| On the basis of ozonesonde records up to 1998 the responses on the
equatorial quasi-biennial oscillation (QBO), manifesting in ozone,
temperature, and wind (QBO effects) were isolated in the region from the
ground to altitudes as high as 35km at 22 stations located in Europe (7),
North America (7), Japan (4), Hawaii (1), Australia (2), and Antarctic (1).
The vertical structures of the QBO effects of ozone are represented as an
alternation of layers of well-developed quasi-biennial signals, whose phases
gradually change with height and thin transitional layers of ill-developed
signals, whose phases change abruptly with height. The amplitudes of the
effects depend on height and reach the maxima of 3–6nbar in the lower
stratosphere. At the majority of sites the effects are found to be
approximately in phase between 20 and 23km.
Two types of the vertical structures of the temperature QBO effects are
found. At most of the sites located equatorward of about 50° the
stratospheric temperature anomalies are characterized by downward
propagation, whereas at sites situated poleward of about 50° they
look as column-like structures. Near the tropopause the effects frequently
reveal dipole-like structure, when the stratospheric and tropospheric
anomalies are of opposite signs. The amplitudes of the effects are in the
range of 0.5–1°C.
The vertical structures of the QBO effects of horizontal wind components
reveal a diversity of patterns. The amplitudes of the QBO effects of the
meridional and zonal winds are comparable and lie in the range of 0.5–2m s–1. As a rule, the maxima of the effects are noticed slightly below the
tropopause, as well as in the middle stratosphere.
In general, a statistical assurance of the obtained QBO effects is rather
poor. However, a considerable part of them reveal similarity, which can be
hardly explained by chance. Furthermore, the results agree with possible
physical mechanisms of off-equatorial influence of the QBO, as well as with
results of other observational studies.
Differences between the QBO effects obtained at different sites can be
induced by peculiarities of corresponding ozonesonde records, differing by periods,
gaps, number of sondes, errors of measurements, etc. Also, the
differences can be associated with an inconstancy of characteristics of the
equatorial QBO itself, as well as with an interdependency of the QBO and the
annual cycle. Finally, the differences can reflect real regional
characteristics of the QBO effects associated with local peculiarities of
the large-scale circulation.
Key words. Meteorology and atmospheric dynamics (climatology;
general circulation; middle atmosphere dynamics) |