
VIP01. NDVI. Acquired June 18, 2004. South America.
The NASA Making Earth System Data Records for Use in Research Environments (MEaSUREs) Vegetation Index and Phenology (VIP) global datasets were created using Advanced Very High Resolution Radiometer (AVHRR) N07, N09, N11, and N14 datasets (1981 - 1999) and Moderate Resolution Imaging Spectroradiometer (MODIS)/Terra MOD09 surface reflectance data (2000 - 2014). The VIP Vegetation Index (VI) product was developed to provide consistent measurements of the Normalized Difference Vegetation Index (NDVI) and modified Enhanced Vegetation Index (EVI2) spanning more than 30 years of data from multiple sensors. The EVI2 is a backward extension of AVHRR. Vegetation indices such as NDVI and EVI2 are useful for assessing the biophysical properties of the land surface, and are used to characterize vegetation phenology. Phenology tracks the seasonal life cycle of vegetation, and provides information on the biotic response to environmental changes.
The VIP01 VI data product is a daily global file at 0.05 degree (5600 meters (m)) spatial resolution in geographic (Lat/Lon) grid format. The data are stored in Hierarchical Data Format-Earth Observing System (HDF-EOS) file format. The VIP01 VI product contains 11 Science Datasets (SDS), which includes the calculated VIs (NDVI and EVI2) as well as information on the quality assurance/pixel reliability, the input Visible/Near Infrared (VNIR) surface reflectance data, and viewing geometry. The Blue and Middle Infrared (MIR) surface reflectance data are only available for the MODIS era (2000 - 2014). Gaps in the daily product are filled using long term mean VI records derived from the more than 30 year time series of data, and are indicated as gap-filled in the Pixel Reliability SDS.
Citation
PI Name: Kamel Didan
DOI: 10.5067/MEaSUREs/VIP/VIP01.004
| Characteristic | Description |
|---|---|
| Temporal Granularity | Daily |
| Temporal Extent | 1981 - 2014 |
| Spatial Extent | Global |
| File Size | |
| Coordinate System | Geographic Latitude and Longitude |
| Datum | WGS84 |
| File Format | HDF-EOS |
| Geographic Dimensions | Global |
| Characteristic | Description |
|---|---|
| Number of Science Dataset (SDS) Layers | 11 |
| Columns/Rows | 7200 x 3600 |
| Pixel Size | 5600 m |
| SDS Name | Description | Units | Data Type | Fill Value | Valid Range | Scale Factor |
|---|---|---|---|---|---|---|
| CMG 0.05 Deg Daily NDVI |
Climate Modeling Grid (CMG) 0.05 Degrees resolution Daily NDVI |
NDVI | Int16 |
-15000 |
-10000 to 10000 |
10000 |
| CMG 0.05 Deg Daily EVI2 |
Climate Modeling Grid (CMG) 0.05 Degree resolution Daily Modified EVI2 |
EVI2 | Int16 |
-15000 |
-10000 to 10000 |
10000 |
| CMG 0.05 Deg Daily VI Quality |
Climate Modeling Grid (CMG) 0.05 Degree resolution Daily VI Quality |
Bits | UInt16 |
65535 |
0,65534 |
N/A |
| CMG 0.05 Deg Daily Pixel Reliability |
Climate Modeling Grid (CMG) 0.05 Degree resolution Daily Pixel Reliability |
Rank | Int8 |
-4 |
-4 to 11 |
1 |
| CMG 0.05 Deg Daily RED reflectance |
Climate Modeling Grid (CMG) 0.05 Degree resolution Daily Red Reflectance |
Reflectance | Int16 |
-28672 |
-100 to 16000 |
10000 |
| CMG 0.05 Deg Daily NIR reflectance |
Climate Modeling Grid (CMG) 0.05 Degree resolution Daily NIR |
Reflectance | Int16 |
-28672 |
-100 to 16000 |
10000 |
| CMG 0.05 Deg Daily BLUE reflectance* |
Climate Modeling Grid (CMG) 0.05 Degree resolution Daily Blue Reflectance |
Reflectance | Int16 |
-28672 |
-100 to 16000 |
10000 |
| CMG 0.05 Deg Daily MIR reflectance* |
Climate Modeling Grid (CMG) 0.05 Degree resolution Daily Middle Infrared Reflectance |
Reflectance | Int16 |
-28672 |
-100 to 16000 |
10000 |
| CMG 0.05 Deg Daily Solar Zenith Angle |
Climate Modeling Grid (CMG) 0.05 Degree resolution Daily Solar Zenith Angle |
Degree | Int16 |
0 |
0 to 18000 |
100 |
| CMG 0.05 Deg Daily View Zenith Angle |
Climate Modeling Grid (CMG) 0.05 Degree resolution Daily View Zenith Angle |
Degree | Int16 |
0 |
0 to 18000 |
100 |
| CMG 0.05 Deg Daily Relative Azimuth Angle** |
Climate Modeling Grid (CMG) 0.05 Degree resolution Daily Relative Azimuth Angle |
Degree | Int16 |
0 |
-18000 to 18000 |
100 |
*BLUE and MIR SDS are only available for MODIS (2000-2014). The Middle Infrared reflectance data used for AVHRR was generated using a MODIS based model that correlates the Red and NIR with the MIR band. The model is then applied to AVHRR Red/NIR to generate false MIR reflectance data useful for image generation.
From the NASA MEaSUREs VIP ATBD/User Guide: While only a single Fill_Value is listed,in practice there are multiple Fill Values to separate between the different reasons of missing data. For example, the Pixel Reliability has 4 different value for Fill depending of where the pixel is located (-1 over land, -2 over high latitude, -3 over Antarctica, and -4 over Water/Ocean).
See the NASA MEaSUREs VIP ATBD/User Guide Table 6.
**The Relative Azimuth Angle (RAA) from the MOIS era, which is simply passed along from the MODIS data, was computed based on an absolute value of all the finer resolution pixels, resulting in only positive values and minor usefulness. For AVHRR data relative Azimuth Angle, which is also passed along in our processing from Input provided by the LTDR group, has an issue with the valid range. The actual range is [-360° to 360°] and it should have been [-180° to 180°]. To correct the range users can convert the value using the following simple routine (http://ltdr.nascom.nasa.gov/ltdr/docs/AVHRR_LTDR_V4_Document.pdf):
SinRelativeAz=sin(RAA)
CosRelativeAz=cos(RAA)
Correct-RAA = atan2(SinRelativeAz,CosRelativeAz)
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