利用资料同化方法优化观测系统的空间布局:以泰国湾为例   总被引：1，自引：0，他引：1  

史军强  尹训强  乔方利 《海洋学报》2018,40(2):14-29

海洋观测费用高昂，设计科学高效的观测系统可以充分发挥观测的效能。本文以泰国湾高频地波雷达观测系统为例，利用数据同化方法对观测系统进行了最优布局。首先基于FVCOM海洋数值模式建立了泰国湾海域高分辨率三维斜压水动力模式，在此基础上利用一种改进的高效集合卡曼滤波同化方法对岸基高频地波雷达表层海流观测系统开展观测效能评估数值实验。通过观测区域的不同组合方式将3个区域的雷达表层海流数据同化到数值模式中，实验结果表明，岸基高频地波雷达表层海流观测系统可有效降低高分辨数值模式的海流模拟误差。但不同观测区域的组合提供的观测数据对改善海流模拟的作用存在明显差别，泰国湾现有观测系统雷达站位布设方式应进一步优化。本文最后给出了研究区域最优观测站位的布局方案，可作为下一步观测系统进行布局调整的指导。  相似文献   

带有侧摩擦和底摩擦的绕岛理论     

杨延召  魏泽勋  王冠琳  连展  王立伟 《海洋学报(英文版)》2019,38(4):146-153

绕岛理论来自于Sverdrup理论，被广泛用于估计和分析通过岛屿之间海峡的输运情况。以往的研究得到了带有侧摩擦或底摩擦的单岛理论或多岛理论。本文在线性情况下考虑了风驱动环流下的解析模型。在同时考虑侧摩擦和底摩擦的情况下，推导出了岛屿周围输运流函数的解析解，并给出了通过岛屿之间通道的流量输运。其结果与Wajsowicz相似，但摩擦常数表示不同的值。从解析解上看，摩擦常数与侧摩擦和底摩擦之间的关系比较复杂，为了推导出它们之间的相互作用原理，本文在正压β平面上随机选取了一些侧摩擦和底摩擦的值。结果表明，在构成摩擦常数方面，侧摩擦和底摩擦近似呈线性关系。我们研究了宽度对通道输运值的影响，结果表明摩擦在一定宽度内提高了流量，这种现象和只考虑侧摩擦时比较相似。本文也比较了在不同深度下的流量，发现当水平涡粘性系数和底部拖曳系数固定时，水深越大，输运减少率越小。为了进一步揭示侧摩擦和底摩擦耗散的联合作用，在两个岛屿的情况下，本文在不同宽度的通道中与Wajsowicz的只考虑底摩擦或侧摩擦的模型进行了比较。结果表明，当通道比较窄，尤其是在小于Munk边界层厚度时，侧摩擦的作用大于底摩擦。当通道宽度远大于Munk边界层厚度时，底摩擦的作用大于侧摩擦。将模型应用到印尼贯穿流，得到大约20%的输运减少量。  相似文献   

Differences in Meteorological Conditions between Days with Persistent and Non-Persistent Pollution in Beijing,China     

Ting?You  Renguang?WuEmail author  Gang?Huang

《Acta Meteorologica Sinica》2018,32(1):81-98

We compared the regional synoptic patterns and local meteorological conditions during persistent and non-persistent pollution events in Beijing using US NCEP–Department of Energy reanalysis outputs and observations from meteorological stations. The analysis focused on the impacts of high-frequency (period < 90 days) variations in meteorological conditions on persistent pollution events (those lasting for at least 3 days). Persistent pollution events tended to occur in association with slow-moving weather systems producing stagnant weather conditions, whereas rapidly moving weather systems caused a dramatic change in the local weather conditions so that the pollution event was short-lived. Although Beijing was under the influence of anomalous southerly winds in all four seasons during pollution events, notable differences were identified in the regional patterns of sea-level pressure and local anomalies in relative humidity among persistent pollution events in different seasons. A region of lower pressure was present to the north of Beijing in spring, fall, and winter, whereas regions of lower and higher pressures were observed northwest and southeast of Beijing, respectively, in summer. The relative humidity near Beijing was higher in fall and winter, but lower in spring and summer. These differences may explain the seasonal dependence of the relationship between air pollution and the local meteorological variables. Our analysis showed that the temperature inversion in the lower troposphere played an important part in the occurrence of air pollution under stagnant weather conditions. Some results from this study are based on a limited number of events and thus require validation using more data.  相似文献   

Erratum to: Regional Meteorological Patterns for Heavy Pollution Events in Beijing     

Ting You  Renguang Wu  Gang Huang 《Acta Meteorologica Sinica》2018,32(3):516-516

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Performance of CMIP6 models in simulating the dynamic sea level: Mean and interannual variance          下载免费PDF全文

《大气和海洋科学快报》2023,16(1):100288

Observational data from satellite altimetry were used to quantify the performance of CMIP6 models in simulating the climatological mean and interannual variance of the dynamic sea level (DSL) over 40°S–40°N. In terms of the mean state, the models generally agree well with observations, and high consistency is apparent across different models. The largest bias and model discrepancy is located in the subtropical North Atlantic. As for simulation of the interannual variance, good agreement can be seen across different models, yet the models present a relatively low agreement with observations. The simulations show much weaker variance than observed, and bias is apparent over the subtropics in association with strong western boundary currents. This nearshore bias is reduced considerably in HighResMIP models. The underestimation of DSL interannual variance is at least partially due to the misrepresentation of ocean processes in the CMIP6 historical simulation with its relatively low resolution. The results identify directions for future model development towards a better understanding of the mean and interannual variability of DSL.摘要本研究采用卫星测高数据与第六次国际耦合模式比较计划 (CMIP6) 海平面动力进行对比, 重点针对40°S–40°N地区的动力海平面 (DSL) , 评估了模式对其平均态与年际变率的综合模拟能力. 结果表明, 对于DSL平均态的模拟, 模式与观测结果非常吻合, 模式之间的差异较小. 其中, 副热带北大西洋是模拟偏差和模式间差异较为显著的区域. 对于DSL年际变率的模拟, 模式之间保持较高的一致性, 但是, 模式与观测结果存在明显差异, 模式普遍低估了DSL的年际方差; 其中, 误差大值区域出现在副热带西边界流附近. 模式分辨率会影响CMIP6对中小尺度海洋过程的重现能力, 这可能是导致CMIP6历史模拟出现误差的原因之一.  相似文献   

海洋再分析资料中IOD-ENSO遥相关的海洋通道机制分析   总被引：1，自引：1，他引：0  

徐腾飞  周慧 《海洋学报》2016,38(12):23-35

本文利用滞后相关分析,研究了海洋再分析资料（SODA、ORAS4和GODAS）中的IOD-ENSO滞后遥相关关系,并与观测资料进行对比。结果显示,3套再分析资料中热带东南印度洋秋季海表温度/海表高度异常和赤道太平洋冷舌次年秋季海表温度/海表高度异常之间显著相关,与观测结果一致。在次表层,观测和再分析资料均显示,热带东南印度洋秋季海表温度异常与赤道太平洋次表层海温异常之间的显著相关关系在冬季至次年秋季沿赤道太平洋垂向剖面向东移动,并于次年夏季和秋季在冷舌区上升至海表。热带东南印度洋和赤道太平洋冷舌滞后1年的相关关系是由海洋通道机制引起的,即IOD事件引起印尼贯穿流流量异常,导致赤道太平洋温跃层异常,激发赤道Kelvin波向东传播,从而影响赤道中-东太平洋冷舌海表温度异常。观测及SODA与ORAS4资料中,热带东南印度洋和赤道太平洋冷舌滞后1年的相关关系在去除ENSO信号后仍然显著,表明海洋通道机制是独立于ENSO事件的;而在GODAS资料中,这些显著相关关系在去除ENSO信号后消失。印尼贯穿流流量异常和Niño3.4及DMI（Dipole Mode Index）指数之间超前-滞后12个月的相关关系显示,在SODA和ORAS4资料中,印尼贯穿流流量同时受到ENSO和IOD的影响,与观测结果一致;而在GODAS中,印尼贯穿流流量异常仅与Niño3.4指数显著相关,极少受到IOD事件的影响,这部分解释了GODAS资料中去除ENSO信号后,IOD-ENSO滞后遥相关关系消失的原因。  相似文献   

Quantifying the contribution of natural variability to September Arctic sea ice decline   总被引：1，自引：0，他引：1  

SONG Mirong  WEI Lixin  WANG Zhenzhan 《海洋学报(英文版)》2016,35(5):49-53

Arctic sea ice extent has been declining in recent decades. There is ongoing debate on the contribution of natural internal variability to recent and future Arctic sea ice changes. In this study, we contrast the trends in the forced and unforced simulations of carefully selected global climate models with the extended observed Arctic sea ice records. The results suggest that the natural variability explains no more than 42.3% of the observed September sea ice extent trend during 35 a(1979–2013) satellite observations, which is comparable to the results of the observed sea ice record extended back to 1953(61 a, less than 48.5% natural variability). This reinforces the evidence that anthropogenic forcing plays a substantial role in the observed decline of September Arctic sea ice in recent decades. The magnitude of both positive and negative trends induced by the natural variability in the unforced simulations is slightly enlarged in the context of increasing greenhouse gases in the 21st century.However, the ratio between the realizations of positive and negative trends change has remained steady, which enforces the standpoint that external forcing will remain the principal determiner of the decreasing Arctic sea ice extent trend in the future.  相似文献   

冲绳海槽中段表层沉积物物质来源的定量分离:Sr-Nd同位素方法   总被引：16，自引：2，他引：16  

孟宪伟  杜德文  吴金龙 《海洋与湖沼》2001,32(3):319-326

利用1994年85－904航次获取的冲绳海槽中段表层沉积物样品，测定其硅酸盐相的^87Sr/^86Cr和^143Nd/^144Nd比值，以定量研究冲绳海槽中段表层沉积物硅酸盐物质的来源，结果表明，冲绳海槽中段陆坡区表层沉积物硅酸盐相的^87Sr/^86Sr/^143Nd/^144Nd与东海陆架沉物硅酸盐相的^87Sr/^86Sr和^143Nd/^143Nd相当，槽底和东坡沉积物硅酸盐相的^87Sr/^86Cr和^143Nd/^144Nd值介于中国大陆硅酸盐物质和海槽水山碎屑的^87Sr/^86Sr,^143Nd/^144Nd比值之间，并大致具有两端员混合特征，利用以Sr同位素为参数的二端员混合方程进行物源定量分析的结果表明，冲绳海槽中段的西坡和槽底表层沉积物硅酸盐相以陆源物质为主，最大值为91．07％，由西向东，陆源物逐渐减少，在海槽东坡含量最小，最小值为9．93％，火山源物质在东坡含量最高，量大值为64．92％，由东向西，由北向东，火山源物质逐渐减少为零。  相似文献   

Teleconnection of IOD signal in the upper troposphere over southern high latitudes     

Na Liu  Hong-Xia Chen  Lian-Gang Lü 《Journal of Oceanography》2007,63(1):155-157

Evidence has been found for the teleconnection of Indian Ocean Dipole mode (IOD) events in the southern high latitude sea surface pressure field, although the mechanisms that might lead to such far-reaching links remain unresolved. Based on the teleconnection pattern between IOD and the climate anomaly in the upper troposphere, we propose one such mechanism here: the energy propagation theory of the atmospheric planetary wave. Ray traces of the atmospheric planetary waves suggest that the energy propagation of the waves could be responsible for the teleconnection between IOD and tropospheric climate anomalies in southern high latitudes.  相似文献   

基于光谱阈值法和分裂合并聚类算法的“HY-1A”CCD云检测算法和应用     

王瑞富  孙凌  张杰  宋平舰 《海洋学报》2006,28(6):158-163

“海洋1号A”卫星(简称“HY-1A”)是我国第一颗海洋卫星,它搭载了水色扫描仪和CCD成像仪,其中CCD成像仪主要应用于海岸带地区.为了对海岸带地区进行准确的信息提取和分析,必须去除云的影响和干扰,因此本文针对“HY-1A”CCD数据的特点,对云检测算法进行了评估、遴选和改造,实现了业务化应用,这也是“HY-1A”卫星CCD成像仪海岸带应用示范系统的重要工作之一.云检测的方法众多,主要可以分为可见光/红外阈值法和聚类法两种,每种方法还可以辅以空间均匀性判识.  相似文献