| Summary: | Den termohalina cirkulationen är en global havscirkulation driven av densitetsskillnader, som gör att varmt vatten transporteras mot polerna och kallt vatten mot ekvatorn. Densiteten påverkas av temperatur och salinitet (och tryck, som vanligtvis ignoreras). Därför heter cirkulationen termohalin. Saliniteten minskar när vatten tillförs genom nederbörd, havsissmältning eller landavrinning. Saliniteten ökar genom avdunstning och isbildning. Nordatlanten (vid Grönlandshavet och Norska havet) och haven vid Antarktis (Ross- och Weddellhavet) är viktiga platser där kallt, salt vatten sjunker. The world ocean is of great importance for the Earth’s climate system, and affects climate in a number of ways. Approximately 71 % of the Earth’s surface is covered by oceans. Most of the solar radiation is received by the ocean. The heat capacity and circulation of the ocean makes it possible to both store and redistribute this heat before it returns to the atmosphere and radiates back into space. The thermohaline circulation is a global ocean circulation, driven by differences in density, which transports warm water to the polar regions and cold water equatorward. Density is a function of temperature and salinity (and pressure, which is usually neglected). That is why the circulation is called thermohaline. When water is added to the system the salinity decreases by land runoff, sea ice melting and precipitation. Evaporation and ice formation increases the salinity. The North Atlantic Ocean (the Greenland and Norwegian Seas) and the Antarctic Ocean (the Ross and Weddell Seas) are prime regions for downwelling of cold water. The thermohaline circulation has numerous effects on our climate in Northern Europe. Since warm waters are driven northward, this contributes to the warm weather here. Differences in temperature and salinity also affect the marine ecology in the North Atlantic Ocean. Cold water is nutrient-rich and contains high concentration of carbon dioxide, warm water is oxygenated, has a small amount of nutrients and ...
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