---|
0–1 | LandSea Pass-Thru | 00 | 0 LAND AggrQC(3,5)values{001} |
01 | 1 SHORE AggrQC(3,5)values{000,010,100} | ||
10 | 2 FRESHWATER AggrQC(3,5)values{011,101} | ||
11 | 3 OCEAN AggrQC(3,5)values{110,111} | ||
2 | Snow_Ice (from Aggregate_QC bits) | 0 | No snow/ice detected |
1 | Snow/ice detected | ||
3 | Aerosol | 0 | No or low atmospheric aerosol levels detected |
1 | Average or high aerosol levels detected | ||
4 | Cirrus | 0 | No cirrus detected |
1 | Cirrus was detected | ||
5 | MODAGAGG_Internal_CloudMask | 0 | No clouds |
1 | Clouds were detected | ||
6 | MODAGAGG_Cloud_Shadow | 0 | No cloud shadow detected |
1 | Cloud shadow detected | ||
7 | SCF_Biome_Mask | 0 | Biome outside interval <1,4> |
1 | Biome in interval <1,4> |
MYD15A2 Fill Values
Table 1: For Fpar_1km and Lai_1km
Value |
Description |
---|---|
255 |
Fillvalue, assigned when: * the MODAGAGG surface reflectance for channel VIS, NIR was assigned its _Fillvalue, or * land cover pixel itself was assigned _Fillvalue 255 or 254 |
254 | land cover assigned as perennial salt or inland fresh water |
253 | land cover assigned as barren, sparse vegetation (rock, tundra, desert.) |
252 | land cover assigned as perennial snow, ice |
251 | land cover assigned as "permanent" wetlands/inundated marshlands |
250 | land cover assigned as urban/built-up |
249 | land cover assigned as "unclassified" or not able to determine |
Table 2: For FparStdDev_1km and LaiStdDev_1km
Value |
Description |
---|---|
255 |
Fillvalue, assigned when: * the MODAGAGG surface reflectance for channel VIS, NIR was assigned its _Fillvalue, or * land cover pixel itself was assigned _Fillvalue 255 or 254 |
254 | land cover assigned as perennial salt or inland fresh water |
253 | land cover assigned as barren, sparse vegetation (rock, tundra, desert.) |
252 | land cover assigned as perennial snow, ice |
251 | land cover assigned as "permanent" wetlands/inundated marshlands |
250 | land cover assigned as urban/built-up |
249 | land cover assigned as "unclassified" or not able to determine |
248 | no standard deviation available, pixel produced using backup method. |
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Sioux Falls, SD 57198-0001
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