中尺度非均—边界层气候的数值研究——(Ⅱ)夏季的数值试验

用修改的 Nickerson 等提出的中尺度模式,对我国北方夏季非均一下垫面上的边界层气候特征进行了研究。结果表明,在晴朗、静风和无扰动系统的条件下,下垫面的非均一性对边界层气候起着决定性的影响。边界层气候特征和低空急流强度与局地环流关系密切。干燥裸地上边界层内出现的逆湿现象,是由下垫面非均一的湿度场和中尺度平流共同引起的。     

Shear waves at a corrugated interface between anisotropic elastic and visco-elastic solid half-spaces

Rayleigh’s method of approximation is employed to find out the reflection and transmission coefficients due to an incident plane SH wave at a corrugated interface between a laterally and vertically inhomogeneous anisotropic elastic solid half-space and a laterally and vertically inhomogeneous isotropic visco-elastic solid half-space. The lateral and vertical inhomogeneities are described by the exponential variations of elastic parameters. The formulae of reflection and transmission coefficients are derived in closed form for the first-order approximation of the corrugation. The effects of the corrugation of the interface, the inhomogeneity, the anisotropy, the visco-elasticity and the frequency of the incident wave on these coefficients are studied analytically and numerically for a specific model containing a periodic interface. The results of earlier workers have been reduced as particular cases from the present formulation.     

Are Io's Alfvén wings filamented? Galileo observations

The interaction of Io with the Jovian magnetosphere generates auroral and radio emissions. The underlying electron acceleration process is not understood and few observations exist to constrain the theoretical models. The source of energy for the electron acceleration is in all likelihood supplied from the Alfvén wings that stretch out from both poles of Io into the two Jovian hemispheres. The form of the current system associated with the Alfvén wings has been disputed, some suggesting that the greatly slowed flow near Io implies that a steady current loop links Io to Jupiter's ionosphere, others arguing that the return waves appear only downstream of Io and others suggesting that both forms develop. Given the finite inclination of the Alfvén wings implied by the finite value of the Alfvén Mach number and the strong reflection that occurs at the boundary of the Io torus, we argue that no steady current loop can be invoked between Io and Jupiter's ionosphere. However, the energetics of the auroral and radio emissions imply that most of the energy in the Alfvén wings is transformed into electron acceleration at high-latitudes, that is, outside the Io torus. The dilemma then is to understand how a large fraction of the power penetrates the reflecting boundary. We present data from Galileo's multiple flybys of Io that suggest that the coupling with the Jovian ionosphere is mediated by filamentary Alfvén wings associated with electromagnetic waves propagating out of the torus. In particular, we report on the systematic observation, within the cross-section of Io's Alfvén wings and in their immediate vicinity, of intense electromagnetic waves at frequencies up to several times the proton gyrofrequency. We interpret these “high-frequency/small-scale” waves as the signature of a strong filamentation/fragmentation of the Alfvén wings before they reflect off of the sharp boundary gradient of the Io torus. As a consequence, we suggest that most of the primary energy is converted into “high-frequency/small-scale” electromagnetic waves that can propagate out from the torus toward Jupiter's ionosphere. Reaching high-latitudes, these waves are able to accelerate electrons to almost relativistic speeds.     

气温序列非均一性检验方法的研究

采用距平累加法、连续t-检验及回归检验法对分布於25个省(区)31个站的气温序列进行了非均一性检验。结果表明这3种方法在显著性水平α=0.01时，能有效地检验气温序列的非均一性，其结论适用於全国。     

利用卫星重力数据计算地球内部密度异常

地球外部重力场是由地球内部物质分布决定的。本文利用ＲＡＰＰ８１１８０阶卫星重力位系数根据异常源埋深与重力位系数阶数的关系和重力场分离方法计算了经度为９０°Ｅ的地球密度异常剖面，得到了地球内部不同深度的密度异常结果，并初步作了地球物理解释．计算结果得到的深度为６５ｋｍ处的低密度异常带与地球模型的ＬＩＤ层和Ｃ层较为接近。     

强震前水氡异常台站时空分布非均匀性变化特征

研究了华北地区６级左右强震前水氡观测值异常的时空非均匀分布变化特征。结果表明,在强震前水氡观测异常台站的空间分布非均匀性发生显变化,Ｃｖ值明显的和蔼同过程。这说明,强震前短临地震前兆异常空间分布的非均匀性增强,变得更加不均匀,这可能邮地壳应力场的增强过程。     

形变场多重分形谱异常与强震关系研究

以平均形变速率梯度概率为变量, 研究了唐山地区、甘肃河西地区和北京地区多期垂直形变场图像的动态多重分形特征及其与强震的关系。结果表明, 震前一至数年形变场图像的多重分形谱Dq 值域变宽, 即- q 区上翘, + q区下降现象, 在强震孕育发生的过程中, 形变场时空表现出从准均匀到不均匀的演化趋势。结合地震活动和岩石力学实验结果认为, 形变场不均匀化可能是中长期地震复杂性前兆的一个重要标志。     

辽宁地区前兆异常空间分布的集中性与非均匀性研究

通过对1988年以来辽宁地区年度前兆异常空间分布特征的分析与计算, 结果发现, 辽宁及邻区5级以上地震前1～3年中短期异常空间分布非均匀性指标C_V值均出现明显的高值(大于等于2倍均方差)。 异常空间分布集中度R_V值与异常频次正相关, 与最大震级反相关, 可作为参考指标, 配合C_V值使用。 当C_V值出现高值异常期间, 若R_V低于均值并接近30 km时, 1年内辽宁地区发生M≥5.0地震的可能性较大。     

堆积的地球及其初始不均一性

从天体化学和地球科学的研究成果出发，认为地球是在一较窄的类地行星区域内，主要由硅酸盐质星子随机吸积而成。在星子形成之前，初始太阳星云已经历了挥发性元素的强烈亏损事件，同时也已发生了硫化物、金属和硅酸盐成分之间的分馏作用，随着行星的形成，行星内部的分馏作用将会持续进行。在形成地球的独立吸积区内，混合作用不彻底，星子群之间的化学成分不均一，因此，构成地球的将是一套具有各自独立化学成分组成的星子群，而不同于地球上现已发现的任何陨石或者它们的组合。     

Thermohaline structure inhomogeneity associated with polynia at the northern margin of Emery Ice-shelf

Based on the hydrographic data in austral summer during the 22nd Antarctic Expedition of China(2005/2006),some features can be found about the northern margin of Emery ice shelf as follows.The heat content in the surface layer(0-50 m) at the eastern end and the western end of the ice-shelf margin is much higher than that at the middle.The upper mixing-layer depth and the seasonal thermocline depth at the middle of the ice-shelf northern margin are much shallower than those at the both ends.However there is much less difference between the middle and the ends in the bottom layer.The remote sensing photos show that the inhomogeneity in the surface-layer water is closely related to the spatial distribution of the floes and polynia in the area.