Local atmospheric forcing driving an unexpected California Current System response during the 2015–2016 El Niño

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• 作者：Martin Frischknecht ; Matthias Münnich ; Nicolas Gruber
• 刊名：Geophysical Research Letters
• 出版年：2017
• 出版时间：16 January 2017
• 年：2017
• 卷：44
• 期：1
• 页码：304-311
• 全文大小：1.3MB
• ISSN：1944-8007

文摘

The 2015–2016 El Niño contributed to large anomalies across the California Current System (CalCS), but these anomalies ceased unexpectedly in late 2015. Here we use a suite of three hindcast simulations with the Regional Oceanic Modeling System to assess the responsible mechanisms for this development. We find that the early buildup was primarily driven by the early onset of this event in the tropical Pacific, driving anomalies in the CalCS through the propagation of coastally trapped waves. In contrast, the abrupt end in the central CalCS was caused by the unusual onset of upwelling favorable winds in the fall of 2015, which offset the continuing remote forcing through the coastal waveguide. Nevertheless, low-nutrient anomalies persisted, causing anomalously low phytoplankton abundance in the upwelling season of 2016. This is a recurring pattern for all El Niño events over the last 37 years, suggesting predictive skill on seasonal timescales.