The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part B7. Beijing 2008 
(i.e., in 1 to 1 or n to 1 relation) during the period. It’s a very 
reasonable assumption for forest type. However, it may not 
work for cropland which may break our assumption because of 
different crop calendar. For example, if two patches of bare soil 
are similar in theASTER image but different in MODIS target 
date (i.e., in 1 to n relation such as one grows vs. one not), this 
model will not be able to capture different changes unless 
additional information are introduced. Therefore, it is more 
appropriate to use more informative leave-on images and 
normalize it to a leaf-on or leaf-off MODIS target date. 
5. ACKNOWLEDGEMENTS 
This work was supported by the NASA EOS project and the 
USGS LDCM science team project. Authors thank Dr. 
Chengquan Huang for providing ASTER data for testing. 
6. REFERENCE 
Abrams, M., 2000. The Advanced Spacebome Thermal 
Emission and Reflection Radiometer (ASTER): Data products 
for the high spatial resolution imager on NASA's Terra platform. 
International Journal of Remote Sensing, 21(5), pp. 847-859. 
Gao, G., and Masek, J., 2008, Towards a consistent data set 
from multiple mid-resolution satellite data using general 
empirical relation model (GERM) and MODIS surface 
reflectance product, Remote Sensing of Environment, submitted. 
Masek, J. G., Vermote, E. F., Saleous, N. E., Wolfe, R., Hall, F. 
G., Huemmrich, F., Gao, F., Kutler, J., & Lim, T. K., 2006. A 
Landsat surface reflectance data set for North America, 1990- 
2000. IEEE Geoscience and Remote Sensing Letters, 3, pp. 69- 
72. 
Powell, S. L., Pflugmacher, D., Kirschbaum, A. A., Kim, Y., & 
Cohen W. B., 2007. Moderate resolution remote sensing 
alternatives: a review of Landsat-like sensors and their 
applications. Journal of Applied Remote Sensing, 1, 012506 
[DOI: 10.1117/12.785479]. 
Vermote E. F., Saleous, N. El, & Justice, C., 2002. Atmospheric 
correction of the MODIS data in the visible to middle infrared: 
First results. Remote Sensing of Environment, 83, pp. 97-111 
Wulder, M.A., J.C. White, S.N. Goward, J.G. Masek, J.R. Irons, 
M. Herold, W.B. Cohen, T.R. Loveland, & C.E. Woodcock, 
2008. Large area land cover monitoring: Issues and 
opportunities related to Landsat continuity. Remote Sensing of 
Environment, in press. 
Figure 1. Processing flow chart of the improved GERM approach. Solid lines and rectangles show the design of original GERM 
approach. Dashed lines and rectangles shows the improvements. 
Spectral Bandwidth (p) 
Ground Resolution 
Swath W idth/Repeat 
ASTER 
ETM+ 
MODIS 
ASTER 
ETM+ 
ASTER 
ETM+ 
Bl: 0.45-0.52 
B3: 0.459-0.479 
30 m 
60 km 
/16 days 
185 km 
/16 days 
Bl: 0.52-0.60 
B2: 0.52-0.60 
B4: 0.545-0.565 
15 m 
B2: 0.63-0.69 
B3: 0.63-0.69 
Bl: 0.620-0.670 
B3: 0.76-0.86 
B4: 0.76-0.90 
B2: 0.841-0.876 
B4: 1.60-1.70 
B5: 1.55-1.75 
B6: 1.628-1.652 
30m 
B5: 2.145-2.185 
B7: 2.09-2.35 
B7: 2.105-2.155 
B6: 2.185-2.225 
B7: 2.235-2.285 
B8: 2.295-2.365 
B13: 10.25-10.95 
B6: 10.4-12.5 
B31: 10.78-11.28 
90 m 
60 m 
B14: 10.95-11.65 
B32: 11.77-12.27 
Table 1. Sensor characteristics among ASTER (black), ETM+ (blue) and MODIS (green) 
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