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Wave equation tomographyin baseband with phase correction from the first arrival traveltimes

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石油物探 2017年第1期56卷 69-74页

作者： YIN Feng Jerry HARRIS department of geophysics Stanford University

We use the first arrival traveltime to correct the phase distortion in a nonlinear wave equation inversion *** improves the precision of tomographic reconstruction of a velocity structure with large variations and helps solve the ill-posed problem of wave equation *** the variation of the velocity distribution is large,general non-linear wave equation inversions are very ill-posed and for such strong nonlinear we can not obtain a correct *** of main reasons is that the calculated and observed phase of the wavefield differs greatly if the initial model is far from the true *** leads to highly mismatched phase between the calculated and the observed wave *** is so-called"Cycle Skipping"problem in the full waveform *** phase mismatch is even more pronounced if a high operating frequency is employed in order to increase *** address this problem,we use the first arrival to"demodulate"the wave field in the frequency domain with a goal of restoring the phase of wave *** we minimize an objective function consisting of so called"demodulated"wave field to solve wave equation inversion *** this way,we find that the inversion is much improved,and when the velocity perturbation in a complicated model reaches 35%,we can still obtain a good inversion.A computer simulation shows that our method is very robust for acoustical wave inversion with good reconstruction precision.

关键词：全波形反演随机边界异构并行作业池速度反演

Analysis of Indian Monsoon and Associated Low-Level Circulation in 1980 and 1981

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Advances in Atmospheric Sciences 1989年第1期6卷 113-119页

作者：陶祖钰 department of geophysics Peking University Beijing

In this paper, Indian monsoon of 1980 and 1981 is analysed based on the seasonal and half-month averaged data of 850 hPa of ECMWF analysis. The results show that Indian monsoon is related to Somali jet, the low-latitude easterlies and the mid-latitude westerlies over southern Indian Ocean, which are associated with the stationary wave of Southern Hemisphere. The forces affecting on the low-level flow are diagnosed, which display the relationship between Indian monsoon and the associated low-level flow.

关键词： In Analysis of Indian Monsoon and Associated Low-Level Circulation in 1980 and 1981

The Solitary Waves of the Barotropic Quasi-Geostrophic Model with the Large-scale Orography

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Advances in Atmospheric Sciences 1998年第3期15卷 122-129页

作者：陈炯刘式适 department of geophysics Peking University Beijing

Starting from a modified barotropic quasi-geostrophic model equation, considering the actual situation of the large-orography of the Tibetan Plateau, neglecting its slope in x direction, and using the reductive perturbation method, then the solitary waves are obtained. The results show that the orography is essential factor exciting solitary Rossby waves in a flow without shear.

关键词： Barotrophic quasi-geostrophic model Reductive perturbation method Solitary wave

On the atmospheric internal ship waves

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Science China Earth Sciences 1997年第6期40卷 592-598页

作者：桑建国 department of geophysics Peking University Beijing 100871 China

The analytical solutions of the atmospheric internal ship waves induced by three-dimensional terrain are obtained by solving the atmospheric wave equation. The solutions show that the waves consist of the untrapped and trapped parts. The patterns of the diverging wave and transverse wave in the untrapped parts are mainly determined by the shape and orientation of the terrain. This kind of wave may transport the wave energy to the upper atmosphere. The patterns of trapped lee waves are decided by the atmospheric conditions such as stratification, mean wind speeds and wind shear.

关键词： untrapped wave trapped wave diverging wave transverse wave

DOES THE PULSAR BEAM HAVE AN ELLIPTICAL CROSS SECTION?

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Chinese Science Bulletin 1989年第13期34卷 1116-1120页

作者：吴鑫基沈志强 department of geophysics Peking University

According to the RC model proposed by Radhakrishnan and Cooke in 1969, the pulsar beam is a cone of circular cross section. However, Jones first put forward a proposal that pulsar beams may be elongated in the latitud... 详细信息

关键词： pulsar beam cone

3D and 2D topographic correction to estimated geothermal gradient from the base of gas hydrate stability zone in the Andaman Forearc Basin

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Energy Geoscience

Energy Geoscience 2024年第2期5卷 314-320页

作者： Uma Shankar department of geophysics Institute of ScienceBHUVaranasiIndia

Methane gas hydrate related bottom-simulating reflectors(BSRs)are imaged based on the in-line and cross-line multi-channel seismic(MCS)data from the Andaman Forearc *** depth of the BSR depends on pressure and temperature and pore water *** these assumptions,the BSR depth can be used to estimate the geothermal gradient(GTG)based on the availability of in-situ temperature *** calculation is done assuming a 1D conductive model based on available in-situ temperature measurement at site NGHP-01-17 in the study ***,in the presence of seafloor topography,the conductive temperature field in the subsurface is affected by lateral refraction of heat,which focuses heat in topographic lows and away from topographic *** 1D estimate of GTG in the Andaman Forearc Basin has been validated by drilling results from the NGHP-01 expedition.2D analytic modeling to estimate the effects of topography is performed earlier along selected seismic profiles in the study *** study extended to estimate the effect of topography in 3D using a numerical *** corrected GTG data allow us to determine GTG values free of topographic *** difference between the estimated GTG and values corrected for the 3D topographic effect varies up to~5℃/*** conclude that the topographic correction is relatively small compared to other uncertainties in the 1D model and that apparent GTG determined with the 1D model captures the major features,although the correction is needed prior to interpreting subtle features of the derived GTG maps.

关键词： Gas hydrate BSR Geothermal gradient 3D and 2D topographic modeling Andaman Forearc Basin

METHOD OF INTEGRATED GREEN'S FUNCTION FOR THE CALCULATION OF TILT LOAD TIDE CAUSED BY THE OCEANIC TIDES

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Science China Chemistry 1990年第12期33卷 1517-1528页

作者： WU QING-PENG AND ZHU WEN-LU (department of geophysics, Peking Uuiversity, Beijing 100871, PRC) department of geophysics Peking Uuiversity Beijing 100871 PRC

The method of integrated Green's function for the calculation of the tilt(?)load tide proposed by this paper is sn improvement and s development of the current widely used method proposed by Farrell, and it is s new method of calculation. According to this method, the integrated Green's function of tilt load tide has been calculated first, then on the basis of the cotidal charts the tilt load tide caused by the oceanic tides at any point on the continent can be easily calculated through algebraic procedures. As an example of application of this method the tilt load tides of M_2 have been calculated on the basis of cotidal charts of Schwiderski for the following three stations: Wuchang, Tai'an and Xuzhou.

关键词： tilt load tide load Love numbers integrated Green’s function

Seasonal and Interannual Variations of Upper Tropospheric Water Vapor Band Brightness Temperature over the Global Monsoon Regions

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Advances in Atmospheric Sciences 1998年第3期15卷 55-63页

作者：钱维宏朱亚芬谢安叶谦 department of geophysics Peking University Beijing

The upper-troposphere water vapor (UTWV) band brightness temperature (BT) dataset derived from the High-resolution Infrared Radiation Sounder (HIRS) channel 12 of the National Oceanic and Atmospheric Administration (NOAA) polar satellites from 1979 to 1995 is used to analyze the seasonal and interannual variations for the global monsoon regions. Results show that (i) there are three major regions where the UTWV band BT varies significantly with season, i.e., South Asia, the western coastal South-North America tropical region and the low-latitude African region; (ii) UTWV band BT clearly reveals the water vapor temporal/spatial features as well as the atmospheric circulation structure over the low-latitude during the monsoon onset; and (iii) there is a remarkable relationship between the interannual variation of the UTWV band BT over the monsoon regions and the sea surface temperature anomaly in the eastern equatorial Pacific.

关键词： Monsoon Seasonal variation Interannual variability Upper tropospheric water vapor Brightness temperature

Multiple time-space scale atmosphere-ocean interactions and improvement of Zebiak-Cane model

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Science China Earth Sciences 1997年第6期40卷 577-583页

作者：钱维宏王绍武 department of geophysics Peking University Beijing 100871 China

In a real climate system there are multiple time-space scale atmosphere-ocean interactions, ranging from the planetary scale and basin scale to local air-sea interactions. The Zebiak-Cane (ZC) model with one-level atmosphere described only local air-sea interaction process. Thus the planetary scale Hadley cell and Walker cell anomalies should be introduced in the model. Including the planetary scale Hadley cell anomaly in the model improved the prediction skill. It showed that the improved model provided satisfactory prediction of the equatorial eastern Pacific SST anomaly with lead time of 9-10 months not only for 1970-1991 but also for 1992-1995.

关键词： multiple time-space scale atmosphere-ocean interaction Zebiak-Cane model model improvement