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首页> 外文期刊>International journal of remote sensing >Variability of chlorophyll-α off the southwest coast of India
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Variability of chlorophyll-α off the southwest coast of India

机译：印度西南沿海地区叶绿素-α的变异性

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摘要

Coastal upwelling off the southwest coast of India during the southwest monsoon is a well-known phenomenon that enhances the chlorophyll-α (chl-α) biomass. The present study explores this property and examines the variability of surface chl-α using satellite data obtained from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) for the period from September 1997 to December 2010. Spatial variability showed substantial cross-shore as well as along-shore gradients during the southwest monsoon. Temporal variability in chl-α was studied in conjunction with satellite observations on sea-surface temperature, sea-surface height anomaly, winds, and currents. The results revealed the dominant influence of the West India Coastal Current on chl-α variability during the upwelling and downwelling periods. Moreover, noticeable intra- and inter-annual variability was observed in the parameter. Therefore, an empirical mode decomposition (EMD) method was used to identify the oscillations influencing variability. SeaWiFS chl-α data for the period 2008-2010 were omitted from this analysis due to gaps in the record. EMD analysis revealed oscillations ranging from seasonal to a five-year periodicity. Quasi-biennial oscillations are identified as the dominant factor causing inter-annual variability in chlorophyll in the study area, compared with the El-Nino Southern Oscillation and Indian Ocean Dipole. Chl-α was also studied in two smaller grids of size 0.5° × 0.5° separated by around 300 km and representing coastal and offshore areas, to understand the nature of variability in these areas. The annual range of variability was high (0.1-8.0 mg m~(-3)) near the coast consequent on high upwelling intensity, and very low (about 0.1 mg m~(-3)) in the offshore grid due to the absence of upwelling.
机译：在西南季风期间，印度西南海岸附近的沿海上升流是一种众所周知的现象，可增强叶绿素-α（chl-α）生物量。本研究探索了这一特性，并使用从1997年9月至2010年12月期间的海景宽视场传感器（SeaWiFS）获得的卫星数据检查了表面chl-α的变异性。空间变异性表明，西南季风期间的沿岸和沿岸梯度。结合卫星对海面温度，海面高度异常，风和洋流的观测，研究了chl-α的时间变异性。结果表明，在上升和下降期间，西印度洋沿海洋流对chl-α变异具有显着影响。此外，在参数中观察到了明显的年内和年际变化。因此，使用经验模式分解（EMD）方法来识别影响变异性的振荡。由于记录中的空白，本分析中未包含2008-2010年的SeaWiFSchl-α数据。 EMD分析揭示了从季节性到五年周期的波动。与厄尔尼诺南方涛动和印度洋偶极子相比，准双年度振荡被确定为导致研究区域叶绿素年际变化的主要因素。还研究了Chl-α的两个较小的网格，大小为0.5°×0.5°，相隔约300 km，分别代表沿海和近海区域，以了解这些区域的变异性。由于上升流强度较高，因此海岸附近的年变化范围较大（0.1-8.0 mg m〜（-3）），而由于缺少该区，年变化范围很小（约0.1 mg m〜（-3））。上升流

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  • 来源
    《International journal of remote sensing》 |2014年第14期|5420-5433|共14页
  • 作者

    S. Shalin; K.V. Sanilkumar;

  • 作者单位

    Naval Physical and Oceanographic Laboratory, Defence Research and Development Organization, Ministry of Defence, Kochi 682021, India;

    Naval Physical and Oceanographic Laboratory, Defence Research and Development Organization, Ministry of Defence, Kochi 682021, India;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);
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  • 正文语种 eng
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