ON THE IMPROVEMENT OF GEOPOTENTIAL
MODEL USING GRAVITY DATA IN CHINA
Huang Motao, Guan Zheng and Yang Y ongzhong
Tianjin Institute of Hydrographic Surveying and Charting,
40 Youyi Road, Tianjin 300061, P. R. of China
ABSTRACT
For the determination of regional geoid in China, an updated set of
30' x 30' mean free-air gravity anomalies was calculated for China in
1993. Then the new geopotential model DQM94 has been calculated using
this new set of 30' x 30' mean free-air gravity anomalies merged with
other available 30' x 30' mean values in the vicinity of China. The
calculation of the tailored model, complete to degree and order 360, is
based on the OSU91A coefficient set, that was used as a start model.
The RMS value of the differences between the 6841 mean values and the
model derived values decreased from 21.13 mGal to 8.05 mGal for OSU91A
resp. DQM94. Especially comparisons of the
two models with
GPS/levelling data in China show an improved accuracy of the DQM94
model. The RMS value of the differences relative to OSU91A is 1. 708 m
and 1. 051 m for DQM94. Furthermore, it is proved that the features, out
of China, of the DQM94 model are almost kept the same as that of the
OSU91A model.
INTRODUCTION
Geopotential models are being used to great effect to provide reference
fields for the anomalous gravity field used for local and regional
geoid determination (Kearsley and Forsberg,
1990).
For sake of
computations, regional geoid determination are usually carried out by a
combination of spherical harmonic expansions of the earth's potential
(i. e. geopotential model) and a set of observed point or mean gravity
anomalies (Weber and Zomorrodian, 1988). It is better first
to take
into account the long wavelength features as given by any recent
combined solution of the geopotential and then to integrate the so
-called "residual anomalies" by means of Stokes formula (Albuisson et
aI, 1979). In the past several years, numerous techniques have been
applied to combined data to achieve more accurate and representative
186
MODEL USING GRAVITY DATA IN CHINA
Huang Motao, Guan Zheng and Yang Y ongzhong
Tianjin Institute of Hydrographic Surveying and Charting,
40 Youyi Road, Tianjin 300061, P. R. of China
ABSTRACT
For the determination of regional geoid in China, an updated set of
30' x 30' mean free-air gravity anomalies was calculated for China in
1993. Then the new geopotential model DQM94 has been calculated using
this new set of 30' x 30' mean free-air gravity anomalies merged with
other available 30' x 30' mean values in the vicinity of China. The
calculation of the tailored model, complete to degree and order 360, is
based on the OSU91A coefficient set, that was used as a start model.
The RMS value of the differences between the 6841 mean values and the
model derived values decreased from 21.13 mGal to 8.05 mGal for OSU91A
resp. DQM94. Especially comparisons of the
two models with
GPS/levelling data in China show an improved accuracy of the DQM94
model. The RMS value of the differences relative to OSU91A is 1. 708 m
and 1. 051 m for DQM94. Furthermore, it is proved that the features, out
of China, of the DQM94 model are almost kept the same as that of the
OSU91A model.
INTRODUCTION
Geopotential models are being used to great effect to provide reference
fields for the anomalous gravity field used for local and regional
geoid determination (Kearsley and Forsberg,
1990).
For sake of
computations, regional geoid determination are usually carried out by a
combination of spherical harmonic expansions of the earth's potential
(i. e. geopotential model) and a set of observed point or mean gravity
anomalies (Weber and Zomorrodian, 1988). It is better first
to take
into account the long wavelength features as given by any recent
combined solution of the geopotential and then to integrate the so
-called "residual anomalies" by means of Stokes formula (Albuisson et
aI, 1979). In the past several years, numerous techniques have been
applied to combined data to achieve more accurate and representative
186