海洋湍流模式应用研究

海洋湍流模型研究自二十世纪 70年代中发展至今 ,在海洋动力学研究中 ,特别是关于混合 /层化研究中广泛应用 ,近年来由于认识到湍流对海洋生物过程的重要影响 ,对海洋湍流的客观描述更加关注。文中详细介绍了几个主要海洋动力学模型中的湍流封闭模式 ,如 HAMSOM中的Prandtl混合长模型、Johns模式中的 k-方程模型、POM中的 k- kl模型、水动力学中常用的 k-ε模型等等 ,介绍了海洋湍流模型的应用。对于湍流模型的使用提出针对具体问题选择的原则 ,复杂的并非最优的。     

Reproductive biology of the mackerel scad Decapterus macarellus from Cabo Verde and the implications for its fishery management

The mackerel scad Decapterus macarellus is of great social and economic importance to Cabo Verde citizens; however, in recent years catches have shown an unexplained decline. The harvest is regulated by way of a minimum legal size and a seasonal closure, with both measures based on the results of reproductive studies that did not consider the microscopic characteristics of the gonads. This study aimed to analyse the gonads microscopically in order to classify the sexual development stage of individuals and to estimate the size at first maturity and the reproductive season. This information was then used to analyse the match between the reproductive parameters and the management measures. The samples comprised 284 females (20–36 cm fork length [FL]) and 85 males (21–35 cm FL). The annual variation in gonadosomatic index and the monthly frequencies of mature phases suggest that the reproductive season occurs from March to October, with two spawning peaks, one in March and another from July to October. The current seasonal closure (from July to September) covers the main reproductive period. However, the species has a long spawning period and the timing of peaks can vary between years; hence, a reassessment of this management measure is recommended. The sizes at first maturity were estimated at 24.1 cm FL for females, and 26.6 cm FL for males. These values are higher than the minimum legal size (20 cm FL) currently established for management of the species at Cabo Verde; thus, we strongly recommend an increase in the minimum legal size in an attempt to reduce catches of immature individuals.     

Comparison of methods for quantifying surface sublimation over seasonally snow‐covered terrain

Snow sublimation can be an important component of the snow‐cover mass balance, and there is considerable interest in quantifying the role of this process within the water and energy balance of snow‐covered regions. In recent years, robust eddy covariance (EC) instrumentation has been used to quantify snow sublimation over snow‐covered surfaces in complex mountainous terrain. However, EC can be challenging for monitoring turbulent fluxes in snow‐covered environments because of intensive data, power, and fetch requirements, and alternative methods of estimating snow sublimation are often relied upon. To evaluate the relative merits of methods for quantifying surface sublimation, fluxes calculated by the EC, Bowen ratio–energy balance (BR), bulk aerodynamic flux (BF), and aerodynamic profile (AP) methods and their associated uncertainty were compared at two forested openings in the Colorado Rocky Mountains. Biases between methods are evaluated over a range of environmental conditions, and limitations of each method are discussed. Mean surface sublimation rates from both sites ranged from 0.33 to 0.36 mm day^?1, 0.14 to 0.37 mm day^?1, 0.10 to 0.17 mm day^?1, and 0.03 to 0.10 mm day^?1 for the EC, BR, BF and AP methods, respectively. The EC and/or BF methods are concluded to be superior for estimating surface sublimation in snow‐covered forested openings. The surface sublimation rates quantified in this study are generally smaller in magnitude compared with previously published studies in this region and help to refine sublimation estimates for forested openings in the Colorado Rocky Mountains. Copyright © 2016 John Wiley & Sons, Ltd.     

基于证据理论的聚类集成方法

单个聚类方法得到的结果会存在不稳定性等问题,为了克服这些问题,本文在证据理论（又称为信任函数理论）的基础上提出了一种新的聚类集成方法.多数情况下,聚类集成方法主要包含2个关键步骤：得到一组基划分,以及结合基划分得到最终聚类结果,本文的方法重点考虑第2步.在第1步得到基划分之后,将其转换成一种中间表示,可以称这种中间表示为关系表示.在证据理论中,我们认为得到的关系表示是不可靠的,可以用折扣过程对关系表示进行预处理,然后就可以用不同的结合法则融合关系表示.从融合后的关系表示中提取信任矩阵或似然矩阵,将其视为样本间的互相关矩阵.为了能够充分利用样本间的传递性,将得到的互相关矩阵视为一个模糊关系,对其做传递闭包处理,从而得到一个模糊等价关系.将模糊的等价关系视为新的相似性数据,用能够处理相似性数据的聚类方法得到最终的结果.通过实验,表明了该聚类集成方法的稳定性和有效性.     

一种自动搜索水准环及计算闭合差的方法研究

本文采用深度优先搜索算法(Depth-First-Search)实现自动搜索水准闭合环,并结合ArcGIS的图形拓扑关系技术来获得最小水准环的信息;将此项技术应用于水准测量闭合环的闭合差计算,最终实现了自动计算水准闭合环的闭合差及精度统计。     

A semi-analytical solution for the three-dimensional advection–diffusion equation considering non-local turbulence closure

Atmospheric air pollution turbulent fluxes can be assumed to be proportional to the mean concentration gradient. This assumption, along with the equation of continuity, leads to the advection–diffusion equation. Moreover, large eddies are able to mix scalar quantities in a manner that is counter to the local gradient. In this work we present a semi-analytical solution for the three-dimensional steady-state advection–diffusion equation, considering non-local turbulence closure using the Generalized Integral Advection Diffusion Multilayer Technique (GIADMT). We report some examples of applications of the new solution for two different datasets and for a water tank experiment.     

Towards Closing the Surface Energy Budget of a Mid-latitude Grassland

Observations for May and August, 2005, from a long-term grassland meteorological station situated in central Netherlands were used to evaluate the closure of the surface energy budget. We compute all possible enthalpy changes, such as the grass cover heat storage, dew water heat storage, air mass heat storage and the photosynthesis energy flux, over an averaging time interval. In addition, the soil heat flux was estimated using a harmonic analysis technique to obtain a more accurate assessment of the surface soil heat flux. By doing so, a closure of 96% was obtained. The harmonic analysis technique appears to improve closure by 9%, the photosynthesis for 3% and the rest of the storage terms for a 3% improvement of the energy budget closure. For calm nights (friction velocity u _* < 0.1 m s⁻¹) when the eddy covariance technique is unreliable for measurement of the vertical turbulent fluxes, the inclusion of a scheme that calculates dew fluxes improves the energy budget closure significantly.     

隆升幅度及隆升速率研究方法综述

对有关隆升幅度和速率定量研究的古生物、古气候法、古地球法、地质压力计法、热年代学方法及变质作用ｐ－Ｔ－ｔ轨迹法作了概括，重点阐述了近年来热年代学方法在隆升幅度和速率量研究中的应用。此外，对这些方法应用的前提和条件作了评述。     

应用随机辐射传输模型反演云南松林分郁闭度

随机辐射传输模型可用于模拟水平分布不均一森林的辐射传输过程。本文以云南松林分为研究对象，提出一种应用随机辐射传输模型的郁闭度反演方法。该方法以随机辐射传输模型中参数与林分郁闭度的定量关系为基础，提出了针对云南松的冠型等效模型，构建了郁闭度和卫星反射率（GF-1和Landsat 8卫星影像）的查找表，并实施了反演。基于野外实测的30个样地进行了郁闭度数据验证，并和基于NDVI回归模型的反演方法进行对比。结果表明，反演结果能够较准确反映云南松林分郁闭状况（R²=0.8345，RMSE=0.0688），通过冠型修正能够降低反演误差，冠型等效模型是合理的。反演方法机理清晰且适用范围广，研究成果可为大面积森林郁闭度反演提供模型和方法支持。