Geostrophic departure: Difference between revisions

Revision as of 15:19, 20 February 2012

geostrophic departure[edit | edit source]

(Also called geostrophic deviation, ageostrophic wind.) The vector (or sometimes only the magnitude) difference between the real (or observed) wind and the geostrophic wind.

In the atmospheric boundary layer, winds can be subgeostrophic due to turbulent drag against the surface. This causes a steady-state geostrophic departure, written here as separate Cartesian components (V - V_g) and (U - U_g), or

where (U, V) are horizontal wind components, C_D is a drag coefficient, M is total wind speed, (U_g, V_g) are geostrophic winds components, f_c is the Coriolis parameter, and z_i is depth of the boundary layer. The equations above are only approximate (they assume a slab boundary layer with no entrainment), but illustrate the effect.

INDEX
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W
X
Y
Z
0
1
2
3
4
5
6
7
8
9

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-<div class="definition"><div class="short_definition">(<br/>''Also called'' geostrophic deviation, [[ageostrophic wind]].) The [[vector]]  (or sometimes only the magnitude) difference between the real (or observed) [[wind]] and the  [[geostrophic wind]].</div><br/> <div class="paragraph">In the [[atmospheric boundary layer]], winds can be subgeostrophic due to turbulent [[drag]]  against the surface. This causes a steady-state geostrophic departure, written here as separate  Cartesian components (''V'' &minus; ''V''<sub>''g''</sub>) and (''U'' &minus; ''U''<sub>''g''</sub>), or  <div class="display-formula"><blockquote>[[File:ams2001glos-Ge22.gif|link=|center|ams2001glos-Ge22]]</blockquote></div><div class="display-formula"><blockquote>[[File:ams2001glos-Ge23.gif|link=|center|ams2001glos-Ge23]]</blockquote></div> where (''U'', ''V'') are horizontal wind components, ''C''<sub>''D''</sub> is a [[drag coefficient]], ''M'' is total [[wind  speed]], (''U''<sub>''g''</sub>, ''V''<sub>''g''</sub>) are geostrophic winds components, ''f''<sub>''c''</sub> is the [[Coriolis parameter]], and ''z''<sub>''i''</sub> is  depth of the boundary layer. The equations above are only approximate (they assume a slab  boundary layer with no [[entrainment]]), but illustrate the effect.</div><br/> </div>
+<div class="definition"><div class="short_definition">(''Also called'' geostrophic deviation, [[ageostrophic wind]].) The [[vector]]  (or sometimes only the magnitude) difference between the real (or observed) [[wind]] and the  [[geostrophic wind]].</div><br/> <div class="paragraph">In the [[atmospheric boundary layer]], winds can be subgeostrophic due to turbulent [[drag]]  against the surface. This causes a steady-state geostrophic departure, written here as separate  Cartesian components (''V'' - ''V''<sub>''g''</sub>) and (''U'' - ''U''<sub>''g''</sub>), or  <div class="display-formula"><blockquote>[[File:ams2001glos-Ge22.gif|link=|center|ams2001glos-Ge22]]</blockquote></div><div class="display-formula"><blockquote>[[File:ams2001glos-Ge23.gif|link=|center|ams2001glos-Ge23]]</blockquote></div> where (''U'', ''V'') are horizontal wind components, ''C''<sub>''D''</sub> is a [[drag coefficient]], ''M'' is total [[wind  speed]], (''U''<sub>''g''</sub>, ''V''<sub>''g''</sub>) are geostrophic winds components, ''f''<sub>''c''</sub> is the [[Coriolis parameter]], and ''z''<sub>''i''</sub> is  depth of the boundary layer. The equations above are only approximate (they assume a slab  boundary layer with no [[entrainment]]), but illustrate the effect.</div><br/> </div>
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