129
1991, Bougeault et al. 1991) showed evidence of the existence of OMCs between a forest
and agricultural areas. Segal et al. (1989) observed a significant difference in turbulent
activity, air temperature and water vapor in the lower boundary layer between irrigated
areas and surrounding dry land. More recently, Mahrt et al. (1994) observed a cool
moist inland breeze which flowed outward from the center of an irrigated area during the
California Orone Deposition Experiment. This evidence is still inconclusive, however it
should be kept in mind that OMCs of different origin, such as sea and lake breezes, and
slope and urban island circulations are known to occur regularly and to significantly affect
regional climates (e.g. Atkinson 1981, Giorgi and Mearns 1991). Therefore, even if the
global impact of OMCs is not large, the effect of OMCs can be significant on the regional
scale and may need to be accounted for in climate simulations applied to regional studies.
5. Summary considerations
In this paper surface modeling has been placed within the context of the emergency of
a new research activity in environmental and climate modeling, that of coupled climate
system modeling. Within this context, ESEMs acquire the very important role of interfacing modules between the different components of the climate system, a role which is
substantially more complex than that traditionally assumed by ESEMs in current climate
models. This will likely require new thinking in the development of physical formulations
as well as modeling architectures.
In particular, this new perspective will require a truly interdisciplinary effort of understanding the structure and behavior of models of the different climate system components
and the temporal and spatial scales characteristic of the interactions among these components. The range of scales involved is very wide and may differ for different physical
processes. Representing the interactions of processes occurring on broad ranges of scales
is one of the great challenges facing climate system modeling.
In this paper a review was presented of different approaches to surface modeling,
from the early highly parameterized model formulations to state-of-the-art ESEMs which
include attempts to describe the basic biophysical processes which regulate the surface
water and energy budgets. State-of-the-art ESEMs have reached a high level of complexity, a complexity that is considered sometimes excessive when compared to other physics
representations in climate models and to the availability of observations. We have seen,
however, that within the context of climate system modeling, ESEMs assume a central
interfacing role, so that they need to describe the complex range of processes which determine the interactions between the atmosphere, the biosphere and the hydrosphere.
Many different ESEMs are today available, with performances surprisingly different
from each other, given that they mostly derive from a few basic schemes. A strong
1991, Bougeault et al. 1991) showed evidence of the existence of OMCs between a forest
and agricultural areas. Segal et al. (1989) observed a significant difference in turbulent
activity, air temperature and water vapor in the lower boundary layer between irrigated
areas and surrounding dry land. More recently, Mahrt et al. (1994) observed a cool
moist inland breeze which flowed outward from the center of an irrigated area during the
California Orone Deposition Experiment. This evidence is still inconclusive, however it
should be kept in mind that OMCs of different origin, such as sea and lake breezes, and
slope and urban island circulations are known to occur regularly and to significantly affect
regional climates (e.g. Atkinson 1981, Giorgi and Mearns 1991). Therefore, even if the
global impact of OMCs is not large, the effect of OMCs can be significant on the regional
scale and may need to be accounted for in climate simulations applied to regional studies.
5. Summary considerations
In this paper surface modeling has been placed within the context of the emergency of
a new research activity in environmental and climate modeling, that of coupled climate
system modeling. Within this context, ESEMs acquire the very important role of interfacing modules between the different components of the climate system, a role which is
substantially more complex than that traditionally assumed by ESEMs in current climate
models. This will likely require new thinking in the development of physical formulations
as well as modeling architectures.
In particular, this new perspective will require a truly interdisciplinary effort of understanding the structure and behavior of models of the different climate system components
and the temporal and spatial scales characteristic of the interactions among these components. The range of scales involved is very wide and may differ for different physical
processes. Representing the interactions of processes occurring on broad ranges of scales
is one of the great challenges facing climate system modeling.
In this paper a review was presented of different approaches to surface modeling,
from the early highly parameterized model formulations to state-of-the-art ESEMs which
include attempts to describe the basic biophysical processes which regulate the surface
water and energy budgets. State-of-the-art ESEMs have reached a high level of complexity, a complexity that is considered sometimes excessive when compared to other physics
representations in climate models and to the availability of observations. We have seen,
however, that within the context of climate system modeling, ESEMs assume a central
interfacing role, so that they need to describe the complex range of processes which determine the interactions between the atmosphere, the biosphere and the hydrosphere.
Many different ESEMs are today available, with performances surprisingly different
from each other, given that they mostly derive from a few basic schemes. A strong