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When these droplets then crash back into the sea, they transfer this momentum to the sea surface
as a surface stress. Thus, conceptually at least, sea spray has the potential to alter the near-surface
distributions of momentum and stress on both the air and the water sides of the air-sea interface.
Munk
(
1955
) may have been the first to identify this process.”
In the broader context of the effects of particles suspended in an incompressible gas on
its dynamics, this physical problem had been scrutinised even earlier (
Barenblatt
,
1953
,
1955
;
Kolmogorov
,
1954
). This general-fluid-mechanics approach has been successfully
employed across a very wide range of geophysical applications such as dust storms, snow
avalanches, and suspended sediment both in the ocean and rivers (e.g.
Barenblatt & Golit-
syn
,
1974
;
Bridge & Dominic
,
1984
;
Bintanja
,
2000
). With respect to wave boundary
layer (WBL) in general and high-wind conditions in particular, these old papers have now
been actively referenced too, and their theories are revisited and further advanced (e.g.
Barenblatt
,
1996
;
Makin
,
2005
;
Barenblatt
et al.
,
2005
;
Kudryavtsev
,
2006
;
Kudryavt-
sev & Makin
,
2007
,
2009
,
2010
;
Rastigejev
et al.
,
2011
). Other mechanisms of the sea-
spray influence on the dynamics of WBL have also been explored over the years (e.g.
Bortkovskii
,
1973
;
Borisenkov
,
1974
;
Ling & Kao
,
1976
;
Korolev
et al.
,
1990
;
Lighthill
,
1999
, among others).
In this context, that is the influence of the suspended particles on the turbulent gas (air)
flow, the dynamic impact of the particles (droplets) has two effects: redistribution of the
momentum between the droplets and air-water as in
Andreas
(
2004
) quoted above, and
damping the turbulence in the air.
Kudryavtsev
(
2006
) and
Kudryavtsev & Makin
(
2009
,
2010
) point out that the second effect is stronger.
In general terms, this effect
“leads to suppression of the turbulent mixing and, as a consequence, to the acceleration of the wind
velocity and suppression of the sea-surface drag”
(
Kudryavtsev & Makin
,
2010
).
For modelling this phenomenon, more detailed knowledge on spume generation is needed
in terms of the size of the droplets, the rate of their production and the altitude of their
emission, and the shape of the spume cloud.
The role of the spray emitted into, suspended in and then taken from the air is, however,
not limited to its contributions to the mechanics of air-sea interactions. Around the same
time as the early 'mechanical' papers mentioned above,
Riehl
(
1954
) suggested that the
spray plays a part in providing the heat necessary for the generation and development of
tropical storms.
Different theories have been proposed to explain such heat fluxes over the years.
Andreas
& Emanuel
(
2001
), for example, suggested a mechanism based on a combination of sensi-
ble and latent heat exchanges between the suspended droplets and surrounding air. That is,
their spray particles cool faster than they evaporate, i.e. they give away their sensible heat
while airborne, but are deposited back into the sea before extracting the latent heat from
the air.
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