RELATIONSHIP BETWEEN OCEAN AND ATMOSPHERE
Gulf Stream is a surface ocean current, warm along the
US coast from the Gulf of Mexico and that goes to the north-eastern
Atlantic Ocean, pushed by the prevailing southwestern winds,
getting gradually cooling . The Gulf Stream is one of the
strongest currents. It moves warm water from the subtropical
zones toward the poles.
In autumn, the Gulf Stream moves to the north, while
in the winter and spring it moves to the south (Auer 1987
; Kelly and Gille 1990 ; Frankignoul et al. 2001). Compared
to the width of the current (approximately 100-200 kilometers),
the range of this variation (30-40 km) is relatively small
(Hogg and Johns 1995). However, recent studies by Mariano
and others (2002) suggest that the southern range of the annual
change in the path of the Gulf Stream could be closer to 100
According to Geosat altimetry results, the current carries
a maximum amount of water in autumn and minimum in spring,
in phase with the shifts north-south position (Kelly and Gille
1990; Zlotnicki 1991; Kelly 1991; Hogg and Johns 1995). Rago
and Rossby (1985) and Fu et al. (1987) found similar results
when they looked at the differences in the level of the sea.
All these studies have found that the Gulf Stream has a marked
seasonal variability, with the peak to peak amplitude of surface
height sea of 10-15 centimeters. The fluctuation is mostly
confined to 200-300 m above the water, it is a result of global
warming and the seasonal expansion of surface waters (Hogg
and Johns 1995). But changes in the transport of deep water
seem to be almost opposite to the phase of surface waters,
and their size is more significant (Hogg and Johns 1995).
Le Gulf Stream jusqu'à la la Mer du Nord
Le Gulf Stream à la sortie
du Golfe du Mexique
Ocean currents like the Gulf Stream, distribute heat
around the globe, as the atmosphere. According to calculations,
ocean currents provide much of the heat released in the winter.
But contrary to what many people think, the Gulf Stream has
a small influence on the thermal contrast between the Europeans
and Americans winters. On the other hand, ocean currents play
a more important role in the north, by preventing the formation
of sea ice along the Norwegian coasts. Based on numerical
simulations oceanic transport of heat increases winter temperatures
in Northeastern America and Western Europe up 35,6 to 37,4°F
(2 to 3°C) either 10% of the warming generated by atmospheric
OF HEAT BETWEEN THE OCEAN AND THE ATMOSPHERE
Like the atmosphere, the ocean plays an important rule
on the climate. The water heats up more slowly than air, but
it cools less rapidly unlike at the air. The ocean has a "memory"
significantly longer than the atmosphere of the seasonal order
concerning current of surfaces of the decade at least in regard
to large masses of water in the deep ocean.
La The heat stored like that in the water of the tropics
is returned to the atmosphere at higher latitudes. Thus are
generated ocean surface currents and depths that carry the
heat from the equator to the poles. This helps to balance
the excess of solar radiation received by the equatorial regions.
Atlantic conveys probably more heat from the equator to the
north thand the Pacific. It is estimated that the ocean contributes
of about 30% to transport of the heat from equator to the
poles, made by the climate system.
here to see an larger animation of the evolution
of the ocean temperatures according to month
During this transport, ocean and atmosphere
continually exchange energy: on the surface of the ocean,
these exchanges form superior flows to those streams proceeding
from the Sun in the form of visible light. They are in the
form of infrared radiation at wavelengths of the order of
10 to 12 µm. On the other hand, a very important exchange
(in fact dominant) is made in the form of latent heat by the
evaporation and condensation of the ocean water in the atmosphere.
With the evaporation of water, this is higher in tropical,
salinity increases but decreases with contribution of freshwater
from rainfall and rivers.
A second essential term in exchange of energy
between the ocean and the atmosphere is due to the friction
of the wind on the ocean surface.
In summer, the sunniness is more important
that warms the ocean surface. The winds shake the ocean water
and redistribute this heat on a layer of a few about ten of
meters of depth. Then this layer stores this energy. Then
when winter comes, the sunniness is less important and the
winds more violent. Ocean cools slowly releasing its heat
into the atmosphere.
On the left stocking of the heat during summer.
On the right after the dropping of the heat,
the waters become colder and denser
blue) and plunge.
Then they are replaced with deeper water
warmer and less dense (dark
here to see currently the temperature of the surface of the