
VIPPHEN_EVI2. Average VI. 2014. South America.
The NASA MEaSUREs Vegetation Index and Phenology (VIP) global datasets were created using surface reflectance data from the Advanced Very High Resolution Radiometer (AVHRR) N07, N09, N11, and N14 datasets (1981 – 1999) and Moderate Resolution Imaging Spectroradiometer (MODIS) 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 VIPPHEN data product is provided globally 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 VIPPHEN phenology product contains 26 Science Datasets (SDS) which include phenological metrics such as the start, peak, and end of season as well as the rate of greening and senescence. The product also provides the maximum, average, and background calculated VIs. The VIPPHEN SDS are based on the daily VIP product series and are calculated using a 3-year moving window average to smooth out noise in the data. A reliability SDS is included to provide context on the quality of the input data.
Citation
PI Name: Kamel Didan
DOI: 10.5067/MEaSUREs/VIP/VIPPHEN_EVI2.004
| Characteristic | Description |
|---|---|
| Temporal Granularity | Annually |
| 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 | 26 |
| Columns/Rows | 7200 x 3600 |
| Pixel Size | 5600 m |
| SDS Name | Description | Units | Data Type | Fill Value | Valid Range | Scale Factor |
|---|---|---|---|---|---|---|
| Start of Season 1 |
Start of Season 1 |
Days | Int16 |
-2 |
1 to 366 |
1 |
| End of Season 1 |
End of Season 1 |
Days | Int16 |
-2 |
1 to 366 |
1 |
| Length of Season 1 |
Length of Season 1 |
Days | Int16 |
-2 |
1 to 366 |
1 |
| Day of Peak Season 1 |
Day of Peak Season 1 |
Days | Int16 |
-2 |
1 to 366 |
1 |
| Rate of Greening Season 1 |
Rate of Greening Season 1 |
VI/Day | Int16 |
-15000 |
|
100 |
| Rate of Senescence Season 1 |
Rate of Senescence Season 1 |
VI/Day | Int16 |
-15000 |
|
100 |
| Max VI Season 1 |
Maximum Vegetation Index Season 1 |
VI | Int16 |
-15000 |
-10000 to 10000 |
10000 |
| Start of Season 2 |
Start of Season 2 |
Days | Int16 |
-2 |
1 to 366 |
1 |
| End of Season 2 |
End of Season 2 |
Days | Int16 |
-2 |
1 to 366 |
1 |
| Length of Season 2 |
Length of Season 2 |
Days | Int16 |
-2 |
1 to 366 |
1 |
| Day of Peak Season 2 |
Day of Peak Season 2 |
Days | Int16 |
-2 |
1 to 366 |
1 |
| Rate of Greening Season 2 |
Rate of Greening Season 2 |
VI/Day | Int16 |
-15000 |
|
100 |
| Rate of Senescence Season 2 |
Rate of Senescence Season 2 |
VI/Day | Int16 |
-15000 |
|
100 |
| Max VI Season 2 |
Maximum Vegetation Index Season 2 |
VI | Int16 |
-15000 |
-10000 to 10000 |
10000 |
| Start of Season 3 |
Start of Season 3 |
Days | Int16 |
-2 |
1 to 366 |
1 |
| End of Season 3 |
End of Season 3 |
Days | Int16 |
-2 |
1 to 366 |
1 |
| Length of Season 3 |
Length of Season 3 |
Days | Int16 |
-2 |
1 to 366 |
1 |
| Day of Peak Season 3 |
Day of Peak Season 3 |
Days | Int16 |
-2 |
1 to 366 |
1 |
| Rate of Greening Season 3 |
Rate of Greening Season 3 |
VI/Day | Int16 |
-15000 |
|
100 |
| Rate of Senescence Season 3 |
Rate of Senescence Season 3 |
VI/Day | Int16 |
-15000 |
|
100 |
| Max VI Season 3 |
Maximum Vegetation Index Season 3 |
VI | Int16 |
-15000 |
-10000 to 10000 |
10000 |
| Cumulative VI |
Cumulative Vegetation Index |
VI | Int16 |
-15000 |
0 to 10000 |
1000 |
| Average VI |
Average Vegetation Index |
VI | Int16 |
-15000 |
-10000 to 10000 |
10000 |
| Background VI |
Background Vegetation Index |
VI | Int16 |
-15000 |
-10000 to 10000 |
10000 |
| Number of Seasons |
Number of Seasons |
N/A | Int8 |
-2 |
1 to 3 |
1 |
| Reliability |
Reliability |
N/A | Int8 |
-1 |
0 to 6 |
1 |
From the 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.
| Fill Value | Description |
|---|---|
| 1 | Over Land |
| -2 | Over Water |
| Fill Value | Description |
|---|---|
| -13,000 | Over Land |
| -15,000 | Over Water |
| QA Rank | Description |
|---|---|
| 0 | Excellent |
| 1 | Good |
| 2 | Acceptable |
| 3 | Marginal |
| 4 | Poor |
| 5 | Unreliable |
| 6 | Long Season Stable |
| -1 | Fill Value Over Land |
| -2 | Fill Value Over Water |
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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