Bureau Gravimetrique International ( BGI) R ole and Services to Terrestrial Gravimetry

Bureau Gravimetrique International (BGI)Role and Services to Terrestrial Gravimetry

S. Bonvalot, G. Balmino, F. Reinquin, A. Briais, G. Gabalda, L. Seoane

Bureau Gravimetrique International (BGI)Toulouse, France

H. Wilmes, H. Wziontek

Federal Agency for Cartography and Geodesy (BKG)Frankfurt/Leipzip, Germany

IAG Symposium on Terrestrial Gravimetry : Static and Mobile Measurements – September 1 7– 20, 2013 – St Petersburg, Russia

OBJECTIVES / PARTNERSHIPS

BKG Germany Absolute

gravimetry

CU AustraliaWorld Gravity Map

Int. Geoid ServiceNewton’s Bulletin

International schools

NGA, USA World Gravity Map

French supporting organizations 13 Institutions & Universities

International collaborations (mostly within IAG/IGFS frame) some examples

BIPMAbsolute

gravimetry

Compilation, validation & long term archiving of gravimetric dataAims at facilitating the diffusion of gravity information to the scientific community

IAG Symposium on Terrestrial Gravimetry : Static and Mobile Measurements – September 1 7– 20, 2013 – St Petersburg, Russia

Global databases & products Relative & absolute gravity measurements

Gravity modeling Ex : World Gravity Map

Software developments Gravity analysis, modeling, terrain correction…

Field surveys Relative & Absolute (Europe, South America, Africa, Asia…)

Education / Summer schools Collab. With IGeS

IAG commission & working groups in gravimetry IGFS, GGOS, CCM-BIPM, etc.

Instrumentation Support from French teams for a future cold atom gravimeter (AQG by MuQuans)

MAIN ACTIVITIES

Focus here on main data & products recently provided by BGI

IAG Symposium on Terrestrial Gravimetry : Static and Mobile Measurements – September 1 7– 20, 2013 – St Petersburg, Russia

Relative land measurements(a few millions of data)

Relative marine measurements(> 10 millions of data)

Reference stationsIGSN71 / Potsdam networks(>4500 stations)

Absolute measurements(started in 2007)

OVERVIEW OF THE GLOBAL GRAVITY DATABASES

Consultation / Request from the BGI website http://bgi.obs-mip.fr

IAG Symposium on Terrestrial Gravimetry : Static and Mobile Measurements – September 1 7– 20, 2013 – St Petersburg, Russia

Motivation

Increasing number of AG instruments few µGal level measurements in lab & field

Need to register AG measurements and to share information globally

Scientific interest / Benefits

Reference network for relative gravity surveys & relative meter calibration

Support and registry for inter-comparisons of AG instruments

Study of static and temporal gravity changes / Link to other geophysical observations

New International Gravity Reference System (replacement of IGSN71)

Joint operation by BKG and BGI since 2007as a contribution to IAG / IGFS

ABSOLUTE GRAVITY DATABASE

IAG Symposium on Terrestrial Gravimetry : Static and Mobile Measurements – September 1 7– 20, 2013 – St Petersburg, Russia

Web-based user interface developed in 2008Available at 2 mirrored sites : BKG: http://agrav.bkg.bund.de/agrav-meta/

BGI : http://bgi.obs-mip.fr

Overview about stations, observation, epochs, gravimeters and institutions

Current status of the database - 08/2013768 stations / 2607 observations / 45 instruments / 41 institutions (24 countries)

ABSOLUTE GRAVITY DATABASE

Who measured ? Where and When ?

Provision of contact information

Sharing results (gravity values)

Data repository and long term availability

Upload of data done by users using their own ‘project’-files (ask for login)

IAG Symposium on Terrestrial Gravimetry : Static and Mobile Measurements – September 1 7– 20, 2013 – St Petersburg, Russia

ABSOLUTE GRAVITY DATABASE

New web application AGrav is under development at BKG

Improved functionalities New interactive map (OpenStreetMap) Clustering of stations Classification of available networks Plot of gravity time series Report generator Bibliographic references to related

publications …

Similar structure but new functionalities

(Wziontek et al., 2013, 17th International Symposium on Earth Tides, Warsaw, Poland)

IAG Symposium on Terrestrial Gravimetry : Static and Mobile Measurements – September 1 7– 20, 2013 – St Petersburg, Russia

ABSOLUTE GRAVITY DATABASE

Relation of AG and SC (GGP) stations

New web application AGrav is under development at BKG

(Wziontek et al., 2013, 17th International Symposium on Earth Tides, Warsaw, Poland)

IAG Symposium on Terrestrial Gravimetry : Static and Mobile Measurements – September 1 7– 20, 2013 – St Petersburg, Russia

ABSOLUTE GRAVITY DATABASE

Link to SG data (common sites) Data structure compatible to GGP Possibility of download SG time series Plots of SG/AG time series …

(Wziontek et al., 2013, 17th International Symposium on Earth Tides, Warsaw, Poland)

Expected to make better reliability between AG and SG observations

New web application AGrav is under development at BKG

IAG Symposium on Terrestrial Gravimetry : Static and Mobile Measurements – September 1 7– 20, 2013 – St Petersburg, Russia

Project initiated in 2008

Collaboration with the Commission for the Geological Map of the World (CGMW)

Initially aimed at providing worldwide Bouguer & Isostatic anomalies

Contribution to the global geological & geophysical mapsedited by CGMW / UNESCO for education and research purposes

(extensively used in geophysical interpretation but usually computed at regional scale)

Challenging project providing new global products

Based on rigorous and homogeneous computation of anomalies in spherical geometry

Including global high resolution terrain corrections (1 arc-minute)

Using up-to-date global models for gravity (EGM08, DTU10) and topography

WORLD GRAVITY MAP (WGM)

IAG Symposium on Terrestrial Gravimetry : Static and Mobile Measurements – September 1 7– 20, 2013 – St Petersburg, Russia

Proposed approach (analytic approach : Spherical Harmonic)

Computation of the whole terrain effect (Bouguer shell + Terrain Corrections)

Based on new developments by G. Balmino to perform SHA/SHS (up to d/o 32600)

See : Balmino et al. (Jounal of Geodesy, 2012)

Geodetic definition

High resolution computations (d/o 10800)

Realistic Earth model (all surface masses )

Continents

Oceans

Inner sears – Lakes

Ice caps

WORLD GRAVITY MAP (WGM)

IAG Symposium on Terrestrial Gravimetry : Static and Mobile Measurements – September 1 7– 20, 2013 – St Petersburg, Russia

Land b.s.l.Chott Algeria-TunisiaQattara (depression)Death ValleyNetherlands (part)Turfan (depression)

Closed seasAral seaCaspian seaDead sea

LakesBaikalBalkachBear lakeConstanceErieEyreHuronLadogaLemanMalawiMaracaiboMichiganOnegaSaltonSlavesSuperiorTanganykaTiberiadeTiticacaVictoriaWinnipegYssyk-Koul

Oceans

Ice capsOver GreenlandOver Antarctica

Lands

Ice shelvesRossRonne-Filchner,Larsen, Amery

Data sourcesETOPO1 (surface & bedrock)

SRTM30ILEC Data base

Densities (kg/m3)Crust (2670)Upper Mantle (3270)Ocean water (1027) Ice (917)

Surface masses taken into account(according to their position w.r.t. mean sea level)

WORLD GRAVITY MAP (WGM)

IAG Symposium on Terrestrial Gravimetry : Static and Mobile Measurements – September 1 7– 20, 2013 – St Petersburg, Russia

1’x1’ grid of spherical terrain corrections(applicable to any observed gravity field)

Computation of gravity contribution of surface masses (derived from ETOPO1)Lands / Oceans / Inland seas & major lakes / Ices (Antarctica, Greenland)

WORLD GRAVITY MAP (WGM)

IAG Symposium on Terrestrial Gravimetry : Static and Mobile Measurements – September 1 7– 20, 2013 – St Petersburg, Russia

Spherical complete Bouguer anomaly(based on EGM08 / DTU10 gravity models)

WORLD GRAVITY MAP (WGM)

IAG Symposium on Terrestrial Gravimetry : Static and Mobile Measurements – September 1 7– 20, 2013 – St Petersburg, Russia

Spherical complete isostatic anomaly (Airy-Heiskanen)(based on EGM08 / DTU10 gravity models)

WORLD GRAVITY MAP (WGM)

IAG Symposium on Terrestrial Gravimetry : Static and Mobile Measurements – September 1 7– 20, 2013 – St Petersburg, Russia

Free-air anomaly (Molodensky)(based on EGM08 / DTU10 gravity models)

WORLD GRAVITY MAP (WGM)

IAG Symposium on Terrestrial Gravimetry : Static and Mobile Measurements – September 1 7– 20, 2013 – St Petersburg, Russia

Free-air anomaly (Molodensky)(based on EGM08 / DTU10 gravity models)

WORLD GRAVITY MAP (WGM)

Version 1.0 (WGM2012) achieved in 2012

Bonvalot et al. (World Gravity Map, 2012) ; Balmino et al. (Jounal of Geodesy, 2012)

Set of 3 spherical anomalies (Bouguer, Isostatic, surface free-air)Distributed by CGMW / UNESCO : http://ccgm.free.fr

Digital grids of anomalies downloadable at 2’x2’ : http://bgi.obs-mip.fr

On-line tool for grid extraction and visualisation

Upgraded versions as soon as new EGM is available (including GOCE and new surface data)

IAG Symposium on Terrestrial Gravimetry : Static and Mobile Measurements – September 1 7– 20, 2013 – St Petersburg, Russia

WGM2012 gravity anomalies and global tectonic map (in progress)

OTHER WORK IN PROGRESS

Information derived from the global tectonic map Tectonic plates

Major geological units & ages (oceanic crust, continental crust)

Major faults (thrust, subduction, transform…)

Sedimentary basins, igneous and effusive rocks, etc…

IAG Symposium on Terrestrial Gravimetry : Static and Mobile Measurements – September 1 7– 20, 2013 – St Petersburg, Russia

WGM2012 gravity anomalies and global tectonic map (in progress)

OTHER WORK IN PROGRESS

Better interpretation / teaching of the Earth’s gravity anomalies at large scale

IAG Symposium on Terrestrial Gravimetry : Static and Mobile Measurements – September 1 7– 20, 2013 – St Petersburg, Russia

Interactive application for 3D view (based on NASA World Wind)

OTHER WORK IN PROGRESS

IAG Symposium on Terrestrial Gravimetry : Static and Mobile Measurements – September 1 7– 20, 2013 – St Petersburg, Russia

Interactive application for 3D view (based on NASA World Wind)

OTHER WORK IN PROGRESS

WGM2012 Complete Bouguer anomaly

IAG Symposium on Terrestrial Gravimetry : Static and Mobile Measurements – September 1 7– 20, 2013 – St Petersburg, Russia

Interactive application for 3D view (based on NASA World Wind)

OTHER WORK IN PROGRESS

WGM2012 free-air anomaly

IAG Symposium on Terrestrial Gravimetry : Static and Mobile Measurements – September 1 7– 20, 2013 – St Petersburg, Russia

Interactive application for 3D view (based on NASA World Wind)

OTHER WORK IN PROGRESS

WGM2012 complete Isostatic anomaly

IAG Symposium on Terrestrial Gravimetry : Static and Mobile Measurements – September 1 7– 20, 2013 – St Petersburg, Russia

Interactive application for 3D view (based on NASA World Wind)

OTHER WORK IN PROGRESS

IAG Symposium on Terrestrial Gravimetry : Static and Mobile Measurements – September 1 7– 20, 2013 – St Petersburg, Russia

OTHER WORK IN PROGRESS

Gravity anomalies and global tectonics (in progress)

Interactive application for 3D view (based on NASA World Wind)

IAG Symposium on Terrestrial Gravimetry : Static and Mobile Measurements – September 1 7– 20, 2013 – St Petersburg, Russia

RECENT ON-LINE TOOLS

Prediction of gravity at a given site theoretical & interpolated values

Requests for metrology purpose needing an estimation of the local gravity

IAG Symposium on Terrestrial Gravimetry : Static and Mobile Measurements – September 1 7– 20, 2013 – St Petersburg, Russia

On-line availability of « old » BGI Bulletins collection (1959-2002)

RECENT ON-LINE TOOLS

Achieved in August 2013 (contains internal matters + contributing papers)

IAG Symposium on Terrestrial Gravimetry : Static and Mobile Measurements – September 1 7– 20, 2013 – St Petersburg, Russia

CONCLUSIONS / PERSPECTIVES To provide relevant services to IAG scientific users

Global gravity database : Compilation / Re-processing of surface gravity data

Global / Regional gravity modeling : Including surface and GOCE data

Earth’s Reference Gravity System : Contribution to the realization of the future system

Active collaborations in progress within IGFS

BKG (Germany), IGeS (Italy), NGA (USA), DTU (Denmark), CU (Australia)…

Feel free to contact BGI !

[email protected]

BGI : http://bgi.obs-mip.fr

BKG: http://agrav.bkg.bund.de/agrav-meta

Information update from users is still very welcome !

With surface gravity observations (land & marine surveys) – Products from airborne surveys ?

With absolute gravity measurements (FG5, A10 or others)

With any software, documentation believed to be useful for other scientists

IAG Symposium on Terrestrial Gravimetry : Static and Mobile Measurements – September 1 7– 20, 2013 – St Petersburg, Russia