Wind, Circulation, and Topographic Effects on Alongshore Phytoplankton Variability in the California Current
Wind, Circulation, and Topographic Effects on Alongshore Phytoplankton Variability in the California Current
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DOI：
10.1002/2017gl076839
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发表时间：
2018-04-16
影响因子：
5.2
通讯作者：
Moore, Andrew M.
中科院分区：
文献类型：
--
作者：
Fiechter, Jerome;Edwards, Christopher A.;Moore, Andrew M.
使用物理-生物地球化学模式对1988-2010年间加州海流中近岸浮游植物的变异性进行了3公里分辨率的回溯性分析。该模拟受益于区域环流再分析的缩小尺度，该再分析在高分辨率域中提供了改进的物理海洋状态估计。这种新出现的模式是一种局部上升流的加强，响应于海角背风处近岸风应力的增加，受到地转环流中近岸弯道的调制。虽然在大多数主要地形特征附近出现了更强的上升流，但浮游植物生物量的大幅增加只有在当地环流模式有利于上升流营养物质的搁置时才会随之而来。营养物质输送和叶绿素积累高峰的位置也表现出明显大于周围陆架地区的年际变化和趋势，从而表明加州洋流的长期浮游生态系统响应表现出显著的局部尺度(O(100公里))近岸分量。在本研究中，海洋环流和浮游食物网的数值模式被用来解释海岸线特征(如海角)、区域风型和洋流输送的变化如何结合在一起，在美国西海岸的食物网基础上创造出提高产量的局部区域。这项研究的主要发现是，尽管加州海流地区的大部分地区都受到风的影响，但由于洋流往往会重新分配可利用的营养物质，因此有利于浮游植物生长的风模式使海岸线上只有少数局部地区的浮游植物生物量显著增加。
A physical-biogeochemical model is used to produce a retrospective analysis at 3-km resolution of alongshore phytoplankton variability in the California Current during 1988-2010. The simulation benefits from downscaling a regional circulation reanalysis, which provides improved physical ocean state estimates in the high-resolution domain. The emerging pattern is one of local upwelling intensification in response to increased alongshore wind stress in the lee of capes, modulated by alongshore meanders in the geostrophic circulation. While stronger upwelling occurs near most major topographic features, substantial increases in phytoplankton biomass only ensue where local circulation patterns are conducive to on-shelf retention of upwelled nutrients. Locations of peak nutrient delivery and chlorophyll accumulation also exhibit interannual variability and trends noticeably larger than the surrounding shelf regions, thereby suggesting that long-term planktonic ecosystem response in the California Current exhibits a significant local scale (O(100 km)) alongshore component.Plain Language Summary The California Current region off the west coast of North America is one of the four main upwelling systems of the World Ocean, and it supports a productive marine ecosystem including economically important fisheries. In the present study, a numerical model of the ocean circulation and planktonic food web is used to explain how changes in coastline features (such as capes), regional wind patterns, and transport by ocean currents combine to create local regions of enhanced production at the base of the food web along the west coast of the United States. The main finding from this study is that even though most of the California Current region is subjected to wind patterns that favor the growth of phytoplankton by bringing deep nutrients near the ocean's surface, only a few localized areas of the coastline see significant increases in phytoplankton biomass because of how ocean currents tend to redistribute available nutrients.