Biological and chemical consequences of the 1997-1998 El Nino in central California waters
Biological and chemical consequences of the 1997-1998 El Nino in central California waters
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DOI：
10.1016/s0079-6611(02)00050-2
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发表时间：
2002-01-01
影响因子：
4.1
通讯作者：
Collins, CA
中科院分区：
文献类型：
--
作者：
Chavez, FP;Pennington, JT;Collins, CA
根据从船舶、系泊设备、验潮仪和卫星上收集的时间序列，描述和解释了与1997 - 1998年强厄尔尼诺有关的加州中部沃茨的物理、化学和生物扰动。加州附近厄尔尼诺现象的演变与在热带太平洋观测到的模式密切相关。1997年6月，温暖的南方沃茨异常涌入，沿海海平面和温跃层深度的信号很弱，标志着厄尔尼诺现象在加州中部的开始。时间是一致的传播从热带地区通过赤道和沿海波导。到1997年底，典型的分层海洋条件，深温跃层，高海平面和温暖的海面温度（SST）通常与厄尔尼诺现象有关，占主导地位的沿海地区。1998年上半年，加州海流的核心紧贴着海岸，通常在距离海岸几百公里的地方就能探测到，这是一条低盐度、低营养水的河流。在凉爽的年份，从海岸到离岸约200公里的南北带出现的高营养、多产的沃茨在厄尔尼诺现象期间消失了。地表沃茨中的硝酸盐含量低于正常水平的20%，新产量减少了近70%。拉尼娜现象的恢复阶段始于1998年秋季，当时海表温度低于正常水平，海洋生产力反弹至高于正常水平。与厄尔尼诺现象有关的沿海加州初级生产力的减少估计为5000万公吨碳（5 × 10（13）gC）。这种减少无疑对浮游动物、鱼类和海洋哺乳动物产生了有害影响。1992-1993年的厄尔尼诺现象比1997-1998年的厄尔尼诺现象温和，但由于持续时间较长，其总体化学和生物影响可能相当。生态系统对厄尔尼诺现象的反应有多强烈似乎与太平洋的长期背景气候状态有关。1982-1983年和1992-1993年的厄尔尼诺现象发生在太平洋年代际振荡（PDO）的暖期。PDO可能在1997-1998年厄尔尼诺期间改变了符号，导致生态影响比根据温度异常的强度预测的要弱。(C)2002爱思唯尔科技有限公司。保留所有权利。
The physical, chemical and biological perturbations in central California waters associated with the strong 19971998 El Nino are described and explained on the basis of time series collected from ships, moorings, tide gauges and satellites. The evolution of El Nino off California closely followed the pattern observed in the tropical Pacific. In June 1997 an anomalous influx of warm southerly waters, with weak signatures on coastal sea level and thermocline depth, marked the onset of El Nino in central California. The timing was consistent with propagation from the tropics via the equatorial and coastal wave-guide. By late 1997, the classical stratified ocean condition with a deep thermocline, high sea level, and warm sea surface temperature (SST) commonly associated with El Nino dominated the coastal zone. During the first half of 1998 the core of the California Current, which is normally detected several hundred kilometers from shore as a river of low salinity, low nutrient water, was hugging the coast. High nutrient, productive waters that occur in a north-south band from the coast to approximately 200 km offshore during cool years disappeared during El Nino. The nitrate in surface waters was less than 20% of normal and new production was reduced by close to 70%. The La Nina recovery phase began in the fall of 1998 when SSTs dropped below normal, and ocean productivity rebounded to higher than normal levels. The reduction in coastal California primary productivity associated with El Nino was estimated to be 50 million metric tons of carbon (5 X 10(13)gC). This reduction certainly had deleterious effects on zooplankton, fish, and marine mammals. The 1992-1993 El Nino was more moderate than the 1997-1998 event, but because its duration was longer, its overall chemical and biological impact may have been comparable. How strongly the ecosystem responds to El Nino appears related to the longer-term background climatic state of the Pacific Ocean. The 1982-1983 and 1992-1993 El Ninos occurred during the warm phase of the Pacific Decadal Oscillation (PDO). The PDO may have changed sign during the 1997-1998 El Nino, resulting in weaker ecological effects than would otherwise have been predicted based on the strength of the temperature anomaly. (C) 2002 Elsevier Science Ltd. All rights reserved.