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Data Analysis and Modeling
of the Amundsen Sea Embayment
Yoshihiro Nakayama, Ralph Timmermann, Michael Schr
der
ö
and Hartmut H. Hellmer
Abstract The Pine Island Ice Shelf (PIIS) is melting rapidly, which may have a
large impact on ice sheet dynamics, sea-level rise, and changes in water mass
properties of the surrounding ocean. The reason for the PIIS melting is the relatively
warm (
C) Circumpolar Deep Water (CDW) that approaches the PIIS cavity
through two submarine glacial troughs located on the Amundsen Sea continental
shelf. Since CDW causes melting of some other glaciers in West Antarctica in a
similar way, understanding the PIIS melting helps to understand the impact of
ocean-ice sheet interaction on the mass balance of the West Antarctic ice sheet and
the impact of climate change in the Southern Ocean. Thus, in my PhD study, we
investigate the CDW intrusion onto the Amundsen Sea continental shelf by (a)
analyzing hydrographic data obtained during ANTXXVI/3 in 2010 and (b) using
the Finite Element Sea ice-Ocean Model (FESOM). We focus on the intruding
CDW properties and demonstrate the dif
1.2
°
*
culties of modeling CDW intrusion onto
the Amundsen Sea continental shelf. We further show that the choice of forcing is
not the reason for the difficulties in reproducing the CDW intrusions.
1 Introduction
Pine Island Ice Shelf (PIIS) and Thwaites Glacier (TG) are the major ice streams of
the West Antarctic Ice Sheet (WAIS), draining around 393,000 km
2
, and driving
the largest ice loss of the Antarctic ice sheet (e.g. Shepherd et al.
2001
; Rignot et al.
2002
,
2008
,
2011
,
2013
; Wingham et al.
2009
; Joughin and Alley
2011
; Shepherd
et al.
2012
). The reason for the large ice loss is increased basal melting due to the
interaction of deep-drafted ice shelves with Circumpolar Deep Water (CDW) which
is about 3
°
C warmer than the in situ freezing point (e.g. Jacobs et al.
2011
;
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