Geodesy Discipline: Progress and Perspective

The geodesy discipline has been evolving and constantly intersecting and merging with other disciplines in the last 50 years,due to the continuous progress of geodetic observation techniques and expansion of application fields.This paper first introduces the development and roles of geodesy and its formation.Secondly,the development status of geodesy discipline is analyzed from the progress of observation techniques and cross-discipline formation is analyzed from the expansion of application fields.Furthermore,the development trend of geodesy is stated from the perspective of national requirements and scientific developments.Finally,the sub-disciplines for geodesy are suggested at the present stage,based on the requirements of the National Natural Science Foundation of China and development status of geodesy itself,which can provide references for topic selection and fund application of geodetic scientific research.

Advances, Problems and Prospects of Modern Geodesy Applied in Tibetan Geodynamic Changes

Modern geodetic techniques have developed rapidly in recent years, providing reliable observation data and new effective approaches, and greatly enhancing studies of the Tibetan geodynamics. For instance, the well-known GPS technique has been employed to measure seismic slips for many faults in the Tibetan Plateau. GPS data agree well with the hypothesis of a thickening crust and eastward mass flow. Moreover, absolute gravimetric data have been applied to interpret geophysical phenomena such as crust movement, co-seismic gravity change, GIA, and ground water change. The satellite gravity mission GRACE launched in 2002 provided global gravity models with unprecedentedly high precision and high spatial resolution. It has been used in implementing temporal gravity changes and improving our knowledge of the Earth＇s interior, including lithosphere dynamics, mantle viscosity and rheology, plateau uplift, and subduction processing. It is noteworthy that gravity presents unique advantages for the study of Tibetan geodynamics because of its sensitivity to mass migration and dynamic redistribution. To date, great advances have been made in applying modern geodetic data in studying dynamic changes of Tibetan plateau. For instance, the horizontal displacement field from GPS data revealed dynamical characteristics of the present-day Tibetan plateau. The combination of gravity anomalies and topographic data describe the tectonic characteristics of Tibetan plateau. The combination of gravity data and GPS data show present properties of the Tibetan plateau such as crust thickening, Moho＇s subsidence, and plateau uplift. GRACE data were used to estimate the distribution of ice/snow melting. These results demonstrate that mere application of integrated geodetic data as well as geophysical methods and numerical simulations can enhance our knowledge of Tibetan plateau dynamics. It must be pointed out that GRACE data include various geophysical signals such as crust vertical movement, denudation, ice and snow melting, GIA, ground water change, and permafrost degradation. To separate the tectonic information from other impulses, each physical signal must be evaluated and corrected carefully from the GRACE data. The Tibetan geodynamic problem is a complicated and synthetic issue that must be addressed through collaboration of workers in many fields. Succinctly put, although great achievements have been made in studying Tibetan plateau dynamics from each field, the dynamical process remains unclear. Some fundamental problems remain unresolved. They should be solved with modern geodetic data, such as GRACE, GPS, and absolute gravity data, combined with meteorological and geological data, for quantitative analysis of Tibetan plateau dynamics affected by respective geophysical sources. This review article introduces and discusses the scientific importance, advances, problems, and prospects of modern geodesy applied to the study of geodynamic changes of the Tibetan plateau.

Recent developments in seismological geodesy

With the advanced development of the modern geodetic techniques, the geodetic obser- vations have been proved to be more powerful to uncover the geophysical phenomena, especially the seismic one, than that in the past time. The recent developments and achievements in the seismological geodesy are summarised here. Several popular geodetic techniques, such as high-rate GNSS, InSAR and Satellite Gravimetry, are introduced first to present their recent contributions in studying the seismic deformations. The developments of the joint inversion of the seismic source parameters from multiple observations are then highlighted. Some outlooks in seismological geodesy are presented in the end.

A tectonic geodesy mapping software based on QGIS

To overcome the high cost of learning,non-visual operation,and cumbersome steps of fine-tuning map elements in Generic Mapping Tools(GMT)and other geoscience mapping softwares,we present the Tectonic Geodesy Application(TGA),a user-friendly 64-bit tectonic geodesy mapping software based on the secondary development interface of the open source geographic information system QGIS.In this paper,we detailly introduce the architecture and function modules of our software,and highlight the functions of rendering and map decoration through four cases:the geologic map of Papua New Guinea,the seismicity in China and surrounding regions,the seismicity and crustal deformation of the Tibetan Plateau and the coseismic deformation of the 2017 Jiuzhaigou earthquake in China.Compared with GMT,the tectonic geodesy mapping software we developed has the advantages of simple operation,low learning cost and user-friendly interface.

Compression of the North Hemisphere derived from space geodesy

The convergent and divergent velocities of active plate boundaries in the North Hemisphere are obtained with space geodetic data. The relative motions of adjacent plates in north-south direction are almost convergent; the spreading rates of the north mid-Atlantic ridge are smaller than the south mid-Atlantic ridge; the closed differences of the baseline length rates between stations on different plates along the latitudinal circle of 7.7, 23.3? 34.8? 42.0?and 51.0?are all negative. All these show that the North Hemisphere is a compressive hemisphere.

The 4-D integrated geodesy and strain analysis

Research of the practical 4-D integrated geodesy(IG) and strain analysis is presented in this paper.The practical model and basic observation equation are established by using IG and dynamic adjustment.Furthermore,the observation equations about gravity vector,zenith distance,azimuth angle,difference are derived and determination of local gravity field covariance solved.The 3-D strain formular is derived and the strain parameters calculated from it.The improvement of the OPERA software of Landan and Hem etc,FRG has been done to get a new software in Fortran Language which implements in MASSCOMP computer.Using the software,the integrated adjustment of two term observation data of triangle chain, triangle net,gravity,level,astronomic observation and strain analysis are established.The result is satisfactory.

Applications of the Fictitious Compress Recovery Approach in Physical Geodesy

The fictitious compress recovery approach is introduced, which could be applied to the establishment of the Rungerarup theorem, the determination of the Bjerhammar＇s fictitious gravity anomaly, the solution of the ＂downward con- tinuation＂ problem of the gravity field, the confirmation of the convergence of the spherical harmonic expansion series of the Earth＇s potential field, and the gravity field determination in three cases： gravitational potential case, gravitation case, and gravitational gradient case. Several tests using simulation experiments show that the fictitious compress recovery approach shows promise in physical geodesy applications.

International Union of Geodesy and Geophysics: 27th General Assembly Conference

"Beyond 100: The next century in Earth and Space Science"The 27th IUGG General Assembly will be held July 8-18,2019 at the Palais des Congrès in Montréal,Québec,Canada.This is a special opportunity for participants from Canada and from around the world to come together and share their science and culture.2019 marks the 100th anniversary of IUGG;we will look back on the accomplishments of the previous century of Earth and space science research,and forward to the next century of scientific advancement.Join us for a host of scientific activities,including special public lectures,keynote Union lectures and a wide variety of themed sessions.

Recent Advances in Marine Geodesy of China

The ocean accounts for approximately 71%of the total area of the Earth.Whether it is studying the shape of the Earth itself through geodesy or the future development of earth system science,strengthening the construction of ocean geodesy disciplines and innovating ocean geodetic observation technologies have evident theoretical and practical significance.In recent years,the discipline of ocean geodesy in China has been continuously developing and growing,and notable breakthroughs have been made in ocean satellite geodesy and seafloor geodetic observation technology.Research on ocean geodetic observation models and algorithms has also made great progress.

International Collaborations In Geodesy Advance Geoscience Research

UNAVCO supports geoscience research at 113 US academic Member institutions,and another 104 Associate Member institutions include international universities,laboratories,observatories,academies of science,and a museum.This diverse membership shares UNAVCO’s purpose at home and abroad,giving UNAVCO global reach in advancing geodesy.Since the mid-1980s,modern geodesy has evolved into a cutting-edge,multi-faceted toolbox with remarkably diverse research and real-world applications,including studies and observation or forecasting of solid-Earth hazards,the dynamics of the atmosphere,climate,near-Earth space environment,and of key environmental parameters such as water storage,soil moisture,and seaand lake-level changes.UNAVCO operates facilities on behalf of the U.S.National Science Foundation to support investigators who use geodetic tools across all of these Earth and atmospheric domains.UNAVCO has built a number of large dense regional networks of GPS stations,including the Earth Scope Plate Boundary Observatory in North America,the COCONetCaribbean network,TLALOCNet in Mexico,GNET in Greenland,and ANET in Antarctica.Going forward,UNAVCO plans to federate the Plate Boundary Observatory(USA),TLALOCNet(Mexico),and COCONet(Caribbean)GPS networks as the Network of the Americas,with upgrades to state-of-the-art,multi-sensor,multi-GNSS observations.While UNAVCO community scientists actively engage in using space and terrestrial geodetic techniques to study geodynamics at all scales,this proliferation of continuous networks is the basis for a suite of recent contributions that focus on improved daily positioning to sense Earth’s elastic response and other perturbations to loading by atmospheric and surface water,oceans,and ice.Day-to-day and sub-daily variations in the GPS vertical and horizontal correlate to increasingly well-understood short-term mass variability,such as monsoonal flooding in Bangladesh,sub-daily changes in tidal loading at continent scales,day-to-day surface water and ice storage in the western U.S.,variations in the rate of GIA in Greenland across a variety of scales,and improved understanding of the inter-annual variation in sea level rise due to changes in terrestrial water storage.

Geodesy and Geodynamics

Aims and Scope Geodesy and Geodynamics is committed to the publication of quality scientific papers in English in the fields of Geodesy and Geodynamics from authors around the world.Its aim is to promote a combination between Geodesy and Geodynamics,deepen the application of Geodesy in the field of Geoscience and quicken worldwide fellows’understanding on scientific research activity in China.It mainly publishes

Geodesy and Geodynamics

Aims and Scope Geodesy and Geodynamics is committed to the publication of quality scientific papers in English in the fields of Geodesy and Geodynamics from authors around the world.Its aim is to promote a combination between Geodesy and Geodynamics,deepen the application of Geodesy in the field of Geoscience and quicken worldwide fellows’understanding on scientific research activity in China.It mainly publishes newest research achievements in the field of Geodesy,Geodynamics,Science of Disaster and so on.

《Geodesy and Geodynamics》发展探索

介绍《Geodesy and Geodynamics》创刊目的、发展目标,分析了创办中的困难以及采取的解决办法。

Journal of Geodesy and Geoinformation Science Aims and Scopes

Aims:The Journal of Geodesy and Geoinformation Science is an official publication of the Chinese Society for Geodesy,Photogrammetry and Cartography. The Journal aims to facilitate and strengthen academic exchange on geodesy and geoinformation research between China and other countries. Furthermore,it makes efforts to offer a forum for discussion between researchers in China and abroad.

Rapid rupture characterization for the 2023 M_(S)6.2 Jishishan earthquake

On December 18, 2023, the M_(S)6.2 Jishishan earthquake occurred in the northeastern region of the QinghaiXizang Plateau, causing heavy casualties and property damage in Gansu and Qinghai Provinces. In this study,we integrate space imaging geodesy, finite fault inversion, and back-projection methods to decipher its rupture property, including fault geometry, coseismic slip distribution, rupture direction, and propagation speed. The results reveal that the seismogenic fault dips to the southwest at an angle of 29°. The major slip asperity is dominated by reverse slip and is concentrated within a depth range of 7–16 km, which explains the significant uplift near the epicenter observed by both the Sentinel-1 ascending and descending In SAR data. Moreover, the teleseismic array waveforms indicate a northwest propagating rupture with an overall slow rupture velocity of~1.91 km/s(AK array) or 1.01 km/s(AU array).

Monitoring the Deformation of Cableways

One type of aerial cableway consists of a continuous cable,which works at the same time as carrying cable and drawing cable.This kind of cableway is supported by many towers,which divide the total length in linear sections.Even small deviations from the planed layout can increase the strain of the cable and the danger of derailments.The deviations of the position of the towers from the planed layout are due to local sliding or sinking of the foundation or other mechanical movements.Up to now the axis of the cableways were periodically measured by traditional methods.The goal of this project is to demonstrate the possibility of measuring the axis of a cableway with GPS techniques,while the cable is moving.The results show that the proposed measuring device provides precise results in a simple and reliable way.

Russian VLBI network "Quasar":Current status and outlook

This paper presents the past,present and future status of the Russian VLBI network "Quasar".This network has been developed for at least 20 years by the Institute of Applied Astronomy of the Russian Academy of Sciences(IAA RAS). The equipment installed currently at each "Quasar" station and the facilities for processing observational data are described briefly. The latest results are presented, including the Earth orientation parameters(EOP) determined from the "Quasar" VLBI data and comparison with those from other processing centers. Our future plans to extend the "Quasar" VLB I network to the east and to the west will be carried out by establishing the Ussurijsk station in the Far East and the RussianCuban station in the west. They are considered in the context of the Russian section activity in the GGOS project. The expected improvement of the EOP determination accuracy can be obtained within the future configuration of the "Quasar" network,which is proved by simulation.

Prospect on Present-Day Crustal Kinematics and Dynamics Research in Sichuan-Yunnan Area with Geodetic Data

Combining the dense GPS and gravity observation data in Sichuan-Yunnan area, where there are the relatively complete active tectonic zones and seismic data, this paper applies the geodesy and geophysical inversion technique and the advanced numerical simulation to the synthesis study of geodesy inversion to find the dynamic process of tectonic movement and deformation in the area and finally to investigate the kinematics characteristic of the geological structure of different layer and different scale. This paper discusses the kinematics, dynamics model about the crustal movement of active blocks in Sichuan-Yunnan area and its adjacent areas.