66
Overall, the kinematic arguments resorted to for gaining insight into the upwelling
mechanism are seemingly in accordance with the momentum budget, although there remain
some minor discrepancies.
Conclusion. The interpretation methods used above have been able to reduce, by hefty dose
of physical intuition, three-dimensional results to two-dimensional plots, "rms" figures or
simple, short, analytic formulae, such as (37). Synthetic information has thus been obtained
from the 26,900 grid nodes where the flow field variables are discretized.
The analysis technique of the vertical velocity, based on the distinction between upsloping
and upwelling velocity fields, has been shown to work rather well for two main reasons. First,
upsloping and upwelling are very different processes. Second, the typical profiles of the
corresponding vertical velocities are completely dissimilar.
The vertical velocity field produced by the model in the vicinity of the Anadyr Strait is
qualitatively in agreement with the observations. According to the results of the model, the
Anadyr Strait plume of cold water is caused by an upwelling process, possibly combined with
upsloping and turbulent diffusion. The upwelling mechanism identified in the simulated
currents closely resembles the classical Ekman pumping process, which is a concept generally
applied to the surface or bottom boundary layers in deep seas. It is proposed that the notion of
shallow-sea Ekman pumping be introduced, as a process concerning the whole water column.
The velocity field discussed above has been used as an input to an ecological model,
confirming the crucial role of the Anadyr Strait upwelling in fuelling the primary production
(Adam, 1990; Nihoul et ai., 1993b).
6. Some results of a World Ocean model
Another problem of interest is that of predicting the evolution of the Earth's climate under
natural and anthropogenic forcings.
Mankind is currently conducting an "experiment" with the global climate. Each year, billions
of tons of carbon dioxide, an acknowledged greenhouse gas, are released into the atmosphere,
primarily as a result of the combustion of fossil fuels, i.e., coal, oil or gas. Other greenhouse
gases, namely methane, nitrous oxide and chlorofluorocarbons, are also being released. Large
amounts of these gases remain in the atmosphere, so that the atmospheric concentration in
greenhouse gases is increasing, which will significantly alter the Earth's climate. In a few
decades, the global temperature may increase to a level unprecedented in the recorded history of
mankind (Houghton et aI., 1990; Houghton et aI., 1992). It is believed that all human activities
will be affected, directly or indirectly, by any warming of the atmosphere - even of a few
degrees - and any associated modification of the rainfall.
Mathematical models are the only tools that can take up the challenge of predicting future
climates.
The Earth's climate system consists of the atmosphere, the hydrosphere, the cryosphere, the
surface lithosphere and the biosphere. These components have quite different physical
characteristics and time scales, and are linked to each other and to conditions external to the
system by a variety of physical processes. Ideally, climate models should treat all these
components in an interactive way, which is virtually impossible today, since the power of the
available computers is not sufficient.
Overall, the kinematic arguments resorted to for gaining insight into the upwelling
mechanism are seemingly in accordance with the momentum budget, although there remain
some minor discrepancies.
Conclusion. The interpretation methods used above have been able to reduce, by hefty dose
of physical intuition, three-dimensional results to two-dimensional plots, "rms" figures or
simple, short, analytic formulae, such as (37). Synthetic information has thus been obtained
from the 26,900 grid nodes where the flow field variables are discretized.
The analysis technique of the vertical velocity, based on the distinction between upsloping
and upwelling velocity fields, has been shown to work rather well for two main reasons. First,
upsloping and upwelling are very different processes. Second, the typical profiles of the
corresponding vertical velocities are completely dissimilar.
The vertical velocity field produced by the model in the vicinity of the Anadyr Strait is
qualitatively in agreement with the observations. According to the results of the model, the
Anadyr Strait plume of cold water is caused by an upwelling process, possibly combined with
upsloping and turbulent diffusion. The upwelling mechanism identified in the simulated
currents closely resembles the classical Ekman pumping process, which is a concept generally
applied to the surface or bottom boundary layers in deep seas. It is proposed that the notion of
shallow-sea Ekman pumping be introduced, as a process concerning the whole water column.
The velocity field discussed above has been used as an input to an ecological model,
confirming the crucial role of the Anadyr Strait upwelling in fuelling the primary production
(Adam, 1990; Nihoul et ai., 1993b).
6. Some results of a World Ocean model
Another problem of interest is that of predicting the evolution of the Earth's climate under
natural and anthropogenic forcings.
Mankind is currently conducting an "experiment" with the global climate. Each year, billions
of tons of carbon dioxide, an acknowledged greenhouse gas, are released into the atmosphere,
primarily as a result of the combustion of fossil fuels, i.e., coal, oil or gas. Other greenhouse
gases, namely methane, nitrous oxide and chlorofluorocarbons, are also being released. Large
amounts of these gases remain in the atmosphere, so that the atmospheric concentration in
greenhouse gases is increasing, which will significantly alter the Earth's climate. In a few
decades, the global temperature may increase to a level unprecedented in the recorded history of
mankind (Houghton et aI., 1990; Houghton et aI., 1992). It is believed that all human activities
will be affected, directly or indirectly, by any warming of the atmosphere - even of a few
degrees - and any associated modification of the rainfall.
Mathematical models are the only tools that can take up the challenge of predicting future
climates.
The Earth's climate system consists of the atmosphere, the hydrosphere, the cryosphere, the
surface lithosphere and the biosphere. These components have quite different physical
characteristics and time scales, and are linked to each other and to conditions external to the
system by a variety of physical processes. Ideally, climate models should treat all these
components in an interactive way, which is virtually impossible today, since the power of the
available computers is not sufficient.