57A008
High-resolution East Antarctic landfast sea-ice extent and
variability from 2000 to 2008
Alexander D. Fraser, Robert A. Massom, Kelvin J. Michael, Petra
Heil, Jan L. Lieser
Corresponding author: Alexander D. Fraser –
adfraser@utas.edu.au
This work presents the first time series of high
spatio-temporal resolution (2 km, 20 day) maps of East Antarctic landfast sea
ice (10° W to 172° E), as well as a detailed study of the interannual
variability of fast ice, from 2000 to 2008. Fast-ice maps are generated from
cloud-free MODIS composite imagery, augmented by AMSR-E ASI sea-ice
concentration composite images when necessary. Several key fast-ice-related
parameters have been retrieved in this area for the first time, including: the
ratio of winter maximum extent to summer minimum (~3.1:1); the timing of maximum
(DOY 261–280) and minimum (DOY 61–80) extent; and the shape of the
annual cycle (a broad maximum, with a much more pronounced minimum). A small but
significant (at the 99% level) positive trend in fast-ice area/extent was
identified from the fast-ice extent time series, though the 9 year length of the
time series provided is likely too short to provide a true indication of
longer-term variability. This is compared with the large-scale behaviour of the
pack ice in this region over this time period. The location of annually
recurring fast-ice features was found to be closely related to the distribution
of grounded icebergs, both large (with fast ice often forming on the eastern
side due to dynamic advection) and small (with fast ice forming between groups
of small, subpixel-scale icebergs). Wind speed and direction were investigated
as important factors in local fast-ice growth/breakout events.
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