Evaluation of the CAMEL Land Surface Emissivity Model over the
Taklimakan Desert using Field Observations
Abstract
A set of LSE observations from field experiments were conducted on 16-18
Oct 2013 along a south/north desert road in the Taklimakan Desert (TD),
China. The observed LSEs (EOBS) are thus used in this study as the
reference to evaluate the quality of Combined ASTER MODIS Emissivity
over Land (CAMEL). Analysis of these data shows four main results.
Firstly, the CAMEL appears to capture the spatial variations of LSE from
the oasis to the hinterland of TD well, especially in the quartz
reststrahlen band 8.1 mm, 8.6 mm and 9.1 mm. From site 1 at the south
edge of the TD to site 10 at the north edge, the EOBS and the
corresponding CAMEL in the quartz reststrahlen band firstly decrease and
reach their minimum around sites 4-6 at the hinterland of the TD. Then
the LSE increases gradually and finally gets their maximum at site 10
with clay ground surface, which is higher at the edges of the desert and
lower in the center. Second, the CAMEL at 8.3 mm has a Zonal
distribution characteristic of northeast-southwest strike. Third, the
unrealistic variation of original EOBS can be filtered out with useful
signals remaining by the first 6 principal components from PCA upon the
laboratory measured hyperspectral emissivity spectra (ELAB). Fourth, the
CAMEL correlates well with the measured LSE at the ten observation
sites, with the EOBS slightly smaller than CAMEL in general.