基于中尺度模式MM5下的海洋蒸发波导预报研究

蒸发波导是发牛在海气边界层的一种异常折射现象,由于其分布范围广、发生概率大,被认为是对海上电子设备影响最为显著的波导类型,成为各国海军竞相研究的焦点.然而由于其形成机制复杂,且在近岸沿海地区由于海陆分布不均,以及海岸地形和海陆风等因素的作用,会造成蒸发波导的近岸效应,这种效应会影响蒸发波导高度诊断的准确率.目前国内外蒸发波导诊断模式有P-J模式、MGB模式、NPS模式、Babin模式等,但其基本原理都足依赖Monin-Obukhov相似理论,只是用于确定近地层通量和特征尺度的方法不同,且仅适用于定常和水平均匀的开阔海域,并没有考虑到蒸发波导的近岸效应.针对这一问题,文中在Babin模式的基础上引入张强、胡隐樵的通量廓线关系(非线性修正冈子αν)与阵性风速ωg,从而将蒸发波导诊断模式的适用范围扩展到近岸沿海地区和甚低风速条件下.此外在中尺度模式MM5的基础上,耦合改进的Babin模式,发展建立了一个海洋蒸发波导高度预报模式,并对预报模式进行数值模拟,利用2002年5月25-26日福建平潭岛的海上大气实测数据与雷达探测结果对预报模式输出结果进行了验证.验证结果表明:在0～48小时内模式输出值与实测值拟和较好且变化规律一致,预报蒸发波导高度平均误差为0.193;且蒸发波导高度预报结果与雷达实际探测结果一致.     

CO2 threshold for millennial-scale oscillations in the climate system: implications for global warming scenarios

We present several equilibrium runs under varying atmospheric CO₂ concentrations using the University of Victoria Earth System Climate Model (UVic ESCM). The model shows two very different responses: for CO₂ concentrations of 400 ppm or lower, the system evolves into an equilibrium state. For CO₂ concentrations of 440 ppm or higher, the system starts oscillating between a state with vigorous deep water formation in the Southern Ocean and a state with no deep water formation in the Southern Ocean. The flushing events result in a rapid increase in atmospheric temperatures, degassing of CO₂ and therefore an increase in atmospheric CO₂ concentrations, and a reduction of sea ice cover in the Southern Ocean. They also cool the deep ocean worldwide. After the flush, the deep ocean warms slowly again and CO₂ is taken up by the ocean until the stratification becomes unstable again at high latitudes thousands of years later. The existence of a threshold in CO₂ concentration which places the UVic ESCM in either an oscillating or non-oscillating state makes our results intriguing. If the UVic ESCM captures a mechanism that is present and important in the real climate system, the consequences would comprise a rapid increase in atmospheric carbon dioxide concentrations of several tens of ppm, an increase in global surface temperature of the order of 1–2°C, local temperature changes of the order of 6°C and a profound change in ocean stratification, deep water temperature and sea ice cover.     

概率扩张与概率赋范空间中非线性方程的解

给出了概率扩张的定义，并研究了概率赋范空间中非线性方程解的存在性和唯一性     

一个简化气候系统的非线性特征

文中建立一个包含年平均云量、地表温度及边界层气温的零维能量平衡模式。研究表明：该模式在适当的参数值范围内，能模拟出接近实际的气候状态；根据与该模式相应的偏差方程，讨论了气候系统的非线性特征以及云对气候状态演化的作用。     

地震非线性动力学系统的演化过程

本文从能量守恒定律出发，建立了孕震系统的非线性动力学方程。从孕震过程中的无序状态、有序状态和混沌状态的三个阶段出发，探讨了某些地震学参数对其判别的效能，同时对近几年来辽宁省地震活动的自组织演化过程作了分析，阐述了地震活动出现的新特征。     

非线性最优化问题的一个算法及其收敛性

讨论了具有广泛应用的线性等式、线性不等式及非负约束的非线性最优化问题。以极方向的特殊组合加上修正向量为搜索方向，给出一个具有超线性收敛速度的算法。较以往的算法有明显的优点，具有较好的稳定性和实用性。     

Finite element analysis of two-dimensional nonlinear sloshing problems in random excitations

A two-dimensional nonlinear random sloshing problem is analyzed by the fully nonlinear wave velocity potential theory based on the finite element method. A rectangular container filled with liquid subjected to specified horizontal random oscillations is studied. Both wave elevation and hydrodynamic force are obtained. The spectra of random waves and forces have also been investigated, and the effects of the peak frequencies and spectral width of the specified spectrum used for the generation of the random oscillations are discussed. It is found that the energy mainly concentrates at the natural frequencies of the container and is dominant at the ith order natural frequency when the peak frequency is close to the ith order natural frequency. Some results are compared between the fully nonlinear solutions, the linear solutions and the linear plus second-order solutions.