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3st PART
THE EFFECTS OF OCEAN ON CLIMATE CHANGES 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.
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 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
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
droughts,
sometimes catastrophic.
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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