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Lejiang Yu
,
Qinghua Yang
,
Timo Vihma
,
Svetlana Jagovkina
,
Jiping Liu
,
Qizhen Sun
, and
Yubin Li

Abstract

Observed daily precipitation data were used to investigate the characteristics of precipitation at Antarctic Progress Station and synoptic patterns associated with extreme precipitation events during the period 2003–16. The annual precipitation, annual number of extreme precipitation events, and amount of precipitation during the extreme events have positive trends. The distribution of precipitation at Progress Station is heavily skewed with a long tail of extreme dry days and a high peak of extreme wet days. The synoptic pattern associated with extreme precipitation events is a dipole structure of negative and positive height anomalies to the west and east of Progress Station, respectively, resulting in water vapor advection to the station. For the first time, we apply self-organizing maps (SOMs) to examine thermodynamic and dynamic perspectives of trends in the frequency of occurrence of Antarctic extreme precipitation events. The changes in thermodynamic (noncirculation) processes explain 80% of the trend, followed by the changes in the interaction between thermodynamic and dynamic processes, which account for nearly 25% of the trend. The changes in dynamic processes make a negative (less than 5%) contribution to the trend. The positive trend in total column water vapor over the Southern Ocean explains the change of thermodynamic term.

Full access
Jeff Wilson
,
Thomas Jung
,
Eric Bazile
,
David Bromwich
,
Barbara Casati
,
Jonathan Day
,
Estelle De Coning
,
Clare Eayrs
,
Robert Grumbine
,
Jun Ioue
,
Siri Jodha S. Khalsa
,
Jorn Kristiansen
,
Machiel Lamers
,
Daniela Liggett
,
Steffen M. Olsen
,
Donald Perovich
,
Ian Renfrew
,
Vasily Smolyanitsky
,
Gunilla Svensson
,
Qizhen Sun
,
Taneil Uttal
, and
Qinghua Yang
Open access
David H. Bromwich
,
Kirstin Werner
,
Barbara Casati
,
Jordan G. Powers
,
Irina V. Gorodetskaya
,
Francois Massonnet
,
Vito Vitale
,
Victoria J. Heinrich
,
Daniela Liggett
,
Stefanie Arndt
,
Boris Barja
,
Eric Bazile
,
Scott Carpentier
,
Jorge F. Carrasco
,
Taejin Choi
,
Yonghan Choi
,
Steven R. Colwell
,
Raul R. Cordero
,
Massimo Gervasi
,
Thomas Haiden
,
Naohiko Hirasawa
,
Jun Inoue
,
Thomas Jung
,
Heike Kalesse
,
Seong-Joong Kim
,
Matthew A. Lazzara
,
Kevin W. Manning
,
Kimberley Norris
,
Sang-Jong Park
,
Phillip Reid
,
Ignatius Rigor
,
Penny M. Rowe
,
Holger Schmithüsen
,
Patric Seifert
,
Qizhen Sun
,
Taneil Uttal
,
Mario Zannoni
, and
Xun Zou
Full access
David H. Bromwich
,
Kirstin Werner
,
Barbara Casati
,
Jordan G. Powers
,
Irina V. Gorodetskaya
,
François Massonnet
,
Vito Vitale
,
Victoria J. Heinrich
,
Daniela Liggett
,
Stefanie Arndt
,
Boris Barja
,
Eric Bazile
,
Scott Carpentier
,
Jorge F. Carrasco
,
Taejin Choi
,
Yonghan Choi
,
Steven R. Colwell
,
Raul R. Cordero
,
Massimo Gervasi
,
Thomas Haiden
,
Naohiko Hirasawa
,
Jun Inoue
,
Thomas Jung
,
Heike Kalesse
,
Seong-Joong Kim
,
Matthew A. Lazzara
,
Kevin W. Manning
,
Kimberley Norris
,
Sang-Jong Park
,
Phillip Reid
,
Ignatius Rigor
,
Penny M. Rowe
,
Holger Schmithüsen
,
Patric Seifert
,
Qizhen Sun
,
Taneil Uttal
,
Mario Zannoni
, and
Xun Zou

Abstract

The Year of Polar Prediction in the Southern Hemisphere (YOPP-SH) had a special observing period (SOP) that ran from 16 November 2018 to 15 February 2019, a period chosen to span the austral warm season months of greatest operational activity in the Antarctic. Some 2,200 additional radiosondes were launched during the 3-month SOP, roughly doubling the routine program, and the network of drifting buoys in the Southern Ocean was enhanced. An evaluation of global model forecasts during the SOP and using its data has confirmed that extratropical Southern Hemisphere forecast skill lags behind that in the Northern Hemisphere with the contrast being greatest between the southern and northern polar regions. Reflecting the application of the SOP data, early results from observing system experiments show that the additional radiosondes yield the greatest forecast improvement for deep cyclones near the Antarctic coast. The SOP data have been applied to provide insights on an atmospheric river event during the YOPP-SH SOP that presented a challenging forecast and that impacted southern South America and the Antarctic Peninsula. YOPP-SH data have also been applied in determinations that seasonal predictions by coupled atmosphere–ocean–sea ice models struggle to capture the spatial and temporal characteristics of the Antarctic sea ice minimum. Education, outreach, and communication activities have supported the YOPP-SH SOP efforts. Based on the success of this Antarctic summer YOPP-SH SOP, a winter YOPP-SH SOP is being organized to support explorations of Antarctic atmospheric predictability in the austral cold season when the southern sea ice cover is rapidly expanding.

Free access