Enhanced chlorophyll at the shelfbreak of the Mid‐Atlantic Bight and Georges Bank during the spring transition
Enhanced chlorophyll at the shelfbreak of the Mid‐Atlantic Bight and Georges Bank during the spring transition
复制标题
春季过渡期间大西洋中湾和乔治浅滩的陆架断裂处的叶绿素增强
DOI：
--
复制
发表时间：
1999
期刊：
影响因子：
--
通讯作者：
P. Cornillon
中科院分区：
文献类型：
--
作者：
J. Ryan;J. Yoder;P. Cornillon
在沿海地区彩色扫描仪 (CZCS) 的 8 年（1979-1986）图像中，我们发现在春季从充分混合条件向分层条件过渡期间，大西洋中湾 (MAB) 和乔治浅滩的陆架断口处的叶绿素逐年增强。增强的空间和时间范围在年际之间变化，并且表达在年内是间歇性的。这一特征可以跨越整个人与生物圈计划和乔治滩南侧（约1,100公里），并且可以表达长达10周（4月中旬至6月下旬）。该特征内的颜料浓度平均是邻近陆架和斜坡水域的两倍多。增强的陆架断裂叶绿素始终与陆架斜坡前缘重合，并且经常延伸到前缘地表露头的近岸几至~10公里。除 1986 年外，在所有年份中，它都与湾流暖核环 (WCR) 或曲流将陆架水夹带入海的时间一致。陆架断裂叶绿素增强在 1980 年期间最为明显。通过卫星和现场观测，我们发现在 1980 年期间，它与陆架斜坡前沿重合了 10 周，并且与春季水华不同，它主要由纳米浮游植物（<20 um）尺寸部分主导。在 1980 年发生的高峰期，四个 WCR 同时与陆架水相互作用，并且一个 WCR 近岸叶绿素增强与斜坡水入侵陆架同时发生。 1980 年 3 月下旬至 6 月 CZCS 图像的经验正交函数 (EOF) 分解表明，架断增强在 EOF 中非常明显，占平均值方差的 10% 以上。这种年度生物特征在卫星海洋颜色图像中得以体现，是人与生物圈计划和乔治浅滩陆架斜坡生态的一个重要方面。
In 8 yr (1979–1986) of Coastal Zone Color Scanner (CZCS) imagery, we find annual enhancement of chlorophyll at the shelfbreak of the Mid‐Atlantic Bight (MAB) and Georges Bank during the spring transition from well‐mixed to stratified conditions. Spatial and temporal extents of enhancement vary interannually, and expression is intermittent intraannually. This feature can span the entire MAB and southern flank of Georges Bank (∼1,100 km) and can be expressed for as long as 10 weeks (mid‐April to late June). Pigment concentrations within the feature average more than two times that of adjacent shelf and slope waters. Enhanced shelfbreak chlorophyll consistently coincided with the shelf‐slope front and often extended inshore of the surface outcrop of the front a few to ∼10 km. In all years except 1986, it coincided with seaward entrainment of shelf water by Gulf Stream warm‐core rings (WCRs) or meanders. Shelfbreak chlorophyll enhancement was most pronounced during 1980. Using satellite and in situ observations, we found that during 1980, it coincided with the shelf‐slope front for 10 weeks, and, unlike the spring bloom, it was dominated by the nanophytoplankton (<20 um) size fraction. During the peak of the 1980 occurrence, four WCRs simultaneously interacted with shelf water, and chlorophyll enhancement inshore of one WCR coincided with a slope‐water intrusion onto the shelf. Empirical orthogonal function (EOF) decomposition of CZCS images for late March–June 1980 showed that shelfbreak enhancement was strongly pronounced in an EOF that accounted for >10% of the variance about the mean. This annual biological feature, brought to light in satellite ocean color imagery, is an important aspect of the shelf‐slope ecology of the MAB and Georges Bank.