Geoscience Reference
In-Depth Information
Table 3.2.
Monthly and annual mean energy budget terms for the Arctic Ocean domain
Mon.
Fluxes and Storage Changes
∂ A
E
/∂t
R
top
−
∇
•
F
A
F
sfc
∂O
E
/∂t
S
o
a
L
i
∇•
F
i
−∇•
F
o
b
Res
.
Jan
−4
−178
81
58
−52
−19
−33
3
3
−35
Feb
4
−175
91
53
−47
−16
−31
3
3
−35
Mar
12
−150
93
41
−34
−9
−25
4
3
−28
Apr
25
−96
72
20
−14
6
−20
4
2
−29
May
20
−37
44
−14
18
27
−9
3
2
−27
Jun
19
16
79
−75
79
40
40
3
2
1
Jul
2
10
91
−100
105
35
69
2
3
−1
Aug
−17
−68
92
−45
50
11
39
1
3
−4
Sep
−28
−150
95
18
−13
−5
−8
2
3
−9
Oct
−22
−186
97
58
−52
−4
−48
3
3
−9
Nov
−11
−186
85
59
−53
−29
−25
3
3
−31
Dec
2
−180
90
59
−52
−37
−15
4
3
−33
Mean
0
−115
84
11
−5
0
−5
3
3
−20
a
L
i
is calculated as the difference between the measured terms
∂O
E
/∂t
and
S
o
b
The residual is calculated as
R
top
−∇
•
F
A
+
F
sfc
-
∂ O
E
/∂t
Source:
From Serreze et al., (
2007
).
to assemble estimates of the major terms of the ocean energy budget except Li,
i
,
which they obtained as a residual. The divergence of latent heat as snow and ice
was based the Fram Strait sea ice export using data from Vinje, N. Nordlund, and
A. Kvarnbekk (
1998
) and the oceanic convergence of sensible heat was estimated
based on output from an ice-ocean model. The latter term represents the sum of
heat transports through the Fram Strait, the Barents Sea opening, the Bering Strait,
and the Canadian Arctic Archipelago. Sub-annual information on modeled heat flux
was only archived as seasonal means, so for the annual cycle, the seasonal means
were repeated for each month within a season. Changes in oceanic sensible heat
storage were calculated from the University of Washington Polar Science Center
Hydrographic Climatology data set. Terms of the atmospheric budget were again
based on ERA-40 data. Monthly budget terms provided in
Table 3.2
, must again be
viewed with the caveat of imbalances related to uncertainties in all of the budget
terms. For example, assuming a steady state, the tendency in annual mean oceanic
heat storage, such as that of the atmospheric heat storage, should be approximately
zero. However, the results in
Table 3.1
indicate a mean annual loss of oceanic heat
of 5 W m
−2
. Serreze et al. (
2007
) argue that this is primarily attributed to the net
surface flux from ERA-40 (11 W m
−2
) being too large; based on comparisons with
other datasets, a value of 6 Wm
−2
is likely closer to the truth.
Like the polar cap, there is a clear annual cycle in atmospheric energy storage,
with large changes in the shoulder seasons, and small changes in mid-summer (July)
and during the winter months. However, as a result of the highly irregular shape of
