  Since the prediction of climate is mainly considered as a prediction of
second kind, it is indispensable to assess the accuracy with which these
boundary conditions can be determined so that we can find a reasonable answer,
whether climate is predictable with a sufficient degree of accuracy or not.
Therefore, our contribution is mainly focused on the accuracy with which the
fluxes of sensible heat and water vapor, required for predicting the lower
boundary conditions in numerical models of the atmosphere using the coupled set
of energy and water flux balance equations for the Earth's surface, can be
determined. The parameterization schemes for the interfacial sublayer in the
immediate vicinity of the Earth's surface and for the fully turbulent layer
above presented and discussed here document that an appreciable degree of
uncertainty exists. It is shown that the great uncertainty inherent in the
universal functions of the Monin-Obukhov similarity laws on which the
parameterization schemes for the fully turbulent atmospheric surface layer are
based is reflected by the considerable scatter in the results of sophisticated
field campaigns. This uncertainty affects also the results for the
gradient-Richardson number, the turbulent Prandtl number, Pr_t, and the
turbulent Schmidt number, Sc_{t,q}, (and the turbulent Lewis-Semenov number,
LS_{t,q}) for water vapor used in such parameterization schemes. It is argued
that the inherent uncertainty prevents that climate is predictable with a
sufficient degree of accuracy.

Atmospheric and Oceanic Physics;Computational Physics