Antarctic Interior Research Articles

The Extraordinary March 2022 East Antarctica “Heat” Wave. Part I: Observations and Meteorological Drivers

Abstract Between 15 and 19 March 2022, East Antarctica experienced an exceptional heat wave with widespread 30°–40°C temperature anomalies across the ice sheet. This record-shattering event saw numerous monthly temperature records being broken including a new all-time temperature record of −9.4°C on 18 March at Concordia Station despite March typically being a transition month to the Antarctic coreless winter. The driver for these temperature extremes was an intense atmospheric river advecting subtropical/midlatitude heat and moisture deep into the Antarctic interior. The scope of the temperature records spurred a large, diverse collaborative effort to study the heat wave’s meteorological drivers, impacts, and historical climate context. Here we focus on describing those temperature records along with the intricate meteorological drivers that led to the most intense atmospheric river observed over East Antarctica. These efforts describe the Rossby wave activity forced from intense tropical convection over the Indian Ocean. This led to an atmospheric river and warm conveyor belt intensification near the coastline, which reinforced atmospheric blocking deep into East Antarctica. The resulting moisture flux and upper-level warm-air advection eroded the typical surface temperature inversions over the ice sheet. At the peak of the heat wave, an area of 3.3 million km2 in East Antarctica exceeded previous March monthly temperature records. Despite a temperature anomaly return time of about 100 years, a closer recurrence of such an event is possible under future climate projections. In Part II we describe the various impacts this extreme event had on the East Antarctic cryosphere. Significance Statement In March 2022, a heat wave and atmospheric river caused some of the highest temperature anomalies ever observed globally and captured the attention of the Antarctic science community. Using our diverse collective expertise, we explored the causes of the event and have placed it within a historical climate context. One key takeaway is that Antarctic climate extremes are highly sensitive to perturbations in the midlatitudes and subtropics. This heat wave redefined our expectations of the Antarctic climate. Despite the rare chance of occurrence based on past climate, a future temperature extreme event of similar magnitude is possible, especially given anthropogenic climate change.

The Extraordinary March 2022 East Antarctica “Heat” Wave. Part II: Impacts on the Antarctic Ice Sheet

Abstract Between 15 and 19 March 2022, East Antarctica experienced an exceptional heat wave with widespread 30°–40°C temperature anomalies across the ice sheet. In Part I, we assessed the meteorological drivers that generated an intense atmospheric river (AR) that caused these record-shattering temperature anomalies. Here, we continue our large collaborative study by analyzing the widespread and diverse impacts driven by the AR landfall. These impacts included widespread rain and surface melt that was recorded along coastal areas, but this was outweighed by widespread high snowfall accumulations resulting in a largely positive surface mass balance contribution to the East Antarctic region. An analysis of the surface energy budget indicated that widespread downward longwave radiation anomalies caused by large cloud-liquid water contents along with some scattered solar radiation produced intense surface warming. Isotope measurements of the moisture were highly elevated, likely imprinting a strong signal for past climate reconstructions. The AR event attenuated cosmic ray measurements at Concordia, something previously never observed. Last, an extratropical cyclone west of the AR landfall likely triggered the final collapse of the critically unstable Conger Ice Shelf while further reducing an already record low sea ice extent. Significance Statement Using our diverse collective expertise, we explored the impacts from the March 2022 heat wave and atmospheric river across East Antarctica. One key takeaway is that the Antarctic cryosphere is highly sensitive to meteorological extremes originating from the midlatitudes and subtropics. Despite the large positive temperature anomalies driven from strong downward longwave radiation, this event led to huge amounts of snowfall across the Antarctic interior desert. The isotopes in this snow of warm airmass origin will likely be detectable in future ice cores and potentially distort past climate reconstructions. Even measurements of space activity were affected. Also, the swells generated from this storm helped to trigger the final collapse of an already critically unstable Conger Ice Shelf while further degrading sea ice coverage.

Scars of tectonism promote ice-sheet nucleation from Hercules Dome into West Antarctica

Geology and bed topography influence how ice sheets respond to climate change. Despite the West Antarctic Ice Sheet’s capacity to retreat and advance quickly over its over-deepened interior, little is known about the subglacial landscape of the East Antarctic elevated interior that probably seeded West Antarctic ice streams and glaciers. At Hercules Dome, we use three-dimensional swath radar technology to image the upstream origin of large subglacial basins that drain ice from the Antarctic interior into West Antarctic ice streams. Radar imaging reveals an ancient, alpine landscape with hanging tributary valleys and large U-shaped valleys. On the valley floors, we image subglacial landforms that are typically associated with temperate basal conditions and fast ice flow. Formation mechanisms for these subglacial landforms are fundamentally inconsistent with the currently slowly flowing ice. Regional aerogravity shows that these valleys feed into larger subglacial basins that host thick sediment columns. Past tectonism probably created these basins and promoted ice flow from Hercules Dome into the Ross and Filchner–Ronne sectors. This suggests that the landscape at Hercules Dome was shaped by fast-flowing ice in the past when the area may have served as or been proximal to a nucleation centre for the West Antarctic Ice Sheet.

Subglacial landscape in the Antarctic interior consistent with past fast ice flow

Subglacial landscape in the Antarctic interior consistent with past fast ice flow

Change at 85 degrees south: Shackleton Glacier region proglacial lakes from 1960 to 2020

Abstract Over the last two decades, anomalous warming events have been observed in coastal Antarctic regions. While these events have been documented in the Ross Sea sector, the Antarctic interior is believed to have been buffered from warming. In this work, we present data from lakes located near Mt. Heekin and Thanksgiving Valley (~85° S) along the Shackleton Glacier, which are believed to be the southern-most Antarctic dry valley lakes. In 2018, the lakes were characterized, repeat satellite images were examined, and lake water chemistry was measured. Our analysis shows that lake areas recently increased, and the water-soluble ion chemistry indicates a flushing of salts from periglacial soils, likely from increased glacial melt as illustrated by water isotope data. Our results show that high southern latitude ice-free areas have likely been affected by warm pulses over the past 60 years and these pulses may be quasi-synchronous throughout the Transantarctic Mountains.

The Coupled Atmosphere–Ocean Response to Antarctic Sea Ice Loss

Abstract Antarctic sea ice is projected to decrease in response to increasing greenhouse gas concentrations. Limited studies so far have examined the coupled atmosphere–ocean response to Antarctic sea ice loss. Here, we isolate the response to Antarctic sea ice loss in the atmosphere and ocean using bespoke sea ice albedo perturbation experiments with HadGEM3-GC3.1-LL, provide the first detailed examination of the global ocean response, and quantify the importance of atmosphere–ocean coupling, through comparison to uncoupled experiments with prescribed Antarctic sea ice loss. Lower-tropospheric warming and moistening over regions of sea ice loss and the nearby Southern Ocean are simulated in both coupled and uncoupled configurations but are of greater magnitude in the coupled model. A weakening and equatorward shift of the tropospheric westerly jet are simulated in both configurations, but are also larger in the coupled model. Ocean coupling allows the warming response to spread northward, and by poleward atmospheric energy transport, back to the Antarctic interior. Warmer tropical sea surface temperatures enhance atmospheric convection, driving upper-tropospheric warming and triggering atmospheric teleconnections to the extratropics, including a weakened Aleutian low. A 20% reduction in Antarctic Circumpolar Current transport and a weakening of the shallow tropical convergence cell are simulated. Surface waters warm and freshen globally, becoming more stratified and stable in the Southern Ocean, with similar changes, but of lesser magnitude, in the Arctic Ocean, where sea ice declines. Our results suggest that the climate effects of Antarctic sea ice loss stretch from pole to pole and from the heights of the tropical troposphere to the depths of the Southern Ocean.

Sensitivity of the West Antarctic Ice Sheet to +2 °C (SWAIS 2C)

Abstract. The West Antarctic Ice Sheet (WAIS) presently holds enough ice to raise global sea level by 4.3 m if completely melted. The unknown response of the WAIS to future warming remains a significant challenge for numerical models in quantifying predictions of future sea level rise. Sea level rise is one of the clearest planet-wide signals of human-induced climate change. The Sensitivity of the West Antarctic Ice Sheet to a Warming of 2 ∘C (SWAIS 2C) Project aims to understand past and current drivers and thresholds of WAIS dynamics to improve projections of the rate and size of ice sheet changes under a range of elevated greenhouse gas levels in the atmosphere as well as the associated average global temperature scenarios to and beyond the +2 ∘C target of the Paris Climate Agreement. Despite efforts through previous land and ship-based drilling on and along the Antarctic margin, unequivocal evidence of major WAIS retreat or collapse and its causes has remained elusive. To evaluate and plan for the interdisciplinary scientific opportunities and engineering challenges that an International Continental Drilling Program (ICDP) project along the Siple coast near the grounding zone of the WAIS could offer (Fig. 1), researchers, engineers, and logistics providers representing 10 countries held a virtual workshop in October 2020. This international partnership comprised of geologists, glaciologists, oceanographers, geophysicists, microbiologists, climate and ice sheet modelers, and engineers outlined specific research objectives and logistical challenges associated with the recovery of Neogene and Quaternary geological records from the West Antarctic interior adjacent to the Kamb Ice Stream and at Crary Ice Rise. New geophysical surveys at these locations have identified drilling targets in which new drilling technologies will allow for the recovery of up to 200 m of sediments beneath the ice sheet. Sub-ice-shelf records have so far proven difficult to obtain but are critical to better constrain marine ice sheet sensitivity to past and future increases in global mean surface temperature up to 2 ∘C above pre-industrial levels. Thus, the scientific and technological advances developed through this program will enable us to test whether WAIS collapsed during past intervals of warmth and determine its sensitivity to a +2 ∘C global warming threshold (UNFCCC, 2015).

Thermal regime and state of hydration of the Antarctic upper mantle from regional-scale electrical properties

Abstract Large-scale electrical resistivity investigations of the Antarctic crust and upper mantle utilizing the magnetotelluric method (MT) are limited in number compared to temperate regions, but provide physical insights hard to achieve with other techniques. Key to the method's success are the instrumentation advances that allow microvolt (µV)-level measurements of the MT electric field in the face of mega-ohm (MΩ) contact resistances. Primarily in this chapter, we reanalyse existing data from three campaigns over the Antarctic interior using modern 3D non-linear inversion analysis, and offer additional geophysical conclusions and context beyond the original studies. A profile of MT soundings over the transitional Ellsworth–Whitmore block in central West Antarctica implies near-cratonic lithospheric geothermal conditions with interpreted graphite–sulfide horizons deformed along margins of high-grade silicate lithological blocks. Reanalysis of South Pole soundings confirms large-scale low resistivity spanning Moho depths that is consistent with limited seismic tomography and elevated crustal thermal regime inferences. Upper mantle under a presumed adiabatic thermal gradient below the Ross Ice Shelf near the central Transantarctic Mountains appears to be of a moderately hydrated state but not sufficient to induce melting. The degree of hydration there is comparable to that below the north-central Great Basin province of the western USA.

A New Machine Learning Algorithm for Numerical Prediction of Near-Earth Environment Sensors along the Inland of East Antarctica

Accurate short-term small-area meteorological forecasts are essential to ensure the safety of operations and equipment operations in the Antarctic interior. This study proposes a deep learning-based multi-input neural network model to address this problem. The newly proposed model is predicted by combining a stacked autoencoder and a long- and short-term memory network. The self-stacking autoencoder maximises the features and removes redundancy from the target weather station’s sensor data and extracts temporal features from the sensor data using a long- and short-term memory network. The proposed new model evaluates the prediction performance and generalisation capability at four observation sites at different East Antarctic latitudes (including the Antarctic maximum and the coastal region). The performance of five deep learning networks is compared through five evaluation metrics, and the optimal form of input combination is discussed. The results show that the prediction capability of the model outperforms the other models. It provides a new method for short-term meteorological prediction in a small inland Antarctic region.

A calibration of cellulose isotopes in modern prostrate Nothofagus and its application to fossil material from Antarctica

Carbon and oxygen isotopes (δ13C and δ18O) in tree rings are widely used to reconstruct palaeoclimate variables such as temperature during the Holocene (12 thousand years ago - present), and are used increasingly in deeper time. However, their use is largely restricted to arboreal trees, which excludes potentially important data from prostrate trees and shrubs, which grow in high latitude and altitude end-member environments. Here, we calibrate the use of δ13C and δ18O as climatic archives in two modern species of southern beech (Nothofagus) from Tierra del Fuego, Chile, at the southern limit of their current range. We show that prostrate trees are potentially suitable archives for recording climatological means over longer periods (on the order of decades), which opens up these important environments for tree ring isotope analysis. We then apply our new understanding to a remarkable late Neogene (17–2.5 Ma) fossil Nothofagus assemblage from the Transantarctic Mountains, Antarctica, representative of a prostrate tundra shrub growing during a period of significant ice sheet retreat. The δ13C of the fossil cellulose was found to be ~4‰ enriched relative to that of the modern tress. This is likely to be due to a combination of a more positive δ13C of contemporaneous atmospheric CO2 and enhanced water use efficiency at the fossil site. Using the cellulose-δ18O in the fossil wood, we are able to reconstruct precipitation oxygen isotopes over the Antarctic interior for the first time for this time period. The results show that δ18Oprecip over Antarctica was −16.0 ± 4.2‰, around 12‰ enriched relative to today, suggesting changes in the hydrological cycle linked to warmer temperatures and a smaller ice sheet.

Snowfall and Water Stable Isotope Variability in East Antarctica Controlled by Warm Synoptic Events

AbstractUnderstanding climate proxy records that preserve physical characteristics of past climate is a prerequisite to reconstruct long‐term climatic conditions. Water stable isotope ratios (δ18O) constitute a widely used proxy in ice cores to reconstruct temperature and climate. However, the original climate signal is altered between the formation of precipitation and the ice, especially in low‐accumulation areas such as the East Antarctic Plateau. Atmospheric conditions under which the isotopic signal is acquired at Aurora Basin North (ABN), East Antarctica, are characterized with the regional atmospheric model Modèle Atmosphérique Régional (MAR). The model shows that 50% of the snow is accumulated in less than 24 days year−1. Snowfall occurs throughout the year and intensifies during winter, with 64% of total accumulation between April and September, leading to a cold bias of −0.86°C in temperatures above inversion compared to the annual mean of −29.7°C. Large snowfall events are associated with high‐pressure systems forcing warm oceanic air masses toward the Antarctic interior, which causes a warm bias of +2.83°C. The temperature‐δ18O relationship, assessed with the global atmospheric model ECHAM5‐wiso, is primarily constrained by the winter variability, but the observed slope is valid year‐round. Three snow δ18O records covering 2004–2014 indicate that the anomalies recorded in the ice core are attributable to the occurrence of warm winter storms bringing precipitation to ABN and support the interpretation of δ18O in this region as a marker of temperature changes related to large‐scale atmospheric conditions, particularly blocking events and variations in the Southern Annular Mode.

Pangea Rifting Shaped the East Antarctic Landscape

AbstractEast Antarctica remains one of the few continental regions on Earth where an understanding of the origin and causal processes responsible for topographic relief is largely missing. Low‐temperature thermochronology studies of exposed Precambrian basement revealed discrete episodes of cooling and denudation during the Paleozoic–Mesozoic; however, the significance of these thermal events and their relationship to topography across the continental interior remains unclear. Here we use zircon and apatite (U‐Th)/He thermochronology to resolve the low‐temperature thermal evolution of a poorly exposed section of East Antarctic basement in the Bunger Hills region and gain insights into the chronology and style of landscape evolution across East Antarctica. Thermal history modeling results indicate that Precambrian basement in the Bunger Hills region experienced a distinct cooling episode during the Late Paleozoic–Triassic, which we relate to ~2–4 km of regional exhumation associated with intracontinental rifting, followed by a second episode of localized cooling and ≤1 km exhumation during the Late Jurassic–Cretaceous separation of India from East Gondwana. These findings, combined with existing thermochronological and tectonic evidence, support a continent‐scale denudation event associated with uplift and exhumation of large sections of Precambrian basement during Late Paleozoic–Triassic Pangea‐wide intracontinental extension. By contrast, continental extension associated with the Jurassic–Cretaceous breakup of East Gondwana resulted in significant denudation only locally in regions west of the Bunger Hills. We propose that the combined effects of these Paleozoic–Mesozoic tectonic events had a profound impact on the topography across the East Antarctic interior and influenced the long‐term landscape evolution of East Antarctica.

Record warming at the South Pole during the past three decades

Over the last three decades, the South Pole has experienced a record-high statistically significant warming of 0.61 ± 0.34 °C per decade, more than three times the global average. Here, we use an ensemble of climate model experiments to show this recent warming lies within the upper bounds of the simulated range of natural variability. The warming resulted from a strong cyclonic anomaly in the Weddell Sea caused by increasing sea surface temperatures in the western tropical Pacific. This circulation, coupled with a positive polarity of the Southern Annular Mode, advected warm and moist air from the South Atlantic into the Antarctic interior. These results underscore the intimate linkage of interior Antarctic climate to tropical variability. Further, this study shows that atmospheric internal variability can induce extreme regional climate change over the Antarctic interior, which has masked any anthropogenic warming signal there during the twenty-first century. Surface air temperatures at the South Pole warmed at over three times the global rate in recent decades. Research shows this trend was driven remotely by the tropics and locally by a positive phase of the Southern Annular Mode, increasing the influx of warm moist air atop anthropogenic warming.

Warming reaches the South Pole

Over the last half of the twentieth century, surface temperature over the South Pole was steady if not slightly cooling, suggesting the high Antarctic interior might be immune to warming. Research now shows a dramatic switch; in the past 30 years, the South Pole has been warming at over three times the global rate.

A Probabilistic Automated Isochrone Picking Routine to Derive Annual Surface Mass Balance From Radar Echograms

The surface mass balance (SMB) of West Antarctica is an important glaciological input to understanding polar climate and sea-level rise but with historically poor in situ data coverage. Previous studies demonstrate the utility of frequency-modulated continuous-wave radar to image subsurface layering in ice sheets, providing an additional source of data with which to estimate SMB. Traditional methods, however, require time-intensive manual oversight. Here, we present a probabilistic, fully automated approach to estimate annual SMB and uncertainties from radar echograms using successive peak-finding and weighted neighborhood search algorithms with the Monte Carlo simulations based on annual-layer likelihood scores. We apply this method to ground-based and airborne radar in a 175-km transect of the West Antarctic interior and compare the results to traditional manual methods and independent estimates from firn cores. The method demonstrates an automated estimation of SMB across a range of accumulation rates (100-450-mm water equivalent per year) and layer gradients up to 2 m/km. Based on likelihood-weighted F-scores, automated layer picks have a success rate between 64% and 84.6% compared with manually picked layers for three validation sites dispersed across the region. Comparisons between the automated SMB estimates and independent firn cores show a bias of 24 ± 70-mm water equivalent per year (12% ± 35% water equivalent of the in situ mean accumulation rate) although individual core site biases differ. This new approach permits the fully automated extraction of annual SMB rates and should be broadly and readily applicable to previously collected and ongoing radar data sets across polar regions.

An Evaluation of Surface Climatology in State-of-the-Art Reanalyses over the Antarctic Ice Sheet

Abstract In this study, we evaluate output of near-surface atmospheric variables over the Antarctic Ice Sheet from four reanalyses: the new European Centre for Medium-Range Weather Forecasts ERA-5 and its predecessor ERA-Interim, the Climate Forecast System Reanalysis (CFSR), and the Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2). The near-surface temperature, wind speed, and relative humidity are compared with datasets of in situ observations, together with an assessment of the simulated surface mass balance (approximated by precipitation minus evaporation). No reanalysis clearly stands out as the best performing for all areas, seasons, and variables, and each of the reanalyses displays different biases. CFSR strongly overestimates the relative humidity during all seasons whereas ERA-5 and MERRA-2 (and, to a lesser extent, ERA-Interim) strongly underestimate relative humidity during winter. ERA-5 captures the seasonal cycle of near-surface temperature best and shows the smallest bias relative to the observations. The other reanalyses show a general temperature underestimation during the winter months in the Antarctic interior and overestimation in the coastal areas. All reanalyses underestimate the mean near-surface winds in the interior (except MERRA-2) and along the coast during the entire year. The winds at the Antarctic Peninsula are overestimated by all reanalyses except MERRA-2. All models are able to capture snowfall patterns related to atmospheric rivers, with varying accuracy. Accumulation is best represented by ERA-5, although it underestimates observed surface mass balance and there is some variability in the accumulation over the different elevation classes, for all reanalyses.

Episodic erosion in West Antarctica inferred from cosmogenic 3He and 10Be in olivine from Mount Hampton

The polar climate of Antarctica results in the lowest erosion rates on Earth. The low long-term erosion history of high elevation mountain tops that are exposed above the ice preserve a record of climate change that can be accessed using cosmogenic nuclides. However, unravelling the complexity of the long-term denudation histories of Antarctic summits is frequently hampered by intermittent ice cover. The aim of this work is to identify denudation rate changes in a surface that has been continuously exposed since the middle Miocene. We have measured stable (3He) and radioactive (10Be) cosmogenic nuclides in olivine from lherzolite xenoliths from the summit of the Mount Hampton shield volcano within the West Antarctic Ice Sheet. The peak (3200 m) has never been covered by the current ice sheet and local ice caps, consequently the data record the subaerial erosion history of a mountain top within the Antarctic interior. The 10Be concentrations in the olivines yield minimum exposure ages (33 to 501 ka) that are significantly younger than those derived from the cosmogenic 3He (90 to 1101 ka). The data reveal a complex exposure history that provide an integrated long-term erosion rate of between 0.2 and 0.7 m/My that is most likely caused by mechanical weathering. Inverse modelling shows that the data are readily explained by episodic erosion, consisting of one to five erosion pulses that may record major regional climatic changes.

Investigating Local and Remote Terrestrial Influence on Air Masses at Contrasting Antarctic Sites Using Radon‐222 and Back Trajectories

AbstractWe report on the first summer of high‐sensitivity radon measurements from a two‐filter detector at Jang Bogo Station (Terra Nova Bay) and contrast them with simultaneous observations at King Sejong Station (King George Island). King Sejong radon concentrations were characteristic of a marine baseline station (0.02–0.3 Bq m−3), whereas Jang Bogo values were highly variable (0.06–5.2 Bq m−3), mainly due to emissions from exposed coastal ground (estimated mean flux 0.09–0.11 atoms cm−2 s−1) and shallow atmospheric mixing depths. For wind speeds of ≤3.5 m s−1 the influence of local radon emissions became increasingly more prominent at both sites. A cluster analysis of back trajectories from King Sejong (62°S) revealed a fairly even distribution between air masses that had passed recently over South America, the Southern Ocean, and Antarctica, whereas at Jang Bogo (75°S) 80% of events had recently passed over the Ross Ice Shelf and West Antarctica, 12% were synoptically forced over Cape Adare, and 8% were associated with subsidence over the Antarctic interior and katabatic flow to the station. When cross‐checked against radon concentrations, only half of the back trajectories ending at Jang Bogo that had indicated distant contact with nonpolar southern hemisphere continents within the past 10 days showed actual signs of terrestrial influence. A simple‐to‐implement technique based on high‐pass filtered absolute humidity is developed to distinguish between predominantly katabatic, oceanic, and near‐coastal air masses for characterization of trace gas and aerosol measurements at coastal East Antarctic sites.

Sedimentation and potential venting on the rifted continental margin of Dronning Maud Land

The relief of Dronning Maud Land (DML), formed by Middle and Late Mesozoic tectonic activity, had a strong spatial control on the early fluvial and subsequent glacial erosion and deposition. The sources, processes, and products of sedimentation along the DML margin and in the Lazarev Sea in front of the DML mountains have been barely studied. The onshore mountain belt parallel to the coast of the DML margin acts as a barrier to the transport of terrigenous sediments from the east Antarctic interior to the margin and into the Lazarev Sea. Only the Jutul–Penck Graben system allows a localized ice stream controlled transport of material from the interior of DML across its old mountain belt. Offshore, we attribute repeated large-scale debris flow deposits to instability of sediments deposited locally on the steep gradient of the DML margin by high sediment flux. Two types of canyons are defined based on their axial dimensions and originated from turbidity currents and slope failures during glacial/fluvial transport. For the first time, we report pipe-like seismic structures in this region and suggest that they occurred as consequences of volcanic processes. Sedimentary processes on the DML margin were studied using seismic reflection data and we restricted the seismic interpretation to the identification of major seismic sequences and their basal unconformities.

Antarctic station‐based seasonal pressure reconstructions since 1905: 1. Reconstruction evaluation

AbstractSeasonal mean Antarctic pressures at 17 stations are reconstructed based on the method of principal component regression, employing midlatitude pressure data as predictors. Several reconstruction methods were performed in order to assess the stability and reliability of the reconstructions obtained, including performing the reconstructions over a shorter 30 year window and withholding the remaining data for an independent validation. Generally, there were small differences between the various approaches, but typically reconstructions conducted on data with the trends still present and over the full period of observations achieved the highest skill. Seasonally, reconstruction skill was high in austral summer across the entire Antarctic continent. Reconstructions that employed gridded pressure data over oceans as well as the observations (here termed “pseudoreconstructions”) also performed remarkably well in austral winter. Spatially, the reconstruction skill was highest near the Antarctic Peninsula in all seasons, and weakest in coastal East Antarctica and the Antarctic Interior during austral spring and autumn; the spatial variability of the skill in part reflects the distance to the nearest midlatitude predictor. Nonetheless, for nearly all seasons and locations the observed trends since 1957 were well captured by the reconstructions, as was the low‐frequency decadal‐scale variability. These results suggest Antarctic pressure observations can be extended throughout the twentieth century with high confidence, especially in summer, allowing for a more precise understanding of the role and magnitude of natural atmospheric circulation variability across Antarctica.