PP33A-2273
Developing a Validated Long-Term Satellite-Based Albedo Record in the Central Alaska Range to Improve Regional Hydroclimate Reconstructions
Wednesday, 16 December 2015
Poster Hall (Moscone South)
Timothy P Godaire1, Karl J Kreutz2, Elizabeth A Burakowski3, Dominic Winski4, Seth W Campbell1, Zhuosen Wang5, Qingsong Sun6, Gordon S Hamilton1, Sean D Birkel1, Cameron P Wake7, Erich C Osterberg4 and Crystal Schaaf6, (1)University of Maine, Orono, ME, United States, (2)Univ Maine, Orono, ME, United States, (3)National Center for Atmospheric Research, Boulder, CO, United States, (4)Dartmouth College, Hanover, NH, United States, (5)NASA Goddard Space Flight Center, Greenbelt, MD, United States, (6)University of Massachusetts Boston, School for the Environment, Boston, MA, United States, (7)University of New Hampshire Main Campus, Durham, NH, United States
Abstract:
Mountain glaciers around the world, particularly in Alaska, are experiencing significant surface mass loss from rapid climatic shifts and constitute a large proportion of the cryosphere’s contribution to sea level rise. Surface albedo acts as a primary control on a glacier’s mass balance, yet it is difficult to measure and quantify spatially and temporally in steep, mountainous settings. During our 2013 field campaign in Denali National Park to recover two surface to bedrock ice cores, we used an Analytical Spectral Devices (ASD) FieldSpec4 Standard Resolution spectroradiometer to measure incoming solar radiation, outgoing surface reflectance and optical grain size on the Kahiltna Glacier and at the Kahiltna Base Camp. A Campbell Scientific automatic weather station was installed on Mount Hunter (3900m) in June 2013, complementing a longer-term (2008-present) station installed at Kahiltna Base Camp (2100m). Use of our in situ data aids in the validation of surface albedo values derived from Moderate Resolution Imaging Spectroradiometer (MODIS) and Landsat satellite imagery. Comparisons are made between ASD FieldSpec4 ground measurements and 500m MODIS imagery to assess the ability of MODIS to capture the variability of surface albedo across the glacier surface. The MODIS MCD43A3 BRDF/Albedo Product performs well at Kahiltna Base Camp (<5% difference from ASD shortwave broadband data), but low biases in MODIS albedo (10-28% relative to ASD data) appear to occur along the Kahiltna Glacier due to the snow-free valley walls being captured in the 500m MODIS footprint. Incorporating Landsat imagery will strengthen our interpretations and has the potential to produce a long-term (1982-present) validated satellite albedo record for steep and mountainous terrain. Once validation is complete, we will compare the satellite-derived albedo record to the Denali ice core accumulation rate, aerosol records (i.e. volcanics and biomass burning), and glacier mass balance data. This research will ultimately contribute to an improved understanding of the relationship between glacier albedo, surface processes, and regional glacier hydroclimate.
