Upscaling in situ albedo for validation of coarse scale albedo product over heterogeneous surfaces

ABSTRACT

One of the essential steps for satellite albedo validation is upscaling in situ measurements to corresponding pixel scale over relatively heterogeneous land surfaces. Although the multi-scale validation strategy is applicable for heterogeneous surfaces, the calibration of the high-resolution imagery during upscaling process is never perfect, and thus the upscaling results suffer from errors. The regression-kriging (RK) technique can compensate the calibration part by applying kriging to upscale residuals and produce more accurate upscaling results. In this paper, in situ measurements and high spatial resolution albedo imagery combined with RK technique was proposed. This method is illustrated by upscaling surface albedo from in situ measurements scale to the coarse pixel scale in the core experimental area of HiWATER, where 17 WSN nodes were deployed at heterogeneous area. The upscaling results of this method were compared with the upscaling results from multi-scale strategy. The results show that the upscaling method based on in situ measurements and high-resolution imagery combined with RK technique can capture the spatial characteristics of surface albedo better. Further, an attempt was made to expand this method in time series. Finally, a preliminary validation of the Moderate Resolution Imaging Spectroradiometer albedo product was performed as the tentative application.

KEYWORDS:

• Upscaling
• albedo
• heterogeneous
• validation
• in situ
• multi-scale

Acknowledgements

The authors would like to thank all of the scientists, engineers, and students who participated in the HiWATER campaigns, which provided airborne products and WSN data products for this work.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This research is jointly supported by the National Basic Research Program of China under Grant 2013CB733401, the Natural Science Foundation of China under Grant nos. 41671363 and 91125003.