台风“灿鸿”影响下海浪的数值模拟研究

台风是影响中国黄东海的强天气现象,其引起的强风、巨浪和台风增水严重威胁着沿海地区人民的生命与财产安全。本文以海浪模式SWAN（Simulating Waves Nearshore）与区域海洋模式ROMS（Regional Ocean Modeling System）为基础,构建了中国黄东海海域在201509号台风“灿鸿”影响下的海浪-海洋耦合模式。通过浮标与Jason-2高度计有效波高数据验证了模式结果的准确性。进行了敏感性实验分析,对比耦合（ROMS+SWAN）与非耦合（SWAN）下以及使用不同地形数据（ETOPO1、ETOPO2、GEBCO）、不同物理参数化方案（风能输入、白冠耗散、底摩擦耗散）下的模拟结果差异。结果发现在射阳与前三岛浮标处,使用GEBCO地形数据（15弧秒间隔）下的模拟效果更好且稳定。在空间分布上,台风中心附近的浪流相互作用显著,在其前进方向右侧表现为耦合的有效波高值低于非耦合有效波高值,差值最高可达1米。选择不同风输入与耗散项方案时的模拟差异主要发生在最大波高处,选择不同的风能输入与白冠耗散项方案带来的差异接近0.4米,而底摩擦项方案选择不同带来的差异接近1米。因而在模拟实际的海况时,需要综合考虑这些因素带来的影响,才能达到SWAN海浪模型最好的海浪模拟效果。     

KSS31M型海洋重力仪动态性能的分析

采用海上实测数据对KSS31M(SN 036)海洋重力仪的阻尼延迟时间和可靠性做了分析,提出采用船只机动转向时重力数据和定位数据、厄特渥斯值的响应时间差来确定在该海况和仪器滤波系数时重力仪的阻尼延迟时间。得到的2级海况滤波系数下的阻尼延迟时间为60 s,比厂方提供的理论值更接近实际。本方法有助于提高海洋重力测量的精度。同时重力读数与厄特渥斯值变化的相位和振幅吻合,表明KSS31M海洋重力仪具有很高的可靠性和准确性。     

黄河三角洲浅层地下水位年内变化特征及影响因素

基于黄河三角洲地区3个站位的1小时一次的浅层地下水位连续观测记录,将浅层地下水位与同时期ERA5高分辨率再分析实际蒸发量数据结合,并联合潮位、降水量和径流量等数据,通过快速傅里叶变换、时序分析等方法,分析并阐明了黄河三角洲地区浅层地下水位变化的特征及机制。结果表明：（1）不同的沉积环境导致了浅层地下水位整体变化的差异。表层沉积物渗透性相对较强区域,浅层地下水位波动剧烈;而表层沉积物透水性较差地区,浅层地下水位在6月中上旬存在低谷,但总体相对稳定;（2）潮汐对黄河三角洲浅层地下水位在水平方向的影响范围至少可达7km,但不超过15km。在其影响区域内,浅层地下水位波动滞后于潮汐的时间存在年内变化,分为两个时间上持续各6个月的区间,二者数值相差约12h;（3）降水量与实际蒸发量是黄河三角洲浅层地下水位升降最主要的影响因素。此外,农业活动也对浅层地下水位的变化有一定影响。对黄河三角洲浅层地下水位变化规律研究,能够为本地区土地盐碱化、海水入侵灾害防治与生态保护提供科学依据。     

Evaluating the contribution of satellite measurements to the re-construction of three-dimensional ocean temperature fields in combination with Argo profiles

Assimilation systems absorb both satellite measurements and Argo observations. This assimilation is essential to diagnose and evaluate the contribution from each type of data to the reconstructed analysis, allowing for better configuration of assimilation parameters. To achieve this, two comparative reconstruction schemes were designed under the optimal interpolation framework. Using a static scheme, an in situ-only field of ocean temperature was derived by correcting climatology with only Argo ...     

Different approaches to model error formulation in 4D-Var: a study with high-resolution advection schemes

All numerical models are imperfect. Weak constraint variational data assimilation ( VDA ), which provides a treatment of the modelling errors, is studied; building on the approach of Vidard et al. (Tellus, 56 A, pp. 177–188, 2004). The evolution of model error ( ME ) is modelled using ordinary differential equations, which involve a scalar parameter. These approaches were tested using different high-resolution advection schemes. The first set of experiments were constructed to see if it is possible to account for (numerical) discretization error within such a framework. In other set of experiments, a systematic source of modelling error was introduced by deliberately specifying an incorrect value for the Coriolis parameter in the model. Results with observational state at half of the model state resolution, are also presented. We also discuss a method of estimating the scalar parameter in the ME through VDA . In all cases, the inclusion of ME provides reduction in forecasting errors. Also, our experiments indicate that different settings of the model (e.g. using different high-resolution advection schemes) would need different ME formulation. Results presented in this paper could be used to formulate sophisticated ME forms to account for systematic errors in higher dimensional models with complex advection schemes.     

Assimilation of the data of observations and adaptive prediction of the natural processes

We propose a dynamical model for the prediction of random components of natural processes. The model is based on the system concept of adaptive balance of causes (ABC-model) and contains dynamic equations for the coefficients of influence adapted to the correlations existing in the predicted processes. To improve the accuracy of predictions, we consider two possible schemes of assimilation of the data of observations in the equations of the ABC-model, namely, the Kolmogorov and Kalman schemes. Both schemes are oriented toward the application of sample correlation coefficients for the prediction of time series of measurements and, hence, take into account the nonstationarity of actual natural processes. We present some examples of prediction of the simulated time series clarifying the algorithms of assimilation of the data of observations. A conclusion is made that the methods of systems modeling and adaptive prediction of random processes by the ABC-method are quite promising.     

基于多参数差分相关的海洋时序观测数据滤波算法

随着海洋研究的不断深入,对观测的数据质量要求越来越高,为了有效降低实测数据的不确定性,该文以海水CO₂分压测算的关键因子温度和盐度的相关实测数据为例,针对仪器平台能够进行多参数同步观测的特点,在假设观测指标的变化在较小的时间空间范围内为一平稳过程的基础上,通过ADF平稳性检验理论证实了大部分原始观测序列满足二阶差分平稳性假设,在此基础上提出了一种基于观测序列差分统计特征的测量数据不确定性的表达方式,以及对离异点数据进行识别和多参数差分相关联合滤波的算法。与常用滤波算法对比分析表明,提出的新算法能够有效融合参数间的相关信息,降低序列的不确定性,并且最大程度地保护原始测量数据。     

Doppler radar radial winds in HIRLAM. Part I: observation modelling and validation

An observation operator for Doppler radar radial wind measurements is developed further in this article, based on the earlier work and considerations of the measurement characteristic. The elementary observation operator treats radar observations as point measurements at pre-processed observation heights. Here, modelling of the radar pulse volume broadening in vertical and the radar pulse path bending due to refraction is included to improve the realism of the observation modelling.
The operator is implemented into the High Resolution Limited Area Model (HIRLAM) limited area numerical weather prediction (NWP) system. A data set of circa 133 000 radial wind measurements is passively monitored against the HIRLAM six-hourly background values in a 1-month experiment. No data assimilation experiments are performed at this stage. A new finding is that the improved modelling reduces the mean observation minus background (OmB) vector wind difference at ranges below 55 km, and the standard deviation of the radial wind OmB difference at ranges over 25 km.
In conclusion, a more accurate and still computationally feasible observation operator is developed. The companion paper (Part II) considers optimal super-observation processing of Doppler radar radial winds for HIRLAM, with general applicability in NWP.     

海洋生态系统净生产力研究进展

海洋生态系统净生产力 （net ecosystem production,NEP） 表示总初级生产力 （gross primary production,GPP） 和呼吸作用 （respiration,R） 过程之间的差异,它对碳收支平衡、海洋生态系统营养状态乃至气候变化等研究具有十分重要的指示意义。影响海洋 NEP 的因素有细菌、浮游生物、温度、太阳辐射、海冰融化、水团迁移、富营养有机质排放以及海水酸化等。目前计算 NEP 的方法可分为实验培养测定及数据模型计算两种。溶解氧培养法及同位素标记法等是经典的培养测定方法,但存在误差较大且重现性较差等问题。数据模型计算即借助养分质量平衡、响应面模型、O2/Ar 示踪等方法,通过将现场实测数据和生物地球化学模型结合,进行高时间分辨率的连续性观测,这也是目前测算 NEP 的主流应用手段。然而,相较于发达国家,我国在 NEP 的研究设备、技术、测定方法等方面仍存在一定差距。今后的研究重点将是建立 NEP 指标与表征海洋环境、气候变化之间的耦合关系以及 NEP 测定方法的改进,这将有助于深入理解和探索全球变化背景下海洋生态系统响应机制及变化趋势。     

A comparison between 3DVAR and EnOI techniques for satellite altimetry data assimilation

Two conceptually different assimilation schemes, three dimensional variational (3DVAR) assimilation and Ensemble Optimum Interpolation (EnOI) are compared in the context of satellite altimetric data assimilation. Similarities and differences of the two schemes are briefly discussed and their impacts on the model simulation are investigated.With a tropical Pacific ocean model, two assimilation experiments of sea level anomaly (SLA) data from TOPEX/Poseidon are performed for 5 years from 1997 to 2001. Annual mean states of temperature and salinity fields are compared with analysis data and some independent observations. It is found that EnOI generally produces moderate improvements on both temperature and salinity fields, while changes induced by 3DVAR assimilation are strong and vary remarkably in different areas. For instance, 3DVAR tends to excessively modify the temperature field along the thermocline depth and even deteriorate the simulation, but it is more effective than EnOI below the thermocline depth. However, for the salinity field 3DVAR outperforms EnOI nearly for almost the whole layer. As the difference relative to the WOA01 analysis is compared, it is apparently reduced to below 0.3 psu in most areas in the 3DVAR experiment. On the other hand, the pattern of difference in the EnOI experiment resembles that of the simulation and the magnitude is only diminished to some extent. One advantage of EnOI is that it yields more consistent improvements even in areas where there are large model errors. It is more reliable than 3DVAR in such a sense. It is also revealed that the T–S relation plays a very important role in altimetric data assimilation. Further, the distinct performance of the two schemes can be partly accounted for by their inherent assumptions and settings.     

Comparison of the satellite and ground-based measurements of the hydrogen fluoride content in the atmosphere

Satellite and ground-based measurements of the hydrogen fluoride (HF) total content (TC) are analyzed and compared. The HF profiles measured with an FTS device on the ACE satellite are used to calculate the TC and compare it with the ground-based measurements near St. Petersburg in 2009–2011. A comparison indicated that the seasonal variations in HF TC based on two independent measurements are in good qualitative agreement. Rare (nine) cases of direct comparison between two measurement types coordinated with respect to time (during the day) and site (no farther than 500 km) gave the following characteristics: the average difference is 8% and satellite data predominate over ground data; the standard deviation of a difference is 7%. In two cases of close measurement pairs (closer than 200 km), a comparison gave differences of 1 and 7%. The statistical characteristics of differences between two measurement types are in good agreement with the independent comparison of the ACE-FTS HF TC measurements with the NDACC network data.     

SeaWiFS探测1997年闽南赤潮模型研究

在１９９７年秋季厦门附近海域微吓灌赤潮水体现场反射光谱测量的基础上,根据对ＳｅｓＷｉＦＳ可见光范围内各波段离水辐射率变化的分析,提出３、４、５波段离水辐射率差值（Ｌｗ５＋Ｌｗ３－２Ｌｗ４）〉Ｃ模型,用它计算了１９９７年１１月和１２月 潮时相的ＳｅａＷｉＦＳ图象,结果和赤潮发生的实际状况一致。     

海水的氧饱和度与韦斯方程

1973年 ,联合国教科文组织 (U NESCO)汇同英国国立海洋研究所 (NOI)联合颁布了“国际海洋学用表”第二卷 ,即由国际海洋学用表与标准联合专家小组监督制订 ,由 NOI与 UNESCO,依据韦斯方程编辑出版的海水氧饱和度表。韦斯方程是海水中氧的溶解度与温度和盐度关系的一组方程式 ,它提供了一种计算海水中氧的溶解度的简便而又系统的方法。本文主要介绍了韦斯方程的推导过程、计算方法、数据引用、适用范围及公式精度等技术问题 ,供海洋科技工作者研究、参考 ,以利于进一步提高海水溶解氧的观测技术及计量标准工作的水平     

On the parameterization of drag coefficient over sea surface

Six parameterization schemes of roughness or drag coefficient are evaluated on the basis of the data from six experiments. They present great consistency with measurement when friction velocity u*<0.5 m/s (approximately corresponding to 10 m wind speed U10 <12 m/s) and large deviation from measurement when u*≥0.5 m/s (approximately U10≥12 m/s). In order to improve the deviation, a new parameterization of drag coefficient is derived on the basis of the similarity theory, Charnock relationship and Toba 3/2 power law. Wave steepness and wind-sea Reynolds number are considered in the new parameterization. Then it is tested on the basis of the measurements and shows significant improvement when u*≥0.5 m/s. Its standard errors are much smaller than the ones of the other six parameterizations. However, the new parameterization still needs more tests especially for high winds.     

东中国海海温场对厄尔尼诺与反厄尔尼诺事件的响应

本文根据多年历史资料统计分析了东中国海海面温度（海温）场对厄尔尼诺与反厄尔尼诺 事件的遥响应情况,结果表明东中国海海温与厄尔尼诺事件有密切的关系,其年际变化特征与 一些学者提出的水文气象要素的变化相吻合,同时,分析还发现上半年发生的厄尔尼诺事件的 前冬半年海温异常的偏高,而下半年发生的厄尔尼诺事件的前冬半年海温异常的偏低,这是一 个值得深入探讨的问题。     

面向岛礁应急监测的多手段组网设计与实验

为了对今后的岛礁应急监测研究提供参考和借鉴,作者以无线自组网技术为基础,提出了一种面向岛礁应急监测的多手段组网设计方案,并依托实际应用场景,开展了初步的实验,提高了岛礁监测的效率,取得了一定的数据成果。     

一种高Q值单频水声信号放大提取电路的设计

针对水声信号所处环境复杂、背景噪声源多的特点,提出了一种基于JFET的超低噪音放大电路,该电路选用两片低噪音的场效应管2SK170作为第一级放大器件,经过CR高通滤波连接到同相放大电路,整体电路增益可达70dB;为进一步提升接收信号信噪比,结合双T滤波器特点优化设计出一种高Q值选频电路;通过Multisim14仿真表明,设计的电路在1 Hz处的电压噪声密度仅为2.4 nV/Hz^0.5,滤波器Q值可达25.6,结合实际电路测试结果表明,设计的电路能够满足水声测量要求。     

MDT测试资料确定气水界面的方法研究

通过对MDT测压资料的分析,发现了造成测试点压力值存在误差的主要原因有两个方面：一方面是由于部分测压点储层物性差,测试探针抽吸地层流体后储层压力恢复需要的时间较长,然而由于实际原因测试压力恢复无法等待足够的测试时间;另一方面是由于部分物性较差储层较难形成好的泥饼,以至于受到比较严重的泥浆侵入使得测试点产生超压现象,测试得到的地层压力和实际压力相比偏大.同时分析发现物性较好的储层往往能够得到相对可靠的测试压力.合理的气水界面对于计算探明地质储量有着很重要的意义,尤其是高温高压气田,气水过渡带往往较大,可能会达到30m左右,这种情况下无法仅从钻遇情况分析气水界面,此时可以结合MDT测压资料分析气水界面,从而确定合理的地质储量.通过分析实际MDT测压资料,对不同测压点进行了误差分析并在此基础上提出了压力数据点的筛选原则.通过实际检验认为新的回归方法确定出的气水界面科学合理.     

顾及地形变化的多测线粗差剔除方法在一体化水深测量中的应用

单波束测深仪是现代海洋和内河水下地形测量中使用最为频繁的测量仪器。硬件设备固有特性和水下复杂的特殊环境,易导致单波束测深仪在实际使用中产生各类型的粗差。单波束采集时按照每条测线进行处理,在数据处理上往往存在不同船只、不同测线难以一体化处理的问题。文中针对水深值粗差的特点,设计了单波束数据采集和处理一体化方法,在区域处理单波束数据的基础上,提出一种顾及地形的单波束水深测量数据多测线粗差检测方法,并针对上海周边实测区域对单波束测深数据采集和处理进行全方位的验证,结果表明应用本方法不但提升了数据精度和数据处理可靠性,而且大幅提高了作业效率。     

HY-2A卫星高度计不同重跟踪方案对反演海浪有效波高的影响

本文基于Amarouche的二阶理论回波模型,导出了带有偏度系数的二阶理论回波模型;针对HY-2A卫星高度计波形特点,引入了奇异值分解滤波,并根据最大似然估计算法反演参数的不同得到6种重跟踪方案;利用其中的五参数方案处理该波形数据,获得海面散射点高度概率密度函数中偏度的合理取值为0.15;将结果分别与浮标、Jason-1和HY-2AIDR有效波高对比,分析6种方案反演有效波高的准确度,确定了MLE4_SVD(波形重跟踪之前进行滤波)对HY-2A高度计重跟踪更适合反演有效波高。