The spatial distribution and seasonal variations of the hypoxic zone in the eastern equatorial Indian Ocean were investigated using survey data collected from four cruises from 2013 to 2018.Results showed that hypoxic...The spatial distribution and seasonal variations of the hypoxic zone in the eastern equatorial Indian Ocean were investigated using survey data collected from four cruises from 2013 to 2018.Results showed that hypoxic zone occurred all year round in the eastern equatorial Indian Ocean,and it spread southward in the shape of a double tongue at two depths with one at subsurface centered at a depth of 150 m and the other in intermediate water centered at a depth of 800 m.The southward expansion and maximum thickness of the hypoxic zone were greatest in the spring inter-monsoon and least in the summer monsoon.The hypoxic zone originated from the southward expansion of the hypoxic water in the Bay of Bengal and its spatial distribution was driven by southward output flux of mid-deep(100–1000 m)hypoxic water from the Bay of Bengal.The hypoxia southward expansion was blocked near the equator in the subsurface layer,because of mixing with multiple zonal circulations(e.g.,Wyrtki Jets and the equatorial undercurrent),which meant that the hypoxic zone extended over a smaller area than in the intermediate water.These new findings will contribute to an improved understanding of the hypoxic zone and will contribute to circulation research,particularly about intermediate circulation in the eastern equatorial Indian Ocean.展开更多
The data from the Southern Ocean observations of World Ocean Circulation Experiment （WOCE） are used for analysis and illustration of the features and spatial distributions of Circumpolar Deep Water （CDW） in the so...The data from the Southern Ocean observations of World Ocean Circulation Experiment （WOCE） are used for analysis and illustration of the features and spatial distributions of Circumpolar Deep Water （CDW） in the southern Indian Ocean. It is learnt from the comparison among the vertical distributions of temperature/ salinity/oxygen along the 30°E, 90°E and 145°E sections respectively that some different features of CDW and the fronts can be found at those longitudes, and those differences can be attributed to the zonal transoceanic flow and the merizonal movement in the Circumpolar Deep Water. In fact, the zonal transoceanic flow is the main dynamic factor for the water exchange between the Pacific Ocean and the /ndian Ocean or between the Atlantic Ocean and the Indian Ocean, and for the effects on the spatial distributions of the physical properties in CDW.展开更多
【目的】探究中西太平洋围网鲣鱼渔场时空分布及其与海洋环境因子之间的关系。【方法】根据2017―2021年上海开创远洋渔业有限公司“金汇58轮”中西太平洋鲣鱼(Katsuwonus pelamis)围网生产统计的数据及遥感获取的海表面温度、叶绿素a...【目的】探究中西太平洋围网鲣鱼渔场时空分布及其与海洋环境因子之间的关系。【方法】根据2017―2021年上海开创远洋渔业有限公司“金汇58轮”中西太平洋鲣鱼(Katsuwonus pelamis)围网生产统计的数据及遥感获取的海表面温度、叶绿素a浓度和海表面高度等环境数据,应用广义相加模型(GAM)对鲣鱼单位捕捞努力量渔获量(Catch per unit of fishing effort,CPUE)进行标准化处理,并逐步回归分析CPUE与各因子的差异显著性,利用软件Arcgis10.7对标准化后鲣鱼CPUE进行空间因子和环境因子的叠加分析。【结果】经度和环境因子(海表面温度、叶绿素a浓度和海表面高度)对鲣鱼CPUE均有显著影响(P<0.05),叶绿素a浓度和海表面温度表现为极显著影响(P<0.01),海表面温度对CPUE的影响最显著,其次为叶绿素a浓度、经度、海表面高度;2017―2021年,中西太平洋鲣鱼年均CPUE最大值(46.59 t/网)出现在2018和2020年,月均最大值(51.79 t/网)出现在2月,作业渔场主要分布在5.0°S―5.0°N、165.0°E―180.0°E;鲣鱼平均CPUE较大值(>42.25 t/网)出现在5.5°―4.5°S,166.5°―168.5°E;1.5°―0.5°S,166.5°―173.5°E;1.5°―0.5°S,173.5°―169.5°W四点连成的海域内。【结论】鲣鱼渔场最适海表面温度为29.25~30.25℃,最适叶绿素a质量浓度为0.138~0.171 mg/m3,最适海表面高度为65.00~75.60 cm。展开更多
利用1967—2009年的逐月海表温度(Sea Surface Temperature,SST)资料和降水资料,以及经验正交函数(Empirical Orthogonal Function,EOF)和相关分析方法,探讨了亚印太交汇区(Joining Area of Asia and Indian-Pacific Ocean,AIPO)SST的...利用1967—2009年的逐月海表温度(Sea Surface Temperature,SST)资料和降水资料,以及经验正交函数(Empirical Orthogonal Function,EOF)和相关分析方法,探讨了亚印太交汇区(Joining Area of Asia and Indian-Pacific Ocean,AIPO)SST的时空分布及其对中国降水的影响。结果表明:海表温度EOF分析第1主分量(即EOF1)的空间分布在整个AIPO区为均一分布,时间系数呈现出明显的年代际变化特征。在年代际尺度上,当AIPO区的SST升高后,北太平洋地区SST开始降低,在11个月后达到最低。另外,AIPO区的SST升高会使南海季风区和东亚季风区的降水增加,使青藏高原西部降水减少。第2主分量(即EOF2)的空间分布在西太平洋基本与东印度洋(包括南海地区)为反相变化,时间系数呈现出明显的2 a和4～5 a为主的年际振荡周期。当Ni o 3.4区SST出现正异常后4个月左右,东印度洋地区有SST正异常,而西太平洋地区有SST负异常。西太平洋地区的SST升高及东印度洋地区的SST降低将导致西北太平洋地区降水增加,东北和华北地区降水减少。而且,AIPO区SST第二模态影响华北和东北的降水要比西北太平洋地区至少超前3个月。展开更多
根据2009—2012年南太平洋长鳍金枪鱼（Thunnus alalunga）延绳钓生产统计数据及遥感获取的海表温度（sea surface temperature,SST）、叶绿素a浓度（chlorophyll a concentration,Chl-a）和海面高度距平（sea surface height anomaly,S...根据2009—2012年南太平洋长鳍金枪鱼（Thunnus alalunga）延绳钓生产统计数据及遥感获取的海表温度（sea surface temperature,SST）、叶绿素a浓度（chlorophyll a concentration,Chl-a）和海面高度距平（sea surface height anomaly,SSHA）等环境数据,分析了长鳍金枪鱼单位捕捞努力量渔获量（catch per unit of fishing effort,CPUE）的时空分布及其与环境因子的相关性。结果表明：长鳍金枪鱼作业渔场主要集中在4°S—28°S、158°E—176°E附近海域;长鳍金枪鱼渔场CPUE呈明显的季节性变化,1—3月CPUE值较低（〈12.5尾·千钩-1）,随后逐渐增加,至7月达到最大值为18.1尾·千钩-1,而8—12月基本呈逐渐降低趋势;1月渔场重心位于16°S、168°E附近海域,2—3月向西北偏移,而在3—7月逐渐向东南方向转移,8月以后开始逐渐回撤至西北方向,在9—12月渔场重心变化幅度相对较小,主要位于15°S—16°S、168°E—169°E海域;总体来说,长鳍金枪鱼中心渔场最适SST为27.0～30.5℃,次适SST为20～24℃;最适叶绿素a浓度为0.02～0.08mg·m-3,最适海面高度距平为3～23 cm。展开更多
Spatial distribution of rainfall and wind speed forecast errors associated with landfalling tropical cyclones(TC)occur significantly due to incorrect location forecast by numerical models.Two major areas of errors are...Spatial distribution of rainfall and wind speed forecast errors associated with landfalling tropical cyclones(TC)occur significantly due to incorrect location forecast by numerical models.Two major areas of errors are:(i)over-estimation over the model forecast locations and(ii)underestimation over the observed locations of the TCs.A modification method is proposed for real-time improvement of rainfall and wind field forecasts and demonstrated for the typical TC AMPHAN over the Bay of Bengal in 2020.The proposed method to improve the model forecasts is a relocation method through shifting of model forecast locations of TC to the real-time official forecast locations of India Meteorological Department(IMD).The modification is applied to the forecasts obtained from the operational numerical model,the Global Forecast System(GFS)of IMD.Application of the proposed method shows considerable improvement of both the parameters over both the locations.The rainfall forecast errors due to displacement are found to have improved by 44.1%–69.8%and 72.1%–85.2%over the GFS forecast locations and over the observed locations respectively for the respective forecast lead times 48 h,72 h,and 96 h.Similarly,the wind speed forecasts have improved by 27.6%–56.0%and 63.7%–84.6%over the GFS forecast locations and over the observed locations respectively for the respective forecast lead times 60 h,72 h,and 84 h.The results show that the proposed technique has capacity to provide improved spatial distributions of rainfall and wind speed forecasts associated with landfalling TCs and useful guidance to operational forecasters.展开更多
基金supported by the National Natural Science Foundation of China(No.41806099)the Global Change and Air-Sea Interaction Project of China(No.GASI-04-HYST-06).
文摘The spatial distribution and seasonal variations of the hypoxic zone in the eastern equatorial Indian Ocean were investigated using survey data collected from four cruises from 2013 to 2018.Results showed that hypoxic zone occurred all year round in the eastern equatorial Indian Ocean,and it spread southward in the shape of a double tongue at two depths with one at subsurface centered at a depth of 150 m and the other in intermediate water centered at a depth of 800 m.The southward expansion and maximum thickness of the hypoxic zone were greatest in the spring inter-monsoon and least in the summer monsoon.The hypoxic zone originated from the southward expansion of the hypoxic water in the Bay of Bengal and its spatial distribution was driven by southward output flux of mid-deep(100–1000 m)hypoxic water from the Bay of Bengal.The hypoxia southward expansion was blocked near the equator in the subsurface layer,because of mixing with multiple zonal circulations(e.g.,Wyrtki Jets and the equatorial undercurrent),which meant that the hypoxic zone extended over a smaller area than in the intermediate water.These new findings will contribute to an improved understanding of the hypoxic zone and will contribute to circulation research,particularly about intermediate circulation in the eastern equatorial Indian Ocean.
基金the National Science Foundation of China under Contract Nos.40376009 and 40676011.
文摘The data from the Southern Ocean observations of World Ocean Circulation Experiment （WOCE） are used for analysis and illustration of the features and spatial distributions of Circumpolar Deep Water （CDW） in the southern Indian Ocean. It is learnt from the comparison among the vertical distributions of temperature/ salinity/oxygen along the 30°E, 90°E and 145°E sections respectively that some different features of CDW and the fronts can be found at those longitudes, and those differences can be attributed to the zonal transoceanic flow and the merizonal movement in the Circumpolar Deep Water. In fact, the zonal transoceanic flow is the main dynamic factor for the water exchange between the Pacific Ocean and the /ndian Ocean or between the Atlantic Ocean and the Indian Ocean, and for the effects on the spatial distributions of the physical properties in CDW.
文摘【目的】探究中西太平洋围网鲣鱼渔场时空分布及其与海洋环境因子之间的关系。【方法】根据2017―2021年上海开创远洋渔业有限公司“金汇58轮”中西太平洋鲣鱼(Katsuwonus pelamis)围网生产统计的数据及遥感获取的海表面温度、叶绿素a浓度和海表面高度等环境数据,应用广义相加模型(GAM)对鲣鱼单位捕捞努力量渔获量(Catch per unit of fishing effort,CPUE)进行标准化处理,并逐步回归分析CPUE与各因子的差异显著性,利用软件Arcgis10.7对标准化后鲣鱼CPUE进行空间因子和环境因子的叠加分析。【结果】经度和环境因子(海表面温度、叶绿素a浓度和海表面高度)对鲣鱼CPUE均有显著影响(P<0.05),叶绿素a浓度和海表面温度表现为极显著影响(P<0.01),海表面温度对CPUE的影响最显著,其次为叶绿素a浓度、经度、海表面高度;2017―2021年,中西太平洋鲣鱼年均CPUE最大值(46.59 t/网)出现在2018和2020年,月均最大值(51.79 t/网)出现在2月,作业渔场主要分布在5.0°S―5.0°N、165.0°E―180.0°E;鲣鱼平均CPUE较大值(>42.25 t/网)出现在5.5°―4.5°S,166.5°―168.5°E;1.5°―0.5°S,166.5°―173.5°E;1.5°―0.5°S,173.5°―169.5°W四点连成的海域内。【结论】鲣鱼渔场最适海表面温度为29.25~30.25℃,最适叶绿素a质量浓度为0.138~0.171 mg/m3,最适海表面高度为65.00~75.60 cm。
文摘利用1967—2009年的逐月海表温度(Sea Surface Temperature,SST)资料和降水资料,以及经验正交函数(Empirical Orthogonal Function,EOF)和相关分析方法,探讨了亚印太交汇区(Joining Area of Asia and Indian-Pacific Ocean,AIPO)SST的时空分布及其对中国降水的影响。结果表明:海表温度EOF分析第1主分量(即EOF1)的空间分布在整个AIPO区为均一分布,时间系数呈现出明显的年代际变化特征。在年代际尺度上,当AIPO区的SST升高后,北太平洋地区SST开始降低,在11个月后达到最低。另外,AIPO区的SST升高会使南海季风区和东亚季风区的降水增加,使青藏高原西部降水减少。第2主分量(即EOF2)的空间分布在西太平洋基本与东印度洋(包括南海地区)为反相变化,时间系数呈现出明显的2 a和4～5 a为主的年际振荡周期。当Ni o 3.4区SST出现正异常后4个月左右,东印度洋地区有SST正异常,而西太平洋地区有SST负异常。西太平洋地区的SST升高及东印度洋地区的SST降低将导致西北太平洋地区降水增加,东北和华北地区降水减少。而且,AIPO区SST第二模态影响华北和东北的降水要比西北太平洋地区至少超前3个月。
文摘根据2009—2012年南太平洋长鳍金枪鱼（Thunnus alalunga）延绳钓生产统计数据及遥感获取的海表温度（sea surface temperature,SST）、叶绿素a浓度（chlorophyll a concentration,Chl-a）和海面高度距平（sea surface height anomaly,SSHA）等环境数据,分析了长鳍金枪鱼单位捕捞努力量渔获量（catch per unit of fishing effort,CPUE）的时空分布及其与环境因子的相关性。结果表明：长鳍金枪鱼作业渔场主要集中在4°S—28°S、158°E—176°E附近海域;长鳍金枪鱼渔场CPUE呈明显的季节性变化,1—3月CPUE值较低（〈12.5尾·千钩-1）,随后逐渐增加,至7月达到最大值为18.1尾·千钩-1,而8—12月基本呈逐渐降低趋势;1月渔场重心位于16°S、168°E附近海域,2—3月向西北偏移,而在3—7月逐渐向东南方向转移,8月以后开始逐渐回撤至西北方向,在9—12月渔场重心变化幅度相对较小,主要位于15°S—16°S、168°E—169°E海域;总体来说,长鳍金枪鱼中心渔场最适SST为27.0～30.5℃,次适SST为20～24℃;最适叶绿素a浓度为0.02～0.08mg·m-3,最适海面高度距平为3～23 cm。
文摘Spatial distribution of rainfall and wind speed forecast errors associated with landfalling tropical cyclones(TC)occur significantly due to incorrect location forecast by numerical models.Two major areas of errors are:(i)over-estimation over the model forecast locations and(ii)underestimation over the observed locations of the TCs.A modification method is proposed for real-time improvement of rainfall and wind field forecasts and demonstrated for the typical TC AMPHAN over the Bay of Bengal in 2020.The proposed method to improve the model forecasts is a relocation method through shifting of model forecast locations of TC to the real-time official forecast locations of India Meteorological Department(IMD).The modification is applied to the forecasts obtained from the operational numerical model,the Global Forecast System(GFS)of IMD.Application of the proposed method shows considerable improvement of both the parameters over both the locations.The rainfall forecast errors due to displacement are found to have improved by 44.1%–69.8%and 72.1%–85.2%over the GFS forecast locations and over the observed locations respectively for the respective forecast lead times 48 h,72 h,and 96 h.Similarly,the wind speed forecasts have improved by 27.6%–56.0%and 63.7%–84.6%over the GFS forecast locations and over the observed locations respectively for the respective forecast lead times 60 h,72 h,and 84 h.The results show that the proposed technique has capacity to provide improved spatial distributions of rainfall and wind speed forecasts associated with landfalling TCs and useful guidance to operational forecasters.
