In the absence of ground-based measurements, MODIS LAI can be a great starting point. However, you juts need to be careful in using LAI values at a resolution if 1 km x 1 km for small scale hydrological analysis. Vegetation can be highly heterogeneous within one MODIS tile. Also, cloud contamination can be another issue to keep in mind.

Mohammad,

Thanks for the reply. I suppose a more regional analysis, followed by the selection of a particular grid cell is a more appropriate method for determining LAI values. I'll have to attempt this later. For now, I've been using ORNL's web-interface (due to time constraints) to dig up data, as opposed to getting into more GIS myself.

LINK: http://daac.ornl.gov/cgi-bin/MODIS/GLBVIZ_1_Glb/modis_subset_order_global_col5.pl

As a follow up to the original question, if you or anyone else knows of good studies discussing scaling and validation of MODIS data with ground observations, I'd appreciate the links. I've seen numerous articles describing the inherent difficulties in such analyses, but I have yet to see many articles where those are overcome.

Validating a gridded product such as MODIS LAI against a ground based point observation is challenging bcz of scale mismatch. There has been some effort to utilize the Landsat data (see for example Cohen et al., 2003;Tian et al., 2002) and also develop scaling techniques (see Xue et al., 2011).

Can you give me the title of the Xue's investigation please?. I was searching, but I can't find the manuscript.

Jocelyn,

I don't have the Xue paper, but I'd expect that a simlar reference would be Morisette et al - 2006 - Validation of Global Moderate-Resolution LAI Products: A Framework Proposed Within the CEOS Land Product Validation Subgroup.

Thanks! is exactly what I need.

Xue et al., 2011. Validation of collection 5 MODIS LAI product by scaling-up method using field measurements. Proc. SPIE 8174, Remote Sensing for Agriculture, Ecosystems, and Hydrology XIII, 81742H (October 07, 2011); doi:10.1117/12.898228

http://proceedings.spiedigitallibrary.org/proceeding.aspx?articleid=1269621

Regarding Mohammad Safeeq´s statement "Validating a gridded product such as MODIS LAI against a ground based point observation is challenging bcz of scale mismatch." I would like to mention that while this is generally true for ground truthing based on Eddy Correlation techniques or other point measurements, the problem can be overcome using Scintillometers which have the advantage of giving average fluxes over several kilometer distances. Spacially heteogeneous vegetation can also be measured using this method. At least in the case of energy balance modeling, scintillometry offers a way to obtain in situ measurements on the same scale as the MODIS images.

Helene, Thanks for the detailed answer. I'll have to look into this a bit more