The influence of winds, sea-surface temperature and precipitation anomalies on Antarctic regional sea-ice conditions during IPY 2007

• Published in: Deep Sea Research Part II: Topical Studies in Oceanography
• Main Authors: Stammerjohn, Sharon, Maksym, Ted, Heil, Petra, Massom, Robert A., Vancoppenolle, Martin, Leonard, Katherine C.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Elsevier 2011
• Subjects: Marine Sciences; Glaciology; Atmospheric Sciences; Antarctic; Southern Ocean; The Antarctic; Weddell; Antarc*; Antarctica; International Polar Year; IPY; Sea ice
• Online Access: http://nora.nerc.ac.uk/id/eprint/14643/; http://www.sciencedirect.com/science/article/pii/S0967064510003048

The 2007 International Polar Year (IPY) in the Antarctic was distinguished by strong regional and seasonal ice-atmosphere-ocean anomalies associated with an overall weakening of the prevailing westerly circulation. Here we assess the ice-atmosphere-ocean conditions leading up to and during two IPY field campaigns that took place in early spring (September-October): the U.S.-led Sea Ice Mass Balance Antarctica (SIMBA, 68-72 degrees S, 90-95 degrees W) and the Australian-led Sea Ice Physics and Ecosystems eXperiment (SIPEX, 63-67 degrees S, 115-130 degrees E). Our regional analysis is presented within the context of circumpolar and inter-annual variability relevant to other IPY Antarctic studies. Using satellite-derived and numerically analyzed surface and atmospheric variables, we examine relationships between (i) winds and sea-ice concentration and drift, (ii) sea-surface temperature and ice-edge anomalies, and (iii) precipitation and snow accumulation. Though Antarctic-averaged sea-ice extent in September 2007 was the second highest observed for 1979-2007, the SIMBA and SIPEX studies sampled the two regions showing the largest negative sea-ice anomalies in the Southern Ocean. Maps of sea-surface temperature (SST) and sea-ice concentration (SIC) anomalies revealed distinct regional patterns, showing warm SST/low SIC in the greater SIMBA (including all of the Bellingshausen and Amundsen seas) and western SIPEX regions, versus cool SST/high SIC in the Weddell, Ross and eastern SIPEX regions. In the SIMBA and western SIPEX regions, warm northerly winds in May (overlying the warm SSTs) brought anomalously high precipitation to those regions, but due to the regional delays in sea-ice advance (by up to 2 months), most fell on open ocean, which in turn contributed to negative and near-zero September snow depth anomalies in those two regions, respectively. During autumn (March to May), warm SSTs offshore of those regions extended from mid-to-high latitudes, resulting from meridional advection of heat associated with a ...