01957nas a2200133   4500008004100000245010200041210006900143260005300212490000900265520146100274100002201735700002401757856004201781       2020                        eng d00aGlacial meltwater modeling to simulate lake water budget (1996-2013) in Taylor Valley, Antarctica0 aGlacial meltwater modeling to simulate lake water budget 1996201  aPortland, ORbPortland State Universityc01/20200 vM.S.3 a<p>The McMurdo Dry Valleys (MDV), the largest ice-free region (4,500 km2) in Antarctica, are a polar desert with an average annual temperature of -18 ̊C. In Taylor Valley, one of the MDV, closed-basin, perennially ice-covered lakes occupy the valley floor. Their water balance is controlled by inflow from glacial meltwater runoff and loss due to sublimation, making them sensitive indicators of climate. In this study, a physically-based model of glacier meltwater and lake ice sublimation is adapted to explain modern (1996 to 2013) lake-level variations. Meltwater model results were improved by the inclusion of MODIS remotely-sensed albedo measurements (E = 0.47; nRMSE = 0.73). After 2008 the meltwater model significantly under-predicted streamflow and only through decreasing albedo by -30% (equivalent to a decrease of -0.18 on average) did the results match observations (E = 0.79; nRMSE = 0.45). This study provides the first estimate of direct (unmeasured) glacier inflow to the lakes, 69%, 73% and 28%, and sublimation loss rates, 0.37 m yr<sup>-1</sup>, 0.24 m yr<sup>-1</sup> and 0.16 m yr<sup>-1</sup>, for Lakes Bonney, Hoare and Fryxell, respectively. Despite similar meltwater volumes entering Lakes Bonney and Fryxell, the difference in basin hypsometry results in a much faster lake rise at Bonney from 2002-13. If future climate conditions match current (1996-2013) conditions, all lakes will rise through the end of the century.</p>1 aCross, Julian, M.1 aFountain, Andrew, G  uhttps://archives.pdx.edu/ds/psu/3080603158nas a2200181   4500008004100000245011200041210006900153260001200222300001200234490000700246520256300253100002402816700002502840700002002865700002102885700002202906856004802928       2020                        eng d00aThe seasonal evolution of albedo across glaciers and the surrounding landscape of Taylor Valley, Antarctica0 aseasonal evolution of albedo across glaciers and the surrounding  c03/2020  a769-7880 v143 a<p>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&thinsp;∘C, the MDV ecosystem in general, and glacier melt dynamics in particular, are both 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 meltwater. However, the seasonal evolution or spatial variability of albedo in the valleys has yet to fully characterized. In this study, we aim to understand the drivers of landscape albedo change within and across seasons. To do so, a box with a camera, GPS, and shortwave radiometer was hung from a helicopter that flew transects four to five times a season along Taylor Valley. Measurements were repeated over three seasons. These data were coupled with incoming radiation measured at six meteorological stations distributed along the valley to calculate the distribution of albedo across individual glaciers, lakes, and soil surfaces. We hypothesized that albedo would decrease throughout the austral summer with ablation of snow patches and increasing sediment exposure on the glacier and lake surfaces. However, small snow events (&lt;6&thinsp;mm water equivalent) coupled with ice whitening caused spatial and temporal variability of albedo across the entire landscape. Glaciers frequently followed a pattern of increasing albedo with increasing elevation, as well as increasing albedo moving from east to west laterally across the ablation zone. We suggest that spatial patterns of albedo are a function of landscape morphology trapping snow and sediment, longitudinal gradients in snowfall magnitude, and wind-driven snow redistribution from east to west along the valley. We also compare our albedo measurements to the MODIS albedo product and found that overall the data have reasonable agreement. The mismatch in spatial scale between these two datasets results in variability, which is reduced after a snow event due to albedo following valley-scale gradients of snowfall magnitude. These findings highlight the importance of understanding the spatial and temporal variability in albedo and the close coupling of climate and landscape response. This new understanding of landscape albedo can constrain landscape energy budgets, better predict meltwater generation on from MDV glaciers, and how these ecosystems will respond to changing climate at the landscape scale.</p>1 aBergstrom, Anna, J.1 aGooseff, Michael, N.1 aMyers, Madeline1 aDoran, Peter, T.1 aCross, Julian, M.  uhttps://www.the-cryosphere.net/14/769/2020/