Impact of coastal East Antarctic ice rises on surface mass balance: insights from observations and modeling

Kausch, Thore; Lhermitte, Stef; Lenaerts, Jan T. M.; Wever, Nander; Inoue, Mana; Pattyn, Frank; Sun, Sainan; Wauthy, Sarah; Tison, Jean‐Louis; Berg, Willem Jan van de

doi:10.5194/tc-14-3367-2020

Cited by 17 publications

(31 citation statements)

References 46 publications

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“…Indeed, during average weather conditions in coastal areas, synoptic air masses carry moist air across the surface topography, releasing a significant fraction of their moisture as snow on the windward side, creating a dry accumulation shadow on the leeward side. This has been observed by Lenaerts et al (2014) and Kausch et al (2020) for the ice rises of the DML coast. Small-scale accumulation asymmetries across ice rises have also been observed in other regions (King et al, 2004;Morse et al, 1998) and can occur on larger scales, such as across ice divides (Urbini et al, 2008) or the AP mountain chain (Datta et al, 2018).…”

Section: Wind Effects On Smb and Sat Signalssupporting

confidence: 64%

“…This has been observed by Lenaerts et al (2014) and Kausch et al (2020) for the ice rises of the DML coast. Small-scale accumulation asymmetries across ice rises have also been observed in other regions (King et al, 2004;Morse et al, 1998) and can occur on larger scales, such as across ice divides (Urbini et al, 2008) or the AP mountain chain (Datta et al, 2018). However, stronger winds can affect this accumulation asymmetry by bringing more moisture and therefore more snow on the windward side, while the leeward side will either remain dry or begin accumulating more snow if wind speeds allow for redistribution (Frezzotti et al, 2004).…”

Section: Wind Effects On Smb and Sat Signalssupporting

confidence: 64%

“…Because wind direction with respect to surface slope and wind strength influences SMB and SAT locally (Frezzotti et al, 2004;King et al, 2004;Black and Budd, 1964;Grima et al, 2014), we take both into account in the mean (surface) slope in the (mean) wind direction (MSWD). MSWD is defined as the dot product between the mean surface slope and the mean wind direction (Scambos et al, 2012;Das et al, 2013;Dattler et al, 2019):…”

Section: Wind Effects On Smb and Sat Signalsmentioning

confidence: 99%

“…Added complexity in snow accumulation records originates from smaller-scale (several kilometers or less) windbased redistribution of snow that is superimposed on the patterns originating from the spatial variability in precipitation. Wind speeds that reach a threshold speed (∼ 5 m s −1 ) can pluck snow from the surface and redeposit it up to several kilometers away where winds decelerate or remove it through blowing snow sublimation (Frezzotti et al, 2004;King et al, 2004;Lenaerts et al, 2019;Agosta et al, 2019). Due to the temperature inversion that commonly occurs near the surface of the ice sheet, the surface air is negatively buoyant and flows downslope through the influence of gravity (van den Broeke et al, 2002).…”

Section: Introductionmentioning

confidence: 99%

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Reconciling the surface temperature–surface mass balance relationship in models and ice cores in Antarctica over the last 2 centuries

et al. 2020

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Abstract. Ice cores are an important record of the past surface mass balance (SMB) of ice sheets, with SMB mitigating the ice sheets' sea level impact over the recent decades. For the Antarctic Ice Sheet (AIS), SMB is dominated by large-scale atmospheric circulation, which collects warm moist air from further north and releases it in the form of snow as widespread accumulation or focused atmospheric rivers on the continent. This suggests that the snow deposited at the surface of the AIS should record strongly coupled SMB and surface air temperature (SAT) variations. Ice cores use δ18O as a proxy for SAT as they do not record SAT directly. Here, using isotope-enabled global climate models and the RACMO2.3 regional climate model, we calculate positive SMB–SAT and SMB–δ18O annual correlations over ∼90 % of the AIS. The high spatial resolution of the RACMO2.3 model allows us to highlight a number of areas where SMB and SAT are not correlated, and we show that wind-driven processes acting locally, such as foehn and katabatic effects, can overwhelm the large-scale atmospheric contribution in SMB and SAT responsible for the positive SMB–SAT annual correlations. We focus in particular on Dronning Maud Land, East Antarctica, where the ice promontories clearly show these wind-induced effects. However, using the PAGES2k ice core compilations of SMB and δ18O of Thomas et al. (2017) and Stenni et al. (2017), we obtain a weak annual correlation, on the order of 0.1, between SMB and δ18O over the past ∼150 years. We obtain an equivalently weak annual correlation between ice core SMB and the SAT reconstruction of Nicolas and Bromwich (2014) over the past ∼50 years, although the ice core sites are not spatially co-located with the areas displaying a low SMB–SAT annual correlation in the models. To resolve the discrepancy between the measured and modeled signals, we show that averaging the ice core records in close spatial proximity increases their SMB–SAT annual correlation. This increase shows that the weak measured annual correlation partly results from random noise present in the ice core records, but the change is not large enough to match the annual correlation calculated in the models. Our results thus indicate a positive correlation between SAT and SMB in models and ice core reconstructions but with a weaker value in observations that may be due to missing processes in models or some systematic biases in ice core data that are not removed by a simple average.

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Section: Wind Effects On Smb and Sat Signalssupporting

confidence: 64%

Section: Wind Effects On Smb and Sat Signalssupporting

confidence: 64%

Section: Wind Effects On Smb and Sat Signalsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Reconciling the surface temperature–surface mass balance relationship in models and ice cores in Antarctica over the last 2 centuries

et al. 2020

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“…Analysis of an ice core collected in the rift zone of the ice shelf farther downstream reveal relatively little accretion of marine ice compared to other parts of Antarctica (Pattyn and others, 2012). A 208-m-deep ice core was drilled at the ice-rise summit for detailed climatic reconstructions, supplemented by surface radar and automatic-weather station measurements (Kausch and others, 2020). SMB derived from dated radar isochrones show high upwind–downwind contrast (up to 1.5 times) with a local erosion driven minimum near the summit.…”

Section: The Dml and Enderby Land Coastsmentioning

confidence: 99%

Characteristics of ice rises and ice rumples in Dronning Maud Land and Enderby Land, Antarctica

et al. 2020

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Ice rises and rumples, locally grounded features adjacent to ice shelves, are relatively small yet play significant roles in Antarctic ice dynamics. Their roles generally depend upon their location within the ice shelf and the stage of the ice-sheet retreat or advance. Large, long-stable ice rises can be excellent sites for deep ice coring and paleoclimate study of the Antarctic coast and the Southern Ocean, while small ice rises tend to respond more promptly and can be used to reveal recent changes in regional mass balance. The coasts of Dronning Maud Land (DML) and Enderby Land in East Antarctica are abundant with these features. Here we review existing knowledge, presenting an up-to-date status of research in these regions with focus on ice rises and rumples. We use regional datasets (satellite imagery, surface mass balance and ice thickness) to analyze the extent and surface morphology of ice shelves and characteristic timescales of ice rises. We find that large parts of DML have been changing over the past several millennia. Based on our findings, we highlight ice rises suitable for drilling ice cores for paleoclimate studies as well as ice rises suitable for deciphering ice dynamics and evolution in the region.

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Three-decade spatial patterns in surface mass balance of the Nivlisen Ice Shelf, central Dronning Maud Land, East Antarctica

et al. 2021

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The coastal Droning Maud Land in East Antarctica is characterized by small ice shelves with numbers of promontories and locally grounded isles, both called ice rises. These ice rises are typically dome-shaped and surface elevations are hundreds of meters above the surrounding ice shelves, which cause strong orographic effects on surface mass balance (SMB). We conducted shallow ice-penetrating radar sounding to visualize firn stratigraphy in the top 35 m over ~400 km of profiles across the Nivlisen Ice Shelf, and in a grid pattern over two adjacent ice rises (Djupranen and Leningradkollen). We tracked six reflectors (isochrones) and dated them using two ice cores taken at the ice rise summits, from which SMB over six periods in the past three decades was retrieved. The overall SMB pattern across the ice shelf remained similar for all periods; however, the eastwest contrast in SMB varies by a factor of 1.5–2 between the Leningradkollen and Djupranen grounding lines. The SMB patterns over the ice rises are more varied owing to complex interactions between topography, snowfall and wind. We use our results to evaluate the regional climate model RACMO2.3p2 in terms of the spatial SMB distribution and temporal changes over the ice shelf and ice rises at regional scale.

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Impact of coastal East Antarctic ice rises on surface mass balance: insights from observations and modeling

Cited by 17 publications

References 46 publications

Reconciling the surface temperature–surface mass balance relationship in models and ice cores in Antarctica over the last 2 centuries

Reconciling the surface temperature–surface mass balance relationship in models and ice cores in Antarctica over the last 2 centuries

Characteristics of ice rises and ice rumples in Dronning Maud Land and Enderby Land, Antarctica

Three-decade spatial patterns in surface mass balance of the Nivlisen Ice Shelf, central Dronning Maud Land, East Antarctica

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