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Rotation of the Earth as a Triaxial Rigid Body

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Geo-Spatial Information Science 2007年第2期10卷 85-90页

作者： SHEN Wenbin CHEN Wei WANG Wenjun LIANG Yiqiang key lab. of geospace environment and geodesy MEC 129 Luoyu Road Wuhan 430079 China School of geodesy and Geomatics Wuhan University 129 Luoyu Road Wuhan 430079 China.

The Earth is taken as a triaxial rigid body, which rotates freely in the Euclidian space. The starting equations are the Euler dynamic equations, with A smaller than B and B smaller than C. The Euler equations are solved, and the numerical results are provided. In the calculations, the following parameters are used: (C-B)/A=0.003 273 53; (B-A)/C=0.000 021 96; (C-A)/B=0.003 295 49, and the mean angular velocity of the Earth's rotation, ω =0.000 072 921 15 rad/s. Calculations show that, besides the self-rotation of the Earth and the free Euler procession of its rotation, there exists the free nutation: the nutation angle, or the angle between the Earth's momentary rotation axis and the mean axis that periodically change with time. The free nutation is investigated.

关键词： Earth's rotation triaxial rigid body problem variation of Eulerian angles

Accuracy Analysis of Gravity Model Based on Fictitious Compress Recovery Approach

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Geo-Spatial Information Science 2007年第3期10卷 157-162页

作者： SHEN Wenbin TAO Benzao key lab. of geospace environment and geodesy of mec 129 Luoyu Road Wuhan 430079 China School of geodesy and Geomatics Wuhan University 129 Luoyu Road Wuhan 430079 China. 不详

The potential field determined based on the fictitious compress recovery approach is influenced by the errors contained in the boundary （the Earth＇s surface or the surface corresponding to the satellite altitude） values. Given the boundary value with definite accuracy, the accuracy of the field determined based on the fictitious compress recovery approach is estimated, and it is theoretically shown that the determined field has the same accuracy level as the given boundary value.

关键词： fictitious compress recovery error function error estimate accuracy of the potential field

On the Generation Algorithm of VRS Virtual Observations

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Geo-Spatial Information Science 2007年第2期10卷 91-95页

作者： WEI Erhu CHAI Hua LIU Jingnan AN Zhiguo School of geodesy and Geomatics Wuhan University 129 Luoyu Road Wuhan 430079 China key lab. of geospace Enviroment and geodesy MEC 129 Luoyu Road Wuhan 430079 China

In the past few years, network RTK positioning technology, especially the VRS technology, has been widely used in some parts of China and in many countries around the world. The principle of the VRS technology is discussed with corresponding formula deduction, and detailed descriptions and applications of VRS corrections and virtual observations generation algorithm are given.

关键词： network-RTK MRS corrections generation algorithm virtual observation

Morphology of polar ionospheric O^+ ion upflow: FAST observations during quiet time

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Chinese Science Bulletin 2007年第24期52卷 3403-3415页

作者： DANG Ge MA ShuYing ZHOU YunLiang key lab.of geospace environment and geodesy CNEM College of Electronic Information Wuhan University Wuhan 430079 China

With energetic ion measurements on FAST satellite, the morphologic features of quiet-time ionospheric O+ ion upflowing at altitudes of 2000 to 4000 km are drawn out for the first time. The pre-noon cusp/cleft is the predominant region of upflowing occurrence for O+ with lower energy. Meanwhile the pre-dawn sector near the equatorward edge of the plasma convection dominates the occurrence for the higher energy O+ ions. No matter whether the energy is lower or higher, the upflows occur often over a wide MLT range of lower latitudes outside the auroral oval. The upflowing within the pre-midnight (21:00― 22:00 MLT) auroral oval carrys larger energy fluxes, with extremely large fluxes for higher energy O+ appearing near the polar cap boundary. For altitudes of 2000―4200 km under observation, the ion conics occur much more frequently than ion beams. Ion beams are rarely found below 3000 km, while the conics occur uniformly over the observed altitudes.

关键词：双极电离层氧离子流磁气圈耦合人造卫星观测

Numerical study of the auroral particle transport in the polar upper atmosphere

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Science China(Technological Sciences) 2008年第10期51卷 1759-1771页

作者： CAI HongTao1,2, MA ShuYing1,2 & PU ZuYin3 1 School of Electronic Information, Wuhan University, Wuhan 430079, China 2 key lab.ratory of geospace environment and geodesy, Ministry of Education of PRC, Wuhan 430079, China 3 School of Earth and Space Sciences, Peking University, Beijing 100871, China School of Electronic Information Wuhan University key lab.ratory of geospace environment and geodesy Ministry of Education of PRC School of Earth and Space Sciences Peking University

Starting from the Boltzmann equation and with some reasonable assumptions, a one-dimensional transport equation of charged energetic particles is derived by taking account of major interactions with neutral species in the upper atmosphere, including the processes of elastic scattering, the excitation, the ionization and the secondary electron production. The transport equation is numerically solved, for a simplified atmosphere consisting only of nitrogen molecules (N2), to obtain the variations of incident electron fluxes as a function of altitude, energy and pitch angle. The model results can describe fairly the transport characteristics of pre-cipitating auroral electron spectra in the polar upper atmosphere; meanwhile the N2 ionization rates calculated from the modeled differential flux spectra also exhibit good agreements with existing empirical models in terms of several key parameters. Taking the energy flux spectra of precipitating electrons observed by FAST satellite flying over EISCAT site on May 15, 1997 as model inputs, the model-calculated ionization rate profile of neutral atmosphere consists reasonably with that recon-structed from electron density measurements by the radar.

关键词： aurora particle precipitation polar upper atmosphere electron transport equation numerical simulation

Cluster observations of high-altitude cusp during multiple fast-turning IMF

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Chinese Science Bulletin 2010年第12期55卷 1178-1185页

作者： CAI HongTao MA ShuYing DUNLOP M W BOGDANOVA Y DAVIES J A PITOUT F School of Electronic Information Wuhan University Wuhan 430079 China key lab.of geospace environment and geodesy CNEM Wuhan 430079 China SSTD Rutherford Appleton Laboratory Chilton OX11 OQX UK Department of Physics La Trobe University Melbourne Victoria 3086 Australia Max-Planck-lnstitut fiir Extraterrestrische Physik Garching D-37191 Germany

Using coordinated observations from the Cluster,DMSP and ESR radar,high-altitude cusp was investigated for a time period characterized by four fast reversals of the IMF *** February 12,2003,Cluster was flying sunward at duskside over the Northern Hemisphere,across the high-altitude northern cusp *** the two crossings are during steady northward IMF interval,whereas ion fluxes detected during the time period are quite *** cusp in the first crossing is a "typical" northward-IMF one,with short-lived ion injections of evident "reversed" dispersion *** the second crossing,however,the cusp appears to be a region reminiscent of the Stagnant Exterior Cusp (SEC).In addition,evident upward-flowing O+ ion bursts,possibly original from polar ionosphere,are also detected during the second cusp crossing,together with enhancement of trapped magnetospheric-like electron *** suggest that the SEC-like cusp is likely on newly closed field lines,which were first reconnected (being opened) at low latitudes and later reconnected again (being closed) poleward of the northern cusp.

关键词：国际货币基金组织高海拔群集观测十字路口离子检测低纬度地区气象卫星