水平层状横向同性地层中频率测深资料全参数快速迭代反演

提出水平层状横向同性地层中频率测深资料的全参数快速迭代反演算法,以便从测量资料中同时确定各个地层的横向、 纵向电导率及层界面深度.首先,利用水平层状介质中电磁场并矢Green函数在频率波数域中的解析解和Sommerfeld积分的 快速计算技术确定正演响应.然后,利用摄动理论和Fourier逆变换公式,研究建立一套快速求解全参数Fréchet导数的 有效算法,并利用规范化处理和奇异值分解技术给出迭代反演过程.最后,给出数值试验证明反演理论的有效性以及反演算法 的抗噪声能力.     

基于海面散射模型的全极化合成孔径雷达海洋环境探测关键技术参数设计仿真研究

技术参数设计研究是提升全极化SAR海洋环境探测能力的有效途径. 本文通过分析噪声等效后向散射系数和辐射分辨率与海洋环境探测的地球物理联系,提出一种全极化SAR关键技术参数设计方法. 采用全极化海面散射模型计算不同海洋环境条件下的雷达后向散射系数,据此确定全极化SAR对海探测的噪声等效后向散射系数,再将其作为合成孔径雷达方程输入参数,以辐射分辨率和信噪比的函数关系为约束条件,开展信噪比、辐射分辨率和系统功率孔径积等技术参数设计研究. 论文通过全极化海面散射模型的仿真计算,发现对海探测的噪声等效后向散射系数设计为-35.0 dB,可满足全极化SAR不同海洋环境条件的探测需求. 通过研究辐射分辨率与信噪比的函数关系,发现对海探测的最优信噪比为8.0 dB. C波段机载全极化SAR设计结果表明,由于兼顾了海洋环境探测需求,本文设计方法使得全极化SAR技术参数同时满足了海洋环境应用需求和系统设计要求. 关键词： 海面散射模型 全极化合成孔径雷达 海洋环境探测 技术参数设计     

A single-scattering approximation for infrared radiative transfer in limb geometry in the Martian atmosphere

We present a single-scattering approximation for infrared radiative transfer in limb geometry in the Martian atmosphere. It is based on the assumption that the upwelling internal radiation field is dominated by a surface with a uniform brightness temperature. It allows the calculation of the scattering source function for individual aerosol types, mixtures of aerosol types, and mixtures of gas and aerosol. The approximation can be applied in a Curtis-Godson radiative transfer code and is used for operational retrievals from Mars Climate Sounder measurements. Radiance comparisons with a multiple scattering model show good agreement in the mid- and far-infrared although the approximate model tends to underestimate the radiances in realistic conditions of the Martian atmosphere. Relative radiance differences are found to be about 2% in the lowermost atmosphere, increasing to ∼10% in the middle atmosphere of Mars. The increasing differences with altitude are mostly due to the increasing contribution to limb radiance of scattering relative to emission at the colder, higher atmospheric levels. This effect becomes smaller toward longer wavelengths at typical Martian temperatures. The relative radiance differences are expected to produce systematic errors of similar magnitude in retrieved opacity profiles.     

调QNd:YAG倍频激光器的测深模拟实验研究

本文报道了利用Nd:YAG激光器产生的1.064μm的红外激光脉冲和二次谐波倍频后的532um的激光脉冲进行水深测量的模拟实验研究.实验通过探测水面的红外回波及水下的反射回波信号来实现水深的探测.文章介绍了实验原理和实验过程,并对实验结果进行了分析和讨论.     

地基CO2廓线探测差分吸收激光雷达

研制了一台利用气溶胶散射信号的CO₂廓线探测差分吸收激光雷达. 系统利用染料激光器实现波长调制, 采用双光路气体吸收池, 结合Voigt拟合方法实现了脉冲红外激光的高精度定标. 针对输出激光带宽较宽的问题, 采取仿真实验评估了影响, 并设计了基于吸收池的订正因子获取方案. 进而, 开展了水平、垂直和连续观测实验, 通过与地面CO₂分析仪测量值的对比, 证明了系统具备优越的精密性和精确性. 实验表明, 该样机能够俘获CO₂浓度随高程和时间变化而产生的变化.     

铁路隧道工程勘察中高频大地电磁测深应用效果研究

铁路隧道周围一定范围内的岩溶洞穴及断层构造,都将对隧道施工产生安全隐患,本文阐述采用EH?4电导率成像系统的高频大地电磁法能够准确快速的探测一定深度范围内的溶洞、断层等地质构造,对施工区的地质构造和岩溶的赋存状态进行超前的宏观预测,并将野外的成功实例进行分析。     

长短脉冲间自同步的光探针

一、引言 在六路激光系统中,我们采用从主激光输出中分出一部分进行喇曼频率变换和脉冲压缩,获得了最短脉宽为25ps的630nm的光,用此喇曼光我们进行了等离子体的阴影、纹影、干涉和磁场的测量,得到了一系列有用的信息。我们将此喇曼光用BBO晶体倍频,进一     

地面核磁共振导电性的等效影响

地面核磁共振测深中，导电性影响一般用等效导电半空间代替．这种等效性合理性如何尚没有任何讨论．本文利用2层模型和与其等效的均匀导电半空间模型为例，对两种模型的磁场变化规律、地面核磁共振的核函数变化情况以及核磁响应进行了数值模拟分析．结果表明，任意层状导电介质与其等效的均匀导电半空间模型的磁场分布规律不同，导致在地面核磁共振测深中相应的积分核函数在深度上衰减规律出现差异，表现为地面核磁共振测深信号的差异．导电性的等效性不是核磁共振测深的等效性．     

Operational retrieval algorithms for JEM/SMILES level 2 data processing system

To measure the thermal emission from stratospheric minor species with high sensitivity, the Superconducting Submillimeter-wave Limb-Emission Sounder (SMILES) aboard the Japanese Experiment Module (JEM) of the International Space Station (ISS) carries 4 K cooled Superconductor–Insulator–Superconductor (SIS) mixers. The major feature of the SMILES is its high-sensitive measurement ability with low system noise temperature less than 700 K.As a part of the ground system for the SMILES, a level 2 data processing system (DPS-L2) has been developed. It retrieves the density distributions of the target species from calibrated spectra in near-real-time. The retrieval process consists of two parts: the forward model, which computes radiative transfer, and the inverse model, which deduces atmospheric states. Since the forward model must provide the most accurate basis for results and be implemented under limited computing resources, the forward model algorithm for an operational system has to be accurate and fast. Hence, the algorithm is improved (1) by designing accurate instrument functions such as the instrumental field of view (FOV), sideband rejection ratio of sideband separator, and spectral responses of acousto-optic spectrometer (AOS) and (2) by optimizing radiative transfer calculation.This paper presents the development of the DPS-L2 along with the details on its algorithm and the algorithm performance. The accuracy of this algorithm is better than 1%, and the processing time for single-scan spectra is less than 1 min with eight parallel processings using a 3.16-GHz Quad-Core Intel Xeon processor. Thus, this algorithm is suitable for the SMILES measurement.     

Atmospheric trace gases profile retrievals using the nonlinear regularized total least squares method

We discuss the regularized total least squares (RTLS) method for the nonlinear overdetermined ill-posed problem of atmospheric trace gas retrieval. The RTLS method is used for the automatic determination of the regularization strength of the ill-conditioned matrix in an iterative process, and a mixed quadratic and cubic line search method is used for the nonlinear retrievals. Additional retrieval metrics, such as the model resolution matrix and the degrees of freedom in the retrieval, which characterize the vertical resolution of the retrievals, are also derived. Simulated retrievals as well as the retrieval from the data of a balloon-based spectroscopic measurement will be discussed. Retrieval results obtained using O₃ and CH₄ as test cases will be presented.