Geoscience Reference
In-Depth Information
1.8 Climate Unit of the Global Model
The climatic component of the GIMS is the greatest dif
culty in the synthesis of the
global model, because it is characterized by a lot of feedbacks, most of which being
unstable. Among them are such as ice-albedo, water vapour-radiation, cloudiness-
radiation, aerosol-radiation, and many others. The functioning of the Earth climatic
system is determined by the state of the atmosphere, oceans, cryosphere, surface of
the continents with land biota, lakes, rivers, ground waters, and various anthro-
pogenic structures. Therefore the construction of the model of climate requires a
consideration of numerous factors, whose role in its formation in many cases has
been studied inadequately. So far, attempts to derive a numerical model of the Earth
climatic system have not given the results that could be used in the GIMS. Also, it
is not safe to say that a realization of the GCP plans will clarify the problem. But
without a parameterization of climate the questions concerning the problem of the
greenhouse effect will remain unanswered.
There are two approaches to the synthesis of the climatic system. One approach
is based on inclusion of biospheric components into the existing climate models or
in those under development. The other approach consists in the development of a
unit within the numerical model of the biosphere, which would simulate depen-
dences of biospheric components on climate parameters. In the former case,
problems appear of unstable solutions of the respective systems of differential
equations, which make it dif
cult to predict global environmental changes. In the
latter case there is a possibility to obtain steady prognostic estimates of the envi-
ronmental changes, but their reliability depends on the accuracy of parameterization
of correlations between the elements of climate and the biosphere. The second
approach is preferable, because it permits one to combine the climate models,
which can be described on the level of scenario, with the numerical model of the
biosphere. A detailed analysis of the problems of climate modeling and assessment
of the present state of the problems can be found in Kondratyev et al. (2004a).
Some models of individual components of the BCSS, which correspond to the
second approach, are discussed here. Among them are models of the atmospheric
general circulation, atmosphere-ocean interaction, sensitivity of climate parameters
to boundary conditions on the Earth
'
s surface, interaction of biogeochemical and
climatic processes, and others.
The climatic system is a physical-chemical-biological system with unlimited
degrees of freedom. Therefore, any attempts to model this complex system are
connected with serious dif
culties. This explains a diversity of parametric descrip-
tions of some processes in this system. For the global model with a time step of
digitization up to 1 year, the use of two versions can be acceptable. The
first version
consists in a combined use of correlations between particular processes of the for-
mation of the climatic situation on a given territory together with the climate sce-
narios. The second version is based on the use of the global monitoring data, which
are the basis for the formation of data series about climatic parameters with their
territorial and temporal attachment and used to retrieve a complete pattern of their
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