Observations of hydrography and downflow of brine-enriched shelf water in the Storfjorden polynya, Svalbard
Observations of hydrography and downflow of brine-enriched shelf water in the Storfjorden polynya, Svalbard
复制标题
斯瓦尔巴群岛斯托峡湾冰间湖富含盐水的陆架水的水文和下流观测
DOI：
10.1029/2007jc004452
复制
发表时间：
2008
影响因子：
--
通讯作者：
I. Fer
中科院分区：
文献类型：
--
作者：
R. Skogseth;L. Smedsrud;F. Nilsen;I. Fer
[1]介绍了2004年4月和2006年4月在活跃的Storfjorden Polynya进行野外考察时的水文和水流观测结果。波利尼亚因其高效的制冰而增加盐分，通常增加密度∼0.15公斤m−3。在这两年都捕获了从沿海波尼亚向下流入斯托夫约登海床包围的更深盆地的稠水。2006年4月，波利尼亚地区经历了一段强烈的热损失和剧烈的脆弱冰生长时期。这造成了最大盐度为35.25的富盐水陆架水向下流动，即密度增加了∼0.4 kg m−3，高于源水的密度。2004年4月，盐度仍然低于BSW(S>；34.8.)，反映了2003年秋季巴伦支海西部厚冰条件下的淡水来源。这种水源的一部分(0.05Sv)可能通过Freemansundet进入Storfjorden，在那里平均水流从巴伦支海西北部输送较少的咸水和较暖的水。弗里曼桑德特还有一股强潮流，最大值位于S−1的53厘米处，以M2分量为主。潮汐波通过狭窄的声音传播，产生浅水成分和局部混合良好的水柱。2004年冬季的估计冰产量是2006年冬季的两倍，但无法克服盐度较低、混合良好的水源水。观测到了斯托夫约登内的BSW下行流，并对其进行了模拟，发现其发生在水深较陡的地区。我们的观测表明，高分辨率的水文数据，间距小于0.5公里，是解决这种下降流所必需的。与观测到的波尼亚水盐度一致，目前的数据显示，2004年的溢出量比2006年弱。2006年4月，在斯托夫乔登河床东部观察到BSW溢流，表明在冻结期间，整个河床宽度都发生了溢流。溢流的电流、温度和盐度数据表明，从BSW生产到基床之间有12-18天的时间间隔。数值实验和解析标度证实了这一下溢联系，使结果适用于其他多尼雅。
[1] Observations of hydrography and currents in the active Storfjorden polynya during fieldwork in April 2004 and 2006 are presented. The polynya adds salt from its efficient ice production, usually increasing the density ∼0.15 kg m−3. Downflow of dense water from the coastal polynya to the deeper basin enclosed by the Storfjorden sill was captured in both years. April 2006 had a period of strong heat loss and intense frazil ice growth in the polynya. This created downflow of brine-enriched shelf water (BSW) with a maximum salinity of 35.25, i.e., an increased density ∼0.4 kg m−3 above that of the source water. In April 2004, the salinity remained lower than BSW (S > 34.8), reflecting the fresh source water in fall 2003 due to the heavy ice conditions in the western Barents Sea that year. A portion (0.05 Sv) of such source water probably enters Storfjorden through Freemansundet where the mean current transports less saline and warmer water from the northwestern Barents Sea. Freemansundet has additionally a strong tidal current peaking at 53 cm s−1, dominated by the M2 component. The tidal wave propagates through the narrow sound producing shallow water components and a locally well-mixed water column. The estimated ice production in winter 2004, twice as large as that of winter 2006, could not overcome this less saline well-mixed source water. BSW downflow within Storfjorden was both observed and modeled to occur in areas with steep bathymetry. Our observations show that high-resolution hydrographical data, spacing less than 0.5 km, are necessary to resolve such downflow. Consistent with the observed polynya water salinity, current data at the sill showed weaker overflow in 2004 than in 2006. Overflow of BSW was observed on the eastern part of the Storfjorden sill in April 2006, indicating that overflow occurs across the entire sill width during the freezing period. Current, temperature, and salinity data from the overflow indicate a time lag of 12–18 days between the BSW production and the sill. This downflow–overflow link is confirmed by a numerical experiment and analytical scaling, making results applicable to other polynyas.