Folder Vegetation Indices (MOD13C1)

Examples-of-MODIS-NDVI-left-and-EVI-right-products-from-July-2013Vegetation Indices (MOD13C1) Vegetation indices quantify the concentrations of green leaf vegetation (chlorophyll)
around the globe, in an attempt to monitor and correlate vegetation health and stress. The
MODIS vegetation products include the Normalized Difference Vegetation Index (NDVI)
and an Enhanced Vegetation Index (EVI). Included in the MOD13C1 product is both NDVI
and EVI, so both have been provided for the CAFF Dedicated Pan-Arctic Satellite Remote
Sensing Products and Distribution System. These indices come in a variety of resolutions,
but MTRI has provided a monthly global composite on a 0.05° Climate Model GRID
(CMG).
The NDVI algorithm exploits the relationship between the near-infrared (NIR) and
the red wavelengths of the light spectrum, as healthy, green vegetation reflects large amounts
of infrared and near-infrared light. This relationship can be seen in Equation 1. This
algorithm calculates a value for each pixel in the raster with values ranging from -1 to 1.
Values close to 1 represent healthy vegetation, zero represents no vegetation, and values
close to -1 indicate absorption of the near-infrared wavelengths, and represent features such
as water. NDVI is very sensitive to Chlorophyll, and can identify drought and water stress in
areas with diminished reflectance of NIR light.
EVI is similar to NDVI, and exploits the same relationship between red and NIR
wavelengths, but is optimized to improve sensitivity in areas with high biomass levels, such
as dense jungle-like vegetation. EVI is more responsive to canopy structure variations,
including Leaf Area Index (LAI), canopy type, plant physiognomy, and canopy architecture.
This is achieved by the inclusion of the blue band and some aerosol resistance terms, as
shown in Equation 2 (Huete et al., 1999).
It is important to note that with the presence of snow, NDVI decreases, but EVI
increases. This distinction is important Arctic applications, so a comparison of both indices
is suggested.

 

For usage please see ABDS Data Policy
Suggested citation:
CAFF (2015). Vegetation Indices: Arctic Land Cover Change Index. Conservation of Arctic Flora and Fauna, Arctic Biodiversity Data Service (ABDS).

 

Basic Info

  Data Set Characteristics

Temporal Coverage July 4, 2002 -
Area Global
File Size ~100 MB
Projection Lat/Lon
Data Format HDF-EOS
Dimensions 3600 x 7200 rows/columns
Resolution 0.05 degree (5600-meter)
Science Data Sets (SDS HDF Layers) 13

Layers

Science Data Sets for MODIS Aqua Vegetation Indices 16-Day L3 Global 0.05Deg CMG V005 (MYD13C1):

Science Data Sets (HDF Layers) (13)

UNITS

BIT TYPE

FILL

VALID RANGE

MULTIPLY BY SCALE FACTOR

CMG 0.05 Deg 16 days NDVI NDVI 16-bit signed integer -3000 -2000,10000 0.0001
CMG 0.05 Deg 16 days EVI EVI 16-bit signed integer -3000 -2000, 10000 0.0001
CMG 0.05 Deg 16 days VI Quality Bit Field 16-bit unsigned integer 65535 0, 65534 NA
CMG 0.05 Deg 16 days red reflectance (Band 1) Reflectance 16-bit signed integer -1000 0, 10000 0.0001
CMG 0.05 Deg 16 days NIR reflectance (Band 2) Reflectance 16-bit signed integer -1000 0, 10000 0.0001
CMG 0.05 Deg 16 days blue reflectance (Band 3) Reflectance 16-bit signed integer -1000 0, 10000 0.0001
CMG 0.05 Deg 16 days MIR reflectance (Band 7) Reflectance 16-bit signed integer -1000 0, 10000 0.0001
CMG 0.05 Deg 16 days Avg sun zenith angle Degree 16-bit signed integer -10000 -9000, 9000 0.01
CMG 0.05 Deg 16 days NDVI std dev NDVI 16-bit signed integer -3000 -2000–10000 0.0001
CMG 0.05 Deg 16 days EVI std dev EVI 16-bit signed integer -3000 -2000–10000 0.0001
CMG 0.05 Deg 16 days #1km pix used Pixels 8-bit unsigned integer 255 0–36 1.0
CMG 0.05 Deg 16 days #1km pix +-30deg VZ Pixels 8-bit unsigned integer 255 0–36 1.0
CMG 0.05 Deg 16 days pixel reliability Rank 8-bit signed integer -1 0–4 1.0

The QA information below is excerpted from the Quality Science Data Set within an HDF-EOS MOD13C1 file.

A summary Quality layer has been included in the MOD13C1: “pixel reliability.” This layer contains ranked values describing overall pixel quality (Table 1 below).

TABLE 1: MYD13C1 Pixel Reliability

Rank Key

Summary QA

Description

-1 Fill/No Data Not Processed
0 Good Data Use with confidence
1 Marginal data Useful, but look at other QA information
2 Snow/Ice Target covered with snow/ice
3 Cloudy Target not visible, covered with cloud
4 Estimated From MODIS historic time series

TABLE 2: MYD13C1 VI Quality

Bit 0 is the least significant (read bit words right to left)

bit

Long Name

Value

Key

0–1 MODLAND_QA 00 VI produced, good quality
01 VI produced, but check other QA
10 Pixel produced, but most probably cloudy
11 Pixel not produced due to other reasons than clouds
2–5 VI usefulness 0000 Highest quality
0001 Lower quality
0010 Decreasing quality
0100 Decreasing quality
1000 Decreasing quality
1001 Decreasing quality
1010 Decreasing quality
1100 Lowest quality
1101 Quality so low that it is not useful
1110 L1B data faulty
1111 Not useful for any other reason/not processed
6–7 Aerosol quantity 00 Climatology
01 Low
10 Average
11 High
8 Adjacent cloud detected 1 Yes
0 No
9 Atmosphere BRDF correction performed 1 Yes
0 No
10 Mixed Clouds 1 Yes
0 No
11–13 Land/Water Flag 000 Shallow ocean
001 Land (Nothing else but land)
010 Ocean coastlines and lake shorelines
011 Shallow inland water
100 Ephemeral water
101 Deep inland water
110 Moderate or continental ocean
111 Deep ocean
14–15 Geospatial quality 00 <= 25% of the finer 1km resolution contributed to this CMG pixel
01 >25% and <= 50% of the finer 1km resolution contributed to this CMG pixel
10 >50% and <= 75% of the finer 1km resolution contributed to this CMG pixel
11 >75% and <=100% of the finer 1km resolution contributed to this CMG pixel

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