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Figure 3.5 Observed
zonal (east-west) winds over
the planet Jupiter, averaged
over longitude, as functions
of pressure as the vertical
coordinate and latitude as
the horizontal. Winds are
expressed in units of meters
per second. (Adapted from
Flasar et al.
2004
)
1
0
40
40
40
0
0
0
0
40
10
0
0
0
0
0
40
40
80
100
40
40
120
80
30
0
-30
-80
Latitude (degree)
characteristics found in the terrestrial QBO. Additionally, as with terrestrial
models, simulations of planetary atmospheres, such as that of Jupiter, have
produced unstable zonal jets.
Strong linkages also exist between the QBO and solar activity. For
example, while the QBO is primarily driven by gravity wave interaction,
researchers identified as early as the 1980s that a linkage exists between the
QBO and sunspot activity. Although previous research stated that the north
polar stratosphere during winter tended to be colder during the west phase of
the QBO, Labitzke discovered that, at solar maximum, the polar stratosphere
was warm if the QBO was in its west phase (Labitzke
1987
). Subsequent
work by Labitzke with van Loon showed that the solar cycle and QBO were
linked such as in the case of west-phase QBO years (Labitzke and van Loon
1988
). There was a strong correlation with warmer winters when the Sun was
active and colder winters when the Sun was less active. Although their results
were statistically significant, they could not identify a strong physical expla-
nation for the linkage.
Recent studies have refined that initial work by suggesting that a strong
connection exists between solar ultraviolet irradiance and the QBO. Small
changes in solar radiative forcing - as seen through modeling studies - can
serve as pacemakers to the period and phrase of the QBO. For example, a
recent study indicated that average UV irradiance tends to be higher for the
east QBO phase and lower for the west phase.
A key impact of this stratospheric oscillation in equatorial winds is the
generation and propagation of planetary scale waves that move poleward.
These planetary scale waves strongly influence the extratropical tropospheric
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