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The Cryosphere An interactive open-access journal of the European Geosciences Union
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Volume 11, issue 4
The Cryosphere, 11, 1781-1795, 2017
https://doi.org/10.5194/tc-11-1781-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
The Cryosphere, 11, 1781-1795, 2017
https://doi.org/10.5194/tc-11-1781-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 01 Aug 2017

Research article | 01 Aug 2017

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 Kimberly A. Casey et al.
  • 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, US Army Corps of Engineers, Fairbanks, AK 99709, USA
  • 4Department of Computer Science, Stanford 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, US 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 (Moderate Resolution Imaging Spectroradiometer) 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., 500–2000m, 2000m and greater) conditions over the summer season from 1 June to 31 August. Notably, the visible-wavelength declining reflectance trends identified in several bands of MODIS C5 data from previous studies are only slightly detected at reduced magnitude in the C6 versions over the dry snow area. Declining albedo in the wet snow and ice area remains over the MODIS record in the C6 product, albeit at a lower magnitude than obtained using C5 data. Further analyses of C6 spectral reflectance trends show both reflectance increases and decreases in select bands and regions, suggesting that several competing processes are contributing to Greenland Ice Sheet albedo change. Investigators using MODIS data for other ocean, atmosphere and/or land analyses are urged to consider similar re-examinations of trends previously established using C5 data.

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We analyzed Greenland Ice Sheet (GrIS) average summer surface reflectance and albedo (2001–2016). MODIS Collection 6 data show a decreased magnitude of change over time due to sensor calibration corrections. Spectral band maps provide insight into GrIS surface processes likely occurring. Correctly measuring albedo and surface reflectance changes over time is crucial to monitoring atmosphere–ice interactions and ice mass balance. The results are applicable to many long-term MODIS studies.
We analyzed Greenland Ice Sheet (GrIS) average summer surface reflectance and albedo...
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