New method to solve electromagnetic parabolic equation

This paper puts forward a new method to solve the electromagnetic parabolic equation （EMPE） by taking the vertically-layered inhomogeneous characteristics of the atmospheric refractive index into account. First, the Fourier transform and the convo- lution theorem are employed, and the second-order partial differential equation, i.e., the EMPE, in the height space is transformed into first-order constant coefficient differential equations in the frequency space. Then, by use of the lower triangular characteristics of the coefficient matrix, the numerical solutions are designed. Through constructing ana- lytical solutions to the EMPE, the feasibility of the new method is validated. Finally, the numerical solutions to the new method are compared with those of the commonly used split-step Fourier algorithm.     

Ocean internal waves interpreted as oscillation travelling waves in consideration of ocean dissipation

Most studies of the synthetic aperture radar remote sensing of ocean internal waves are based on the solitary wave solutions of the Korteweg-de Vries （KdV） equation, and the dissipative term in the KdV equation is not taken into account. However, the dissipative term is very important, both in the synthetic aperture radar images and in ocean models. In this paper, the traveling-wave structure to characterize the ocean internal wave phenomenon is modeled, the results of numerical experiments are advanced, and a theoretical hypothesis of the traveling wave to retrieve the ocean internal wave parameters in the synthetic aperture radar images is introduced.     

无线电掩星滑动频谱方法和后传播方法的分析比较

本文详细介绍了滑动频谱方法,并通过模拟仿真和实测资料处理与后传播方法进行比较. 通过对模拟仿真信号反演发现:后传播方法和滑动频谱方法均能削弱大气多路径的影响,后传播方法在一定程度上优于滑动频谱方法;在模拟信号的相位中加入高斯噪声对后传播方法影响不大,但对滑动频谱方法影响较大,尤其在边界层以下. 分别用后传播方法和滑动频谱方法对2007年第71天至73天共约4500个COSMIC掩星数据进行处理. 将折射率反演结果与ECMWF分析场资料进行统计比较,结果显示:滑动频谱方法反演的掩星廓线深度大于后传播方法;后 关键词： GPS/LEO掩星 多相位屏模型 后传播方法 滑动频谱方法     

Variational assimilation in combination with the regularization method for sea level pressure retrieval from QuikSCAT scatterometer data I: Theoretical frame construction

A new method of constructing a sea level pressure field from satellite microwave scatterometer measurements is presented. It is based on variational assimilation in combination with a regularization method using geostrophic vorticity to construct a sea level pressure field from scatterometer data that are given in this paper, which offers a new idea for the application of scatterometer measurements. Firstly, the geostrophic vorticity from the scatterometer data is computed to construct the observation field, and the vorticity field in an area and the sea level pressure on the borders are assimilated. Secondly, the gradient of sea level pressure (semi-norm) is used as the stable functional to educe the adjoint system, the adjoint boundary condition and the gradient of the cost functional in which a weight parameter is introduced for the harmony of the system and the Tikhonov regularization techniques in inverse problem are used to overcome the ill-posedness of the assimilation. Finally, the iteration method of the sea level pressure field is developed.     

Refractivity estimations from an angle-of-arrival spectrum

This paper addresses the probability of atmospheric refractivity estimation by using field measurements at an array of radio receivers in terms of angle-of-arrival spectrum.Angle-of-arrival spectrum information is simulated by the ray optics model and refractivity is expressed in the presence of an ideal tri-linear profile.The estimation of the refractivity is organized as an optimization problem and a genetic algorithm is used to search for the optimal solution from various trial refractivity profiles.Theoretical analysis demonstrates the feasibility of this method to retrieve the refractivity parameters.Simulation results indicate that this approach has a fair anti-noise ability and its accuracy performance is mainly dependent on the antenna aperture size and its positions.     

不可微预报系统的广义变分同化方法及数值试验

讨论了不可微预报系统中的广义变分同化方法．对于不可微预报系统,由于不可微性,系统不存在切线性系统,而切线性系统的不存在,使得无法用通常的途径导出伴随系统A·D2引进不可微系统的弱形式后,可以不考虑切线性系统,而直接导出伴随系统．主要就3种形式的问题展开了讨论,第1种为低维系统,第2种情形为高维系统整体观测资料,第3种情形为高维系统局部观测资料．可以称此方法为结合反问题思想的广义变分同化方法．     

大气中非线性波动的非频散解——Ⅱ.非线性波速公式

本文的第二部分主要讨论非线性波速公式。由于非线性波动的波速公式与波形有关,为此文中引入了反映波形的无量纲量M。我们发现M可以表征波动非线性程度的大小,此即为M判据。文中还给出了非线性Rossby波与非线性重力惯性波的波速公式,对前者振幅大的波动相速度小,而对后者则相反。此外,文中还讨论了在求非线性波动的近似解时应用Taylor展开时所必须注意的问题。     

ON DISCONTINUOUS PERIODIC SOLUTION AND DISCONTINUOUS SOLITARY WAVE OF TWO-DIMENSION SHALLOW WATER EQUATION

In this papepr we discues discomunucus peridic solution and discontinuous solitarywave of the shallow water model of geophysical fiuid dynamics.When we consider theproperties of vajeciory necr non一epuiulmium nom point.i.e.singular we fund that if weintraduce the concept of gendralized solution smoothing continuous solution),then the system will produce discontinueus periodle solution and the condition ofdiscontinuous periodic solution can be obtahed When the system is dagenerated.we findthat the discontinucus solitary wave is existent in the system. In this paper we consider aserdes of problems and obtain analyvic expression of discontinuous solution.This result iscompared with squall lime in the anmosphere, and both of them have many thing in common.     

二阶超复方程的广义解及拟Neumann问题

§1 引言对于一般形式的椭圆型方程组,在引进 Douglis 代数后,可以表示成 D_w+A_w+B_=C 的形式,这里 w、A、B、C 都是超复函数。关于一阶方程由于引进了 Pompieu 算子 J_G 以后对一系列性质与边值问题进行了研究,为了研究二阶及高阶椭圆型耦合方程组,必须引进对 J_G 的微分踅算,由于     

E_2类二阶椭圆型方程组的斜微商问题

本文考虑形如(?)复形式的二阶线性椭圆型方程组,其中h(z,ω,ω-(?),ω_z,)=r_1(z)ω_z~(?) r_2(Z)ω_2 r_3(z)ω_(z)~ r_4(z)(?)