Geography Reference
In-Depth Information
Analysis 12UTC 21 February 1979
H
L
L
Fig. 12.10
10 hPa geopotential height analyses for February 11, 16, and 21, 1979 at 12UTC showing
breakdown of the polar vortex associated with a wave number 2 sudden stratospheric
warming. Contour interval: 16 dam. Analysis from ERA-40 reanalysis courtesy of the
European Centre for Medium-Range Weather Forecasts (ECMWF).
and Newtonian cooling, S
αq
, where α is the dissipation rate coefficient.)
Multiplying (12.23) by q
and averaging zonally after noting that
=
∂q
∂x
=
u
2
∂q
2
∂x
=
u q
0
yields with the aid of (10.26)
∂A
∂t
+
∇·
F
=
D
(12.25)
where
wave activity
, A, and dissipation, D, are defined, respectively, as
ρ
0
(q
)
2
2∂q/∂y
, and D
ρ
0
S
q
∂q/∂y
.
A
≡
≡−
(12.26)