01744nas a2200205 4500008004100000022001400041245006100055210005900116260001200175300001400187490000700201520112200208653001501330653001301345653001701358100002401375700002401399700002101423856009401444 2016 eng d a0022-143000aGlaciers in equilibrium, McMurdo Dry Valleys, Antarctica0 aGlaciers in equilibrium McMurdo Dry Valleys Antarctica c07/2016 a976 - 9890 v623 a

The McMurdo Dry Valleys are a cold, dry polar desert and the alpine glaciers therein exhibit small annual and seasonal mass balances, often <±0.06 m w.e. Typically, winter is the accumulation season, but significant snow storms can occur any time of year occasionally making summer the accumulation season. The yearly equilibrium line altitude is poorly correlated with mass balance because the elevation gradient of mass balance on each glacier can change dramatically from year to year. Most likely, winds redistribute the light snowfall disrupting the normal gradient of increasing mass balance with elevation. Reconstructed cumulative mass balance shows that the glaciers have lost <2 m w.e. over the past half century and area changes show minimal retreat. In most cases these changes are less than the uncertainty and the glaciers are considered in equilibrium. Since 2000, however, the glaciers have lost mass despite relatively stable summer air temperatures suggesting a different mechanism in play. Whether this trend is a harbinger of future changes or a temporary excursion is unclear.

10aAntarctica10aglaciers10amass balance1 aFountain, Andrew, G1 aBasagic, Hassan, J.1 aNiebuhr, Spencer uhttps://www.cambridge.org/core/services/aop-cambridge-core/content/view/S002214301600086102527nas a2200181 4500008004100000245016700041210006900208260001200277300001600289490000700305520184500312100002102157700002402178700002402202700002102226700001702247856008102264 2015 eng d00aPressure-driven, shoreline currents in a perennially ice-covered, pro-glacial lake in Antarctica, identified from a LiCl tracer injected into a pro-glacial stream0 aPressuredriven shoreline currents in a perennially icecovered pr c05-2015 a2212 - 22310 v293 a

The distribution of streamwater within ice-covered lakes influences sub-ice currents, biological activity and shoreline morphology. Perennially ice-covered lakes in the McMurdo Dry Valleys, Antarctica, provide an excellent natural laboratory to study hydrologic–limnologic interactions under ice cover. For a 2 h period on 17 December 2012, we injected a lithium chloride tracer into Andersen Creek, a pro-glacial stream flowing into Lake Hoare. Over 4 h, we collected 182 water samples from five stream sites and 15 ice boreholes. Geochemical data showed that interflow travelled West of the stream mouth along the shoreline and did not flow towards the lake interior. The chemistry of water from Andersen Creek was similar to the chemistry of water below shoreline ice. Additional evidence for Westward flow included the morphology of channels on the ice surface, the orientation of ripple marks in lake sediments at the stream mouth and equivalent temperatures between Andersen Creek and water below shoreline ice. Streamwater deflected to the right of the mouth of the stream, in the opposite direction predicted by the Coriolis force. Deflection of interflow was probably caused by the diurnal addition of glacial runoff and stream discharge to the Eastern edge of the lake, which created a strong pressure gradient sloping to the West. This flow directed stream momentum away from the lake interior, minimizing the impact of stream momentum on sub-ice currents. It also transported dissolved nutrients and suspended sediments to the shoreline region instead of the lake interior, potentially affecting biological productivity and bedform development.

1 aCastendyk, Devin1 aMcKnight, Diane, M.1 aWelch, Kathleen, A.1 aNiebuhr, Spencer1 aJaros, Chris uhttp://doi.wiley.com/10.1002/hyp.v29.9http://doi.wiley.com/10.1002/hyp.10352