Submitted to: International Journal of Remote Sensing
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/10/2003
Publication Date: 11/10/2003
Citation: Fang, H., Liang, S., Chen, M., Walthall, C.L., Daughtry, C.S. 2003. Statistical comparison of MISR, ETM+ and MODIS land surface reflectances and albedo production of the BARC land validation core site, USA. International Journal of Remote Sensing. 25(2):409-422. Interpretive Summary: The amount of absorbed sunlight for photosynthesis by plants (fraction of absorbed photosynthetically active radiation or FPAR) and plant foliage density (expressed as leaf area index or LAI) are important inputs to weather and climate models, plant growth and crop yield models, and biogeochemical cycle models. FPAR and LAI are calculated from NASA Terra satellite MISR and MODIS sensor data. Several variations of MISR and MODIS spectral albedo are first produced and then used to calculate FPAR and LAI. Landsat ETM+ sensor data can also be used to calculate directional reflectance products, FPAR and LAI. The scale of Landsat observations is 30 m, MISR observations are 1.1 km and MODIS observations are 1.0 km. A comparison of the products from these three systems was conducted to provide users with benchmarks for the use of each. Simple statistical comparisons showed that under clear sky conditions several of the directional reflectance products from MISR are very similar. The Landsat products compare well with MISR products, except when clouds, snow and shadows appear in the imagery. For clear conditions the MISR products compare well with the MODIS products but are also affected by snow and shadows. Spectral albedo from MISR are closer to Landsat values than MODIS values. The results validate the different algorithms used to produce the products, and demonstrate that finer resolution satellite data calibration with surface measurements can be aggregated for comparisons with coarser scale satellite measurements.
Technical Abstract: The MISR and MODIS onboard NASA's EOS Terra satellite are crucial for generation of other products such as FPAR and LAI. The analysis reported here compares the reflectance and albedo products from MODIS (MOD09 and MOD43B3), MISR and Landsat ETM+ data using general statistical methods. Four MISR land surface products are examined: HDRF, BRF, BHR and DHR. Ground measurements were used to validate ETM+ reflectance and albedo products (30 m) which were then upscaled and compared with MISR products (1.1 km). The results from May 11 and Dec 5, 2000 and Jan 22, 2001 show that (1) under clear-sky conditions, MISR BRF and HDRF, BHR and DHR are nearly the same (R2>99%); (2) There are strong correlations between ETM+ surface reflectance and MISR nadir-view BRF, however, the relationship is affected by the cloud, snow and shadow; (3) in clear areas, MISR BRF is similar to MOD09, but is greater for the haze and snow regions and smaller for shadows; and (4) the MISR albedo product is closely related to the ETM+, and to a lesser extent, MODIS.