Analysis On Water Masses And Seasonal Variations Of The Steric Sea Level In The Seas Near The Greenland

The seas near the Greenland Island (mainly including Greenland Sea, Iceland Sea, Norwegian Sea and Barents Sea) are the main channels connecting the Arctic and other Oceans, where significant water and energy exchange take place. They play an important role in the global climate change.The analysis on water masses, which has a great impact on the further research of the dynamic environment of sea water, is a main way of understanding the physical, chemical and biological character of sea water. The sea level is one basic element of the marine environment, and the steric sea level calculated by temperature and salinity is a crucial part of the sea level.The analysis of water mass in the seas near the Greenland Island is examined based on analysis of the temperature and salinity seasonal fields which come from Polar science center Hydrographic Climatology (PHC3.0) data sets. Here we firstly use cluster analysis on water masses with the method of Ward, then apply Bayes discriminatory analysis, and combine the predecessors'research results, combining circulations in the surrounding environment, finally we divide the region into eight water masses:Modi?ed North Atlantic Water(MNAW), North Atlantic Water(NAW), Baltic Sea Surface Water(BSSW), Norwegian Sea Arctic Water (NSAW), Greenland Sea Surface Water(GSSW), Norwegian Sea Deep Water(NSDW), North Atlantic Surface Water(NASW), and Modi?ed East Icelandic Water(MEIW).Based on the special characteristic of temperature and salinity, as well as special distribution of water masses, we can draw the following conclusions:A part of North Atlantic water which flows north along the North Atlantic Current to Iceland-Scotland region, as well as Atlantic water which cross the Nordic seas between Greenland and Iceland, modifies as Modified North Atlantic water because of the mixing between North Atlantic water and the Mediterranean water lower. The North Atlantic Water is the water mass transported by the Continental Slope Current. The Baltic Sea Surface Water exits in the Baltic Sea surface layer with cold and low salinity, hardly affected by season. Norwegian Sea Arctic Water is from the north Atlantic, because of the fierce cooling effect from polar atmosphere and the melting in the northwest of West Spitsbergen, the temperature and salinity of which decrease rapidly. Greenland Sea Surface Water with low temperature and salinity is distributed in the Greenland Sea above 150m, which is mostly affected by the solar radiation and glacier melting, and its seasonal variety is significant. Norwegian Sea Deep Water is distributed in the water layer below 2000m in the Norwegian sea, its character of temperature and salinity is fairly stable, and seasonal variation is not conspicuous, and the amplitude of salinity variation doesn't surpass 0.1. The water mass carried by the North Atlantic Current, enters into Norwegian sea, affected by local environment, finally formed the North Atlantic Surface Water. Modi? ed East Icelandic Water is the water mass in the Iceland-Faroe Ridge north, which forms a cold tongue and sinks along the Jan Mayen front, and moves south to the Faroe Islands. In the process of transmission, the water mass occurs mixing and modifying.The seasonal steric sea level is examined based on analysis of the temperature and salinity monthly fields which come from PHC3.0 data sets. A model proposed by Tabata et al. (1986) is used to calculate the steric sea level. The change associated with the thermal expansion is termed as the thermosteric component (TC) and the change associated with the haline contraction is termed as the halosteric component (SC). This paper analyze the spatial distribution and seasonal variation of steric sea level in different sea region. The results show that, the distribution of the thermosteric component (TC) to the total steric sea level (TSSL) is larger than the halosteric component (SC) in the entire region, especially in Norwegian Sea, Iceland Sea and Barents Sea. However, in the Greenland Sea, the halosteric component (SC) dominates. Over the most regions, the annual variation of the total steric sea level (TSSL) is larger than 50mm, with maximums larger than 200 mm at some locations (e.g.,308 mm at 76.5°N,12.5°E and 246 mm at 77.5°N,17.5°W). The annual variation of the most sea region in the south of 66°N surpasses 70mm.