Geoscience Reference
In-Depth Information
3.4. Conclusion
The ocean-atmosphere interactions are central in the climate
functioning, through their role in the transfer of energy and matter
between both systems. They are involved in small-scale processes but
with spatial and temporal variations on all scales. These complex
processes involve the physics, chemistry and biology inside extremely
variable turbulent phenomena, bubbles and waves. Surface fluxes are
also difficult to measure and quantify precisely because of the
immensity of the oceanic regions. However, recent work (particularly,
since the 1990s) has permitted the consolidation of simple
parameterization approaches enabling fluxes to be estimated using
average data, whether they are measured
in situ
or from space, while
new, more precise instrumented platforms (moored buoys and surface
floats, either drifting or remotely guided) are coming into use.
These developments essentially concern local processes. The
transfer to larger scales (those that are represented in coupled ocean-
atmosphere models) remains open to discussion: how are the
exchange processes in space and time aggregated, taking into account
different scales of variability in the ocean and atmosphere? What
errors occur through the use of simplified local formulations in the
study or modeling of the mechanisms of interseasonal to interannual
climatic variability?
If satellite observations shed light on otherwise inaccessible
information, the retrieved variables are likely to be obtained with
insufficient precision, and are hence often of poor spatial and temporal
resolution. Areas for improvement range from the sensors, to their use
in models, but the question of how representative this information is for
the ocean-atmosphere interface is crucial, in terms of precision and
the scale of observation.
The challenges for the coming years are to be defined by the joint
use of available information. The assimilation tools for the data and
modeling will be essential in making the link between local and
regional scales. Already, approaches which use coupled models on a
fine scale for particular climatic regions are being developed to
understand the causes of systematic biases in climatic simulations.
