Global LAI from Satellite Remote Sensing

Satellite remote sensing provides a unique way to obtain LAI over large areas. Table 1 lists some representative sensors that are providing the LAI product through their science teams. An example of the global LAI is given in

Figure 7. This LAI map is produced from the moderate resolution imaging spectroradiometer (MODIS) abroad the Terra satellite. The LUT method is used by the MODIS science team to estimate LAI from a three-dimensional radiative transfer model. The MODIS LAI product is a 1 km global data product updated once each 8 day period throughout each calendar year. It is available free of charge to users from the Earth Resources Observation Systems (EROS) Data Center Distributed Active Archive Center (DAAC). Major landscape units are clearly distinguishable in Figure 7. The forest LAI values are generally higher than grasses and agricultural crops. The LAI is the lowest for urban, snow, and desert areas.

In addition to MODIS, some other satellite sensors are providing global LAI maps through their science teams. The multiangle imaging spectroradiometer (MISR) onboard Terra provides global LAI product and the associated uncertainty at a 1.1 km resolution. The National Oceanic and Atmospheric Administration (NOAA) -advanced very high resolution radiometer (AVHRR) data, widely used all over the world, are unique for long-term surface change analysis and global research. The Envisat - medium-resolution imaging spectrometer

Table 1 Some representative satellite instruments that provide LAI through their science teams

Satellite

Instrument

Resolution (km)

Websites

Terra

MODIS

1

http://modis.gsfc.nasa.gov

Terra

MISR

1.1

http://www-misr.jpl.nasa.gov

NOAA

AVHRR

1.1

http://noaasis.noaa.gov/NOAASIS/ml/avhrr.html

Envisat

MERIS

0.3

http://Envisat.esa.int/instruments/meris

SPOT

VEGETATION

1

http://www.spot-vegetation.com

ADEOS

POLDER

6

http://smsc.cnes.fr/POLDER/

ADEOS

GLI

1

http://sharaku.eorc.nasda.go.jp/hatoyama/satellite/satdata/adeos2.

Green leaf area index (LAI)

2.1- 2.8 2.8- 3.4 g 3.4-4.4 4.4- 5.4 5.4- 6.0 ■ 6.0- 7.0

MODIS, Version 4, 4 km, July 2001

Green leaf area index (LAI)

MODIS, Version 4, 4 km, July 2001

Global Lai
Figure 7 Global LAI distribution estimated from Terra MODIS (July 2001). Image courtesy of Prof. Ranga Myneni.

(MERIS), the ADEOS - polarization and directionality of the Earth's reflectances (POLDER), and the SPOT VEGETATION are among some other notable satellite instruments that provide a global LAI product with various spatial and temporal resolutions.

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