| Arctic rapid changes has an important influence on the surrounding lands and sea areas,even the global climate system,so the arctic physical oceanography and climate change has become a hot issue of polar research.The Bering Sea is an important sea area that connect the Arctic Ocean and the sea in low latitudes,it is also the intensive area of the Chinese arctic scientific expedition in recent years.Up to now,China has carried out 7 times Arctic scientific expeditions and obtained a lot of valuable data.This article aims at the analysis of the hydrological elements distribution,the structure characteristics and seasonal variation of water masses in the Bering Sea,on the basis of the Chinese 1st ~ 6th arctic expeditions’ temperature,salinity and dissolved oxygen data and international sharing data set.The main research conclusions are as follows:1.In Bering Sea basin,high temperature and high salinity property is shown above 30 m.The thermocline is present in 40 m and the cold water appears under the thermocline while the salinity increases with depth in vertical direction.The salinity is higher in the south than the north in the middle layer.As for dissolved oxygen content,it also can be divided into three layers vertically,water in 0~200m has the highest content level,in 200~1500m has the lowest level.In the Bering Sea shelf on the north of the St.Lawrence Island,the surface water in the eastern part has the properties of high temperature,low salinity and low dissolved oxygen content,while the western part has the characteristics of low temperature and high salinity.The thermocline is present in 20 m in the south shelf area of the St.Lawrence Island.Besides,the distribution of dissolved oxygen in this area shows a certain correlation with the temperature and salinity.2.In the Bering Sea basin,there are there kinds of water masses in summer: the Bering Sea Upper Water with high temperature and low salinity which present above 40 m has its thermohaline range in 4.2 °C<T<11.0 °C,31.5<S<33.3.The Bering Sea Intermediate Water with low temperature which present between 50 m and 150 m has its thermohaline range in 0.5°C<T<4.2 °C,32.3<S<33.8.The Bering Sea Deep Water with high salinity has its thermohaline range in 1.2°C<T<4.2 °C,33.8<S<34.7.The eastern part of the Bering Sea shelf is the Alaska Coast Water,the western part of the northern St.Lawrence Island is the Anadyr Water,and the middle part is the Bering Sea Shelf Water.There are three other water masses in the south of St.Lawrence Island,including the Bering Sea Shelf Water,Bering Sea Slope Water,Mixed Water and Alaska Coast Water.3.The thickness of Bering Sea Intermediate Water increased from south to north.It can extend to 379 m,the lowest temperature in the middle layer of cold water can reach 0.54°C(1999)and the highest temperature is 1.99°C(2014).In the west of Bering Sea shelf,the lowest temperature of the cold water mass is below-2°C(1999)and the highest temperature of the cold core is-1.33°C(2003).The distribution of cold water mass in 1999,2008 and 2012 is relatively large,while the cold cores’ temperature are lower among survey years,these years are obviously "cold years" of the cold water masses.In 2003,2005 and 2014,the lowest temperature of cold cores are high,the distribution and the average thickness of cold water mass are relatively small,and it is characterized with "warm years4.In the western part of the Bering Sea shelf,the average temperature of the sea surface in winter of 2000 ~ 2005 and 2014 are higher than that in other years,and the temperature of the cold core are relatively high,and the change between the two is highly consistency.The first time modal results of the EOF in the Bering Sea and the Okhotsk Sea show that the cold water mass in the continental shelf area is in the negative phase of the dipole-type sea ice in the cold years,while in the warm years,the dipole-type sea ice changes of the cold water mass are in the positive phase. |
