TITLE:
The Role of the Southern Hemisphere Polar Cell on Antarctic Sea Ice Variability
AUTHORS:
Praveen Rao Teleti, Alvarinho J. Luis
KEYWORDS:
Antarctica, Sea Ice, Polar Cell, PCI, ENSO, Teleconnection
JOURNAL NAME:
International Journal of Geosciences,
Vol.7 No.2,
February
24,
2016
ABSTRACT: The study explores modes
of variability in the Southern Polar Cell and their relationship with known
global climate modes and Antarctic sea ice. It is found that Polar Cell is
barotropic in nature and 500 hPa geo-potential height (Z500) field
can satisfactorily represent variability in the Polar Cell. First, three
leading Empirical Orthogonal Function (EOF) modes of Z500account for nearly 80% of observed
variability in the Polar Cell. Dominant mode (PC1500) comprises of
high pressure divergence zone over Antarctica. Second leading mode (PC2500)
is low pressure zone covering Amundsen-Bellingshausen Sea (ABS) similar to ABS
low feature. A new climate mode called Polar Coastal Index (PCI) is defined,
which describes more than 15% and close to 30% variability of circumpolar
trough and ABS low, respectively. Out of four modes defined in this study, only
PCI and PC2500show
linear trends and clear seasonality. Interestingly, both modes are affected by
modulation of ABS low due to tropical ENSO forcing. SAM signature is present in
Polar Cell as PC1500shares
large variance with it. The largest impact on sea ice comes from PC2500followed by PC1500in the Antarctic Dipole regions.
However, this study suggests contemporary sea ice trends cannot be sustained,
and can reverse given that trends in PCI and PC2500favour a reversal. These results
indicate that ENSO-driven Polar Cell variability plays a crucial role influencing
Antarctic sea ice as it interacts with other climate modes and leads the
combined impact at the interannual time scale.