scholarly journals Review of ” Water tracks intensify surface energy and mass exchange in the Antarctic McMurdo Dry Valleys” by Linhardt et al. tc-2019-8

2019 ◽  
Author(s):  
Anonymous
2019 ◽  
Author(s):  
Tobias Linhardt ◽  
Joseph S. Levy ◽  
Christoph K. Thomas

Abstract. We evaluated the hypotheses that water tracks alter the surface energy balance in the Antarctic McMurdo Dry Valleys and may serve as an indicator of landscape response to climate change in this dry, cold and ice-sheet-free environment. Water tracks are channel-shaped high moisture zones in the active layer of polar soils. The surface energy balance was measured for one water-track and two non-water-track reference locations in Taylor Valley during the Antarctic summer of 2012–2013. Turbulent atmospheric fluxes of sensible heat and evaporation were observed using the eddy-covariance method in combination with flux footprint modeling, which was the first application of this state-of-the-art technique in the Dry Valleys. Soil heat fluxes were analyzed separately for thawed and frozen layers at all locations via computing the change of the heat storage in the thawed layer from measurements. The results showed that for both water track and reference locations over 50 % of the net radiation was transferred to sensible heat exchange, about 30 % to melting the seasonally thawed layer, and the remainder to evaporation. The net energy flux in the thawed layer was zero. For the water track location, evaporation was increased by a factor of 3.0 relative to the references, ground heat fluxes by 1.4, and net radiation by 1.1, while sensible heat fluxes were reduced down to 0.7. Entertaining a realistic scenario of climate change in Taylor Valley in which the land cover fraction of water tracks increases by 50 %, the total evaporation from lower Taylor Valley would increase by 4 % to 0.30 mm d−1. In summary, our findings show that water tracks have a strong impact on the surface energy balance in ice-sheet free Antarctic regions. Water tracks are hot spots of change and are likely to respond faster to climate change signals than the dominant dry glacial till in the McMurdo Dry Valleys. Their spatiotemporal dynamics may therefore serve as indicator of high-sensitivity for change in permafrost-dominated cold landscapes.


2017 ◽  
Vol 5 (27) ◽  
Author(s):  
Claudia Coleine ◽  
Sawyer Masonjones ◽  
Laura Selbmann ◽  
Laura Zucconi ◽  
Silvano Onofri ◽  
...  

ABSTRACT The draft genome sequences of Rachicladosporium antarcticum CCFEE 5527 and Rachicladosporium sp. CCFEE 5018 are the first sequenced genomes from this genus, which comprises rock-inhabiting fungi. These endolithic strains were isolated from inside rocks collected from the Antarctic Peninsula and Battleship Promontory (McMurdo Dry Valleys), Antarctica, respectively.


2019 ◽  
Vol 13 (8) ◽  
pp. 2203-2219 ◽  
Author(s):  
Tobias Linhardt ◽  
Joseph S. Levy ◽  
Christoph K. Thomas

Abstract. The hydrologic cycle in the Antarctic McMurdo Dry Valleys (MDV) is mainly controlled by surface energy balance. Water tracks are channel-shaped high-moisture zones in the active layer of permafrost soils and are important solute and water pathways in the MDV. We evaluated the hypothesis that water tracks alter the surface energy balance in this dry, cold, and ice-sheet-free environment during summer warming and may therefore be an increasingly important hydrologic feature in the MDV in the face of landscape response to climate change. The surface energy balance was measured for one water track and two off-track reference locations in Taylor Valley over 26 d of the Antarctic summer of 2012–2013. Turbulent atmospheric fluxes of sensible heat and evaporation were observed using the eddy-covariance method in combination with flux footprint modeling, which was the first application of this technique in the MDV. Soil heat fluxes were analyzed by measuring the heat storage change in the thawed layer and approximating soil heat flux at ice table depth by surface energy balance residuals. For both water track and reference locations over 50 % of net radiation was transferred to sensible heat exchange, about 30 % to melting of the seasonally thawed layer, and the remainder to evaporation. The net energy flux in the thawed layer was zero. For the water track location, evaporation was increased by a factor of 3.0 relative to the reference locations, ground heat fluxes by 1.4, and net radiation by 1.1, while sensible heat fluxes were reduced down to 0.7. Expecting a positive snow and ground ice melt response to climate change in the MDV, we entertained a realistic climate change response scenario in which a doubling of the land cover fraction of water tracks increases the evaporation from soil surfaces in lower Taylor Valley in summer by 6 % to 0.36 mm d−1. Possible climate change pathways leading to this change in landscape are discussed. Considering our results, an expansion of water track area would make new soil habitats accessible, alter soil habitat suitability, and possibly increase biological activity in the MDV. In summary, we show that the surface energy balance of water tracks distinctly differs from that of the dominant dry soils in polar deserts. With an expected increase in area covered by water tracks, our findings have implications for hydrology and soil ecosystems across terrestrial Antarctica.


Polar Science ◽  
2010 ◽  
Vol 4 (2) ◽  
pp. 187-196 ◽  
Author(s):  
Genki I. Matsumoto ◽  
Eisuke Honda ◽  
Kazuhiko Sonoda ◽  
Shuichi Yamamoto ◽  
Tetsuo Takemura

Life ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 13 ◽  
Author(s):  
Claudia Coleine ◽  
Nuttapon Pombubpa ◽  
Laura Zucconi ◽  
Silvano Onofri ◽  
Jason E. Stajich ◽  
...  

The microbial communities that inhabit lithic niches inside sandstone in the Antarctic McMurdo Dry Valleys of life’s limits on Earth. The cryptoendolithic communities survive in these ice-free areas that have the lowest temperatures on Earth coupled with strong thermal fluctuations, extreme aridity, oligotrophy and high levels of solar and UV radiation. In this study, based on DNA metabarcoding, targeting the fungal Internal Transcribed Spacer region 1 (ITS1) and multivariate statistical analyses, we supply the first comprehensive overview onto the fungal diversity and composition of these communities sampled over a broad geographic area of the Antarctic hyper-arid cold desert. Six locations with surfaces that experience variable sun exposure were sampled to compare communities from a common area across a gradient of environmental pressure. The Operational Taxonomic Units (OTUs) identified were primarily members of the Ascomycota phylum, comprised mostly of the Lecanoromycetes and Dothideomycetes classes. The fungal species Friedmanniomyces endolithicus, endemic to Antarctica, was found to be a marker species to the harshest conditions occurring in the shady, south exposed rock surfaces. Analysis of community composition showed that sun exposure was an environmental property that explained community diversity and structured endolithic colonization.


2008 ◽  
Vol 21 (1) ◽  
pp. 89-94 ◽  
Author(s):  
Christopher P. McKay

AbstractDry permafrost on Earth is unique to the Antarctic and is found in the upper elevations of the McMurdo Dry Valleys. Despite its widespread presence in the Dry Valleys, the factors that control the distribution of dry permafrost and the ice-cemented ground below it are poorly understood. Here I show, by a combination of theoretical analysis and field observations, that the recurrence of snow can explain the depth of dry permafrost and the location of ice-cemented ground in Antarctica. For data from Linnaeus Terrace at 1600–1650 m elevation in Upper Wright Valley a recurrence intervals of about two years explains the presence of ground ice at 25 cm depth, under 12.5 cm of dry permafrost. Snow recurrence periods longer than 10 years would create only dry permafrost at this site. The snow gradient in University Valley resulting from the windblown snow from the polar plateau creates a corresponding gradient in the depth to ice-cemented ground. On the floor of Beacon Valley, the presence of dry permafrost without underlying ice-cemented ground indicates snow recurrence intervals of more than 10 years and implies that the ancient massive ice in this valley is not stable. Snow recurrence may also set the depth to ground ice on Mars.


Polar Record ◽  
2005 ◽  
Vol 41 (1) ◽  
pp. 77-96 ◽  

The texts of the Decisions and Resolutions, and the text of Measure 1 (2004), together with a summary of the Management Plan for Antarctic Specially Managed area No. 2, McMurdo Dry Valleys, Southern Victoria Land, adopted at XXVII ATCM were reproduced in SCAR Bulletin No 155, October 2004. A summary of the Management Plan for Antarctic Specially Managed Area No. 3, Cape Denison, Commonwealth Bay, George V land, together with Measures 2–4, are reproduced here. The full versions of all the Decisions, Measures and Resolutions are on the Antarctic Treaty Secretariat website at http://www.ats.org.ar/


2010 ◽  
Vol 23 (13) ◽  
pp. 3577-3598 ◽  
Author(s):  
Johanna C. Speirs ◽  
Daniel F. Steinhoff ◽  
Hamish A. McGowan ◽  
David H. Bromwich ◽  
Andrew J. Monaghan

Abstract Foehn winds resulting from topographic modification of airflow in the lee of mountain barriers are frequently experienced in the McMurdo Dry Valleys (MDVs) of Antarctica. Strong foehn winds in the MDVs cause dramatic warming at onset and have significant effects on landscape forming processes; however, no detailed scientific investigation of foehn in the MDVs has been conducted. As a result, they are often misinterpreted as adiabatically warmed katabatic winds draining from the polar plateau. Herein observations from surface weather stations and numerical model output from the Antarctic Mesoscale Prediction System (AMPS) during foehn events in the MDVs are presented. Results show that foehn winds in the MDVs are caused by topographic modification of south-southwesterly airflow, which is channeled into the valleys from higher levels. Modeling of a winter foehn event identifies mountain wave activity similar to that associated with midlatitude foehn winds. These events are found to be caused by strong pressure gradients over the mountain ranges of the MDVs related to synoptic-scale cyclones positioned off the coast of Marie Byrd Land. Analysis of meteorological records for 2006 and 2007 finds an increase of 10% in the frequency of foehn events in 2007 compared to 2006, which corresponds to stronger pressure gradients in the Ross Sea region. It is postulated that the intra- and interannual frequency and intensity of foehn events in the MDVs may therefore vary in response to the position and frequency of cyclones in the Ross Sea region.


Hydrology ◽  
2019 ◽  
Vol 6 (2) ◽  
pp. 54 ◽  
Author(s):  
Neil Foley ◽  
Slawek M. Tulaczyk ◽  
Denys Grombacher ◽  
Peter T. Doran ◽  
Jill Mikucki ◽  
...  

The Southern Ocean receives limited liquid surface water input from the Antarctic continent. It has been speculated, however, that significant liquid water may flow from beneath the Antarctic Ice Sheet, and that this subglacial flow carries that water along with dissolved nutrients to the coast. The delivery of solutes, particularly limiting nutrients like bioavailable iron, to the Southern Ocean may contribute to ecosystem processes including primary productivity. Using a helicopter-borne time domain electromagnetic survey along the coastal margins of the McMurdo Dry Valleys region of Southern Victoria Land, Antarctica, we detected subsurface connections between inland lakes, aquifers, and subglacial waters. These waters, which appear as electrically conductive anomalies, are saline and may contain high concentrations of biologically important ions, including iron and silica. Local hydraulic gradients may drive these waters to the coast, where we postulate they emerge as submarine groundwater discharge. This high latitude groundwater system, imaged regionally in the McMurdo Dry Valleys, may be representative of a broader system of Antarctic submarine groundwater discharge that fertilizes the Southern Ocean. In total, it has the potential to deliver tens of gigagrams of bioavailable Fe and Si to the coastal zone.


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