WMO evaluation of two extreme high temperatures occurring in February 2020 for the Antarctic Peninsula Region

• Published in: Bulletin of the American Meteorological Society
• Main Authors: Márcio Rocha, Francelino, Carlos, Schaefer, Skansi, Maria de los Milagros, Colwell, Steve, Bromwich, David H., Jones, Phil, King, John C., Lazzara, Matthew A., Renwick, James, Solomon, Susan, Brunet, Manola, Cerveny, Randall S.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2021
• Subjects: Antarctic; Antarctic Peninsula; Argentine; Esperanza; Esperanza Station; Seymour; Seymour Island; The Antarctic; Antarc*; permafrost
• Online Access: https://ueaeprints.uea.ac.uk/id/eprint/81309/; https://ueaeprints.uea.ac.uk/id/eprint/81309/1/Accepted_Manuscript.pdf; https://doi.org/10.1175/BAMS-D-21-0040.1

Two reports of Antarctic region potential new record high temperature observations (18.3°C, 6 February 2020 at Esperanza station and 20.8°C, 9 February 2020 at a Brazilian automated permafrost monitoring station on Seymour Island) were evaluated by a World Meteorological Organization (WMO) panel of atmospheric scientists. The latter figure was reported as 20.75°C in the media. The panel considered the synoptic situation and instrumental setups. It determined that a large high pressure system over the area created föhn conditions and resulted in local warming for both situations. Examination of the data and metadata of the Esperanza station observation revealed no major concerns. However, analysis of data and metadata of the Seymour Island permafrost monitoring station indicated that an improvised radiation shield led to a demonstrable thermal bias error for the temperature sensor. Consequently, the WMO has accepted the 18.3°C value for 1200 LST 6 February 2020 (1500 UTC 6 February 2020) at the Argentine Esperanza station as the new “Antarctic region (continental, including mainland and surrounding islands) highest temperature recorded observation” but rejected the 20.8°C observation at the Brazilian automated Seymour Island permafrost monitoring station as biased. The committee strongly emphasizes the permafrost monitoring station was not badly designed for its purpose, but the project investigators were forced to improvise a nonoptimal radiation shield after losing the original covering. Second, with regard to media dissemination of this type of information, the committee urges increased caution in early announcements as many media outlets often tend to sensationalize and mischaracterize potential records.