392
MK’HEL COANTIC A N D ALEXANDRE FAVRE
After the complction of working tests and the addition of some minor
improvements, the l.M.S.’l’.’s air-sea interactions simulation facility has
been put into scientific use. Several measurement programs are presently
underway, and the present paper will be mainly devoted to a description of
some preliminary experimental results.
2. REVIEW OF PRELIMINARY WORK
2.1. Consideration of rkc. Ph,ssicml Proccs.\rs
Small-scale energy transfer between the atmosphere and the oceans results
from four main processes: radiative transfer (both short-wave and longwave). evaporation and turbulent transfer of water vapour and latent heat,
sensible heat transfer, and kinetic energy transfer. These processes are intimately linked together through important reciprocal interactions, the most
obvious of which lies in the control of heat and mass transfer rates by
turbulence obtained primarily from the mean kinetic energy. When
compared to the classical problem of simultaneous turbulent momentum,
heat, and mass transfers, air-sea interactions display two new characteristics: firstly, scalar contaminants no longer remain passive, instead they
now introduce important buoyancy effects; secondly. wave generation by
wind alters the flow structure, and correspondingly the transfer mechanisms.
themselves.
2.2. Rrlrwnt Dbnerisionless PuramPtm
If, as can be done in a first approximation, the effects of radiation are
takcn as additive to those of the turbulent transfers. then the exchange rates
can be expressed through friction coefficients, Nusselt numbers, and Sherwood numbers, which depend, themselves, upon the relevant dimensionless
parameters of the problem. Significant modelling will be achieved only if the
values attained in the laboratory by these parameters are of the same order
as those encountered in nature. Thus, very high Reynolds numbers have to
he obtained for a proper representation of the dynamical structure of the
atmospheric surface layer. Richardson numbers of order unity have to be
reached to observe meaningful stability or instability effects. Sufficiently
high Froude numbers and wave ages are necessary to investigate the effects
of wind-generated gravity waves.
2.3. (;cwr.cil Coni*epl ion qj” the Sirnuluting Facility
Keeping the above considerations in mind, the k i l i t y can be described as
a combination ofa tnicromcteorological wind tunnel with a wind-wave tank.
tlic watcr surface in the Iirtter forming the Hoor of the test section in the
MK’HEL COANTIC A N D ALEXANDRE FAVRE
After the complction of working tests and the addition of some minor
improvements, the l.M.S.’l’.’s air-sea interactions simulation facility has
been put into scientific use. Several measurement programs are presently
underway, and the present paper will be mainly devoted to a description of
some preliminary experimental results.
2. REVIEW OF PRELIMINARY WORK
2.1. Consideration of rkc. Ph,ssicml Proccs.\rs
Small-scale energy transfer between the atmosphere and the oceans results
from four main processes: radiative transfer (both short-wave and longwave). evaporation and turbulent transfer of water vapour and latent heat,
sensible heat transfer, and kinetic energy transfer. These processes are intimately linked together through important reciprocal interactions, the most
obvious of which lies in the control of heat and mass transfer rates by
turbulence obtained primarily from the mean kinetic energy. When
compared to the classical problem of simultaneous turbulent momentum,
heat, and mass transfers, air-sea interactions display two new characteristics: firstly, scalar contaminants no longer remain passive, instead they
now introduce important buoyancy effects; secondly. wave generation by
wind alters the flow structure, and correspondingly the transfer mechanisms.
themselves.
2.2. Rrlrwnt Dbnerisionless PuramPtm
If, as can be done in a first approximation, the effects of radiation are
takcn as additive to those of the turbulent transfers. then the exchange rates
can be expressed through friction coefficients, Nusselt numbers, and Sherwood numbers, which depend, themselves, upon the relevant dimensionless
parameters of the problem. Significant modelling will be achieved only if the
values attained in the laboratory by these parameters are of the same order
as those encountered in nature. Thus, very high Reynolds numbers have to
he obtained for a proper representation of the dynamical structure of the
atmospheric surface layer. Richardson numbers of order unity have to be
reached to observe meaningful stability or instability effects. Sufficiently
high Froude numbers and wave ages are necessary to investigate the effects
of wind-generated gravity waves.
2.3. (;cwr.cil Coni*epl ion qj” the Sirnuluting Facility
Keeping the above considerations in mind, the k i l i t y can be described as
a combination ofa tnicromcteorological wind tunnel with a wind-wave tank.
tlic watcr surface in the Iirtter forming the Hoor of the test section in the