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11.
巴西暖流和马尔维纳斯寒流交汇点的变动及其影响机制的探讨 总被引：1，自引：0，他引：1
西南大西洋的马尔维纳斯寒流(Malvinas Current，MC)和巴西暖流(Brazil Current，BC)交汇点(the Brazil-Malvinas Confluence，BMC)的南移是很多影响因子共同作用的结果。本文从海流流量的变化和风场的变化来分析交汇点变动的原因。利用1993年1月至2016年12月的月平均流场计算截面流量，分析得到MC流量呈现递减趋势，而BC流量则出现递增趋势。2014–2016年的Argo浮标的轨迹线表明MC的水体主要来自于南极绕极流(Antarctic Circumpolar Current，ACC)经过德雷克海峡的3个极锋中的其中之一—亚南极锋(the Subantarctic Front，SAF)。计算SAF的流量，得到其也表现出递减的趋势，这是MC流量减少的重要原因。而和SAF相邻位于其南边的极锋(the Polar Front，PF)的流量出现递增趋势。利用1993–2016年月平均风场数据分析得到南半球盛行西风风应力增加且有向南极偏移的趋势，这会使得ACC也有向南极收缩的趋势，这解释了SAF流量减少而PF的流量增加的原因，故得到南半球盛行西风的南移和BC流量的增加是BMC南移的原因。 相似文献
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基于随机森林的印度洋长鳍金枪鱼渔场预报 总被引：8，自引：1，他引：7
为了提高远洋渔场预报水平和满足渔业生产的需要,提出了一种基于随机森林建立印度洋长鳍金枪鱼(Thunnus alalunga)渔场预报模型的方法。选取2002-2009年各个月份印度洋5°×5°格点渔业环境和时空数据(包括海表温度、叶绿素a浓度、表温距平、叶绿素a浓度距平、海表温度梯度强度和海面高度异常等数据)作为预测变量,利用长鳍金枪鱼的CPUE(Catch per unit effort,单位:尾/千钩数)的三分位点将渔区划分为高CPUE、中等CPUE和低CPUE三种类型,作为响应变量,对数据进行训练。结果表明,当随机森林中决策树达到100以上时,袋外数据OOB(out-of-bag)的分类误差率趋于平稳。将训练得到的随机森林用于2010年印度洋长鳍金枪鱼分月渔场的预测,其概率等值面图与实际生产的渔场分布进行叠加比较,显示高CPUE渔场概率分布与实际渔场的位置及范围变化情况符合。通过ROC(Relative Operating Characteristic)分析,高CPUE、中等CPUE和低CPUE的AUC(Area Under ROC Curve)分别达到0.847、0.743和0.803,表明预测精度较高。最后对中等CPUE渔区预测精度相对较低的原因进行了分析。 相似文献
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Evaluation and fusion of SST data from MTSAT and TMI in East China Sea, Yellow Sea and Bohai Sea in 2008 总被引：1，自引：0，他引：1
Two typical satellite sea surface temperature (SST) datasets, from the Multi-functional Transport Satellite (MTSAT) and Tropical Rainfall Measuring Mission Microwave Imager (TMI), were evaluated for the East China Sea, Yellow Sea, and Bohai Sea throughout 2008. Most monthly-mean availabilities of MTSAT are higher than those of TMI, whereas the seasonal variation of the latter is less than that of the former. The analysis on the one-year data shows that the annual mean availability of MTSAT (61%) is greater than that of TMI (56%). This is mainly because MTSAT is a geostationary satellite, which achieves longer observation than the sun-synchronous TMI. The daily availability of TMI (28%-75%) is more constant than that of MTSAT (9%-93%). The signal of infrared sensors on MTSAT is easily disturbed on cloudy days. In contrast, the TMI microwave sensor can obtain information through clouds. Based on in-situ SSTs, the SST accuracy of TMI is superior to that of MTSAT. In 2008, the root mean square (RMS) error of TMI and MTSAT were 0.77 K and 0.84 K, respectively. The annual mean biases were 0.14 K (TMI) and -0.31 K (MTSAT). To attain a high availability of SSTs, we propose a fusion method to merge both SSTs. The annual mean availability of fusion SSTs increases 17% compared to MTSAT. In addition, the availabilities of the fusion SSTs become more constant. The annual mean RMS and bias of fusion SSTs (0.78 K and -0.06 K, respectively) are better than those of MTSAT (0.84 K and -0.31 K). 相似文献
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卫星遥感海洋环境要素的渔场渔情分析应用 总被引：4，自引：0，他引：4
20世纪70年代初Laurs,Kemmerer,Stevenson等的试验性研究使得卫星遥感海水表层温度（SST）和海洋水色信息在渔场渔情分析中得到初步应用。由于卫星遥感所获取的各类海洋环境要素信息能够帮助渔民减少寻鱼时间,节约燃料,提高渔捞效率,因此,随着卫星遥感技术的快速发展和所获取海洋环境要素的增加,海水叶绿素、海面高度及海流信息等也迅速运用到商业捕捞中。与此同时,卫星遥感反演精度的提高也使得其在渔场渔情分析中的应用从试验研究阶段走向业务化应用。 相似文献
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采用2016—2017年中国印度洋围拖网生产数据和同期的海表温度、叶绿素、表层海流和海面高度数据, 绘制了阿拉伯海鲐鱼Scomber australasicus围网月平均单位捕捞努力量渔获量(CPUE)和环境因子空间叠加图, 分析鲐鱼渔场与海洋环境因子之间关系, 采用频次分析和经验累积分布函数计算鲐鱼渔场最适宜的海洋环境区间。结果表明, 该海域月平均CPUE呈现先减少后增加的趋势; 围网渔场渔汛主要在东北季风期间, 从10月到翌年3月; 作业渔场重心分布在59°—62°E、13°—17°N, 具有明显的月变化, 基本呈现西南移动趋势。空间上, CPUE 分布在西边界流速较大的海域右侧, 在海流最大值和最低值中间区域。在印度洋东北季风期间, 阿拉伯海围网鲐鱼渔场适宜海表温度在25~28℃; 叶绿素浓度在0.2~0.5mg·m -3; 表层海流在0.05~0.25m·s -1; 海表高度0.2~0.35m。 相似文献
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To solve nutrient flux and budget among waters with distinct salinity difference for water-saltnutrient budget,a traditional method is to build a stoichiometrically linked steady state model.However,the traditional way cannot cope appropriately with those without distinct salinity difference that parallel to coastline or in a complex current system,as the results would be highly affected by box division in time and space,such as the Changjiang(Yangtze) River estuary(CRE) and adjacent waters(30.75°-31.75°N,122°10′-123°20′E).Therefore,we developed a hydrodynamic box model based on the traditional way and the regional oceanic modeling system model(ROMS).Using data from four cruises in 2005,horizontal,vertical and boundary nutrient fluxes were calculated in the hydrodynamic box model,in which flux fields and the major controlling factors were studied.Results show that the nutrient flux varied greatly in season and space.Water flux outweighs the nutrient concentration in horizontal flux,and upwelling flux outweighs upward diffusion flux in vertical direction(upwelling flux and upward diffusion flux regions overlap largely all the year).Vertical flux in spring and summer are much greater than that in autumn and winter.The maximum vertical flux for DIP(dissolved inorganic phosphate) occurs in summer.Additional to the fluxes of the Changjiang River discharge,coastal currents,the Taiwan Warm Current,and the upwelling,nutrient flux inflow from the southern Yellow Sea and outflow southward are found crucial to nutrient budgets of the study area.Horizontal nutrient flux is controlled by physical dilution and confined to coastal waters with a little into the open seas.The study area acts as a conveyer transferring nutrients from the Yellow Sea to the East China Sea in the whole year.In addition,vertical nutrient flux in spring and summer is a main source of DIP.Therefore,the hydrodynamic ROMS-based box model is superior to the traditional one in estimating nutrient fluxes in a complicated hydrodynamic current system and provides a modified box model approach to material flux research. 相似文献
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基于粗集的环境机制发现模型及其渔业应用 总被引：3，自引：0，他引：3
地学事件或地学变量受控于环境因子,其关系常为非线性。另一方面,影响变量取值或事件发生的时空范围及其环境要素具有不确定性。环境因子的时空配置关系集中体现这种关系的复杂度。这使得寻找决定事件发生或某些地学变量取值的环境因子及其组合存在困难。针对渔场形成的环境机制发现,构建RS-STAMM模型,将时空离散化,以邻域方法提取空间环境变量,形成决策表,利用粗集约简方法,对环境因子及其时空配置关系进行筛选,进而寻找影响事件或变量取值的环境因子的时空配置结构。最后以发现渔场形成的环境机制为目标,将模型应用在渔业遥感研究中,以海洋鱼类聚集的温度场配置提取为实例,验证模型有效性。 相似文献