Abstract
AbstractSurface albedo typically dominates the mass balance of mountain glaciers, though long-term trends and patterns of glacier albedo are seldom explored. We calculated broadband shortwave albedo for glaciers in the central Chilean Andes (33–34°S) using end-of-summer Landsat scenes between 1986 and 2020. We found a high inter-annual variability of glacier-wide albedo that is largely a function of the glacier fractional snow-covered area and the total precipitation of the preceding hydrological year (up to 69% of the inter-annual variance explained). Under the 2010–2020 ‘Mega Drought’ period, the mean albedo, regionally averaged ranging from ~0.25–0.5, decreased by −0.05 on average relative to 1986–2009, with the greatest reduction occurring 3500–5000 m a.s.l. In 2020, differences relative to 1986–2009 were −0.14 on average as a result of near-complete absence of late summer snow cover and the driest hydrological year since the Landsat observation period began (~90% reduction of annual precipitation relative to the 1986–2009 period). We found statistically significant, negative trends in glacier ice albedo of up to −0.03 per decade, a trend that would have serious implications for the future water security of the region, because glacier ice melt acts to buffer streamflow shortages under severe drought conditions.
Highlights
Surface albedo controls the radiation balance and the melting of snow and ice on glaciers
Glacier-wide albedo and fractional snow-covered area (fSCA) were at a record minimum for 2020 in all sub-zones
We find that reduction of glacier-wide albedo over the observation period is consistent with the magnitudes of glacier fSCA decline which was derived from the near-infrared bands of Landsat, not affected by visible band saturation
Summary
Surface albedo controls the radiation balance and the melting of snow and ice on glaciers. The subsequent exposure of a darkened surface incites further absorption of shortwave radiation and enhances the melting of the glacier ice surface (Oerlemans and others, 2009). Deposition of black carbon and mineral dust has been documented on the surface of the mountain snowpack, valley glaciers and ice sheets due to increasing aerosol emissions (Ming and others, 2012; Rowe and others, 2019), dust storms (Gabbi and others, 2015), locally-sourced mineral dust from bare ground (Yue and others, 2020) and occurrence of forest fires (Klok and others, 2005; de Magalhães Neto and others, 2019). The importance of such events is becoming increasingly apparent (Goelles and others, 2015; Goelles and Bøggild, 2017; de Magalhães Neto and others, 2019)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
