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200 m/sec
400
Equatorward
velocity
300
200
100
908
608
308
08
(a)
400
300
225
Eastward
velocity
2
50
300
200
0
0
100
2
50
275
0
0
2
25
200
25
200
2
25
100
(b)
400
50
0
50
100
15
2
100
2
Temperature
perturbation
300
2
150
2
2
50
250
50
50
0
0
0
2
200
2
250
200
50
0
100
90
8
80
8
70
8
60
8
50
8
Latitude
40
8
30
8
20
8
10
8
0
8
(c)
Figure 3.30a
“Snapshot” of the global disturbance wind at time
2 h after a strong
auroral event. (a) Equatorward neutral wind velocity profiles every 3
◦
in latitude.
(b) Eastward neutral wind velocity. The contour spacing is 100 m/s for the solid lines and
25m/s for the dashed lines. (c) Neutral temperature perturbation. The contour spacing
is 50K. [After Richmond and Matsushita (1975). Reproduced with permission of the
American Geophysical Union.]
=
can be affected by heat input during such storms. Richmond and Matsushita
(1975) have modeled the effect of an isolated magnetospheric substorm lasting
for two hours near 70
◦
latitude. At the end of this time they calculated the pat-
terns of wind and temperature variation shown in Fig. 3.30a. A large disturbance
is seen to propagate equatorward at a speed of about 750m/s. The simulation
shows that the effect reaches the equator with very little attenuation but requires
many hours to arrive. The effect is larger in the meridional wind component than
in the zonal component. An example of a set of waves passing Arecibo, PR, and
later creating an intense convective ionospheric storm (aka equatorial spread F)
at the equator is shown in Fig. 3.30b. This set of waves was caused by a series
of magnetic substorms. Notice the downward phase progression in the lowest
panel, a signature of gravity wave propagation.
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