近岸浅水波的计算

采用理论推导与实验资料验证相结合的方法对近岸浅水波衰减计算进行研究。研究表明，波浪与浅水区运动传播衰减是各种能耗共同作用的结果，为此总结了分子粘性能耗、湍流能耗、底部渗透能耗、底部摩擦能耗、软泥海底弹性能耗等，由建立波能流平衡方程出发进行理论推导，得出各种能耗影响下波浪衰减的计算公式，并将该理论公式与作者１９８０年波浪水槽试验资料比较，两者基本吻合，可适用于线性及非线性各种波能耗情况的计算。     

Numerical modeling of the central Black Sea ecosystem functioning during the eutrophication phase

A one-dimensional coupled physical-biogeochemical model has been developed to simulate the ecosystem of the central Black Sea at the end of the 1980s when eutrophication and invasion by gelatinous organisms seriously affected the stability and dynamics of the system. The physical model is the General Ocean Turbulence Model (GOTM) and the biogeochemical model describes the foodweb from bacteria to gelatinous carnivores through 24 state variables including three groups of phytoplankton: diatoms, small phototrophic flagellates and dinoflagellates, two zooplankton groups: micro- and mesozooplankton, two groups of gelatinous zooplankton: the omnivorous and carnivorous forms, an explicit representation of the bacterial loop: bacteria, labile and semi-labile dissolved organic matter, particulate organic matter. The model simulates oxygen, nitrogen, silicate and carbon cycling. In addition, an innovation of this model is that it explicitly represents processes in the anoxic layer. Biogeochemical processes in anaerobic conditions have been represented using an approach similar to that used in the modeling of diagenetic processes in the sediments lumping together all the reduced substances in one state variable [Soetaert, K., Herman, P., 1996. A model of early diagenetic processes from the shelf to abyssal depths. Geochimica et Cosmochimica Acta 60 (6) 1019-1040]. In this way, processes in the upper oxygenated layer are fully coupled with anaerobic processes in the deep waters, allowing to perform longterm simulations.The mathematical modeling of phytoplankton and zooplankton dynamics, detritus and the microbial loop is based on the model developed by Van den Meersche et al. [Van den Meersche, K., Middelburg, J., Soetaert, K., van Rijswijk P.H.B., Heip, C., 2004. Carbon-nitrogen coupling and algal-bacterial interactions during an experimental bloom: Modeling a 13c tracer experiment. Limnology and Oceanography 49 (3), 862-878] and tested in the modeling of mesocosm experiments and of the Ligurian sea ecosystem [Raick, C., Delhez, E., Soetaert, K., Gregoire, M., 2005. Study of the seasonal cycle of the biogeochemical processes in the Ligurian sea using an 1D interdisciplinary model. Journal of Marine Systems 55 (3-4) 177-203]. This model has been extended to simulate the development of top predators, the aggregation of detritus as well as the degradation and chemical processes in suboxic/anoxic conditions (e.g. denitrification, anoxic remineralization, redox reactions).The coupled model extends down to the sediments ( depth) and is forced at the air-sea interface by the 6 hourly ERA-40 reanalysis of ECMWF data. The model has been calibrated and validated using a large set of data available in the Black Sea TU Ocean Base. The biogeochemical model involves some hundred parameters which are first calibrated by hand using published values. Then, an identifiability analysis has been performed in order to determine a subset of identifiable parameters (i.e. ensemble of parameters that can be together estimated from the amount of data we have at our disposal, see later in the text). Also a subset of 10 identifiable parameters was isolated and an automatic calibration subroutine (Levenberg Marquart) has been used to fine tune these parameters. Additionally, in order to assess the sensitivity of model results to the parameterization of the two gelatinous groups, Monte Carlo simulations were performed perturbing all the parameters governing their dynamics.In order to calibrate the particle dynamics and export, the chemical model was run off-line with the particle and microbial loop model in order to check its capacity of simulating anoxic waters. After a 10⁴ year run, the model simulated profiles similar to observations but steady state was not reached suggesting that the Black Sea deep waters are not at steady state. The fully coupled model was then used to simulate the period 1988-1992 of the Black Sea ecosystem. The model solution exhibits a complex dynamics with several years of transient adjustment. This complexity is imparted by the explicit modeling of top predators. The integrated chlorophyll and phytoplankton biomasses, the maximum concentration and depth of maximum, mesozooplankton biomass, depth of oxycline, primary production, bacterial production, surface concentrations of nutrients and plankton simulated by the model and obtained from available data analysis were compared and showed a satisfactory agreement. Also, as in the data, the model shows a continuous development of phytoplankton throughout the year, with an intense spring bloom dominated by diatoms and a fall bloom dominated by dinoflagellates. Dinoflagellates dominate from summer until late fall while small phototrophic flagellates are never dominant in terms of biomass, but are present almost throughout the year except in winter. The model simulates an intense silicate removal associated to increased diatoms blooms which were promoted by increased nutrient conditions, and by the presence of gelatinous zooplankton. This silicate pumping leads to silicate limitation of diatoms development in summer allowing the development of dinoflagellates.     

锋面通过台湾海峡时引起的快速成长波高推算

每年冬季因中国北方冷空气前缘东移出海南下而形成的锋面是造成台湾海峡内恶劣海况的原因之一，锋面的到临常引发快速增高的波浪，这种海况是目前作业化数值预报模式在操作上不易反映的。经验证明根据元素波模式推衍所得的面积风域法推算波浪，适合于推导季风期间海况的一种方法。本文将锋面期间风域是移动的特性结合面积风域理论，作为推算锋面抵达时推算波高的方法。本文提出加权风场内插法计算各时刻各网格点的风速，使得面积风域理论简化为在网格点上的离散计算。文中根据锋面期间实际观测数据计算波能传播速率与风能传播系数等参数，经由案例分析的结果显示这个离散化面积风域法可以合理地推算锋面期间快速成长的波高。     

Including prior information in the estimation of effective soil parameters in unsaturated zone modelling

In this paper we propose a methodology to include prior information in the estimation of effective soil parameters for modelling the soil moisture content in the unsaturated zone. Laboratory measurements on undisturbed soil cores were used to estimate the moisture retention curve and hydraulic conductivity curve parameters. The soil moisture content was measured at 25 locations along three transects and at three different depths (surface, 30 and 60 cm) on an 80×20 m hillslope for the year 2001. Soil cores were collected in 84 locations situated in three profile pits along the hillslope. For the estimation of the effective soil hydraulic parameters the joint probability distribution of measured parameter values was used as prior information. A two-horizon single column 1D MIKE SHE model based on Richards' equation was set-up for nine soil moisture measurement locations along the middle transect of the hillslope. The goal of the model is to simulate the soil moisture profile at each location. The shuffled complex evolution (SCE) algorithm has been applied to estimate effective model parameters using either wide parameter ranges, referred to as the ‘no-prior’ case, or the joint probability distribution of measured parameter values as prior information (‘prior’ case). When the prior information is incorporated in the SCE optimisation the goodness-of-fit of the model predictions is only slightly worse compared to when no-prior information is incorporated. However, the effective parameter estimates are more realistic when the prior information is incorporated. For both the no-prior and prior case the generalised likelihood uncertainty estimation procedure (GLUE) was subsequently used to estimate the uncertainty bounds (UB) on the model predictions. When incorporating the prior information more parameter sets were accepted for the estimation of the predictive uncertainty and the parameter values were more realistic. Moreover, UB better enclosed the observations. Thus, incorporating prior information in GLUE reduces the amount of model evaluations needed to obtain sufficient behavioural parameter sets. The results indicate the importance of prior information in the SCE and GLUE parameter estimation strategies.     

地震孕育过程中若干地震学特征参量研究

从新疆实际出发提出一种简捷的预报程式,用以判定地震三要素。结果表明,(1)新疆3级地震累积频次低于均值6个月,1年内新疆发生6级地震的概率为90%;(2)以新疆地震活跃期响应地震分布区做为预备震源区,该区未来3年发生中强震的概率为86%;(3)预备震源区出现一年以上低6值,其250 km区域1年内发生6级地震的概率为75%;(4)当系统处于相对稳定状态时系统内部个体的涨落很难使系统出现非线性响应,而当系统处于亚失稳状态时,系统内部个体的涨落有可能触发系统中处于高应力状态下的地震活动。     

Calibration of subsurface batch and reactive-transport models involving complex biogeochemical processes

In this study, the calibration of subsurface batch and reactive-transport models involving complex biogeochemical processes was systematically evaluated. Two hypothetical nitrate biodegradation scenarios were developed and simulated in numerical experiments to evaluate the performance of three calibration search procedures: a multi-start non-linear regression algorithm (i.e. multi-start Levenberg–Marquardt), a global search heuristic (i.e. particle swarm optimization), and a hybrid algorithm that combines the particle swarm procedure with a regression-based “polishing” step. Graphical analysis of the selected calibration problems revealed heterogeneous regions of extreme parameter sensitivity and insensitivity along with abundant numbers of local minima. These characteristics hindered the performance of the multi-start non-linear regression technique, which was generally the least effective of the considered algorithms. In most cases, the global search and hybrid methods were capable of producing improved model fits at comparable computational expense. In other cases, the multi-start and hybrid calibration algorithms yielded comparable fitness values but markedly differing parameter estimates and associated uncertainty measures.     

An Analytic Solution to Well-water Level Changes under Barometric Pressure

Under barometric pressure,groundwater flow in well-aquifer systems is a kind of hydro-mechanical coupling problem.Applying the flux boundary conditions on borehole wall and water pressure equilibrium conditions inside and outside the borehole wall under barometric pressure(BP),an analytic solution to well-water level changes has been proposed in this paper.The formulation shows that the BP coefficients increase with time and tend to BP constant.The Change of BP coefficients over time depends only on the ratio of transmissivity(T) to the well radius squared(r2w),and has nothing to do with the change in BP.The BP constant only relates to aquifer loading efficiency(B),and has nothing to do with the aquifer transmissivity and well radius.The BP coefficients change over time in the analytic formulation is consistent with the analysis of measured data from the Nanxi wells.Based on the BP coefficient changes over time,a parameter estimation method is suggested and discussed in its application to the estimation of the aquifer BP constant(or B) and transmissivity by using the Nanxi well data.     

Inverse determination of soil density and stress state using dispersion wave measurements and cone penetration tests in a non-layered soil

The determination of the void ratio and stress state distribution in undisturbed soil is still an ambitious aim which cannot be reached by sampling from bore holes. Therefore, an alternative method is proposed to determine soil density and stress state using dispersion wave measurements and cone penetration tests. Dispersion wave measurements and resonant-column tests are carried out to measure the shear wave velocity and shear modulus distribution with depth. Using finite element calculations a relationship between cone penetration resistance, stress state and void ratio is derived. From these results the void ratio distribution and the stress state can be calculated inversely. The inverse method is applied to real test data. The results of the inverse parameter determination are shown and assessed regarding the possibilities and the limitations of the presented method.     

Moveout approximation for horizontal transversely isotropic and vertical transversely isotropic layered medium. Part II: effective model‡

We use residual moveouts measured along continuous full azimuth reflection angle gathers, in order to obtain effective horizontal transversely isotropic model parameters. The angle gathers are generated through a special angle domain imaging system, for a wide range of reflection angles and full range of phase velocity azimuths. The estimation of the effective model parameters is performed in two stages. First, the background horizontal transversely isotropic (HTI)/vertical transversely isotropic (VTI) layered model is used, along with the values of reflection angles, for converting the measured residual moveouts (or traveltime errors) into azimuthally dependent normal moveout (NMO) velocities. Then we apply a digital Fourier transform to convert the NMO velocities into azimuthal wavenumber domain, in order to obtain the effective HTI model parameters: vertical time, vertical compression velocity, Thomsen parameter delta and the azimuth of the medium axis of symmetry. The method also provides a reliability criterion of the HTI assumption. The criterion shows whether the medium possesses the HTI type of symmetry, or whether the azimuthal dependence of the residual traveltime indicates to a more complex azimuthal anisotropy. The effective model used in this approach is defined for a 1D structure with a set of HTI, VTI and isotropic layers (with at least one HTI layer). We describe and analyse the reduction of a multi‐layer structure into an equivalent effective HTI model. The equivalent model yields the same NMO velocity and the same offset azimuth on the Earth's surface as the original layered structure, for any azimuth of the phase velocity. The effective model approximates the kinematics of an HTI/VTI layered structure using only a few parameters. Under the hyperbolic approximation, the proposed effective model is exact.     

福建古田水口水库M_L4.8级地震序列震源参数研究

应用福建省区域数字地震台网观测记录到的古田水口水库ML4.8级地震序列的资料,在扣除地震记录数据中传播路径效应、台站场地响应和仪器响应后,采用Atkinson单地震、多台记录平均的反演方法计算震源参数,共计算了序列中的38个ML≥2.5级地震的震源参数。结果显示：地震矩与震级之间有较好的线性关系,统计关系式为logM0=1.08ML＋9.63;建立了用ML震级估算矩震级MW的公式MW=0.72ML＋0.387;其它的参数间虽有一定的相关性,但很难给出定量的关系。对地震序列应力降随时间发展的变化分析认为,在前震期水口水库区域存在应力加速积累的过程,有出现高应力降异常值的发生,临近主震时,应力降有所回调;最大余震后,应力降呈逐步衰减,未出现高异常值。