Seasonality of coastal upwelling off central and northern California: New insights, including temporal and spatial variability
Seasonality of coastal upwelling off central and northern California: New insights, including temporal and spatial variability
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DOI：
10.1029/2011jc007629
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发表时间：
2012-03-17
影响因子：
3.6
通讯作者：
Largier, J. L.
中科院分区：
文献类型：
--
作者：
Garcia-Reyes, M.;Largier, J. L.
加州沿海海洋环境主要由风力驱动的沿海上升流决定，其生态系统与上升流的季节性密切相关。三十年的数据测量的加州大陆架在NOAA浮标被用来描述的季节性变化的风，迫使上升流和沿海海洋的海水温度的响应。此外，表面叶绿素和沿岸流的季节性模式是从十年的数据确定的。除了明确的季节性，所有这些数据表现出明显的空间和非季节性的时间变化的上升流。根据加州中部和北部沿岸风应力特征，将其划分为3个季节：上升流季节（4 ~ 6月），上升流有利风强，标准差大;松弛季节（7 ~ 9月），赤道风弱，变率低;风暴季节（12 ~ 2月），平均风应力弱，变率大。其余的月份是过渡性的，在不同的年份属于一个或另一个季节。除了风应力的大尺度纬度差异外，空间差异与沿海地形有关-特别是海角下游的风加速。海表温度的横向差异取决于局部和大尺度的风应力，但也取决于表面加热和离岸影响。风和海面温度的年内和年际异常与沿海风、大尺度风和近海盆地尺度海洋条件的变化有关。卫星叶绿素浓度显示出最佳的窗口关系与上升流强迫，允许最大浓度在中等风和最小在穷人或强风。
The coastal ocean environment off California is largely determined by wind-driven coastal upwelling, with an ecosystem that is tightly coupled to seasonality in this upwelling. Three decades of data measured over the California shelf at NOAA buoys are used to describe the seasonal variability of the winds that force upwelling and the response of the coastal ocean in terms of sea temperature. Moreover, seasonal patterns in surface chlorophyll and alongshore currents are determined from one decade of data. In addition to clear seasonality, all these data exhibit distinct spatial and non-seasonal temporal variability in upwelling. Based on alongshore wind stress characteristics in central and north California, three seasons are defined: Upwelling Season (April-June) with strong upwelling-favorable winds and large standard deviation due to frequent reversals; Relaxation Season ( July-September) with weak equatorward winds and low variability; and Storm Season ( December-February) characterized by weak mean wind stress but large variability. The remaining months are transitional, falling into one or other season in different years. In addition to large-scale latitudinal differences in wind stress, spatial differences are associated with coastal topography - specifically the acceleration of wind downstream of capes. Latitudinal differences in sea surface temperature depend on wind stress, both local and large-scale, but also on surface heating and offshore influences. Intra-annual and inter-annual anomalies in wind and sea surface temperature are associated with variability in coastal winds, large-scale winds, and offshore basin-scale ocean conditions. Satellite chlorophyll concentration shows an optimal window relation with upwelling forcing, allowing maximum concentrations during moderate winds and minimal during poor or strong winds.