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The paper presents and analyzes, from the point of view of smooth dynamic systems theory, a two-layer baroclinic model of
the troposphere in geostrophic approximation. The model describes airflow in β-channel within the tropospheric part of the
main Hadley circulation cell. It enables to obtain, after application of the Galerkin method, a fairly simple low-parametric
dynamic system describing the phenomena of non-linear interactions, bifurcations and blocking in the atmosphere. This enables
to take into consideration such basic factors influencing the atmospheric dynamics like the heat exchange within the surface,
orography, vertical variability of zonal wind and hydrostatic stability.
Impact of zonal thermal variability of the surface and vertical shear of zonal wind in the troposphere on the orographic bifurcation
was investigated and the oscillation character in the dynamic system after Hopf bifurcation of the second kind was analyzed.
Additionally, the model dynamics was investigated in conditions including momentum forcing in the upper and lower parts of
the troposphere and excluding orographic interaction, as well as in the conditions of thermal interaction between the troposphere
and the surface for the vertical shear of zonal wind in both tropospheric layers. Impact of the mean zonal wind in the troposphere
on the properties of model dynamics was assessed.
It was proved that zonally varied surface temperature and layered mean zonal wind in the atmosphere are the parameters that
have basic influence on the model dynamics. They cause numerous bifurcations and strongly influence the periods of oscillations
of the model variables. They are often Hopf bifurcations of the second kind during which tropospheric states fairly distant
from the ones before the bifurcations are generated. This significantly influences the model predictability. 相似文献
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D. M. Sonechkin N. M. Astafyeva N. M. Datsenko N. N. Ivachtchenko B. Jakubiak 《Theoretical and Applied Climatology》1999,64(1-2):131-142
Summary The surface air temperature time series of both hemispheres and the North Atlantic European area as well as the Southern
Oscillation (SO) index time series were analysed using a wavelet transform technique. The values of the so-called singularity
exponents of these series were estimated and compared with such estimations for some surrogate time series artificially created
from the observed temperature series. It was concluded that the climate dynamics on interannual and interdecadal scales may
be considered as a kind of classical Brownian motion although its consideration as a flicker-noise is also possible. The extracted
temperature variations were shown to be closely coupled with the SO process. The wavelet-transformed SO series reveals itself
as a whole self-similar “tree” the main branches of which are the appearances of the strongest El-Ninos of 1898 – 1899, 1941 – 1942,
and 1982 – 1983. Similar “trees” can be seen in the wavelet-transformed temperature series. Thus, the extracted temperature
variations were shown to be closely coupled with the SO process, and a decomposition of the current global climate dynamics
into three climatic epochs (of about 40-year long) seems to be appropriate.
Received May 4, 1998 Revised April 25, 1999 相似文献
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