Evaluating Highest-Temperature Extremes in the Antarctic

Skansi, María de los Milagros; King, John C.; Lazzara, Matthew A.; Cerveny, Randall S.; Stella, José Luis; Solomon, Susan; Jones, Phil; Bromwich, David H.; Renwick, James; Burt, Christopher C.; Peterson, Thomas C.; Brunet, Manola; Driouech, Fatima; Vose, Russell S.; Krahenbuhl, Daniel

doi:10.1029/2017eo068325

Cited by 12 publications

(17 citation statements)

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“…The present study confirms the suggestion (de los Milagros Skansi et al, 2017) that the record high temperature at Signy Research Station on 30th January 1982 was caused by a combination of exceptional warm air advection together with additional warming resulting from a local föhn effect. Situated immediately downwind of the Coronation Island mountain chain, Signy Island was directly in the path of adiabatically warmed air descending from around summit level.…”

Section: Discussionsupporting

confidence: 91%

“…By contrast, Grytviken station on the subantarctic island of South Georgia, 900 km to the northeast of Signy Island, recorded a station record maximum temperature of 22.9 ∘ C on 31st January 1982. While it is not surprising that a station at the northern limit of the Antarctic region should hold the regional temperature record, the observed temperature was exceptional even for Signy, exceeding the second highest ranked temperature in the record by 1.8 ∘ C. Only 1% of monthly maximum temperatures in the Signy record exceed 15 ∘ C. de los Milagros Skansi et al (2017) considered possible causes of this extreme event and suggested that it was driven by a combination of exceptional warm advection together with a local föhn effect. In this article, we examine these mechanisms in greater detail.…”

Section: Introductionmentioning

confidence: 89%

“…On 30th January 1982, the British Antarctic Survey research station at Signy Island (Figure 1) reported a daily maximum surface air temperature of 19.8 ∘ C. The World Meteorological Organisation (WMO) has recently recognised this as a record high temperature for the Antarctic region, defined as all land and ice shelves lying south of 60 ∘ S (de los Milagros Skansi et al, 2017). To put this record into a regional context, we note that the absolute maximum temperature for the Antarctic continent (17.5 ∘ C on 24th March 2015) was measured at Esperanza station on the Antarctic Peninsula, 660 km southwest of Signy Island.…”

Section: Introductionmentioning

confidence: 99%

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Causes of the Antarctic region record high temperature at Signy Island, 30th January 1982

King

Bannister

Hosking

et al. 2017

Atmospheric Science Letters

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On 30th January 1982, the research station on Signy Island (South Orkney Islands) reported a daily maximum temperature of 19.8 ∘ C. This is a record maximum for any station south of 60 ∘ S. We use surface observations, atmospheric reanalyses and high-resolution atmospheric model simulations to investigate the drivers of this extreme event. At the time of the record temperature exceptionally warm air was being advected southwards towards the South Orkney Islands from the subtropical South Atlantic. This air mass cooled significantly at levels below 1 km during its long track over the cold Southern Ocean but remained relatively warm above this level. Atmospheric model simulations show that warm air from upper levels was brought down towards the surface over Signy Island in a föhn wind generated by northerly flow over Coronation Island, a mountainous island just to the north of Signy Island. Modelled temperatures over Signy Island are in good agreement with observations and thus support the hypothesis that the record temperature was caused by a combination of exceptional warm advection with conditions suitable for the generation of föhn. Since conditions conducive to föhn occur relatively frequently, föhn warming may have a significant influence on the local climate and ecology of Signy Island.

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Section: Discussionsupporting

confidence: 91%

Section: Introductionmentioning

confidence: 89%

Section: Introductionmentioning

confidence: 99%

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Causes of the Antarctic region record high temperature at Signy Island, 30th January 1982

King

Bannister

Hosking

et al. 2017

Atmospheric Science Letters

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“…A few days before the Atacama flood, most surface stations along the western border of South America from 20 • S to 40 • S experienced high temperatures close to all time records (Barrett et al, 2016). Almost simultaneously, Esperanza station (6324 ′ S, 5659 ′ W, 13 m) located at the tip of the Antarctic Peninsula registered the highest temperatures ever recorded for continental Antarctica (Skansi et al, 2017) (17.5 • C on 24 March 2015, see Figure S1b). This extreme Antarctic heat wave triggered a significant melting on the Larsen C ice sheet (Munneke et al, 2018) and was ultimately traced to foehn-induced warming that resulted from a landfalling atmospheric river (Bozkurt et al, 2018).…”

Section: Introductionmentioning

confidence: 78%

Strongest MJO on Record Triggers Extreme Atacama Rainfall and Warmth in Antarctica

Rondanelli

Hatchett

Rutllant

et al. 2019

Geophysical Research Letters

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Tropical perturbations have been shown theoretically and observationally to excite long‐range atmospheric responses in the form of Rossby wave teleconnections that result from the equator to pole gradient of planetary vorticity. An extreme teleconnection event occurred during March 2015 in the Southeastern Pacific. As a result, extreme high temperatures were observed in Southwestern South America and the Antarctic Peninsula simultaneously with an extreme rainfall and flood event in the hyperarid Atacama desert. We show that the origin of these seemingly disconnected extreme events can be traced to a Rossby wave response to the strongest Madden‐Julian Oscillation (MJO) on record in the tropical central Pacific. A barotropic wave number 3 to 4 perturbation with group velocity between 15 and 30 m/s is consistent with the trajectory and timing followed by the upper‐level anomalies radiating away from the tropics after the MJO episode.

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“…The event occurred just at the onset of the strong 2015–2016 El Niño event (between 18 and 27 March 2015), at the same time that the west coast of South America (northern, central, and southern Chile) was experiencing a series of extreme hydrometeorological events (Barrett et al, ; Bozkurt et al, ). Based on careful evaluation of several pieces of evidence (e.g., quality of observation, type and calibration of equipment, and foehn occurrence) by an international evaluation committee within the World Meteorological Organization Commission for Climatology, this extreme observation was certified as the highest temperature recorded for the Antarctic continent (Skansi et al, ).…”

Section: Introductionmentioning

confidence: 99%

Foehn Event Triggered by an Atmospheric River Underlies Record‐Setting Temperature Along Continental Antarctica

et al. 2018

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A record‐setting temperature of 17.5°C occurred on 24 March 2015 at the Esperanza station located near the northern tip of the Antarctic Peninsula (AP). We studied the event using surface station data, satellite imagery, reanalysis data, and numerical simulations. The Moderate Resolution Imaging Spectroradiometer Antarctic Ice Shelf Image Archive provides clear evidence for disintegration and advection of sea ice, as well as the formation of melt ponds on the ice sheet surface at the base of the AP mountain range. A deep low‐pressure center over the Amundsen‐Bellingshausen Sea and a blocking ridge over the southeast Pacific provided favorable conditions for the development of an atmospheric river with a northwest‐southeast orientation, directing warm and moist air toward the AP, and triggering a widespread foehn episode. A control simulation using a regional climate model shows the existence of local topographically induced warming along the northern tip of the AP (∼60% of the full temperature signal) and the central part of the eastern AP (>90% of the full temperature signal) with respect to a simulation without topography. These modeling results suggest that more than half of the warming experienced at Esperanza can be attributed to the foehn effect (a local process), rather than to the large‐scale advection of warm air from the midlatitudes. Nevertheless, the local foehn effect also has a large‐scale advection component, since the atmospheric river provides water vapor for orographic precipitation enhancement and latent heat release, which makes it difficult to completely disentangle the role of local versus large‐scale processes in explaining the extreme event.

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Evaluating Highest-Temperature Extremes in the Antarctic

Abstract: The record high temperature for regions south of 60°S latitude is a balmy 19.8°C (67.6°F), recorded 30 January 1982 at a research station on Signy Island.

Cited by 12 publications

References 0 publications

Causes of the Antarctic region record high temperature at Signy Island, 30th January 1982

Causes of the Antarctic region record high temperature at Signy Island, 30th January 1982

Strongest MJO on Record Triggers Extreme Atacama Rainfall and Warmth in Antarctica

Foehn Event Triggered by an Atmospheric River Underlies Record‐Setting Temperature Along Continental Antarctica

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