Journal cover Journal topic
The Cryosphere An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/tc-2017-38
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
27 Mar 2017
Review status
A revision of this discussion paper was accepted for the journal The Cryosphere (TC) and is expected to appear here in due course.
Impact of MODIS sensor calibration updates on Greenland ice sheet surface reflectance and albedo trends
Kimberly A. Casey1,2,a, Chris M. Polashenski1,3, Justin Chen4, and Marco Tedesco5,6 1Thayer School of Engineering, Dartmouth College, Hanover, NH, 03755, USA
2Cryospheric Sciences Lab, NASA Goddard Space Flight Center, Greenbelt, MD, 20771, USA
3Cold Regions Research and Engineering Laboratory, Alaska Projects Office, U.S. Army Corps of Engineers, Fairbanks, AK, 99709, USA
4Stanford University, Stanford, CA, 94305, USA
5Lamont-Doherty Earth Observatory, Columbia University, NY, 10964, USA
6NASA Goddard Institute for Space Studies, New York, NY, 10025, USA
anow at: Land Remote Sensing Program, U.S. Geological Survey, Reston, VA, 20192, USA
Abstract. We evaluate Greenland Ice Sheet (GrIS) surface reflectance and albedo trends using the newly released Collection 6 (C6) MODIS products over the period 2001–2016. We find that the correction of MODIS sensor degradation provided in the new C6 data products reduces the magnitude of the surface reflectance and albedo decline trends obtained from previous MODIS data (i.e. Collection 5, C5). Collection 5 and 6 data product analysis over GrIS is characterized by surface (i.e. wet vs. dry) and elevation (i.e. 500 m–2000 m, 2000 m and greater) conditions over the summer season from June 1–August 31. Notably, the visible-wavelength declining reflectance trends identified in several bands MODIS C5 data from previous studies are only slightly detected, at reduced magnitude in the C6 versions over the dry snow zone. Wet snow albedo decline over the MODIS record remains in the C6 product, albeit at a lower magnitude than obtained using C5 data. Further analysis of C6 spectral reflectance trends show both reflectance increases and decreases in select bands and regions, suggesting that several competing processes are contributing to ice sheet albedo change. Investigators using MODIS data in other fields may consider similar re-examinations of trends previously established using C5 data.

Citation: Casey, K. A., Polashenski, C. M., Chen, J., and Tedesco, M.: Impact of MODIS sensor calibration updates on Greenland ice sheet surface reflectance and albedo trends, The Cryosphere Discuss., https://doi.org/10.5194/tc-2017-38, in review, 2017.
Kimberly A. Casey et al.
Kimberly A. Casey et al.
Kimberly A. Casey et al.

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Short summary
We analyzed average summer surface characteristics of the Greenland Ice Sheet from 2001–2016. We find that new MODIS Collection 6 data shows a decreased magnitude of change over time due to sensor calibration corrections. Spatial maps allow understanding of surface processes likely occurring. Correctly measuring albedo and surface reflectance changes over time is crucial to the understanding of ice mass balance and sea level rise. The results are applicable to many other long-term MODIS studies.
We analyzed average summer surface characteristics of the Greenland Ice Sheet from 2001–2016. We...
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