Arctic Ocean Circulation
355
and eastern part of the domain and sparse in the northern and westerns parts. The
Atlantic inflow branches in two currents at the northern coast of Norway: one
branch continues northward into the Barents Sea and the other branch (the West
Spitsbergen Current) continues towards Fram Strait. Both branches finally enter
the Arctic basin. A sketch of the circulation over the Arctic basin is plotted in
Fig. 15.4b. A major feature of the circulation is the Arctic Ocean Boundary
Current (AOBC) with a transport of about 3-5 Sv together with cyclonic gyres in
the different basins. There are boundary undercurrents along all of the major topography and these flows are the strongest persistent features in the Arctic Ocean.
These boundary currents are a few tens of kilometers wide and they are trapped
over the margins of each of the major basins.
Additional Material
B: The description of all characteristics of Arctic Oceanography, in particular the
different water masses, is far beyond the scope of this book and other sources
should be consulted. Many details can be found in Chapter 7 of Tomczak and
Godfrey (1994). On the role of the Arctic in the global climate system, see for
example Bobylev et al. (2003).
15.2. Quasi-geostrophic flows with topography
In this section, we will present basic theory to understand the effects of
bathymetry, such as in the Arctic, on the bottom current structure. We will start
with explaining in more detail the concept of geostrophic contours (section 15.2.1)
and then proceed with quasi-geostrophic theory of flows in the presence of closed
geostrophic contours (section 15.2.2).
15.2.1. Geostrophic contours
In section 4.4, the concept of potential vorticity was introduced and its usefulness was shown in many following chapters. If we consider the shallow-water
potential vorticity Π under conditions of small Rossby number (such that the relative vorticity is much smaller than the planetary vorticity), it reduces to
Π=
f
H
,
(15.1)
where f is the local Coriolis parameter (f =2Ωsinθ)andH is the total depth of
the ocean. When Π is conserved and the assuming a steady flow, it follows that
DΠ
dt
= u ·∇Π=u ·∇(
f
H
)=0,
(15.2)
355
and eastern part of the domain and sparse in the northern and westerns parts. The
Atlantic inflow branches in two currents at the northern coast of Norway: one
branch continues northward into the Barents Sea and the other branch (the West
Spitsbergen Current) continues towards Fram Strait. Both branches finally enter
the Arctic basin. A sketch of the circulation over the Arctic basin is plotted in
Fig. 15.4b. A major feature of the circulation is the Arctic Ocean Boundary
Current (AOBC) with a transport of about 3-5 Sv together with cyclonic gyres in
the different basins. There are boundary undercurrents along all of the major topography and these flows are the strongest persistent features in the Arctic Ocean.
These boundary currents are a few tens of kilometers wide and they are trapped
over the margins of each of the major basins.
Additional Material
B: The description of all characteristics of Arctic Oceanography, in particular the
different water masses, is far beyond the scope of this book and other sources
should be consulted. Many details can be found in Chapter 7 of Tomczak and
Godfrey (1994). On the role of the Arctic in the global climate system, see for
example Bobylev et al. (2003).
15.2. Quasi-geostrophic flows with topography
In this section, we will present basic theory to understand the effects of
bathymetry, such as in the Arctic, on the bottom current structure. We will start
with explaining in more detail the concept of geostrophic contours (section 15.2.1)
and then proceed with quasi-geostrophic theory of flows in the presence of closed
geostrophic contours (section 15.2.2).
15.2.1. Geostrophic contours
In section 4.4, the concept of potential vorticity was introduced and its usefulness was shown in many following chapters. If we consider the shallow-water
potential vorticity Π under conditions of small Rossby number (such that the relative vorticity is much smaller than the planetary vorticity), it reduces to
Π=
f
H
,
(15.1)
where f is the local Coriolis parameter (f =2Ωsinθ)andH is the total depth of
the ocean. When Π is conserved and the assuming a steady flow, it follows that
DΠ
dt
= u ·∇Π=u ·∇(
f
H
)=0,
(15.2)