Hydrological contribution on gravity and vertical crustal displacement at
collocated Jiufeng station of China
Haoming YAN1,2, Wu CHEN1, Yaozhong ZHU2, Dawei ZHENG1,3 , Weimin Zhang2, Xiaodong CHEN2 ,
Genyou LIU2 , Jiangcun ZHOU2 , Heping SUN2 , Min ZHONG2 , Yong WANG2
1. Department of Land Surveying and Geo-Informatics, Hong Kong Polytechnic University, Hung
Hom, Kow Loon, Hong Kong, P. R. China
2. Key Laboratory of Dynamic Geodesy, Institute of Geodesy and Geophysics, Chinese Academy of
Sciences, Wuhan 430077, P. R. China
3. Center for Astro-geodynamics Research, Shanghai Observatory, Chinese Academy of Sciences,
Shanghai 210009, P. R. China
The non-geodynamic signals such as atmosphere, ocean bottom pressure and
hydrology, contribute significantly to the geodetic and site observations of gravity
changes and vertical displacement. These geophysical contributions must be provided
consistently for the purpose of correction on both observed geodetic and site time
series. In this paper, the geophysical contributions on both surface gravity changes
and vertical displacement, are studied at collocated Jiufeng station of China during
year 2001 to 2005, by using geodetic technique GPS, and by using independent
surface observations such as super-conducting gravimeter (SG) and absolute
gravimeter (AG). The annual geophysical contributions on gravity and on vertical
displacement fairly agree with the observed SG gravity and GPS height changes by
first removal of concrete pillar and bedrock thermal expansion effects, respectively.
The results indicate that when consider the hydrological contribution, the geophysical
model can successfully explains both the annual gravity changes and vertical
displacement at Jiufeng station. The roles of near-surface hydrology are 71% and 33%
of that of atmosphere on annual gravity and vertical displacement, respectively. While
the underground water can affect the gravity changes remarkably and affect the
vertical displacement at some degree. Thus the hydrology cannot be neglected when
research on both gravity changes and vertical displacement. On the other hand, after
removal of the near-surface geophysical contributions, the high resolution SG surveys
can be used to estimate water storage in the subsurface and could potentially be used
to estimate underground water changes. To constrain the GPS vertical displacement
with gravity or vice versa which is the benefit of collocation observation, the
conversion between the gravity changes and vertical displacement
(gravity/displacement) is very important. We discuss the gravity/displacement ratio
between theory and geophysical model, and give a suitable gravity/displacement ratio
value of -0.21gal/mm at Jiufeng station.
Oral presentation