A study of the response of chlorophyll-a biomass to a winter upwelling event off Western Iberia using SeaWiFS and in situ data
A study of the response of chlorophyll-a biomass to a winter upwelling event off Western Iberia using SeaWiFS and in situ data
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DOI：
10.1016/j.jmarsys.2004.05.031
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发表时间：
2005-01-01
影响因子：
2.8
通讯作者：
Santos, AMP
中科院分区：
文献类型：
--
作者：
Ribeiro, AC;Peliz, A;Santos, AMP
2000年2月，在西伊比利亚浮力羽流（WIBP）影响的地区，对西伊比利亚大陆架/斜坡附近的冬季上升流事件进行了观测。基于原位和卫星资料，分析了叶绿素a （chl-a）生物量的空间格局和时间演变。利用seawifs衍生的chl-a浓度L2产品跟踪叶绿素锋并估计其向西迁移速度（最大可达29 km day(-1)），以及表征锋系统及其演变。一种将像素的光谱特征类型与SeaWiFS探测的叶绿素比例相关联的方法可以在误差区间内估计chl-a生物量。在大陆架和斜坡上观察到高叶绿素浓度（冬季），一直到海岸很远的地方。由于WIBP的作用，形成了一个浅层的Ekman层，几乎与上层分层一致。输送过程包括向西平流和羽流的伸展，与近海深层混合层水的夹带较少。在上升流期间，内前区（IFZ）总面积的相对扩大大致伴随着单位面积平均生物量的维持，考虑到感兴趣深度的水柱。这表明，水柱内chl-a生物量的净增加与IFZ面积的增加大致成正比。WIBP浅层营养丰富的水体中浮游植物的滞留是chl-a生物量增加的关键因素，(C) 2004 Elsevier B.V.版权所有。
Observations of a winter upwelling event off Western Iberia shelf/slope in the area of influence of the Western Iberia Buoyant Plume (WIBP) were conducted in February 2000. Spatial patterns and time evolution of the chlorophyll-a (chl-a) biomass are analysed, based on in situ and satellite data. SeaWiFS-derived chl-a concentration L2 products were used to track the chlorophyll front and estimate its westward migration velocity (maximum up to 29 km day(-1)), as well as to characterize the frontal system and its evolution. A method associating the type of spectral signature of a pixel to the fraction of chlorophyll probed by SeaWiFS enabled the estimation of the chl-a biomass within error intervals. High chlorophyll concentrations (for wintertime) were observed over the shelf and slope, up to large distances to the coast. Due to the WIBP, a shallow Ekman layer developed, being nearly coincident with the stratified upper meters. The transport comprised westward advection and stretching of the plume, with little entrainment with the offshore deep mixed layer waters. The relative enlargement of the total area of the Inside-Front Zone (IFZ) during the upwelling event was roughly accompanied by the maintenance of the average biomass per unit of area, considering the water column up to depths of interest. This suggests that there was a net increase of chl-a biomass inside the water column associated with the IFZ, roughly proportional to the increase in the IFZ area. Retention of phytoplankton in the shallow stratified nutrient-rich waters of the WIBP was a key factor for this increase in chl-a biomass, (C) 2004 Elsevier B.V. All rights reserved.