杭州湾、长江口余流及其物质输运作用的模拟研究Ⅱ．冬季余流及其对物质的输运作用

首先分析了杭州湾、长江口冬季余流和物质输运作用的观测特征,提出了几个值得继续研究的问题．然后,利用杭州湾、长江口三维联合模型,综合考虑径流、风应力、密度流、中国东部海域背景环流和M2,S2,K1,O1四个分潮的综合作用,模拟出了冬季的余流结构及其对物质的输运作用．在此基础上,针对所总结的几个问题,进一步作数值模拟,讨论余流和物质输运作用形成的机制．     

季风转换期印度洋经向热输运的年际变异及其机理

本文采用SODA3.4.2再分析数据和POP2海洋模式研究了季风转换期间（春季和秋季）热带印度洋经向热输运异常（Meridional Heat Transport Anomaly, MHTA）的年际变异特征。春季MHTA存在两个主要模态,即一致模态和辐合辐散模态:一致模态表现为热带印度洋上层一致的向北输运,受热带印度洋海温一致模相关的赤道反对称风场（赤道以北/南为东北风/西北风异常）调控;辐合辐散模态则呈现关于赤道对称的表层辐散次表层辐合特征,受控于赤道以南的热带西南印度洋和副热带东南印度洋海温偶极子。然而,秋季MHTA仅表现为辐合辐散模态,受到印度洋偶极子期间赤道东风和赤道外反气旋式风应力异常影响。此外,POP2敏感性试验也验证了印度洋海温模态影响下异常风场对MHTA的调控作用,即反对称的风引起一致向北的MHTA,赤道东风异常引起MHTA表层辐散、次表层辐合现象。因此,热带印度洋海气耦合模态年际变化对印度洋上层热量再分配有着重要的意义。     

杭州湾,长江口余流及其物质输运作用的模拟研究：Ⅱ.冬季余流及其对物 …

首先分析了杭州湾、长江口冬季余流和物质输运作用的观测特征,提出了几个值得继续研究的问题。然后,利用杭州湾、长江口三维联合模型,综合考虑径流、风应力、密度流、中国东部海域背景环流和Ｍ２,Ｓ２,Ｋ１,Ｏ１四个分潮的综合作用,模拟出了冬季的余流结构及其对物质的输运作用。在此基础上,针对所总结的几个问题,进一步作数值模拟,讨论余流和特技输运作用形成的机制。     

琼州海峡东部水进入北部湾对广西沿海环流的影响

本文通过对琼州海峡东部水域温盐资料和沿岸海洋站同步观测资料的对比发现：夏季，广西涠洲岛盐度变化规律和琼州海峡东部、中部变化规律一致，广西北海略受影响，而远离琼州海峡的龙门和白龙尾两站，则更多反映夏季陆地水文规律。同时，采用琼州海峡多年海流资料和涠洲岛定点站及近期测流站的海流观测资料对比看出，琼州海峡冬夏季余流方向仍然是自东向西。结合数值模拟计算结果，同样得出琼州海峡东部水自东向西进入北部湾的事实。这些温盐分布特征和余流观测结果进一步证实：粤西沿岸流是琼州海峡水向西输运的主要来源，形成粤西沿岸流这种现象的根源在于珠江冲淡水的西向流，它们通过琼州海峡进入北部湾，加强了北部湾北部气旋式环流的形成。夏季，在强的西南风作用下，产生较强北部湾西岸北向沿岸流，促使低盐冲淡水向外海输运，然后在东部涠洲岛附近形成更大范围内气旋式环流。琼州海峡东部水进入北部湾对广西沿海环流影响的研究，直接向琼州海峡冬夏季水体输运方向的传统结论提出了新的挑战。     

琼州海峡余流场季节性变化特征

本文通过利用多年的琼州海峡海流实测资料,研究了琼州海峡潮余流场的季节性变化特征。结果表明该水域全年余流方向总趋势是由东向西的,这和以往研究结论不同:许多研究者认为,夏季受西南季风影响,水体输运方向是由北部湾指向南海的。本文还对其夏季水体输运机制进行了分析。     

杭州湾、长江口余流及其物质输运作用的模拟研究Ⅱ冬季余流及其对物质的运输作用

首先分析了杭州湾、长江口冬季余流和物质输运作用的观测特征,提出了几个值得继续研究的问题．然后,利用杭州湾、长江口三维联合模型,综合考虑径流、风应力、密度流、中国东部海域背景环流和Ｍ２,Ｓ２,Ｋ１,Ｏ１四个分潮的综合作用,模拟出了冬季的余流结构及其对物质的输运作用．在此基础上,针对所总结的几个问题,进一步作数值模拟,讨论余流和物质输运作用形成的机制。     

2008年夏季楚科奇海余流分布特征

根据2008-08-05-09-07在楚科奇海布放的一套浅水潜标系统(71°40′1.4″N,167°58′54.6″W)获得的海流剖面资料及温盐资料,采用Lanczos余弦滤波的方法,研究了楚科奇海中央水道余流剖面及温盐时间序列的结构和变化特征,对表层余流与风场的关系及影响温盐结构的因素进行了分析。结果表明,余流的方向和大小在垂直方向上存在明显的差异:表层余流全流呈现西向流态,平均流速为19.6cm/s,方向为257.4°,受表层风场影响显著;中、下层的余流全流平均流速为6.6cm/s,流向为29.6°,呈现东北偏北方向。在整个观测期间,温度时间序列表现出剧烈的震荡,振幅达到3.7℃以上,而盐度序列变化缓慢,波动区间相对较小,为32.0～32.8,并表现出逐渐降低的趋势;温盐序列的变化受底层余流分布的影响较弱。     

北部湾海浪季节变化和驱动因素的数值模拟研究

基于NCEP CFSV2再分析风场驱动SWAN模型,对南海至北部湾为期1年的海浪逐时过程进行了数值模拟,利用Jason-2卫星和近岸浮标整年观测数据检验了模拟效果。在此基础上,评估了模型空间网格尺度对北部湾内波浪模拟的影响,分析了波浪的季节变化特征,辨析了局地风和南海传入浪对海湾波浪的驱动贡献。研究显示:（1）较Jason-2卫星观测值,有效波高模拟值的均方根误差和分散系数分别约为0.4 m和0.2;较北部湾湾顶近岸浮标逐时观测值,有效波高的均方根误差和分散系数分别约为0.2 m和0.4,平均波周期的均方根误差和分散系数分别约为0.6 s和0.2,平均波向的均方根误差约为30°;（2）空间网格分辨率为12'×12'的模型对北部湾20 m以深开敞海域波浪的模拟效果良好,模拟值较2'×2'模型的平均相对偏差在10%以下;（3）北部湾冬季盛行东北向波,夏季盛行偏南向浪,季风转换期盛行东南向浪,全年波浪在季风期强于季风转换期,冬季最强、冬夏转换期最弱;（4）局地风对北部湾波浪的驱动贡献自湾口向湾内增强,季风期强于季风转换期;南海传入浪的驱动贡献自湾口向湾内减弱,季风转换期强于季风期;海湾中部和北部的波浪以局地风为主控因素,海南岛南部和东部水域以传入浪的影响为主,海南岛西南水域受局地风和传入浪的共同控制。     

南海海面风、浪场时空变化特征及其关系分析

利用长时间序列的卫星观测数据,对南海海域的风、浪场时空分布及其相互关系进行了分析。结果显示,海面风距平场VEOF分解后得到的第一模态具有明显的季节变化,即季风特征,说明季风是影响整个南海风速的主要因素;第二模态具有较强的区域变化特征,是季风转换时期的距平场特征;第三模态反映的是海面风距平场受陆地地形影响所表现的分布特征。有效波高距平场EOF分解后得到的第一模态、第二模态与风距平场的前2个模态的空间分布较为相似,并且,风、浪距平场第一模态间的相关系数达0.76,均说明南海作为边缘海其波浪场与风场变化有很好的相关性。有效波高第三模态的分布与风场的第三模态相关性较弱,反映的是受海底地形影响所表现的分布特征。     

辽东湾中部西岸浅水海域冬季实测海流分析

2015年12月在辽东湾中部西岸浅水海域进行了8个站、连续半个月的坐底ADCP海流剖面观测,通过对分层潮流和余流分析,得到该海域的海流特征如下:1)实测海流以潮流特征占主导,潮流特征为规则半日潮流,优势分潮为M2;M2椭圆长轴大小为25~50 cm/s、方向多为NE-SW向,具有显著的往复流特征。2)观测期间的平均余流为1~10 cm/s,方向多为SW向,平均余流在水平和垂向上的空间差异明显,日均余流波动剧烈;表层余流方向与局地风向具有很好的同步一致性,且距岸较近站位的表层余流受风影响更大;中、底层余流与风的相关性较差。本文得到的余流方向不支持冬季辽东湾北部的边界顺时针环流的存在。     

Variation in the thermohaline front at the mouth of Tokyo Bay

The generation, variation, and disappearance of the thermohaline front at the mouth of Tokyo Bay were investigated using water temperature data obtained by a commercial ferry boat in 1987. The thermohaline front was generated south of Kan-non-zaki in mid November 1987 after the beginning of sea-surface cooling. It moved northward to Kan-non-zaki until the end of the year. The thermohaline front was most intense in February and March and disappeared in late March 1987 when sea-surface warming began.     

Comparison of Multimission Altimetric Sea-Surface Heights with Tide Gauge Observations in the Southern Baltic Sea

One possible technique to validate the observations of altimeter missions is the comparison with sea-surface heights measured by tide gauges. In our investigation, we compared observations of the two tide gauge stations, Sassnitz and Warnemünde, which are located at the southern coast of the Baltic Sea, with sea-surface heights obtained from the altimeter missions Geosat, ERS-1, ERS-2, and TOPEX/Poseidon. For this purpose, the compared sea-surface heights were related to a common reference system and extrapolated to a common location. GPS observations, leveling data, regional geoid information, sea-surface topography, and postglacial rebound were included in the analysis. Considering the uncertainties of all model components, a more reliable estimation of the error budget (source, type, and magnitude of the errors) was performed. The obtained absolute altimeter biases are (-243 - 32) mm for Geosat, (467 - 19) mm for ERS-1, (76 - 19) mm for ERS-2, and (13 - 18) mm for TOPEX.     

基于航次观测和再分析资料的南海海表二氧化碳分压反演及变化机制分析*

海表二氧化碳分压(pCO₂)是指海洋表层水和大气之间的二氧化碳(CO₂)交换处于动态平衡时CO₂的含量, 是描述海-气CO₂交换的一个主要因子。本文利用2008—2014年覆盖南海大部分海域的海表pCO₂观测资料, 结合现场海表温度和海表盐度以及卫星观测的叶绿素a数据, 构建了基于多元线性回归方法的分区域反演模型。模型在水深浅于30m的区域均方根误差为5.3μatm, 其余海区均方根误差为10.8μatm, 与前人基于个别航次的有限区域反演结果的均方根误差相当。利用该模型公式和HYbrid Coordinate Ocean Model(HYCOM)再分析海表温、盐数据及MODIS-Aqua卫星观测的叶绿素a数据进行反演, 得到了时空分辨率为5'×5'的2004—2016年的逐月南海海表pCO₂数据。该数据能较好地反映南海海表pCO₂在海表温度影响下, 春夏高、秋冬低的季节变化特征, 与前人基于航次观测的研究结果相似, 表明反演模型具有较高的可信度。进一步分析发现, 南海及邻近海域平均海表pCO₂具有显著的准十年振荡特征: 2012年附近出现了极小值, 之前表现为降低的趋势, 之后略有升高的趋势。受海表pCO₂的影响, 南海海盆平均海-气CO₂通量在2012年之前出现了显著降低的趋势, 表明南海释放到大气中的CO₂减少, 并在2007年之后的冬季出现了负值(从碳源变为碳汇), 2012年之后变化较为平缓。热带太平洋年代际振荡引起的南海区域海表盐度变化是造成海表pCO₂及海-气CO₂通量准十年变化的主要原因。分区分析的结果表明, 南海北部海表pCO₂变化最为显著, 在南海海表pCO₂的季节和准十年变化中都起到非常重要的作用。     

大亚湾微表层和次表层海水营养盐的研究

根据1998年秋季（10、11月）、1999年春、秋季（4、5、10月）5个航次对大亚湾海区微、次表层的调查结果，分析了微表层海水对氮、磷、硅营养盐的富集概况，讨论了营养盐与环境因子的关系。结果表明：大亚湾海区微表层海水对氮、磷、硅营养盐均有富集作用，因海况及季节不同，富集因数（EF）与其他海区的有所差别；无论夏季或秋季，大亚湾海区微表层海水中无机氮都以NH4－N为主要存在形态；其余水层则以NO3－N为主要存在形态。结果还表明，微表层、次表层海水中NH4－N与BOD5、COD测值都呈高度显著正相关，与PO4－P和SiO3-Si含量均无相关，说明大亚湾海区水中含氮有机物较含磷有机物丰富。     

Determination of temperature and humidity of air,wind speed,and sensible and latent heat fluxes on the ocean surface according to the satellite data

Formulas for the evaluation of temperature and humidity of air, wind speed, and sensible and latent heat fluxes on the ocean surface according to the satellite data on the sea-surface temperature and cloudiness are deduced on the basis of the analysis of many-year radiosonde, meteorological, shipborne, and satellite data. The proposed formulas can also be used for the interpretation of the results of remote sensing of the ocean and atmosphere by radiometers in the visible, infrared, and microwave regions. The transformations of radiation and sensible and latent heat fluxes are described depending on the sea-surface temperature for various cloudiness conditions. The computed values of the amount of water in the atmosphere agree with the radiosonde data obtained throughout the Earth, including the data of research vessels and stationary weather ships, as well as the data obtained in the ATEP test ranges and in the Arctic. __________ Translated from Morskoi Gidrofizicheskii Zhurnal, No. 2, pp. 56–70, March–April, 2007.     

A study on retrieval algorithms in oceanic passive microwave remote sensing using 1.4 GHz and 10.7 GHz bands

To retrieve sea-surface salinity (SSS) from radiometer data at 1.4 GHz, auxiliary data of sea-surface temperature (SST), surface roughness and meteorological variables are needed. The authors study oceanic passive polarimetric microwave remote sensing using 1.4 GHz and 10.7 GHz bands. A set of algorithms are developed for 1.4 GHz and 10.7 GHz microwave polarimetric radiometer at 50° incidence angle to retrieve wind vector, as well as other geophysical parameters, such as SSS, SST, atmospheric volumes of water vapor and liquid water. Idealized retrievals are conducted using 2324 simulated brightness temperatures of full Stokes parameters at 1.4 GHz and 10.7 GHz. Results indicate that SSS, SST, sea-surface wind speed, direction, atmospheric volumes of water vapor and liquid water can be inversed at the same time. This suggests an alternative way for SSS remote sensing.     

大洋海区海-气CO_2通量单参数遥感算法的适用性检验

利用卫星遥感技术的优势,基于LDEO数据库的全球海表二氧化碳分压（PCO2）及海表温度（SST）等实测数据,初步建立东太平洋海区PCO2与SST的单参数经验算法,并采用相同区域的独立实测数据检验.结果表明,单参数算法在寡营养大洋海区具有良好的适用性,反演值与实测值之间的均方根误差（RMS）为0.51 Pa（1 Pa=9.869μatm）,由此估算出2003年6月该海域CO2通量为-1.4 mmol/（m2.d）,与实测估算的碳通量基本相符,能够很好地反映出海区CO2源汇特征.将该遥感算法运用到西大西洋海域（15°~25°N,60°~75°W）,反演值与实测值之间均方根误差（RMS）为0.69 Pa.检验结果表明,在寡营养大洋海区,单参数遥感算法具有一定的适用性,在受相似因子调控的同纬度海区可以使用同一遥感算法.     

深海海面目标单水听器被动测距方法与验证

基于射线理论分析了在深海情况下海面声源产生声场的频率-距离干涉结构,给出了影区内声场频率-距离干涉结构的近似理论表达式,分析得到影区内声场频域干涉周期随收发距离的增加而增大、随着接收水听器深度的增加而减小。因此由单水听器记录的声场干涉结构即可实现被动声源距离估计。在南海深海实验中观测到海面宽带噪声源在声场影区形成的声场干涉结构,对实验获得声场干涉结构的处理结果验证了深海声场影区干涉结构用于被动声源距离估计的有效性。与传统的匹配场被动定位方法相比,该方法不需要已知海底声学参数和大规模的拷贝场计算。     

A high-resolution seismic profiling system using a deep-towed horizontal hydrophone streamer

A seismic reflection profiling system utilising a surface air gun source and a deep-towed horizontal hydrophone streamer has been developed for high resolution studies in the deep ocean. The instrument is deployed on a conventional armoured single conductor cable at depths of up to 6 km. Seismic data from the 30 m long streamer is wide-band frequency modulated up the towing cable to the ship together with a high frequency monitor from a 3.5 kHz echo-sounder mounted on the instrument package. The geometry of the system allows an order of magnitude improvement in spatial resolution compared with that obtained from standard surface source/receiver configurations. The summed hydrophones of the streamer attenuate cable-generated mechanical noise, and the 3.5 kHz sea-surface and bottom reflected returns provide receiver positioning information. The system has been successfully deployed at depths of 5 km in the Vema Fracture Zone in the North Atlantic, and although initially difficulties were experienced in balancing the streamer, subsequent profiles across the transform fault show details of sub-bottom structure which on conventional surface records are generally masked by diffraction hyperbolae.     

Comparison between Eulerian diagnostics and finite-size Lyapunov exponents computed from altimetry in the Algerian basin

Transport and mixing properties of surface currents can be detected from altimetric data by both Eulerian and Lagrangian diagnostics. In contrast with Eulerian diagnostics, Lagrangian tools like the local Lyapunov exponents have the advantage of exploiting both spatial and temporal variability of the velocity field and are in principle able to unveil subgrid filaments generated by chaotic stirring. However, one may wonder whether this theoretical advantage is of practical interest in real-data, mesoscale and sub-mesoscale analysis, because of the uncertainties and resolution of altimetric products, and the non-passive nature of biogeochemical tracers. Here we compare the ability of standard Eulerian diagnostics and the finite-size Lyapunov exponent in detecting instantaneous and climatological transport and mixing properties in the south-western Mediterranean. By comparing with sea-surface temperature patterns, we find that the two approaches provide similar results for slowly evolving eddies like the first Alboran gyre. However, the Lyapunov exponent is also able to predict the (sub-)mesoscale filamentary processes occurring along the Algerian current and above the Balearic Abyssal Plain. Such filaments are also observed, with some mismatch, in sea-surface temperature patterns. Climatologies of Lyapunov exponents do not show any compact relation with other Eulerian diagnostics, unveiling a different structure even at the basin scale. We conclude that filamentation dynamics can be detected by reprocessing available altimetric data with Lagrangian tools, giving insight into (sub-)mesoscale stirring processes relevant to tracer observations and complementing traditional Eulerian diagnostics.