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, 01−Nov−1997 to 26−Sep−1998
u
*0
=
τ
0.02
0.015
0.01
6.7 mm /s
0.005
0
350
400
450
500
550
600
650
c
p
<w'T'>
0
,
01−Nov−1997 to 26−Sep−1998
H
f
=
ρ
50
40
30
20
10
7.7 Wm
-
2
0
350
400
450
500
550
600
650
Day of 1997
Fig. 9.14
Modeled friction velocity and basal heat flux for the entire SHEBA project, where the
3-h time series have been smoothed with a seven-day running mean. Average values for the 11
months are shown by dashed lines. Shading indicates a range of values corresponding to model
calculations for the lowest combination of
z
0
and heat transfer coefficient to the highest, with the
range in mean values shown by the gray dot-dashed lines
SHEBAfloe.Fortheperiod2June1998to3October1998,theyestimatedtheaver-
agevaluetobe17
5Wm
−
2
.Giventhevarietyofassumptionsunderlyingeachesti-
mate, the close agreementis probablyfortuitous,but neverthelessadds credenceto
the approach.Perovichetal. (2003)reportapproximatelyequalamountsof surface
and basal ablation, suggesting that about as much energy was absorbed at the sur-
faceasextractedfromtheoceanbymelting.Ontheotherhand,Perssonetal.(2002,
their Fig. 22g) estimate the total energy flux reaching the top of the ice column at
SHEBAtobeabout35Wm
−
2
duringthesummermonths,JunethroughSeptember.
Thusto balancethe energybudgetwould apparentlyrequirethat abouthalf the en-
ergyreachingthesurfaceoftheice wouldhavemadeits wayintotheocean.
At the time of writing, application of the SLTC model for deriving long time
series of ice/ocean exchange is relatively new. However, preliminary comparisons
between model results (from ADPs and upper ocean
T
.
S
sensors) and direct flux
measurements from unmanned drifting buoys as part of the North Polar Environ-
mentalObservatoryprogramarepromising(Shawetal.2008,inpress).Withanew
generation of drifting buoys equipped with profiling CTDs and ADPs, the method
shouldprovideaccurateestimatesofice/oceanfluxes.
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