The seasonal evolution of albedo across glaciers and the surrounding landscape of the Taylor Valley, Antarctica

• Main Authors: Bergstrom, Anna, Gooseff, Michael, Myers, Madeline, Doran, Peter T.
• Format: Text
• Language: English
• Published: 2019
• Subjects: Austral; McMurdo Dry Valleys; Taylor Valley; Antarc*; Antarctica; polar desert
• Online Access: https://doi.org/10.5194/tc-2019-146; https://www.the-cryosphere-discuss.net/tc-2019-146/

The McMurdo Dry Valleys (MDVs) of Antarctica are a polar desert ecosystem consisting of alpine glaciers, ice-covered lakes, streams, and expanses of vegetation-free rocky soil. Because average summer temperatures are close to 0 °C, glacier melt dynamics in particular, but the Dry Valley ecosystem in general, are closely linked to the energy balance. A slight increase in incoming radiation or change in albedo can have large effects on the timing and volume of melt water. However, we have yet to fully characterize the seasonal evolution or spatial variability of albedo in the valleys. In this study, we aim to understand the drivers of landscape albedo change within and across seasons. To do so, we used a camera, gps, and short wave radiometer from a helicopter-based platform to fly transects 4–5 times a season along Taylor Valley over three seasons. We coupled these data with incoming radiation measured at 6 meteorological stations distributed along the valley to calculate the distribution of albedo across individual glaciers, lakes, and the soil surfaces. We hypothesized that albedo would decrease throughout the austral summer with ablation of snow patches and ice and increasing sediment exposure on the glacier and lake surfaces. However, small snow events (< 6 mm water equivalent) coupled with ice whitening caused spatial and temporal variability of albedo across the entire landscape. We also observed that individual glacier albedo frequently followed a pattern of increasing albedo with increasing elevation as well as increasing albedo moving from up valley to down valley laterally across the ablation zone of a glacier. Finally, we find that meteorological stations on the glacier frequently measure albedo near or above the highest helicopter-based albedo measurements. We suggest that spatial patterns of albedo are a function of landscape morphology trapping snow and sediment, and longitudinal gradients in snowfall magnitude and wind-driven snow redistribution from up- to down-valley. These findings highlight the importance of understanding the spatial and temporal variability in albedo and the close coupling of climate and landscape response. We can use this new understanding of landscape albedo to better constrain landscape energy budgets, better predict melt water generation on from MDV glaciers, and how these ecosystems will respond to changing climate at the landscape scale.