The influence of sea ice

1. Influence on the vertical distribution of marine hydrological elements Because the vertical convection and mixing of seawater often reach a considerable depth during freezing, it can directly reach the seabed in shallow water, resulting in a more uniform vertical distribution of all marine hydrological elements. This process can transport seawater with high dissolved oxygen in the surface layer downward, and at the same time transport fertile seawater rich in nutrients needed by phytoplankton to the surface layer, which is beneficial to the mass reproduction of organisms. Therefore, frozen seas, especially polar seas, are often rich in fishery resources. For example, Antarctic krill and whale fishing grounds are world-famous, which is directly related to this.

When the ice melts, a warm and light water layer will be formed on the surface to cover the cold water with high salt, and a density thermocline will appear, which will affect the vertical distribution of various hydrological elements and the exchange between water and water.

Second, the impact on ocean dynamic phenomena. The existence of sea ice has a great influence on tides and tidal currents, which will damp the decline of tidal level and the movement of tidal currents, and reduce tidal range and velocity. Similarly, sea ice will also reduce the wave height and hinder the wave propagation.

Third, the influence on the thermal state of seawater.

When there is sea ice on the sea surface, the heat exchange between sea water and atmosphere is greatly reduced through evaporation and turbulence, and at the same time, because of the poor thermal conductivity of sea ice, it plays the role of "fur coat" for the ocean. The high reflectivity of sea ice to solar radiation energy and its high latent heat of melting can restrict the change of seawater temperature, so the annual change of water temperature in polar waters is only about 65438 0℃.

4. The formation of ocean bottom water in polar seas, especially the massive freezing of sea water on the Antarctic continental shelf, makes the sea water under ice have the characteristics of increasing salt and low temperature, which can sink to the seabed along the continental shelf, form so-called Antarctic bottom water, and spread to the three oceans, thus having a very important impact on marine hydrological conditions.

In a word, sea ice will not only have a great impact on marine hydrology, atmospheric circulation and climate change, but also directly affect human social practice. For example, it can directly block ports and waterways, block maritime transportation, and destroy offshore engineering facilities and ships. Since the 1940s, high-latitude coastal countries have successively carried out sea ice observation and research, and issued iceberg hazards and sea ice forecasts. Sea ice and icebergs are observed by shore stations, ships, planes, floating ice stations, radars and satellites, and long-term, medium-term and short-term forecasts of sea ice are issued by using mathematical statistics, meteorology and dynamic numerical methods.