The Atmosphere: Part 6: The Hadley Circulation • Composition / Structure • Radiative transfer • Vertical and latitudinal heat transport • Atmospheric circulation • Climate modeling Suggested further reading: James, Introduction to Circulating Atmospheres (Cambridge, 1994) Lindzen, Dynamics in Atmospheric Physics (Cambridge, 1990)
The Atmosphere: Part 6: The Hadley Circulation. Composition / Structure Radiative transfer Vertical and latitudinal heat transport Atmospheric circulation Climate modeling. Suggested further reading: James, Introduction to Circulating Atmospheres (Cambridge, 1994) - PowerPoint PPT Presentation
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The Atmosphere:Part 6: The Hadley Circulation
• Composition / Structure
• Radiative transfer
• Vertical and latitudinal heat transport• Atmospheric circulation• Climate modeling
Suggested further reading:
James, Introduction to Circulating Atmospheres (Cambridge, 1994)
Lindzen, Dynamics in Atmospheric Physics (Cambridge, 1990)
Calculated rad-con equilibrium T vs. observed T
pole-to-equator temperature contrast too big in equilibrium state (especially in winter)
Zonally averaged net radiation
Diurnally-averaged radiation
Implied energy transport: requires fluid motions to effect the implied heat transport
Observed radiative budget
Roles of atmosphere and ocean
Trenberth & Caron (2001)
net
ocean
atmosphere
Rotating vs. nonrotating fluids
Ω
φ
u
ΩΩsinφ
f = 0
f > 0
f < 0
Hypothetical 2D atmosphere relaxed toward RCE
φ
x
0
2D: no zonal variations
Annual mean forcing — symmetric about equator
A 2D atmosphere forced toward radiative-convective equilibrium
Te(φ,p) dQ
dt cp
dTdt
g dzdt
J
(J = diabatic heating rate per unit volume)
dTdt
w J cp
1 T Te , z
Hypothetical 2D atmosphere relaxed toward RCE
dTdt
w 1 T Te , z
φ
dudt
fv g zx
0
u t
v uy
w u z
fv 0
m ur r2
uacos a2 cos2
a
r
φ
Ω
dmdt
m t
u m 0
Above the frictional boundary layer,x
0
Absolute angular momentum per unit mass
Angular momentum constraint
dmdt
m t
u m 0
φ
Above the frictional boundary layer,
In steady state,
u m 0
m uacos a2 cos2
Alan Plumb
Angular momentum constraint
dmdt
m t
u m 0
φ
Above the frictional boundary layer,
In steady state,
u m 0
Either 1) v=w=0 Or 2) but m constant along streamlines
dTdt
w 1 T Te , z
T = Te(φ,z)
m uacos a2 cos2
φ 0 15 30 45 60U(ms-1) 0 32 134 327 695
v Ty
w Tz
1 T Te , z
v, w 0
u a sin 2cos
(if u=0 at equator)
Alan Plumb
Angular momentum constraint
dmdt
m t
u m 0
φ
Above the frictional boundary layer,
In steady state,
u m 0
Either 1) v=w=0 Or 2) but m constant along streamlines
dTdt
w 1 T Te , z
T = Te(φ,z)
m uacos a2 cos2
φ 0 15 30 45 60U(ms-1) 0 32 134 327 695
u a sin 2cos
v Ty
w Tz
1 T Te , z
v, w 0
(if u=0 at equator)
Alan Plumb
u m 0
2) v 0
solution (2) no good at high latitudes
1) v 0 ; T Te , zNear equator, Te A B 2
up
Rfp
Ty
Rap
12 sin
T RB
ap
u finite (and positive) in upper levels at equator; angular momentum maximum there; not allowed
solution (1) no good at equator
Hadley Cell
T = Te
u m 0
2) v 0
solution (2) no good at high latitudes
1) v 0 ; T Te , zNear equator, Te A B 2
up
Rfp
Ty
Rap
12 sin
T RB
ap
u finite (and positive) in upper levels at equator; angular momentum maximum there; not allowed