摘要
利用1982—2008年间的高分辨率CTD数据,对夏季位于北白令海陆架底层的冷水团性质及其多年变化进行了研究。结果表明,依据该区域水体在温盐性质上的差异可以分为4类:陆架冷水团(BSW_C),白令海陆坡流水(BSCW),混合变性水(MW),陆架表层暖水(BSW_S)。以-1℃,2℃和4℃温度等值线指示水团边界,清楚地将这4种水体区分开来。夏季温度在-1℃以下的冷水团通常位于61.5°N以北和深度不超过70 m的陆架底层。部分年份在冷水团的南部会出现"冷中间层"的现象,其原因与陆架水和陆坡流水的相互作用过程有关。据现有数据我们定义了"边缘最低温度"和"核心最低温度"两个指标对冷水团的年际变化进行了研究。北白令海陆架的夏季底层冷水的核心最低温度的多年平均值是-1.61℃,与海水平均冰点温度相差0.2℃,表明夏季冷水团中心仍保留了冬季水的低温特征。1989,1994,2002,2003,2004和2005年冷水团势力分布范围相对于多年平均水平要弱一些,为"暖相年",而最近十年夏季底层水的这种冷暖相位的变化在整个白令海陆架上具有一致的变化趋势。
Using the high resolution CTD data between 1982 and 2008,we investigate the property and inter-annual variations of the summer cold water on the northern shelf of the Bering Sea.The results indicate that the waters in this area can be divided into four masses by the differences in temperature and salinity： Bering Shelf Cold Water（BSW_C）,Bering Slope Current Water（BSCW）,Mixing Modified Water（MW） and Bering Shelf Surface Water（BSW_S）.-1 ℃,2 ℃ and 4 ℃ isolines can be used properly to identify the boundary of the different water masses.In summer,the cold water（T-1 ℃） is generally located on the bottom of the shelf with depth less than 70 m north of 61.5°N.But in some years on the southern side of the cold water a phenomenon called ＂cold intermediate＂ may appear and it is related to the interaction of the Bering Slope Current Water and the Bering Shelf Water.Based on the historical data,we define two different physical parameters,which are called ＂the lowest temperature on the edge＂ and ＂the lowest temperature in the core＂,to investigate the inter-annual variations of the cold water： the long-term average temperature of the cold bottom water on the northern shelf in summer is-1.61 ℃ which is less than 0.2 ℃ compared to the average freezing point,fully demonstrating that the cold pool in summer still keeps the winter shelf water＇s characteristics of low-temperature;The distribution range of the cold pool in the year of 1989,1994,2002,2003,2004 and 2005 is smaller than the long-term average level,and this situation is called ＂warm year＂.Such changes of the cold pool in summer between ＂warm year＂ and ＂cold year＂ took place on the whole Bering Shelf over the past ten years.
出处
《海洋学报》
CAS
CSCD
北大核心
2011年第2期1-10,共10页
基金
全球变化研究国家重大科学研究计划项目(2010CB951403)
国家自然科学基金重点项目"北极环极边界流的结构及其对气候变化贡献的研究"(40631006)
关键词
白令海
北部陆架
夏季冷水团
多年变化
Bering Sea
northern shelf
cold water in summer
inter-annual variations
