Details

Autor(en) / Beteiligte

• Turner, John
• Lu, Hua
• King, John C.
• Carpentier, Scott
• Lazzara, Matthew
• Phillips, Tony
• Wille, Jonathan

Titel

An Extreme High Temperature Event in Coastal East Antarctica Associated With an Atmospheric River and Record Summer Downslope Winds

Ist Teil von

• Geophysical research letters, 2022-02, Vol.49 (4), p.n/a

Ort / Verlag

Washington: John Wiley & Sons, Inc

Erscheinungsjahr

2022

Quelle

Wiley Online Library Journals Frontfile Complete

Beschreibungen/Notizen

• High surface temperatures are important in Antarctica because of their role in ice melt and sea level rise. We investigate a high temperature event in December 1989 that gave record temperatures in coastal East Antarctica between 60° and 100°E. The high temperatures were associated with a pool of warm lower tropospheric air with December temperature anomalies of >14°C that developed in two stages over the Amery Ice Shelf. First, there was near‐record poleward warm advection within an atmospheric river. Second, synoptically driven downslope flow from the interior reached unprecedented December strength over a large area, leading to strong descent and further warming in the coastal region. The coastal easterly winds were unusually deep and strong, and the warm pool was advected westwards, giving a short period of high temperatures at coastal locations, including a surface temperature of 9.3°C at Mawson, the second highest in its 66‐year record. Plain Language Summary The Antarctic continent contains 90 percent of the world's freshwater ice, so any significant melt has serious implications for sea level rise. To date, most ice loss has occurred when warm ocean currents melt coastal ice from below. However, the higher air temperatures predicted for the coming decades are expected to increase surface melt, leading to an additional contribution to sea level rise. We present a case study of an event that occurred in coastal East Antarctica during December 1989 that illustrates how surface temperatures can rise to record levels leading to significant surface ice melt. The event unfolded in two stages. First, a narrow band of warm, moist air arrived in the coastal region from lower latitudes as an “atmospheric river”, raising the temperature to a high, but not extreme level. Second, winds of record summer strength flowed from the interior of the Antarctic to the coastal region, drawing air down to lower levels of the atmosphere. This led to warming of the coastal air through compression, with it reaching 9.3°C at the Australian Mawson station, which was the second highest surface temperature in the 66‐year record. Key Points Sustained horizontal warm advection toward the coast of East Antarctic via an atmospheric river led to marked warming Downslope surface winds of record strength for the summer resulted in descent and adiabatic warming inland of the coast Extremely strong lower tropospheric easterly winds carried the warm air westwards leading to ice melt and record high surface temperatures