Identification, characterization, and change of the near-surface temperature maximum in the Canada Basin, 1993-2008
Identification, characterization, and change of the near-surface temperature maximum in the Canada Basin, 1993-2008
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DOI：
10.1029/2009jc005265
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发表时间：
2010-05-25
影响因子：
3.6
通讯作者：
Ingram, R. G.
中科院分区：
文献类型：
--
作者：
Jackson, J. M.;Carmack, E. C.;Ingram, R. G.
近年来，北冰洋加拿大盆地的海冰显着减少，这可能会改变地表水的性质。先前已经描述了 25-35 m 典型深度处的近地表温度最大值 (NSTM)；然而，其形成机制、季节演变和年际变化尚未确定。根据 2005 年至 2008 年夏季电导率、温度和深度调查以及全年冰系系剖面仪数据，我们发现当足够的太阳辐射使上层海洋变暖时，NSTM 就会形成。一旦积累了足够的海冰融化，将表面混合层与 NSTM 分开，季节性盐跃层就会在夏季形成。 NSTM 被困在夏季盐跃线下方，从而储存太阳辐射的热量。如果盐跃层足够强以持续整个冬季，这些热量可以全年储存在加拿大盆地。此外，风暴驱动的混合产生的能量会削弱夏季盐跃层并夹带NSTM，从而在冬季融化海冰。在整个周期中，埃克曼在会聚的波弗特环流内泵送，以加深 NSTM。从1993年到2007年，NSTM变暖并向北扩展，NSTM和夏季盐跃层相继在较浅的深度形成。在北纬75度以北，NSTM的温度从2004年到2007年每年增加0.13℃，从1997年到2007年，NSTM和夏季盐斜层浅滩分别增加2.1 m/年和1.7 m/年。NSTM的形成和动态是冰反照率反馈效应和加拿大淡水循环变化的表现。盆地。
Sea ice in the Canada Basin of the Arctic Ocean has decreased significantly in recent years, and this will likely change the properties of the surface waters. A near-surface temperature maximum (NSTM) at typical depths of 25-35 m has been previously described; however, its formation mechanisms, seasonal evolution, and interannual variability have not been established. Based on summertime conductivity, temperature, and depth surveys and year-round Ice-Tethered Profiler data from 2005 to 2008, we found that the NSTM forms when sufficient solar radiation warms the upper ocean. A seasonal halocline forms in summer once enough sea ice melt has accumulated to separate the surface mixed layer from the NSTM. The NSTM becomes trapped below the summer halocline, thereby storing heat from solar radiation. This heat can be stored year-round in the Canada Basin if the halocline is strong enough to persist through winter. In addition, energy from storm-driven mixing can weaken the summer halocline and entrain the NSTM, thereby melting sea ice in winter. Throughout this cycle, Ekman pumping within the convergent Beaufort Gyre acts to deepen the NSTM. From 1993 through 2007, the NSTM warmed and expanded northward and both the NSTM and the summer halocline formed at successively shallower depths. North of 75 degrees N, the temperature of the NSTM increased from 2004 to 2007 by 0.13 degrees C/yr, and the NSTM and summer halocline shoaled by 2.1 m/yr and 1.7 m/yr, respectively, from 1997 to 2007. The formation and dynamics of the NSTM are manifestations of both the ice-albedo feedback effect and changes to the freshwater cycle in the Canada Basin.