258
S. Ferrarese et al.
Fig- 6. Latent heat flux measured at 10 m on the inner mast
enthalpy budget in the absence in the first few hundred meters of the boundary
layer, in the vicinity of the Filchner/Ronne ice shelf front in Antarctica, under the
hypothesis of absence of phase exchange of water. In the présent study, on the
contrary, we are interested in investigating also the rôle played by the latent heat
flux in the first few meters of the surface boundary layer on the Hells Gâte ice
sheet (even if some restraint on the présent availability of experimental equipment did not allow us, for the moment, to corne to definite conclusions). In order
to also take the latent heat flux into account, the prognostic first law of thermodynamics, applied to the above-mentioned finite layer in the surface boundary
layer, reads now as follows:
I
II
III
IV
V
VI
ô#
à2#
1 ÔQ.
LÆ
du'.#'
----- + Uj------= Ka------+--------- -2- _ _£--------- 2_
(4)
ax?ax/
pcp axj
pcp
dx}
where # is the potential température,
is the molecular thermal diffusivity, Q is
the net radiation, E is the phase change rate and cp is the spécifie heat at constant
pressure for moist air; term I represents the mean storage of heat (or the local
term),term II describes the advection of heat by the mean wind, term III represents
the mean molecular conduction of heat, term IV is the mean net body source associated with radiation divergence, term V is the body source term associated with
latent heat release and term VI represents the divergence of turbulent heat flux.