Geoscience Reference
In-Depth Information
Measurement level
zz
1
∆
U
V
m(abs)
|V
m(rel)
|
V
0
Fig. 9.6
Diagram showing how measurement of velocity at one level in the IOBL may be used to
estimate the surface velocity and undersurface hydraulic roughness
Fig. 9.7
The model hodograph from the September 20 example. Velocity measured relative to
the ice at 6m is used to scale the surface layer velocity, hence
V
0
. The ice velocity from satellite
navigation, V
ice
, includes inertial and geostrophic shear effects not modeled. North is up
Avector extending from the model coordinate origin to this point then represents
the ice velocity
relativeto the underlyingoceanin the modelreferenceframe.
The model is then oriented by aligning the modeled and measured relative current
vectors at the measurement level. This entails multiplying horizontal velocity vec-
torsbya complexfactor:
(
V
0
)
V
obs
V
m(abs)
−
r
=
(9.3)
V
0
TheentirevelocitysolutionfortheexampleisdiagrammedinplanviewinFig.9.7.
The model velocity relative to an observer on the ice matches the observedcurrent
