Cross-shelf exchange associated with a shelf-water streamer at the Mid-Atlantic Bight shelf edge
Cross-shelf exchange associated with a shelf-water streamer at the Mid-Atlantic Bight shelf edge
复制标题
DOI：
10.1016/j.pocean.2022.102931
复制
发表时间：
2023-01
影响因子：
4.1
通讯作者：
W. Zhang;P. Alatalo;Taylor Crockford;Andrew J. Hirzel;M. G. Meyer;H. Oliver;Emily E. Peacock;Christian M. Petitpas;Z. Sandwith;W. Smith;H. Sosik;R. Stanley;Bethany L. F. Stevens;J. T. Turner;D. McGillicuddy
中科院分区：
文献类型：
--
作者：
W. Zhang;P. Alatalo;Taylor Crockford;Andrew J. Hirzel;M. G. Meyer;H. Oliver;Emily E. Peacock;Christian M. Petitpas;Z. Sandwith;W. Smith;H. Sosik;R. Stanley;Bethany L. F. Stevens;J. T. Turner;D. McGillicuddy
墨西哥湾暖芯环（WCRs）撞击中大西洋湾（MAB）大陆架，将中大西洋湾（MAB）大陆架的亚中尺度细丝水带入开阔海域，从而诱发了中大西洋湾（MAB）大陆架与邻近开阔海域之间的显著交换。陆架水飘带具有独特的表面温度和叶绿素信号，因此从太空中可见。卫星测量的海面高度、温度和叶绿素显示了WCR在2019年2月至8月的6个月寿命期间的演变，以及它在其外围产生的持续大陆架水拖。对2019年7月为期两周的巡航测量结果进行了分析，以调查地表以下大陆架水流的物理、生物和生物地球化学特征，并量化相关的体积、热量、盐、碳和氧的跨大陆架运输。分析表明，拖带对陆架水的海上输送是MAB大陆架与公海之间交换的主要形式，这可能是由环水的陆上入侵或上游陆架水的加强输送所平衡的。拖缆造成了陆地上大量的热量和盐的净输送，以及海洋上大量的有机碳和氧的净输送。流带的初级生产力高于表面周围的斜坡水和环状水，这可能是由于随着上覆水变得更清澈，近海流动的陆架水中的地下营养物质逐渐被消耗。因此，wcr引起的陆架水流带提高了斜坡海的表面生物生产力。中大西洋浅大陆架水域与邻近的深坡海具有明显不同的物理、生物和化学性质。它们之间的混合会影响陆架生态系统和海岸物质向深海的扩散。一种类型的跨大陆架边缘混合过程是由强大的顺时针旋转漩涡——即所谓的矮核环——产生的，这些漩涡是由墨西哥湾流的弯曲形成的。当一个暖核环侵入大陆架边缘时，它经常把大陆架的水吸到离岸，在斜坡海中形成一根细丝。这种细丝被称为陆架水飘带，它具有独特的表面温度和叶绿素信号，从太空中可以看到。暖核环也可以把近海的水推到浅层大陆架上。这项研究考察了2019年一个暖核环在6个月的寿命期间的演变，以及该环在6个月中的5个月里引发的大陆架水流。研究人员检查了2019年7月一次实地考察的跨学科测量结果，以评估拖带的地下模式，并量化热、盐、有机碳和氧的诱发跨大陆架通量。分析表明，拖缆代表了跨大陆架混合的一种主要形式，并导致了大量的热量和盐的陆上运输，以及大量的有机碳和氧的海上运输。
Significant exchanges between the Mid-Atlantic Bight (MAB) continental shelf and the neighboring open ocean can be induced byshelf water streamers, submesoscale filaments of shelf water entrained into the open ocean by Gulf Stream warm-core rings (WCRs) impinging onto the MAB continental shelf. Shelf water streamers have distinctive surface temperature and chlorophyll signals, and are thus visible from space. Satellite-measured sea surface height, temperature and chlorophyll show the evolution of a WCR over its 6-month lifespan in February-August 2019 and the persistent shelf water streamer it generated on its outskirt.In situmeasurements from a two-week cruise in July 2019 were analyzed to investigate the physical, biological and biogeochemical characteristics of the shelf water streamer below the surface, and to quantify the associated cross-shelf transport of volume, heat, salt, carbon and oxygen. The analyses demonstrated that offshore transport of shelf water by the streamer, which was presumably balanced by either onshore intrusion of ring water or enhanced transport of shelf water from upstream, represented a major form of exchange between the MAB continental shelf and the open ocean. The streamer caused significant net onshore transport of heat and salt, and a significant net offshore transport of organic carbon and oxygen. Primary productivity in the streamer was higher than the surrounding slope and ring waters on the surface, which likely resulted from subsurface nutrients in the offshore-flowing shelf water being gradually consumed as the overlying water became clearer. WCR-induced shelf water streamers thus enhanced surface biological productivity in the slope sea.Plain Language Summary:Waters of the shallow Mid-Atlantic Bight continental shelf and the neighboring deep slope sea have distinctly different physical, biological and chemical properties. Mixing between them can affect the shelf ecosystem and the dispersal of coastal materials into the deep ocean. One type of cross-shelf-edge mixing process results from strong clockwise-rotating vortices – so-calledwarm-core rings– formed from meanders of the Gulf Stream. As a warm-core ring intrudes onto the shelf edge, it often draws shelf water offshore, forming a thin filament in the slope sea. This filament is called a shelf-water streamer and has distinctive surface temperature and chlorophyll signals that are visible from space. Warm-core rings can also push offshore water onto the shallow shelf. This study examines the evolution of a warm-core ring over its 6-month lifespan in 2019 and the shelf-water streamer the ring induced in 5 of the 6 months. Interdisciplinary measurements from a field expedition in July 2019 were examined to assess the subsurface patterns of the streamer and to quantify the induced cross-shelf fluxes of heat, salt, organic carbon and oxygen. The analysis showed that the streamer represented a major form of cross-shelf mixing and caused a substantial onshore transport of heat and salt, as well as a substantial offshore transport of organic carbon and oxygen.