Journal cover Journal topic
The Cryosphere An interactive open-access journal of the European Geosciences Union
doi:10.5194/tc-2016-264
© Author(s) 2016. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
15 Dec 2016
Review status
This discussion paper is under review for the journal The Cryosphere (TC).
Unmanned Aerial System nadir reflectance and MODIS Nadir BRDF-Adjusted surface Reflectances intercompared over Greenland
John Faulkner Burkhart1,2, Arve Kylling3, Crystal B. Schaaf4, Zhuosen Wang5,6, Wiley Bogren7, Rune Storvold8, Stian Sølbo8, Christina A. Pedersen9, and Sebastian Gerland9 1Department of Geosciences, University of Oslo, Oslo, Norway
2University of California, Merced, CA, USA
3Norwegian Institute for Air Research, Kjeller, Norway
4School for the Environment, University of Massachusetts Boston, Boston, MA, USA
5NASA Goddard Space Flight Center, Greenbelt, MD, USA
6Earth System Science Interdisciplinary Center, University of Maryland, College Park, MD, USA
7U.S. Geological Survey, Flagstaff, AZ, USA
8Norut-Northern Research Institute, Tromsø, Norway
9Norwegian Polar Institute, Fram Centre, Tromsø, Norway
Abstract. Albedo is a fundamental parameter in earth sciences. Many datasets are developed from the MODIS BRDF/Albedo (MCD43) Algorithms. While derivative albedo products have been evaluated over Greenland, we present a novel direct intercomparison with nadir surface reflectance collected from an Unmanned Aerial System (UAS). The UAS was flown from Summit, Greenland on 200+ km transects coincident with the MODIS sensor overpass on board the Aqua and Terra satellites on 5 and 6 August, 2010. Clear sky acquistions were available from the overpasses within two hours of the UAS flights. The UAS was equipped with updward and downward looking spectrometers (300–920 nm) with a spectral resolution of 10 nm allowing to integrate directly to the MODIS bands 1, 3 and 4. The data provides a unique opportunity to directly compare UAS nadir reflectance with the MODIS Nadir BRDF-Adjusted surface Reflectance (NBAR) products. The data show UAS measurements are slightly higher than the MODIS NBARs for all bands, but agree within their stated uncertainties. Differences in variability are observed as expected due to different footprints of the platforms. The UAS data demonstrate potentially large sub-pixel variability of MODIS reflectance products and the potential to explore this variability using the UAS as a platform. It is also found that even at the low elevations flown typically by UAS, reflectance measurements may be influenced by haze if present at and/or below the flight altitude of the UAS. This impact could explain some differences between data from the two platforms.

Citation: Burkhart, J. F., Kylling, A., Schaaf, C. B., Wang, Z., Bogren, W., Storvold, R., Sølbo, S., Pedersen, C. A., and Gerland, S.: Unmanned Aerial System nadir reflectance and MODIS Nadir BRDF-Adjusted surface Reflectances intercompared over Greenland, The Cryosphere Discuss., doi:10.5194/tc-2016-264, in review, 2016.
John Faulkner Burkhart et al.
John Faulkner Burkhart et al.
John Faulkner Burkhart et al.

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Short summary
In 2010 a group of researchers traveled to Greenland to investigate the reflective characteristics of the ice sheet. In order to measure albedo – a quantity that represents the ratio of reflected to incoming energy at the surface of the Earth – an Unmanned Aerial System, or "Drone", was flown along transects that were coincident with satellites flying similar instrumentation. The satellite observations match well the drone based datasets and provide valuable data for further investigation.
In 2010 a group of researchers traveled to Greenland to investigate the reflective...
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