The record 2013 Southern Hemisphere sea-ice extent maximum

Abstract

Observations of Southern Hemisphere sea ice from passive microwave satellite measurements show that a new record maximum extent of 19.58 � 10 6 km 2 was reached on 30 September 2013; the extent is just over two standard deviations above the 1979-2012 mean and follows a similar record (19.48 � 10 6 km 2 ) in 2012. On the record day in 2013, sea-ice extent was greater than the 30 year average (1981-2010) in nearly all Southern Ocean regions.For the year as a whole, Southern Hemisphere sea-ice area and extent were well above average, and numerous monthly and daily records were broken. Analysis of anomaly patterns and the atmospheric and oceanic events suggests that a sequence of regional wind and cold-freshened surface waters is likely responsible for the record maximum and the generally high 2013 extent. In particular, the Ross Sea sector experienced a combination of cold southerly winds associated with the position and depth of the Amundsen Sea low, and lower than normal sea surface temperatures (up to 28C below normal). The resulting very high anomaly in ice extent in this region was a major component of the overall record maximum.

State of the Climate in 2014

“…The year 2013 saw quite different factors involved in achieving the record extent, with a tongue of colder-than-normal SSTs in the western Ross Sea sector aiding the early advance of sea ice in that region (Fig. SB6.4 and Massom et al 2013;Reid et al 2015). This SST anomaly subsequently advected eastwards after reaching the Antarctic Circumpolar Current in about June 2013, to envelop the ice edge to the north of the Bellingshausen-Amundsen Seas region and aid further thermodynamic expansion of ice there as the year progressed (Fig.…”

Benefits of Increasing the Model Resolution for the Seasonal Forecast Quality in EC-Earth

“…As an example of response to these challenges, the Sea Ice Prediction Network (SIPN; www.arcus.org/sipn) has collected, each year since 2008, submissions from various groups using a range of methods in order to predict the upcoming summer sea ice conditions in the Arctic. Predicting the seasonal development of Antarctic sea ice is arguably less interesting from an end-user perspective, especially over the winter season, but is still challenging from a scientific point of view given the recent chain of high records of sea ice extent in 2012 (Turner et al 2013), 2013(Reid et al 2015, and 2014 (Massonnet et al 2015b). The present section attempts to assess systematically how resolution can impact the skill and biases of sea ice seasonal prediction.…”

Seasonal climate summary southern hemisphere (winter 2013): Australia's third warmest winter on record.

“…Shifts in the depth of the 20 ºC isotherm provide an indication of subsequent temperature changes in SSTs; a shallow thermocline indicates the presence of, or potential for, upwelling, and therefore a cooling of surface temperatures. August as SAM switched to being mostly negative and westerly winds eased (Reid et al 2014). SAM is described further in the Southern Annular Mode section.…”

“…SAM is described further in the Southern Annular Mode section. Transient cyclonic activity in the Ross Sea also provided conditions suitable for wind driven sea ice expansion in that area (the region where positive sea ice extent anomalies were most prominent), augmented by thermal expansion due to the cooler-than-normal SSTs evident to the north of the ice edge (Reid et al 2014). …”