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2017年11月6日“坚白”高端论坛第10期

时间:2017-11-05 来源:未知 点击:
报告题目:Direct topographical effect on the airborne gravity disturbance for Helmert's second method of condensation
报  告  人:黄建梁  博士   加拿大大地测量部
邀  请  人:李建成  院士
报告时间:2017年11月6日上午10:00
报告地点:学院227学术报告厅

报告摘要
Helmert's second method of condensation removes the topographical mass and compensates using a thin mass layer on the geoid, transforming the Earth's gravitational potential to a harmonic field in the space between the geoid and topographical surface. Consequently, the Helmert(ized) gravity anomaly can be continued from the Earth's surface downward to the geoid to meet the requirement of Stokes's integral for the determination of the geoid in the harmonic Earth's gravity field. Finally the geoid can be determined by restoring the topography from the Helmert mass layer. In this process, the Helmert gravity anomaly is determined from the Molodensky-type free-air anomaly by evaluating and correcting for the direct and second indirect topographical effects (DTE and SITE) on the Earth's surface. The Molodensky-type anomaly is defined by the difference between the gravity value at a point on the Earth's surface and the normal gravity at the corresponding point on the telluroid. This approach is suitable when the gravity observation and orthometric/normal height are available on the Earth's surface. The airborne gravity observations provide the gravity disturbance, as ellipsoidal height is generally measured at flight level. To apply Helmert's second method of condensation to the gravity disturbance, only the direct topographical effect is required at flight level. In this paper, we first formulate the direct topographical effect on the gravity disturbance at flight level in terms of both Newton's integral and spherical harmonic series, then numerically determine the requirements on spatial and spectral resolutions of digital elevation model (DEM) for the evaluation of DTE at various flight levels.
 
报告人简历:
        黄建梁,博士,1999年在加拿大大地测量部工作,在大地水准面建模和研制的重要科学期刊及会议上发表/联合发表十多篇同行评议文章。主要研究方向为:重力大地水准面建模的理论与方法,加拿大大地水准面模型确定。主要研究成果包括:研制了加拿大2013重力大地水准面模型,被采纳为官方的大地测量垂直基准;在加拿大自然资源部的地下水地球科学项目中担任GRACE方面的负责人,主要是将GRACE数据用于研究五大湖流域、纳尔逊河流域、阿尔伯塔省以及加拿大16大流域的水储量估计。自2005年至2014年,在IAG的两个工作组中参与EGM2008和GRACE&GOCE模型的评价,相关成果发表在Newton's Bulletin。目前在IAG的4个工作(研究)组中担任会员,并在国际重力场服务咨询委员会中任董事会成员。

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