A statistical correlation method is used to study the effect of instability of the calculation datum （ used in traditional method of indirect adjustment） on calculated gravity results, using data recorded by Longmen...A statistical correlation method is used to study the effect of instability of the calculation datum （ used in traditional method of indirect adjustment） on calculated gravity results, using data recorded by Longmen Mountain regional gravity network during 1996 -2007. The result shows that when this effect is corrected, anomalous gravity changes before the 2008 Wenchuan Ms8. 0 earthquake become obvious and characteristically distinctive. Thus the datum-stability problem must be considered when processing and analyzing data recorded by a regional gravity network.展开更多
A new gravity base network in the south of the Tibetan Plateau was established with a FG5X absolute gravimeter and three CG-6 gravimeters.The gravity base network consists of 10 absolute gravity points and 17 relative...A new gravity base network in the south of the Tibetan Plateau was established with a FG5X absolute gravimeter and three CG-6 gravimeters.The gravity base network consists of 10 absolute gravity points and 17 relative gravity points.Processing of the absolute data,pre-processing of the relative data and gravity network adjustment model are briefly described.Based a constrained weighted least squares,the combined adjustment of absolute and relative gravity measurements results in the gravity values with a precision of about±4.1μGal.展开更多
This study investigates data-processing methods and examines the precipitation effect on gravity measurements at the Dali gravity network, established in 2005. High-quality gravity data were collected during four meas...This study investigates data-processing methods and examines the precipitation effect on gravity measurements at the Dali gravity network, established in 2005. High-quality gravity data were collected during four measurement campaigns. To use the gravity data validly, some geophysical corrections must be considered carefully. We first discuss data-processing methods using weighted least- squares adjustment with the constraint of the absolute gravity datum. Results indicate that the gravity precision can be improved if all absolute gravity data are used as constraints and if calibration functions of relative gravi- meters are modeled within the observation function. Using this data-processing scheme, the mean point gravity pre- cision is better than 12 μgal. After determining the best data-processing scheme, we then process the gravity data obtained in the four measurement campaigns, and obtain gravity changes in three time periods. Results show that the gravity has a remarkable change of more than 50 pgal in the first time period from Apr-May of 2005 to Aug-Sept of 2007. To interpret the large gravity change, a mean water mass change （0.6 m in height） is assumed in the ETOPO1 topographic model. Calculations of the precipitation effect on gravity show that it can reach the same order of the observed gravity change. It is regarded as a main source of the remarkable gravity change in the Dali gravity network, suggesting that the precipitation effect on gravity mea- surements must be considered carefully.展开更多
The Antarctic geodetic datum constitutes a specialized implementation of the modern geodetic reference system within the extreme polar environment.A high-precision,unified,and dynamic Antarctic geodetic datum serves a...The Antarctic geodetic datum constitutes a specialized implementation of the modern geodetic reference system within the extreme polar environment.A high-precision,unified,and dynamic Antarctic geodetic datum serves as critical infrastructure for polar scientific research and engineering safety.This study reviews the composition,current status,and implementation pathways of the Antarctic geodetic datum through four dimensions:coordinate datum,height datum,gravity datum and sounding datum.Preliminary analysis reveals that the development of the Antarctic geodetic datum framework is severely lagging,thereby failing to meet the demands of both scientific expeditions and polar research.To address these challenges,this study proposes an implementation pathway leveraging the 5th International Polar Year(IPY-5)to pioneer regional high-precision geodetic datum in the China’s key research sector covering the area between Amery Ice Shelf and Princess Elizabeth Land,specially highlighting the Prydz Bay–Amery Ice Shelf–Lambert Glacier–Dome A(PANDA)transect,by deploying multi-technique stations andμGal-level superconducting gravimeter networks;and then to integrate multinational observation resources to ultimately establish a high-precision,unified,and dynamic geodetic datum framework.This framework will deliver a spatiotemporal infrastructure for Antarctica to advance the strategic goals of“understanding,protecting,and utilizing Antarctica”.展开更多
基金supported by the Eathquake Science Join Foundation( A07030)
文摘A statistical correlation method is used to study the effect of instability of the calculation datum （ used in traditional method of indirect adjustment） on calculated gravity results, using data recorded by Longmen Mountain regional gravity network during 1996 -2007. The result shows that when this effect is corrected, anomalous gravity changes before the 2008 Wenchuan Ms8. 0 earthquake become obvious and characteristically distinctive. Thus the datum-stability problem must be considered when processing and analyzing data recorded by a regional gravity network.
文摘A new gravity base network in the south of the Tibetan Plateau was established with a FG5X absolute gravimeter and three CG-6 gravimeters.The gravity base network consists of 10 absolute gravity points and 17 relative gravity points.Processing of the absolute data,pre-processing of the relative data and gravity network adjustment model are briefly described.Based a constrained weighted least squares,the combined adjustment of absolute and relative gravity measurements results in the gravity values with a precision of about±4.1μGal.
基金financially supported by the CAS/CAFEA International Partnership Program for creative research teams (No. KZZD-EW-TZ-19)the National Natural Science Foundation of China (Nos. 41331066 and 41174063)
文摘This study investigates data-processing methods and examines the precipitation effect on gravity measurements at the Dali gravity network, established in 2005. High-quality gravity data were collected during four measurement campaigns. To use the gravity data validly, some geophysical corrections must be considered carefully. We first discuss data-processing methods using weighted least- squares adjustment with the constraint of the absolute gravity datum. Results indicate that the gravity precision can be improved if all absolute gravity data are used as constraints and if calibration functions of relative gravi- meters are modeled within the observation function. Using this data-processing scheme, the mean point gravity pre- cision is better than 12 μgal. After determining the best data-processing scheme, we then process the gravity data obtained in the four measurement campaigns, and obtain gravity changes in three time periods. Results show that the gravity has a remarkable change of more than 50 pgal in the first time period from Apr-May of 2005 to Aug-Sept of 2007. To interpret the large gravity change, a mean water mass change （0.6 m in height） is assumed in the ETOPO1 topographic model. Calculations of the precipitation effect on gravity show that it can reach the same order of the observed gravity change. It is regarded as a main source of the remarkable gravity change in the Dali gravity network, suggesting that the precipitation effect on gravity mea- surements must be considered carefully.
文摘The Antarctic geodetic datum constitutes a specialized implementation of the modern geodetic reference system within the extreme polar environment.A high-precision,unified,and dynamic Antarctic geodetic datum serves as critical infrastructure for polar scientific research and engineering safety.This study reviews the composition,current status,and implementation pathways of the Antarctic geodetic datum through four dimensions:coordinate datum,height datum,gravity datum and sounding datum.Preliminary analysis reveals that the development of the Antarctic geodetic datum framework is severely lagging,thereby failing to meet the demands of both scientific expeditions and polar research.To address these challenges,this study proposes an implementation pathway leveraging the 5th International Polar Year(IPY-5)to pioneer regional high-precision geodetic datum in the China’s key research sector covering the area between Amery Ice Shelf and Princess Elizabeth Land,specially highlighting the Prydz Bay–Amery Ice Shelf–Lambert Glacier–Dome A(PANDA)transect,by deploying multi-technique stations andμGal-level superconducting gravimeter networks;and then to integrate multinational observation resources to ultimately establish a high-precision,unified,and dynamic geodetic datum framework.This framework will deliver a spatiotemporal infrastructure for Antarctica to advance the strategic goals of“understanding,protecting,and utilizing Antarctica”.
