Use the table below to go to LAI Intercomparison data access for a particular site.

The CEOS Land Product Validation subgroup identified a set of sites over which they are focusing LAI Intercomparison activities. These sites are indicated in the map below. Many of the sites listed are intercomparison sites used in the overview paper for the IEEE TGARS Special Issue on Land Product Validation, Validation of global moderate resolution LAI Products: a framework proposed within the CEOS Land Product Validation subgroup. View or download this paper here.

This study investigated the performance of four major global LAI products at 1/11.2° spatial sampling and a monthly time step:

• ECOCLIMAP climatology
• GLOBCARBON (from SPOT/VEGETATION and ATSR/AATSR)
• CYCLOPES (from SPOT/VEGETATION)
• MODIS Collection 4 (main algorithm - from MODIS/TERRA)

These products were intercompared during the 2001-2003 period over the BELMANIP network of sites. Their uncertainties were assessed by comparison with 56 LAI high resolution reference maps derived from ground measurements. In this analysis we found that CYCLOPES and MODIS depict realistic spatial variations at continental scale, while ECOCLIMAP poorly captures surface spatial heterogeneity, and GLOBCARBON tends to display erratic variations. ECOCLIMAP and GLOBCARBON show the highest frequency of successful retrievals, while MODIS and CYCLOPES data are frequently missing in winter over mid and Northern latitudes. CYCLOPES and MODIS have consistent temporal profiles over most vegetation types, while ECOCLIMAP does not show any interannual variation, and GLOBCARBON can exhibit temporal instability during the growing season over forests. The CYCLOPES, MODIS, and GLOBCARBON LAI values agree better over croplands and grasslands than over forests, where differences in vegetation structure between algorithms and surface reflectance uncertainties leads to substantial discrepancies between products. CYCLOPES does not reach high enough LAI to properly characterize forests. In contrast, the other products have sufficient dynamic range in LAI to describe the global variability. Overall, the CYCLOPES product is the most similar to the LAI reference maps. However, more accurate ground measurements and better representation of the global and seasonal variability of vegetation are required to refine this result.

Details about the files provided via the links below are described in more detail via the readme and the associated LAI data spreadsheet that the readme refers to. Be sure to download these as well if you access any of the data provided below.

Click on the site name in the table below to go to the directory where intercomparison data are stored.

MODIS image provided by The Blue Marble.

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Curator: Jaime Nickeson
NASA Official: Robert Wolfe
Last Updated: October 6, 2009