Joint Inversion for Surface Accumulation and Geothermal Flux from Ice-Penetrating Radar Observations at Dome A, East Antarctica. Part I: Model Description, Data Constraints, and Inversion Results

Abstract. Antarctic ice core nitrate (NO3-) can provide a unique record of the atmospheric reactive nitrogen cycle. However, the factors influencing the deposition and preservation of NO3- at the ice sheet surface must first be understood. Therefore, an intensive program of snow and atmospheric sampling was made on a traverse from the coast to the ice sheet summit, Dome A, East Antarctica. Snow samples in this observation include 120 surface snow samples (top ∼ 3 cm), 20 snow pits with depths of 150 to 300 cm, and 6 crystal ice samples (the topmost needle-like layer on Dome A plateau). The main purpose of this investigation is to characterize the distribution pattern and preservation of NO3- concentrations in the snow in different environments. Results show that an increasing trend of NO3- concentrations with distance inland is present in surface snow, and NO3- is extremely enriched in the topmost crystal ice (with a maximum of 16.1 µeq L−1). NO3- concentration profiles for snow pits vary between coastal and inland sites. On the coast, the deposited NO3- was largely preserved, and the archived NO3- fluxes are dominated by snow accumulation. The relationship between the archived NO3- and snow accumulation rate can be depicted well by a linear model, suggesting a homogeneity of atmospheric NO3- levels. It is estimated that dry deposition contributes 27–44 % of the archived NO3- fluxes, and the dry deposition velocity and scavenging ratio for NO3- were relatively constant near the coast. Compared to the coast, the inland snow shows a relatively weak correlation between archived NO3- and snow accumulation, and the archived NO3- fluxes were more dependent on concentration. The relationship between NO3- and coexisting ions (nssSO42-, Na+ and Cl−) was also investigated, and the results show a correlation between nssSO42- (fine aerosol particles) and NO3- in surface snow, while the correlation between NO3- and Na+ (mainly associated with coarse aerosol particles) is not significant. In inland snow, there were no significant relationships found between NO3- and the coexisting ions, suggesting a dominant role of NO3- recycling in determining the concentrations.

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Joint Inversion for Surface Accumulation and Geothermal Heat Flow from Ice-Penetrating Radar Observations at Dome A, East Antarctica.

10.5194/egusphere-egu21-13492 ◽

2021 ◽

Author(s):

Michael Wolovick ◽

John Moore ◽

Liyun Zhao

Keyword(s):

Heat Flow ◽

Accumulation Rate ◽

Joint Inversion ◽

Observational Constraints ◽

Dome A ◽

Glacial Cycles ◽

Geothermal Heat ◽

Hydrological System ◽

And Storage ◽

Best Fit

<p>Dome A is the summit of the East Antarctic Ice Sheet (EAIS), underlain by the rugged Gamburtsev Subglacial Mountains (GSM). &#160;The rugged basal topography produces a complex hydrological system featuring basal melt, water transport and storage, and freeze-on. &#160;Here, we present the results of an inverse model used to infer the spatial distributions of geothermal heat flow (GHF) and accumulation rate that best fit a variety of observational constraints.&#160; Our model agrees well with the observed water bodies and freeze-on structures, while also predicting a significant amount of unobserved water and suggesting a change in stratigraphic interpretation that reduces the volume of the freeze-on units. &#160;Our model stratigraphy agrees well with observations, and we predict that there will be two distinct patches of ice up to 1.5 Ma suitable for ice coring underneath the divide. &#160;Past divide migration could have interrupted stratigraphic continuity at the old ice patches, but various indirect lines of evidence suggest that the divide has been stable for about the last one and a half glacial cycles, which is a hopeful but by no means definitive sign for stability in the longer term. &#160;Finally, our GHF estimate is higher than previous estimates for this region, but consistent with possible heterogeneity in crustal heat production. &#160; &#160;&#160;</p>

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Identification of multiple natural and anthropogenic sources of dust in snow from Zhongshan Station to Dome A, East Antarctica

Journal of Glaciology ◽

10.1017/jog.2018.72 ◽

2018 ◽

Vol 64 (248) ◽

pp. 855-865 ◽

Cited By ~ 8

Author(s):

ZHIHENG DU ◽

CUNDE XIAO ◽

MINGHU DING ◽

CHUANJIN LI

Keyword(s):

Major Ions ◽

Isotope Composition ◽

Isotopic Signature ◽

East Antarctica ◽

Anthropogenic Sources ◽

Dome A ◽

Long Distance ◽

Anthropogenic Pollutants ◽

Zhongshan Station ◽

Snow Samples

ABSTRACTThe stable oxygen isotope composition, major ions and isotopic compositions of strontium (Sr), neodymium (Nd) and lead (Pb) in insoluble dust from recent surface snow samples along the transect from the Zhongshan and Progress stations (located on the Amery Ice Shelf, East Antarctica) to Dome A (Summit, Antarctica) were analysed. No previous isotopic fingerprinting studies have been conducted for this transect. These data were used to document the dust provenances in Antarctica along the transect up to the highest site, Dome A, for the first time. The insoluble dust in snow samples along the coast displays an overall crust-line isotopic signature that is characterised by highly radiogenic 87Sr/86Sr values and less radiogenic 143Nd/144Nd values. These signatures are comparable with those of samples collected near the ice-free areas of the Zhongshan and Progress stations. Spatial differences are statistically significant along the transect, and the Sr, Nd and Pb isotope components in insoluble dust from two continuous snow samples at Dome A exhibit marked differences, indicating that additional dust reaches the East Antarctic Plateau. The isotopic characteristics of insoluble dust from this transect indicate that the long-distance natural dust and anthropogenic pollutants in these samples primarily originate from Australia.

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A revised inventory of Antarctic subglacial lakes

Antarctic Science ◽

10.1017/s0954102005002889 ◽

2005 ◽

Vol 17 (3) ◽

pp. 453-460 ◽

Cited By ~ 201

Author(s):

MARTIN J. SIEGERT ◽

SASHA CARTER ◽

IGNAZIO TABACCO ◽

SERGEY POPOV ◽

DONALD D. BLANKENSHIP

Keyword(s):

East Antarctica ◽

Large Lake ◽

Dome A ◽

Lake Vostok ◽

The Third ◽

The Us ◽

Radio Echo Sounding ◽

Subglacial Lakes ◽

Lake Type ◽

Echo Sounding

The locations and details of 145 Antarctic subglacial lakes are presented. The inventory is based on a former catalogue of lake-type features, which has been subsequently reanalysed, and on the results from three additional datasets. The first is from Italian radio-echo sounding (RES) of the Dome C region of East Antarctica, from which 14 new lakes are identified. These data also show that, in a number of occasions, multiple lake-type reflectors thought previously to be individual lakes are in fact reflections from the same relatively large lake. This reduces the former total of lake-type reflectors by six, but also adds a significant level of information to these particular lakes. The second dataset is from a Russian survey of the Dome A and Dome F regions of East Antarctica, which provides evidence of 18 new lakes and extends the coverage of the inventory considerably. The third dataset comprises three airborne RES surveys undertaken by the US in East Antarctica over the last five years, from which forty three new lakes have been identified. Reference to information on Lake Vostok, from Italian and US surveys taken in the last few years, is now included.

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