Geoscience Reference
In-Depth Information
Northward Ice Velocity
0.3
a
0.2
0.1
0
-
0.1
245
250
255
260
265
Eastward Ice Velocity
0.2
b
0
−0.2
−0.4
245
250
255
260
265
SHEBA Wind and Ice Speed
20
0.4
c
15
0.3
Ice Speed
10
0.2
Wind Speed
5
0.1
0
0
257
258
259
260
261
262
263
264
265
Day of 1998
Fig. 8.5 a Northward ice drift velocity during September of the SHEBA project from satellite
global positioning data. b Eastward component. The arrow indicates timeshown in: c Wind speed
anddriftspeedduringthetimefrom257.375(0900UTon14September 1998)to265.0.Thescale
for ice speed is 2%of the wind speed scale (see also Colorplate on p. 210)
the energetic oscillations associated with the rapid change in drift direction from
NW to N (see Fig. 2.3). Reynolds stress measurements are compared with model
estimates in Fig. 8.7. In general, they follow reasonably well, although on day 259
friction velocity6m from the boundaryis inconsistentwith both the 2-m measure-
ments and the model. This may be due to “upstream” disturbance in the underice
morphologyfrom the particular drift direction on that day. Modeled and measured
turbulent heat flux (Fig. 8.8) are also reasonably matched, although the model un-
derestimatesheatfluxat2monday262.Theoverallassessmentisthattherelatively
simple, first-order closure model driven only by wind and initial T/S conditions is
successfulatsimulatingthemainfeaturesofbothsurfacevelocity(includinginertial
oscillation)andupperoceanturbulentfluxes.
 
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