北白令海夏季冷水团的分布及其年际变化研究
Distribution and inter-annual variations of the cold water on the northern shelf of Bering Sea in summer
-
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。Abstract: 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 waters 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.
-
Key words:
- Bering Sea /
- northern shelf /
- cold water in summer /
- inter-annual variations
-
AAGAARD K, ROACH A T, SCHUMACHER J D. On the wind-driven variability of the flow through Bering Strait[J]. J Geophys Res, 1985, 90: 7213—7221. COACHMAN L K, AAGAARD K. On the water exchange through Bering Strait[J]. Limnol Oceanogr, 1966, 11: 44—59. ANDERS S. The North Pacific: A Global-Scale Estuary [J]. J Phys Oceanogr, 1984, 14: 464 470. OVERLAND J E, STABENO P J, SALO S. Direct evidence for northward flow on the northwestern Bering Sea shelf[J]. J Geophys Res, 1996, 101: 8971—8976. COACHMAN L K, AAGAARD K, TRIPP R B. Bering Strait: The Regional Physical Oceanography [M]. Seattle: Univ of Wash Press, 1975:172. ROACH A, AAGAARD K, PEASE C, et al. Direct measurements of transport and water properties through the Bering Strait[J]. J Geophys Res, 1995, 100, C9, doi: 10.1029/95JC01673. CLEMENTA J L, MASLOWSKIA W, COOPERB, L W, et al. Ocean circulation and exchanges through the northern Bering Sea-1979—2001 model results[J]. Deep-Sea Research, 2005, 52: 3509—3540, doi: 10.1016/j.dsr2.2005.09.010. GAWARKIEWICZ G, HANEY J C, CARUSO M J. Summertime synoptic variability of frontal systems in the northern Bering Sea[J]. J Geophys Res, 1994, 99: 7617—7625. WOODGATE R A, AAGAARD K, WEINGARTNER T J. Monthly temperature, salinity, and transport variability of the Bering Strait through flow [J]. Geophys Res Lett, 2005, 32: L04601, doi: 10.1029/2004GL021880. DANIELSON S, AAGAARD K, WEINGARTNER T, et al. The St. Lawrence polynya and the Bering shelf circulation: new observations and a model comparison[J]. J Geophys Res, 2006,111, C09023, doi: 10.1029/2005JC003268. MUENCH R D. Winter currents and hydrographic conditions on the northern central Bering Sea shelf[J]. J Geophys Res, 1988, 93: 516—526. DRUCKER R, MARTIN S, MORITZ R. Observations of ice thickness and frazil ice in the St. Lawrence Island polynya from satellite imagery, upward looking sonar, and salinity/temperature moorings[J]. J Geophys Res, 2003, 108: 3149, doi: 0.1029/2001JC001213. OVERLAND J E, ROACH A T. Northward flow in the Bering and Chukchi Seas[J]. J Geophys Res, 1987, 92: 7097—7105. SCHUMACHER J D,Low-frequency current regimes over the Bering Sea shelf [J]. J Phys Oceanogr, 1983, 13: 607—623. LOUGHLIN T R, OHTANI K. Dynamics of the Bering Sea[M].Farbanks: University of Alaska Sea Grant, 1999:840. FU Hong-li, ZHAO Jin-ping, SHI Jiu-xin,et al. Formation and transportation of high-salinity water produced in Polynyas[J]. J Ocean Univ China, 2010, 9(4): 317—326, doi: 10.1007/s11802-010-1734-9. BARNES C A, THOMPSON T G. Physical and chemical investigations in Bering Sea and portions of the North Pacific Ocean[M]. Seattle:Univ Wash Publ Oceanogr, 1938, 3: 35—79. OHTANI K. Oceanographic structure in the Bering Sea[J]. Memoris Fac Fish Hokkaido Univ, 1973, 21(1): 65—106. AMOS A F, COACHMAN L K. Water mass modification from the Bering into the Chukchi Sea // Results of the Third Joint US-USSR Bering & Chukchi Seas Expedition (BERPAC). U.S. Fish and Wildlife Serv., Washington, D. C. NAGEL P A, 1992:27—35. SCHUMACHER J D, AAGAARD K, PEASE C, et al. Effects of a shelf polynya on flow and water properties in the Northern Bering Sea[J]. J Geophys Res, 1983, 88: 2723—2732. AZUMAYA T, OHTANI K. Effect of winter meteorological conditions on the formation of the cold ??ぴ?om water in the eastern Bering Sea shelf[J]. Journal of Oceanography, 1995, 51: 665—680. OVERLAND J E, STABENO P J. 2004: Is the climate of the Bering Sea warming and affecting the ecosystem?[J]. Eos, 2004, 85(13): 309—316. LAUTH R. Summer bottom and surface emperatures-Eastern Bering Sea // BOLDT J, ZADOR S. Ecosystem Considerations for 2010,Appendix C.Alaska Fisheries Science Center, 2010: 53—54. WHITLEDGE T E, BIDIGARE R R, ZEEMAN S I, et al. Biological measurements and related chemical features in Soviet and U.S. regions of the Bering Sea[J]. Cont Shelf Res, 1988, 8: 1299—1320. GREBMEIER J M, MCROY C P, FEDER H M. Pelagic-benthic coupling on the shelf of the northern Bering and Chukchi Seas:Ⅰ. Food supply source and benthic biomass[J]. Mar Ecol Prog Ser, 1988, 48: 57—67. COOPER L W, COTA G F, POMEROY L R, et al. Modification of NO, PO, and NO/PO during flow across the Bering and Chukchi shelves: Implications for use as Arctic water mass tracers[J]. J Geophys Res, 1999, 104: 7827—7836. KINDER T H, CHAPMAN D C, WHITEHEAD J A. Westward intensification of the mean circulation on the Bering Sea shelf[J]. J Phys Oceanogr, 1986, 16: 1217—1229. COACHMAN L K, SHIGAEV V V. Northern Bering-Chukchi Sea ecosystem: The physical basis // Results of the Third Joint US-USSR Bering & Chukchi Seas Expedition (BERPAC). U.S. Fish and Wildlife Serv., Washington, D. C. NAGEL P A, 1992: 17—27. SCHUMACHER J D, STABENO P J. The continental shelf of the Bering Sea [M]//The Sea: The global coastal ocean regional studies and synthesis. New York: ROBINSON, BRINK K H, 1998, 11: 869—90. MIZOBATA K, SAITOH S I, WANG J. Interannual variability of summer biochemical enhancement in relation to mesoscale eddies at the shelf break in the vicinity of the Pribilof Islands, Bering Sea[J]. Deep-Sea Research Ⅱ, 2008,55: 1717—1728. STABENO P J, VAN MEURS P. Evidence of episodic on-shelf flow in the southeastern Bering Sea[J]. Journal of Geophysical Research, 1999, 104(29): 715—
点击查看大图
计量
- 文章访问数: 1820
- HTML全文浏览量: 11
- PDF下载量: 1456
- 被引次数: 0