RELATIONSHIP BETWEEN OCEAN AND ATMOSPHERE
THE EFFECTS OF OCEAN ON CLIMATE
The salinity of the ocean
In areas where there are high evaporations,
the water of the sea becomes saltier, while salinity drops
in cooler regions, due to melting ice. Salinity of oceans
changes between 30 and 37 (3 and 3,70%). Seawater contains
on average about 35 grams of salt per liter.
As can be expected, the density of sea water is more dependent
on the salinity that temperature. Sea water density is also
more sensitive to temperature than that of fresh water. Note
the maximum density of 4,01 to 5 and salinity 5 (0,50%). (in
fact 39,92 to 37,4°F (4,40 to 3ºC) for 0,50% of salinity)
and a similar value for fresh water at 39,92°F (4ºC).
This maximum of density disappears for ocean water. Cold seawater
is about 2,40% heavier than hot or cold fresh water.
The distribution of the surface salinity is less zonal
than the temperature. The zonal nature of the temperature
distribution is due to the fact that the surface temperature
is related to the sunniness, which strongly depends on the
latitude. The first factor that determines the salinity is
the balance of evaporation - precipitation that is less zonal
than sunniness (strong influence of continental climates).
Thus, the effects of very high evaporation at level of subtropical
anticyclones (such as the Azores) appear clearly in surface
salinity distribution. Conversely, abundant
precipitations of the equatorial region made salinity
lower in the vicinity of the equator. Other phenomena have
visible effects, such as the contribution of the great rivers,
particularly in the Atlantic Ocean, which receives the waters
of the largest rivers of the world (Amazon, Niger, Congo).
Salinity drops in cooler regions, due to melting ice. Ocean
salinity varies between 30 and 37 (3 and 3,70%). Sea water
titrates on average about 35 grams of salt per liter.
The average salinity of surface water
(relative to the average of 1987-1990)
Click here to enlarge
Click here to
see a video (1.73 MB) of the anomaly
of the SSS (Salinity of Sea Surface) simulated
over the period of the years 1582-1825
Annual changes in ocean salinity are low,
except locally, in areas with a climate alternating heavy
rainfalls and a dry periods (eg :
monsoons in the Indian Ocean).
The temperature of the ocean
The ocean is warmer than the air on average
(yearly), the temperature variations are on average quite
low (about 33,44°F (0,80°C) in the tropics) apart
near some coasts and in the glacial regions.
Average annual temperature of the surface
water of the ocean (°C)
Annual variation of monthly temperatures
(in°C).Values shown represent
the difference between the average of the hottest and coldest
This graph was created and is updated
according to the data of NOAA
Variation of precipitations depends on the
variation of the ocean temperature.
On the west of the Pacific, under the influence
of the trade winds a huge
hot water tank forms, as big as the US surface. But in periods
of 3 to 7 years, the trade winds weaken and warm waters reach
the eastern Pacific. This is a climatic anomaly known as El
Niño, appearing in December on the coasts of Peru.
This sea surface temperature anomaly causes significant thunderstorm
activity, where usually reigns drought. Formation of hurricanes
is favored by the transfer of hot water and usually affects
spared areas as Polynesia. El Niño changes climates
causing floods and
here to see a simulation of rainfall anomalies caused by
the temperature of the surface of the sea observed from 1982
In the North Atlantic, a phenomenon called
the North Atlantic Oscillation (NAO)
is the main mode of climate variability in this area. Come
from the interaction between ocean and atmosphere, its activity
is more pronounced in winter.
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