Meteorological change in the Ross Sea region and its link to Antarctic Sea ice
We aim to quantify the linkages between the Amundsen Sea Low (ASL) and intense southerly outflow over the Ross Ice Shelf. We will also identify the fingerprint of these events in high-resolution atmospheric measurements and their impact on remotely sensed sea ice observations to validate simulations. This will allow us to explore the role of the atmosphere in recent increases in sea ice extent in unprecedented detail.
The meteorology over the Ross Sea region has changed over the last 30 years driven by modes of climate variability – the Southern Annular Mode (SAM) and the El Nino Southern Oscillation (ENSO) – and their impacts on the Amundsen Sea Low. The variable position and strength of the clockwise flow around the ASL is linked to stronger northerlies in the Bellingshausen Sea, and southerly winds in the Ross Sea. These changes have been widely examined near the Antarctic Peninsula, where anomalous warm winds from the north have pushed the sea ice edge farther south. The circulation change in the Ross Sea has been examined less thoroughly, but increased cold air outbreaks, known as the Ross Ice Shelf Airstream (RAS), may explain a significant portion of the climate variation in the region, such as increases in sea ice extent (this area has driven the continental increase) and the northward drift of sea ice.
Q1) Has climate change altered the position and strength of the Amundsen Sea Low and subsequently affected the frequency of southerly storms over the Ross Ice Shelf?
Q2) How do southerly surges of air impact sea ice and temperatures and can they explain positive trends in sea ice extent in the Ross Sea and recent warming?
We will examine the link between the ASL and southerly surges of air over the Ross Sea in a global climate model, reanalyses and the Antarctic Mesoscale Prediction System (AMPS). By using a range of models at multiple scales, we will identify whether these regional flows are under-represented in global models. The use of a powerful atmosphere-ocean-chemistry coupled climate model also allows us to determine the relative importance of greenhouse gases and ozone depletion because of its ability to simulate chemistry.
To test the AMPS output, which acts as our reference in the wider study, we will perform a targeted field campaign producing high resolution meteorological observations using SNOW WEB , a unique wireless sensor network already tested in Antarctica. By combining this data with observations from US automated weather stations and remote sensing measurements of sea ice, we will be able to directly examine the relationship between these southerly surges and sea ice.
The project team covers an impressive range of expertise of in-situ observations, remote sensing of the atmosphere and cryosphere, and regional and global atmospheric modelling.
Present Global Circulation Models (GCMs) do not simulate the observed increase in sea ice extent around Antarctica, our analysis will determine whether model studies need to consider unresolved regional flows as a candidate for these increasing trends in sea ice.
Principal Investigator: Adrian McDonald (University of Canterbury)
Olaf Morgenstern (National Institute of Water and Atmosphere)
Wolfgang Rack (University of Canterbury)
Peyman Zawar-Reza (University of Canterbury)
John Cassano (Atmospheric and Oceanic Sciences, University of Colorado, Boulder)
Matthew Lazzara (Antarctic Meteorological Research Center (AMRC), Space Science and Engineering Center (SSEC), University of Wisconsin–Madison (UW–Madison).
Ethan Dale (University of Canterbury)
Peer reviewed publications
 Coggins, J. H. J. and A. J. McDonald (2015). "The influence of the Amundsen Sea Low on the winds in the Ross Sea and surroundings: Insights from a synoptic climatology." Journal of Geophysical Research-Atmospheres 120(6): 2167-2189.
 Ben Jolly, Adrian J. McDonald, Jack H. J. Coggins, Peyman Zawar-Reza, Geoffrey Graeme, Graeme Plank, Orlon Petterson, and Ethan Dale, Matthew Lazzara and John Cassano (2015). “A validation of the Antarctic Mesoscale Prediction System using Self-Organizing Maps and high density observations from SNOWWEB.” Monthly Weather Review (submitted 13th December 2015).
 Ethan Dale, Adrian McDonald, and Wolfgang Rack (2016) “Atmospheric forcing of sea ice anomalies in the Ross Sea Polynya region.” The Cryosphere (submitted).
 Jack Coggins and Adrian McDonald, (2014), “Circulation-driven temperature trends at Scott Base and McMurdo Station”, 2014 SCAR Open Science Conference (25-29 August 2014), Auckland, New Zealand.
 A. McDonald, J. Coggins, J. Cassano, E. Dale, B. Jolly, G. Graham, M. Lazzara, O. Morgenstern, G. Plank, O. Petterson, W. Rack and P. Zawar-Reza (2015). “Meteorological change in the Ross sea region and its link to Antarctic sea ice trends”, Polar Predictability Workshop (8-10 April 2015), Reading University, United Kingdom.
 Ben Jolly an Adrian McDonald, (2015). “A case study of a Ross Ice Shelf Airstream event using high resolution observational data captured by SNOW WEB.”, EGU General Assembly (12-17 April 2015), Vienna, Austria.
 Jack Coggins and Adrian McDonald (2015), “Sea ice trends and cyclone activity in the Southern Ocean.”, EGU General Assembly (12-17 April 2015), Vienna, Austria.
 A. McDonald, J. Coggins, J. Cassano, E. Dale, B. Jolly, G. Graham, M. Lazzara, O. Morgenstern, G. Plank, O. Petterson, W. Rack and P. Zawar-Reza (2015). “Meteorological change in the Ross sea region and its link to Antarctic sea ice trends”, 26th IUGG general assembly (22 June – 2 July 2015), Prague, Czech republic.
 Ethan Dale, Adrian McDonald and Wolfgang Rack (2016). “Atmospheric forcing of sea ice anomalies in the Ross Sea Polynya region”, EGU General Assembly (17-22 April 2016), Vienna, Austria.