Collection Information: Global Vegetation Indexes

search this site

Spatial Extent:	Global (land only)
Spatial Resolution:	0.5 degree gridded
Temporal Characteristics:
Date Classes Represented:	Time-series
Time Steps Available:	10-days
Dates represented:	1998-04-01 - 2002-12-31

These data products are being distributed free of charge. Recipients have a responsibility to:

1) Notify the data provider Dr. Xiangming Xiao, University of New Hampshire, for uses intended for publication or models.
2) Acknowledge the University of New Hampshire, EOS-WEBSTER Earth Science Information Partner (ESIP) as the data distributor.

Summary:

The Global Vegetation Indices collection holds three global gridded data products of vegetation indices: NDVI, EVI and LSWI derived from the VEGETATION (VGT) sensor onboard the SPOT-4 satellite. The original 1 km vegetation indices values have been aggregated to half degree from 75 degrees North latitude to 56 degrees South latitude, and from -180 West to 180 east longitude. The half degree data can be retrieved as a five year (1998-2002) time series of 10-day timesteps. The NDVI, EVI and LSWI will be provided as 1 km global gridded files in the future.

The data was developed from the 10-day composites of the surface reflectance product (S10) from VGT onboard SPOT-4, with fill for cloud pixels according to a technique described in (1). The half degree data is an average of the cloud-free, land pixels. The standard deviation, the total pixels used to calculate the average, and the half-degree pixel area are also distributed with the mean values for the NDVI, the EVI and the LSWI product. The input data is available from Free SPOT Data. To find out more about the VEGETATION sensor on SPOT-4 satellite, click here.

Global Vegetation Indices

Datasets	Full Name
NDVI	Normalized Difference Vegetation Index
EVI	Enhanced Vegetation Index
LSWI	Land Surface Water Index

For Each vegetation Index

Variable	Data Range	Units
Mean	-1.0 to 1.0	ratio
Standard Deviation	-3 to 3	deviation
Area	0 to 3160	km²
Pixels	0 to 3160	pixels used

Spatial & Temporal Scales

These data are gridded in the geographic projection with 0.5 degree by 0.5 degree cell sizes. The data are bounded by 75.0 N to 56.0 S latitude, and by 180.0 W to 180.0 E longitude. The data are approximately 10 day interval timeseries from April 1, 1998 to December 31, 2002.

Composite Period	Days of the month
1	1-10
2	11-20
3	21-end of month

Data Format

The full dataset contains 720 cells in the x-dimension (longitude) and 262 cells in the y-dimension (latitude) of 32-bit real data for the mean, standard deviation and area. The fill value for missing data is –2.0 for mean and standard deviation and missing area data is represented with a value of 0. Missing pixel data is also represented by 0. Data format, x/y grid dimension, and absolute range of the data values may vary depending on the output format and the spatial region you select when ordering the data.

Variable Description:

1) Mean: The average of cloud-free pixels over a specific 10 day period.

SPOT-4 VGT-S10 reflectance data has the following bands of light sensitivity:

Band	Band Range (nm)	Band Energy
B1	430 - 470	Blue
B2	610 - 680	Red
B3	780 - 890	NIR*
SWIR	1580 - 1750	MIR**

* NIR = near-infrared
** MIR = medium infrared/short wave infrared

There are three computed indices: NDVI, EVI and LSWI as described below.

Normalized Difference Vegetation Index

NDVI= (NIR - Red) / (NIR + Red)

Enhanced Vegetation Index

EVI = 2.5*(NIR - Red) / (NIR + 6*Red - 7.5*Blue - 1)

Land Surface Water Index

LSWI = (NIR - MIR) / (NIR + MIR)

2) Standard Deviation

3) Area in km² of the half degree pixel.

4) Pixel Count of land pixels (Integer):

References:

(1)Xiangming Xiao., D. Hollinger, J. Aber, M. Goltz, E. Davidson, Q. Zhang, B. Moore II. 2004. Satellite-based modeling of gross primary production in an evergreen needleleaf forest. Remote Sensing of Environment: Vol. 89, pp. 519-534.

(2)Xiangming Xiao, S. Boles, J. Liu, D. Zhuang, M. Liu. 2002. Characerization of forest types in Northeastern China, using multitemporal SPOT-4 VEGETATION sensor data. Remote Sensing of Environment: Vol 82 (2002), pp 335-348.

(3)Xiangming Xaio, Braswell, B.. Zhang, Q., Boles, S., Frolking, S., Moore III, B. 2003. Sensitivity of vegetation indices to atmospheric aerosols: continental scale observations in Notthern Asia. Remote sensing of Environment: Vol 84 (2003) pp 385-392.

(4)Stephen H. Boles, Xiao, X., Liu, J., Zhang, Q., Munkhtuya, S., Chen, S., Ojima, D. 2004. Land cover characterization of Temperate East Asia using multi-temporal VEGETATION sensor data. Remote Sensing of the Environment: Vol 90 (2004) pp 477-489

Data Provider:

Dr. Xiangming Xiao, Complex Systems Research Center, Institute for the Study of Earth, Oceans, and Space, Morse Hall, University of New Hampshire, Durham, New Hampshire, USA. Ph: 603.862.1792, Fax: 603.862.0188.

Latest Data Update:

8/20/2004

Last Doc. Updated:

9/3/2004

Doc. Updated By:

Rita Freuder