Oceanography (2+1)

Ice in the Oceans

There are two types of ice that cover the oceans. One is the sea ice which is formed by the freezing of sea water and the other is the fresh water ice such as the iceberg which is formed on the continent or on the ice itself and then carried into the ocean. The presence of ice in the ocean is important in many respects. Sea ice formation in high latitudes during winter season causes freezing up of harbours in these latitudes. Thus, sea ice creates navigational problems for ships and limits the usage of many ports in these areas. The floating icebergs in the oceans are dangerous to shipping particularly during fog conditions. Icebergs reach even low latitude areas due to favourable wind and current conditions and hence are the major problem for shipping activity in the oceans.

The transportation of sedimentary debris by ice is very important in high latitude ocean areas. Icebergs carry with them large amounts of material from the land. This material modifies the general topography of the sea floor and contributes significantly to the deep sea deposits. Sea ice also plays an important role in the transportation of sedimentary material. Sea ice tends to carry unsorted material including shells and other remains of organisms, from shallow water into deeper water and hence will give rise to accumulations of remains of organisms and organic material. The change of reflectivity that occurs when the sea freezes over, makes sea ice an important factor in the heat budget of the ocean. Sea ice damps surface waves in the ocean. Sea ice also changes the temperature and salinity in the upper layers of the ocean by the processes of melting and freezing.