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Observed variability of the West India Coastal Current on the continental shelf from 2010–2017
Journal of Earth System Science ( IF 1.3 ) Pub Date : 2021-04-30 , DOI: 10.1007/s12040-021-01603-4
Anya Chaudhuri , P Amol , D Shankar , S Mukhopadhyay , S G Aparna , V Fernando , A Kankonkar

Abstract

We describe the variability of the West India Coastal Current (WICC) during 2009–2017 using data from acoustic Doppler current profilers (ADCPs) attached to moorings deployed on the outer shelf at a water-column depth of 100–200 m at three locations: off Kollam (9°N), Bhatkal (13.9°N), and Goa (15°N). Our study shows that the characteristics of the WICC on the outer shelf are similar to those observed on the slope except for the occasional decorrelation observed between them. Both shelf and slope WICC have a weak mean flow and a strong annual cycle. As seen on the slope, the depth of the undercurrent on the shelf changes with season because of the strong upward phase propagation associated with the annual cycle. Though the currents at all three shelf locations exhibit a strong seasonal cycle, there are prominent differences between the currents off the southwest coast of India (Kollam) and the central west coast of India (Bhatkal and Goa). The seasonal cycle off Kollam is often punctuated by strong intraseasonal bursts, which cause the shelf WICC off Kollam to be highly unpredictable; this unpredictability implies that on a given day of the year, one cannot expect a poleward (equatorward) current during the winter (summer) monsoon. On the central west coast, the poleward (equatorward) direction during the winter monsoon (summer monsoon) is prominent. Comparison with the available datasets shows that the WICC is occasionally coherent along and across the shelf, and the coherence is stronger for the seasonal cycle.

Research highlights

  1. 1.

    Characteristics of the WICC on the outer shelf are similar to those observed on the slope.

  2. 2.

    Shelf WICC has a weak mean flow and a strong annual cycle.

  3. 3.

    Differences observed between currents off central west coast and southwest coast of India.

  4. 4.

    Seasonal cycle off Kollam is often punctuated by strong intraseasonal bursts.



中文翻译:

2010-2017年大陆架上西印度洋沿海流的观测变化

摘要

我们使用来自声多普勒电流剖面仪(ADCP)的数据描述了2009-2017年西印度洋海流(WICC)的变化,该数据附加到在三个位置的水柱深度为100-200 m的外部货架上部署的系泊设备上:离开科隆(9°N),巴特卡尔(13.9°N)和果阿(15°N)。我们的研究表明,在外层架上的WICC的特征与在斜坡上观察到的相似,除了它们之间偶尔观察到去相关。陆架和斜坡WICC均具有较弱的平均流量和较强的年周期。从斜坡上可以看出,由于与年度周期相关的强烈的向上相位传播,架子上的暗流深度随季节而变化。尽管三个架子位置的洋流都表现出强烈的季节性周期,印度西南海岸(库兰)和印度中西部海岸(Bhatkal和果阿)的洋流之间存在显着差异。Kollam以外的季节性周期常常因强烈的季节内爆发而中断,这导致Kollam以外的货架WICC高度不可预测。这种不可预测性意味着,在一年中的某一天,不能期望在冬季(夏季)季风期间出现极向(赤道)气流。在中西部海岸,冬季季风(夏季风)期间的极向(赤道)方向很明显。与可用数据集的比较表明,WICC沿陆架和跨陆架有时是连贯的,并且在季节性周期中连贯性更强。Kollam以外的季节性周期经常被强烈的季节内爆发所打断,这导致Kollam以外的架子WICC高度不可预测。这种不可预测性意味着,在一年中的某一天,不能期望在冬季(夏季)季风期间出现极向(赤道)气流。在中西部海岸,冬季季风(夏季风)期间的极向(赤道)方向很明显。与可用数据集的比较表明,WICC沿陆架和跨陆架有时是连贯的,并且在季节性周期中连贯性更强。Kollam以外的季节性周期常常因强烈的季节内爆发而中断,这导致Kollam以外的货架WICC高度不可预测。这种不可预测性意味着,在一年中的某一天,不能期望在冬季(夏季)季风期间出现极向(赤道)气流。在中西部海岸,冬季季风(夏季风)期间的极向(赤道)方向很明显。与可用数据集的比较表明,WICC沿陆架和跨陆架有时是连贯的,并且在季节性周期中连贯性更强。在中西部海岸,冬季季风(夏季风)期间的极向(赤道)方向很明显。与可用数据集的比较表明,WICC沿陆架和跨陆架有时是连贯的,并且在季节性周期中连贯性更强。在中西部海岸,冬季季风(夏季风)期间的极向(赤道)方向很明显。与可用数据集的比较表明,WICC沿陆架和跨陆架有时是连贯的,并且在季节性周期中连贯性更强。

研究重点

  1. 1。

    外部架子上的WICC的特征与在斜坡上观察到的特征相似。

  2. 2。

    货架WICC的平均流量很弱,而且年度周期很长。

  3. 3。

    在印度中西部沿海和西南沿海附近观测到的洋流之间存在差异。

  4. 4,

    Kollam的季节性周期经常因强烈的季节内爆发而中断。

更新日期:2021-04-30
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