基于目标区的局部角度域方向照明分析及其在偏移成像中的应用

叠前深度偏移已成为近年来地震偏移成像领域广泛应用的技术之一,其中复杂盐丘下方目标区域结构的成像始终是偏移成像中较难解决的问题.局部角度域波场分解可以提供在空间和方向上的双重局部化信息,因而这一技术被广泛地应用在方向照明分析、成像振幅校正等方面.本文在采用局部指数标架小波束进行角度域方向照明分析的基础上,研究采集系统对复杂盐丘下部层状结构成像质量的影响;同时通过分析目标区对应于相对地表采集系统分布的照明能量,确定叠前炮集数据中对盐下目标区成像起重要贡献的部分,并将这些数据用来对目标区成像,从而达到提高盐下结构成像质量的目的.本文将二维SEG-EAGE盐丘模型中盐下反射体作为目标区,分别计算其照明分析和由照明能量分布确定的炮集数据对目标区的偏移成像结果,同时通过与成像振幅校正前后的成像结果对比,说明了该方法对提高目标区结构成像质量的有效性.     

Seismic directional random noise suppression by radial‐trace time–frequency peak filtering using the Hurst exponent statistic

Radial‐trace time–frequency peak filtering filters a seismic record along the radial‐trace direction rather than the conventional channel direction. It takes the spatial correlation of the reflected events between adjacent channels into account. Thus, radial‐trace time–frequency peak filtering performs well in denoising and enhancing the continuity of reflected events. However, in the seismic record there is often random noise whose energy is concentrated in certain directions; the noise in these directions is correlative. We refer to this kind of random noise (that is distributed randomly in time but correlative in the space) as directional random noise. Under radial‐trace time–frequency peak filtering, the directional random noise will be treated as signal and enhanced when this noise has same direction as the signal. Therefore, we need to identify the directional random noise before the filtering. In this paper, we test the linearity of signal and directional random noise in time using the Hurst exponent. The time series of signals with high linearity lead to large Hurst exponent value; however, directional random noise is a random series in time without a fixed waveform and thus its linearity is low; therefore, we can differentiate the signal and directional random noise by the Hurst exponent values. The directional random noise can then be suppressed by using a long filtering window length during the radial‐trace time–frequency peak filtering. Synthetic and real data examples show that the proposed method can remove most directional random noise and can effectively recover the reflected events.     

Directional spectrum of wind waves: Part I—model and derivation

A new model on the directional spectrum of wind waves for deep water is proposed based on the statistics of wind waves. This model contains three parameters: the wave age, the inverse spectral bandwidth and the local spectral-peak angular frequency. The inverse spectral bandwidth is a robust parameter for describing the spectral steepness of wind waves. Using the inverse spectral bandwidth parameter, the proposed model can well describe various observations obtained from the open ocean and laboratory tank.     

Spectrodirectional remote sensing: From pixels to processes

This paper discusses the historical evolution of imaging spectroscopy in Earth observation as well as directional (or multiangular) research leading to current achievements in spectrodirectional remote sensing. It elaborates on the evolution from two separate research areas into a common approach to quantify the interaction of light with the Earth surface. The contribution of spectrodirectional remote sensing towards an improved understanding of the Earth System is given by discussing the benefits of converging from individual pixel analysis to process models in the land-biosphere domain. The paper concludes with an outlook of research focus and upcoming areas of interest emphasizing towards multidisciplinary approaches using integrated system solutions based on remote and in situ sensing, data assimilation, and state space estimation algorithms.     

地面热红外发射率的天顶角变化效应

文中着重研究了自然地表面的红外辐射的方向特征 ,实地测量了发射率随观测天顶角的变化 ,分别对卫星资料反演地面温度和地面辐射测量作出红外发射率的观测天顶角修正 ,两者比较的结果表明 ,发射观测天顶角修正在精确地面温度的反演计算中不可忽视 ,尤其在大角度观测情况下 ,对某些地物发射率方向特征的修正比发射率本身的修正更重要。