East Antarctic Landfast Sea Ice Distribution and Variability, 2000–08

Abstract

This study presents the first continuous, high spatiotemporal resolution time series of landfast sea ice extent along the East Antarctic coast for the period March 2000–December 2008. The time series was derived from consecutive 20-day cloud-free Moderate Resolution Imaging Spectroradiometer (MODIS) composite images. Fast ice extent across the East Antarctic coast shows a statistically significant (1.43% ±0.30% yr−1) increase. Regionally, there is a strong increase in the Indian Ocean sector (20°–90°E, 4.07% ±0.42% yr−1), and a nonsignificant decrease in the western Pacific Ocean sector (90°–160°E, −0.40% ±0.37% yr−1). An apparent shift from a negative to a positive extent trend is observed in the Indian Ocean sector from 2004. This shift also coincides with a greater amount of interannual variability. No such shift in apparent trend is observed in the western Pacific Ocean sector, where fast ice extent is typically higher and variability lower than the Indian Ocean sector. The limit to the maximum fast ice areal extent imposed by the location of grounded icebergs modulates the shape of the mean annual fast ice extent cycle to give a broad maximum and an abrupt, relatively transient minimum. Ten distinct fast ice regimes are identified, related to variations in bathymetry and coastal configuration. Fast ice is observed to form in bays, on the windward side of large grounded icebergs, between groups of smaller grounded icebergs, between promontories, and upwind of coastal features (e.g., glacier tongues). Analysis of the timing of fast ice maxima and minima is also presented and compared with overall sea ice maxima/minima timing.

A glaciochemical study of the 120 m ice core from Mill Island, East Antarctica

“…(Fraser et al, 2012) demonstrated the presence (and, at times, absence) of multi-year landfast ice to the east of Mill Island, which would facilitate snow ramp formation. SIC-m and trace ions can be seen on a monthly basis here.…”

“…The The presence of such an ice island presents a strong dynamical barrier to mobile pack ice being advected westward in the coastal current, leading to higher pack ice concentration to the east of this barrier (Fraser et al, 2012).…”

Observations: Cryosphere

“…Such fast ice is "a preeminent feature of the Antarctic coastal zone and an important interface between the ice sheet and pack ice/ocean" (Fraser et al, 2012). Variability in fast ice extent is often viewed as a sensitive indicator of climate change (Murphy et al, 1995;Heil et al, 2006;Mahoney et al, 2007).…”

Potential regime shift in decreased sea ice production after the Mertz Glacier calving

“…This study is the first observational assessment of the change in the GV region after the MGT calving. Sea ice production estimates are presented using a thin ice thickness algorithm based on satellite Special Sensor Microwave/Imager (SSM/I) data and a heat flux calculation [17][18][19] , in conjunction with a fast ice time series and climatology derived from NASA moderate resolution imaging spectroradiometer (MODIS) satellite imagery 20 . We examine the change in sea ice production in 2010 and 2011, relative to the mean annual sea ice production over the preceding years from 2000-2009.…”