The evaluation of uncertainty in satellite-derived albedo products is critical to ensure their accuracy, stability and
consistency for studying climate change. In this study, we assess the Moderate-resolution Imaging
Spectroradiometer(MODIS) albedo 8 day standard product MOD43B3 using the ground-based albedometer
measurement based on the wireless sensor network (WSN) technology.
The experiment have been performed in Huailai, Hubei province. A 1.5 km*2 km area are selected as study region,
which locates between 115.78° E-115.80° E and 40.35° N-40.37° N. This area is characterized by its distinct landscapes:
bare ground between January and April, corn from May to Octorber. That is, this area is relatively homegeneous from
January to Octorber, but in Novermber and December, the surface is very heterogeneous because of straw burning, as
well as snow fall and snow melting.
It is a big challenge to validate the MODIS albedo products because of the vast difference in spatial resolution between
ground measurement and satellite measurement. Here, we use the HJ albedo products as the bridge that link the ground
measurement with satellite data. Firstly, we analyses the spatial representativeness of the WSN site under green-up,
dormant and snow covered situations to decide whether direct comparison between ground-based measurement and
MODIS albedo can be made. The semivariogram is used here to describe the ground hetergeneity around the WSN site.
In addition, the bias between the average albedo of the certain neighborhood centered at the WSN site and the center
pixel albedo is also calculated.Then we compare the MOD43B3 value with the ground-based value. Result shows that
MOD43B3 agree with in situ well during the growing season, however, there are relatively large difference between
ground albedos and MCD43B3 albedos during dormant and snow-coverd periods.