scholarly journals A simplified method to estimate the run-off in Periglacial Creeks: a case study of King George Islands, Antarctic Peninsula

2018 ◽  
Vol 376 (2122) ◽  
pp. 20170166 ◽  
Author(s):  
Ulrike Falk ◽  
Adrián Silva-Busso ◽  
Pablo Pölcher
Keyword(s):  
Air Temperature ◽  
Antarctic Peninsula ◽  
Rapid Change ◽  
Surface Air Temperature ◽  
Maximum Flow ◽  
West Antarctic ◽  
Run Off ◽  
Marine System ◽  
Glacial Discharge ◽  
Highly Correlated

Although the relationship between surface air temperature and glacial discharge has been studied in the Northern Hemisphere for at least a century, similar studies for Antarctica remain scarce and only for the past four decades. This data scarcity is due to the extreme meteorological conditions and terrain inaccessibility. As a result, the contribution of glacial discharge in Antarctica to global sea-level rise is still attached with great uncertainties, especially from partly glaciated hydrological basins as can be found in the Antarctic Peninsula. In this paper, we propose a simplified model based on the Monte Carlo method and Fourier analysis for estimating discharge in partly glaciated and periglacial hydrological catchments with a summer melt period. Our model offers the advantage of scarce data requirements and quick recognition of periglacial environments. Discharge was found to be highly correlated with surface air temperature for the partially glaciated hydrological catchments on Potter Peninsula, King George Island (Isla 25 Mayo). The model is simple to implement and requires few variables to make most versatile simulations. We have obtained a monthly simulated maximum flow estimates between 0.74 and 1.07 m 3  s −1 for two creeks (South and North Potter) with a very good fit to field observations. The glacial mean monthly discharge during summer months was estimated to 0.44±0.02 m 3  s −1 for South Potter Creek and 0.55±0.02 m 3  s −1 for North Potter Creek. This article is part of the theme issue ‘The marine system of the West Antarctic Peninsula: status and strategy for progress in a region of rapid change’.

An analysis of a 34-year air temperature record from Fossil Bluff (71°S, 68°W), Antarctica

1997 ◽  
Vol 9 (3) ◽  
pp. 355-363 ◽  
Author(s):  
Stephen A. Harangozo ◽  
Steven R. Colwell ◽  
John C. King
Keyword(s):  
Air Temperature ◽  
Antarctic Peninsula ◽  
Surface Air Temperature ◽  
Temperature Record ◽  
West Antarctic ◽  
Air Temperatures ◽  
Marguerite Bay ◽  
First Time ◽  
Snow Temperature

An analysis of a long-term surface air temperature record for Fossil Bluff in the George VI Sound, West Antarctic Peninsula (WAP) documents in detail some important aspects of the climate of this area for the first time. The analysis identifies the close dependency of air temperatures on latitude in the WAP but reveals that the strength of this dependency is greatest in winter. This result along with others leads to the Fossil Bluff climate regime being characterized as ‘continental’ rather than ‘maritime’ as found further north. The WAP as a whole displays large interannual temperature variability but this is greatest in Marguerite Bay rather than the Fossil Bluff area. Evidence is also provided for secular climatic change appearing in summer throughout the WAP over the last few decades. The representativeness of existing Antarctic Peninsula annual air temperature climatologies, based mainly on snow temperature measurements, for the winter and summer periods is also noted.

scholarly journals A ‘shallow bathtub ring’ of local sedimentary iron input maintains the Palmer Deep biological hotspot on the West Antarctic Peninsula shelf

2018 ◽  
Vol 376 (2122) ◽  
pp. 20170171 ◽  
Author(s):  
Robert M. Sherrell ◽  
Amber L. Annett ◽  
Jessica N. Fitzsimmons ◽  
Vincent J. Roccanova ◽  
Michael P. Meredith
Keyword(s):  
Antarctic Peninsula ◽  
Deep Water ◽  
Rapid Change ◽  
Euphotic Zone ◽  
The West ◽  
Inner Shelf ◽  
West Antarctic ◽  
Limiting Nutrient ◽  
Marine System ◽  
West Antarctic Peninsula

Palmer Deep (PD) is one of several regional hotspots of biological productivity along the inner shelf of the West Antarctic Peninsula. The proximity of hotspots to shelf-crossing deep troughs has led to the ‘canyon hypothesis’, which proposes that circumpolar deep water flowing shoreward along the canyons is upwelled on the inner shelf, carrying nutrients including iron (Fe) to surface waters, maintaining phytoplankton blooms. We present here full-depth profiles of dissolved and particulate Fe and manganese (Mn) from eight stations around PD, sampled in January and early February of 2015 and 2016, allowing the first detailed evaluation of Fe sources to the area's euphotic zone. We show that upwelling of deep water does not control Fe flux to the surface; instead, shallow sediment-sourced Fe inputs are transported horizontally from surrounding coastlines, creating strong vertical gradients of dissolved Fe within the upper 100 m that supply this limiting nutrient to the local ecosystem. The supply of bioavailable Fe is, therefore, not significantly related to the canyon transport of deep water. Near shore time-series samples reveal that local glacial meltwater appears to be an important Mn source but, surprisingly, is not a large direct Fe input to this biological hotspot. This article is part of the theme issue ‘The marine system of the West Antarctic Peninsula: status and strategy for progress in a region of rapid change’.

scholarly journals Anatomy of a glacial meltwater discharge event in an Antarctic cove

2018 ◽  
Vol 376 (2122) ◽  
pp. 20170163 ◽  
Author(s):  
Michael P. Meredith ◽  
Ulrike Falk ◽  
Anna Valeria Bers ◽  
Andreas Mackensen ◽  
Irene R. Schloss ◽  
...  
Keyword(s):  
Antarctic Peninsula ◽  
Ocean Circulation ◽  
Rapid Change ◽  
Isotopic Tracers ◽  
Potter Cove ◽  
Geochemical Composition ◽  
Glacial Meltwater ◽  
West Antarctic ◽  
Marine System ◽  
Benthic Ecosystems

Glacial meltwater discharge from Antarctica is a key influence on the marine environment, impacting ocean circulation, sea level and productivity of the pelagic and benthic ecosystems. The responses elicited depend strongly on the characteristics of the meltwater releases, including timing, spatial structure and geochemical composition. Here we use isotopic tracers to reveal the time-varying pattern of meltwater during a discharge event from the Fourcade Glacier into Potter Cove, northern Antarctic Peninsula. The discharge is strongly dependent on local air temperature, and accumulates into an extremely thin, buoyant layer at the surface. This layer showed evidence of elevated turbidity, and responded rapidly to changes in atmospherically driven circulation to generate a strongly pulsed outflow from the cove to the broader ocean. These characteristics contrast with those further south along the Peninsula, where strong glacial frontal ablation is driven oceanographically by intrusions of warm deep waters from offshore. The Fourcade Glacier switched very recently to being land-terminating; if retreat rates elsewhere along the Peninsula remain high and glacier termini progress strongly landward, the structure and impact of the freshwater discharges are likely to increasingly resemble the patterns elucidated here.This article is part of the theme issue ‘The marine system of the West Antarctic Peninsula: status and strategy for progress in a region of rapid change’.

scholarly journals Evaluation of Greenland near surface air temperature datasets

2017 ◽  
Vol 11 (4) ◽  
pp. 1591-1605 ◽  
Author(s):  
J. E. Jack Reeves Eyre ◽  
Xubin Zeng
Keyword(s):  
Air Temperature ◽  
Mean Absolute Error ◽  
Ice Sheet ◽  
Surface Air Temperature ◽  
Absolute Error ◽  
Near Surface ◽  
Satellite Retrieval ◽  
Highly Correlated ◽  
Global Reanalysis

Abstract. Near-surface air temperature (SAT) over Greenland has important effects on mass balance of the ice sheet, but it is unclear which SAT datasets are reliable in the region. Here extensive in situ SAT measurements ( ∼  1400 station-years) are used to assess monthly mean SAT from seven global reanalysis datasets, five gridded SAT analyses, one satellite retrieval and three dynamically downscaled reanalyses. Strengths and weaknesses of these products are identified, and their biases are found to vary by season and glaciological regime. MERRA2 reanalysis overall performs best with mean absolute error less than 2 °C in all months. Ice sheet-average annual mean SAT from different datasets are highly correlated in recent decades, but their 1901–2000 trends differ even in sign. Compared with the MERRA2 climatology combined with gridded SAT analysis anomalies, thirty-one earth system model historical runs from the CMIP5 archive reach  ∼  5 °C for the 1901–2000 average bias and have opposite trends for a number of sub-periods.

scholarly journals Spatially coherent late Holocene Antarctic Peninsula surface air temperature variability

Geology ◽  
2018 ◽  
Vol 46 (12) ◽  
pp. 1071-1074 ◽  
Author(s):  
Dan J. Charman ◽  
Matthew J. Amesbury ◽  
Thomas P. Roland ◽  
Jessica Royles ◽  
Dominic A. Hodgson ◽  
...  
Keyword(s):  
Air Temperature ◽  
Antarctic Peninsula ◽  
Late Holocene ◽  
Surface Air Temperature ◽  
Temperature Variability

Antarctic Peninsula warming triggers enhanced basal melt rates throughout West Antarctica

2021 ◽  
Author(s):  
Andrew Thompson ◽  
Mar Flexas ◽  
Michael Schodlok ◽  
Kevin Speer
Keyword(s):  
Antarctic Peninsula ◽  
Ocean Circulation ◽  
Heat Fluxes ◽  
Coastal Current ◽  
West Antarctica ◽  
Ice Shelf ◽  
West Antarctic ◽  
Freshwater Forcing ◽  
Run Off ◽  
The Antarctic

<p>The acceleration of ice-shelf basal melt rates throughout West Antarctica, as well as their potential to destabilize the ice sheets they buttress, is well documented.  Yet, the mechanisms that determine both trends and variability of these melt rates remain uncertain.  Explanations for the intensification of melting have largely focused on local processes in seas surrounding the ice shelves, including variations in wind stress over the continental slope and shelf.  Here, we show that non-local freshwater forcing, propagated between shelf seas by the Antarctic Coastal Current (AACC), can have a significant impact on ice-shelf melt rates.  </p><p>We present results from a suite of high-resolution (~3-km) numerical simulations of the ocean circulation in West Antarctica that includes a dynamic sea-ice field, ice-shelf cavities and forcing from ice shelf-ocean interactions.  Motivated by persistent warming at the northern Antarctic Peninsula since the 1950’s, freshwater perturbations are applied to the West Antarctic Peninsula.  This leads to a strengthening of the AACC and a westward propagation of the freshwater signal.  Critically, basal melt rates increase throughout the WAP, Bellingshausen and Amundsen Seas in response to this perturbation.  The freshwater anomalies stratify the ocean surface near the coast, enhancing lateral heat fluxes that lead to greater ice-shelf melt rates.  A suite of sensitivity studies show that changes in meltrates are linearly proportional to the magnitude of the freshwater anomaly, changing by as much as 30% for realistic perturbations, but are relatively insensitive to the distribution of the perturbation across the WAP shelf.  These results indicate that glacial run-off on the Antarctic Peninsula, one of the first signatures of a warming climate in Antarctica, could be a key trigger for increased melt rates in the Amundsen and Bellingshausen Seas.</p>

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