Geoscience Reference
In-Depth Information
application area of geodesy, except for application in the discipline of geodesy itself
and the relevant geosciences. GPS positioning devices will become a necessity for
people's socioeconomic activities and daily life in the information era.
Study of the Earth's Gravity Field Is Dedicated to Developing Satellite
and Aerial Gravity Exploration Techniques and to Making a High
Resolution Recovery of the Gravity Field of the Earth
In the last 30 years, the study of the Earth's gravity field has witnessed important
progress such as the creation of satellite gravity technology and the emergence of
absolute and relative gravimeters with microgal-level (1
10
8
m/s
2
)
Gal
¼
μ
accuracy.
In the entire framework of modern geodesy focusing on the study of basic
geosciences, physical geodesy has closely integrated with space geodesy and
constitutes the nucleus of geodesy, together dominating the development of the
discipline. The level of refinement of the Earth's gravity field structure will be one
of the major indicators of the future development of geodesy.
The development of gravity measurement will be dedicated to differentiating the
shortwave spectrum of the gravity field and monitoring the temporal variations in
the gravity field. The development of satellite gravity techniques will enable
measurement of a global gravity field with an accuracy of 1-2 mGal and a
resolution of 50 km. The accuracy of the latest fifth generation absolute gravimeter
reaches
1to
2
Gal; the accuracy of the superconducting (relative) gravimeter
μ
has reached 0.1
Gal. The accuracies of aerial gravity measurement and inertial
gravity measurement are somewhere between
μ
6 mGal, and are effective
techniques for distinguishing the shortwave gravity field with a resolution of less
than 50 km. Thanks to the development of gravimetry techniques, it has already
become possible to monitor the temporal changes in the gravity field to provide new
important data for the study of geodynamics.
1 and
Review and Study Questions
1. What are the technical and scientific objectives of geodesy?
2. What roles does geodesy play in topographic mapping?
3. Briefly summarize the history and trends of development of geodesy.
4. Analyze advantages of space geodesy compared with classical geodesy.
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