基于MODTRAN模型对高分五号卫星断层逸出气体探测能力的辐射模拟     

孙珂  单新建  申旭辉  孙林 《地震》2017,37(2):32-46

地下流体监测数据和地表断层调查都显示构造活动强烈期和大地震前后活动断裂带会伴有大量气体逸出。 中国即将发射的高分五号(GF-5)卫星搭载的大气环境红外甚高光谱分辨率探测仪及全谱段光谱成像仪两个传感器, 主要以大气气体的探测为应用目标。 本文基于两个传感器的参数设置, 使用大气辐射传输模型, 对断层逸出气体中的水汽、 CH₄和CO₂三种气体在大气中的含量变化对卫星传感器的辐射影响进行了仿真模拟, 分析了两个传感器对水汽、 CH₄和CO₂气体异常的探测能力。 结果表明, GF-5卫星两个红外传感器特定的光谱通道对大气水汽、 CH₄和CO₂气体异常变化均有不同程度的敏感性, 可以期待发展具有较高精度的相关气体遥感反演模型, 用于地震的监测及预测。  相似文献   

关于中国西北干旱区陆—气相互作用及其对气候影响研究的最近进展   总被引：13，自引：6，他引：7       下载免费PDF全文

黄荣辉  周德刚  陈文  周连童  韦志刚  张强  高晓清  卫国安  候旭宏 《大气科学》2013,37(2):189-210

本文综述了中国西北干旱区陆—气相互作用及其对气候影响研究的最近进展。文中不仅回顾了“中国西北干旱区陆—气相互作用观测试验”经过连续12年的观测和多次加强期观测所取得的干旱区陆面过程参数的分析以及边界层和陆—气相互作用特征等的分析和研究,而且综述了应用这些参数来优化有关陆面过程模式的参数化方案和改进有关陆面过程模式的研究;并且,本文还综述了关于中国西北干旱区感热输送特征以及西北干旱区陆—气相互作用对中国东部气候的影响及其机理,并揭示了中国西北干旱区春、夏季具有高感热输送特征,此高感热对中国东部夏季气候变异有重要影响。此外,本文还指出今后在此方面应进一步观测和深入研究的科学问题。  相似文献   

Synchrotron emission model of gamma-ray pulsar PSR J2021+3651     

《New Astronomy》2015

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An Improved Mellor–Yamada Level-3 Model with Condensation Physics: Its Design and Verification     

Mikio Nakanishi  Hiroshi Niino 《Boundary-Layer Meteorology》2004,112(1):1-31

A computational scheme for an improved Mellor–Yamada(M–Y) Level-3 model with condensation physics is proposedand its performance is examined against large-eddy-simulationdata on radiation fog. The improved M–Y model greatlycorrects several shortcomings of the original M–Y model:the underestimations of the mixed-layer depth and themagnitude of turbulent kinetic energy, and the discrepanciesin the formation and dissipation times of the fog. Inaddition the improved M–Y model can reproduce theoccurrence of Kelvin–Helmholtz instability and periodicoscillations due to its energy cycle. It is shown that theoptimization of both the closure constants and the masterlength scale is required for this improvement.The improved M–Y model has an improvement also in theLevel-2.5 version. Although the performance of theLevel-2.5 version is not so good as that of the Level-3version, the former has the advantage of relatively lowcomputational cost and is popularly used in operationalweather forecasts. Our computational scheme for theimproved M–Y model allows us to switch its hierarchylevels easily according to the purpose.  相似文献   

Wave set-up in the storm surge along open coasts during Typhoon Anita     

Soo Youl Kim  Tomohiro Yasuda  Hajime Mase 《Coastal Engineering》2010

Wave set-up in storm surges is studied using a numerical model for coasts in Tosa Bay, Japan, open to the Pacific Ocean. Simulation models employing only atmospheric pressures and winds as external forces are unable to properly simulate open coast storm surge heights, such as those due to Typhoon Anita (1970). However, the present study shows that a numerical model incorporating wave-induced radiation stresses, as well as wind stresses and pressure gradients, is able to account for the open coast surge heights. There is a maximum contribution of 40% by the radiation stresses to the peak sea level rises. This study also evaluates the effects of the tides; including the tides improves the agreement between the predicted water surface elevations and the observations. The difference in predictions between one-way coupling from wave to surge models and two-way coupling of the surge and wave models is found to be small.  相似文献   

Hydrodynamics of a headland-bay beach—Nearshore current circulation     

Rodolfo Silva  Asunción Baquerizo  Miguel Ángel Losada  Edgar Mendoza 《Coastal Engineering》2010

This paper is devoted to the analysis of the hydrodynamic equilibrium of a headland or semi-elliptic shaped beach. It is shown that the state of equilibrium depends not only on the in- and outgoing sediment but also on the accommodation of the sediment within the embayment. The shape and relative depth of shoals, or settling zones, also directly affect the wave and current patterns inside the bay, within which the resultant breaker line almost stops wave-induced currents at some locations, whereas the magnitude of current increases at other locations. Several numerical tests are analytically conducted in a semi-elliptic beach with two symmetrical shoals of varying relative depth where circulatory current systems are detected and analyzed. Numerical modelling for wave climate and wave-induced current estimation is also presented in order to corroborate results and provide a tool for complicated and/or physical domains. The results lead to a redefinition of the concept of equilibrium for headland-bay beaches taking into account not only the net sediment transport but also the role of the formation and disappearance of settling zones, as well as sediment interchanges between the beach and shoals.  相似文献   

Effect of radiation on the stability of equilibrium points in the binary stellar systems: RW-Monocerotis,Krüger 60     

M. K. Das  Pankaj Narang  S. Mahajan  M. Yuasa 《Astrophysics and Space Science》2008,314(4):261-274

We have studied the stability of location of various equilibrium points of a passive micron size particle in the field of radiating binary stellar system within the framework of circular restricted three body problem. Influence of radial radiation pressure and Poynting-Robertson drag (PR-drag) on the equilibrium points and their stability in the binary stellar systems RW-Monocerotis and Krüger-60 has been studied. It is shown that both collinear and off axis equilibrium points are linearly unstable for increasing value of β ₁ (ratio of radiation to gravitational force of the massive component) in presence of PR-drag for the binary systems. Further we find that out of plane equilibrium points (L _i , i=6,7) may exists for range of values of β ₁>1 for these binary systems in the presence of PR-drag. Our linear stability analysis shows that the motion near the equilibrium points L _6,7 of the binary systems is unstable both in the absence and presence of PR-drag.  相似文献   

Discovering stellar core collapse events using satellite-born RF detectors     

P. D. Morley  David W. Eastin 《Astrophysics and Space Science》2008,314(4):275-279

Previous research has shown that a massive electromagnetic pulse (MEMP) is the precursor to type II stellar core collapse events. While Earth’s ionosphere makes ground-based detection of this RF (radio frequency) electromagnetic pulse improbable, it can be readily observed by satellite-born detectors. The expected radius of detection using presently available COTS (commercial-off-the-shelf) equipment is 2.67 billion light-years. A new class of astronomical objects is predicted to exist.  相似文献   

Gamma-ray absorption in the microquasar SS433     

M.M. Reynoso  H.R. Christiansen  G.E. Romero   《Astroparticle Physics》2008,28(6):565-572

We discuss the gamma-ray absorption in the inner region of the microquasar SS433. Our investigation includes several contributions to the opacity of this system. They result from the ambient fields generated by the primary star, possibly an A-type supergiant, and a very extended disk around the black hole. Besides the sharp and dramatic absorption effect that occurs every time the star crosses the emission zone, we find in the UV photon field from the extended disk an important source of absorption for very high energy gamma-rays. This results in periodic gamma-ray observational signatures.  相似文献   

切仑科夫线状辐射与类星体的宽发射线起源探讨     

刘当波  袁爱芳  孟宪茹  单增罗布  尤峻汉 《天文学报》2009,50(4)

当具有各向同性速度分布的相对论电子穿过稠密气体区,或者轰击稠密气体区的表面时,切仑科夫效应将会产生1种特殊的原子或离子发射线,称做切仑科夫线状发射.这一预言在光学波段已由实验室的实验所证实.研究指出了切仑科夫线状辐射在类星体和赛弗特1星系的宽发射线研究中的重要性,利用此新机制有可能解决类星体研究中的一些重大且长期没有解决的疑惑.例如宽氢线之间存在的反常强度比,特别是反常Lyα/Lyβ强度比的问题.并且进一步估计了相对论电子穿过宇宙气体时所产生的各种效应的能耗的数量级,并对各种能耗进行比较,证实了切仑科夫线状发射机制在类星体和塞弗特1型星系中的有效性.  相似文献