SECTION II:

“ADVANCED SPACE TECHNOLOGY”

http://geodesy.eng.ohio-state.edu/iag_sectionII

REPORT OF THE PRESIDENT FOR THE PERIOD 1999-2003

President: C.K. Shum (USA), ckshum@osu.edu

Secretary: Pascal Willis (France), pascal.willis@ensg.ign.fr

Summary

Section II, Advanced Space Technology of the International Association of Geodesy, is engaged in new space techniques for geodesy, geophysics, geodynamics, atmosphere, oceanography and other areas of Earth science studies. Its objectives include the participation and promotion of the research and applications using the modern space technologies for a wide variety of interdisciplinary studies in Earth and planetary sciences. Section II organizes Commissions and Special Commissions, Special Study Groups and various Services to fulfill its objectives. This report summarizes the progress for the four-year term (1999-2003) of Section II activities. Specifically, the progress include the following activities:

• Study of innovative space technology for Earth science research and applications, including SAR Interferometry, gravity field mission mapping sensors (gradiometer and satellite-to-satellite microwave tracking), GPS water level, GPS Navigational System (GNSS) atmosphere sounding, and precision orbit determination for LEOs using various tracking techniques
• Coordination of space geodetic techniques for geodesy and geodynamics, including intercomparison of analysis techniques for geodynamic studies, new studies for microwave tracking system including DORIS and interdisciplinary applications using multi-mission radar altimetry
• Promotion of studies to improve mean and time-varying gravity field using advanced gravity mission sensors, including CHAMP, GRACE and GOCE
• Promote and coordinate improved scientific community use of services including IGS, and newly organized services such ILS and IVS; possibility of an International DORIS Service (IDS) and an International Altimeter Service (IAS) have been studied
• Participated and help the transition of IAG components into the new structure, and support the creation of the IGOOS Project

Commission, Special Commissions, and Special Study Groups

The structure of Section II during 1999-2003 has been organized at the IUGG General Assembly in Birmingham in 1999. It consists of:

1. Commission VIII, International Coordination of Space Techniques for Geodesy and Geodynamics (CSTG), http://www.dgfi.badw.de/~cstg/, Chair: Hermann Drewes (Germany), Secretary: Wolfgang Bosch (Germany). The Final report of CSTG is on: http://geodesy.eng.ohio-state.edu/iag_sectionII/CSTGmid-termreport.htm.

Sub commissions are:

(i) Coordination and Combination of the Analysis in Space Geodesy, Chair: Tom Herring (USA), http://bowie.mit.edu/~tah/cstg_comb/.

(ii) Precise Satellite Microwave Systems, Chair: Pascal Willis (France).

(iii) Multi-mission Satellite Altimetry, Chair: Wolfgang Bosch (Germany), http://dgfi2.dgfi.badw-muenchen.de/cstg/SCOMMSA/.

(iv) Precise Orbit Determination for Low Earth Orbiting Satellites, Chair: Markus Rothacher (Germany), http://ww.iapg.bv.tum.de/cstg/index.html.

(v) Project on DORIS, Chair: Gilles Tavernier (France).

2. Special Commission VII, Satellite Gravity Field Missions, Chair: Karl-Heinz Ilk (Germany), Scientific Secretary: Jürgen Kusche (Germany), http://www.geod.uni-bonn.de/SC7/index.html. The Final report is on: http://www.geod.uni-bonn.de/SC7/index.html.

3. Special Study Groups. There are five Special Study Groups (SSG), two could be considered as continuation from the previous 4-year period, three SSGs are newly established. They are:

(i) SSG 2.162, Precise Orbits Using Multiple Space Techniques, Chair: Remko Scharoo (The Netherlands), http://www.deos.tudelft.nl/~remko/ssg2.162

(ii) SSG 2.183: Spaceborne Interferometry Techniques, Chair: Ramon Hanssen (The Netherlands), http://www.geo.tudelft.nl/fmr/research/insar/ssg/ssg2183.html

(iii) SSG 2.192: Spaceborne Atmospheric GNS Soundings, Chairs: Rob Kursinski (USA), Klemens Hocke (Germnay), http://www.gfz-potsdam.de/pb1/IAG/SSG_RO/SSG_RO.htm

(iv) SSG 2.193: Gravity Field Mission: Calibration and Validation, Chairs: Pieter N.A.M. Visser (The Netherlands), Christopher Jekeli (USA), http://www.deos.tudelft.nl/~pieter/IAG.SSG The Final report is on http://www.deos.tudelft.nl/~pieter/IAG.SSG/REPORTS/ReportSSG2.193_2000.htm.

4. SSG 2.194: GPS Water Level Measurements, Chairs: Gerry Mader (USA), Tilo Schone (Germany), Doug Martin (USA), http://op.gfz-potsdam.de/altimetry/SSG_buoys/index.html

5. Services. There are three Services under Section II:

(i) International GPS Service (IGS), Chair: Christopher Reigber, Director of the Central Bureau: Ruth Neilan, http://igscb.jpl.nasa.gov. The Final report is on http://geodesy.eng.ohio-state.edu/iag_sectionII/ruthiag.html.

(ii) International Laser Ranging Service (ILRS), Chair: John J. Degnan, Secretary: Mike Pearlman, Director of the ILRS Central Bureau: John M. Bosworth, http://ilrs.gsfc.nasa.gov. The Final report is on http://geodesy.eng.ohio-state.edu/iag_sectionII/ilrs.htm

(iii) International VLBI Service for Geodesy and Astrometry (IVS), Chair: Wolfgang Schlueter, Director of the Coordinating Center: Nancy Vandenberg, http://ivscc.gsfc.nasa.gov. The Final report is on http://geodesy.eng.ohio-state.edu/iag_sectionII/IVS-midterm.htm.

Progress

July 2000 marked the first satellite gravity mission launch in the decade, CHAMP, for the beginning of a series of spaceborne gravity measurement sensors, followed by GRACE launch in March 2002 and GOCE launch in 2006. For the first time ever, high-low GPS-LEO tracking, low-low LEO-LEO Doppler ranging, spacebrone gradiometer and with 3-axis accelerometers will be flown and represent new space technologies at the frontier of geodetic measurements. SAC-C (2000), CHAMP, GRACE and COSMIC (2005) represent new and abundant missions using GPS limb-sounding or occultation for measuring atmospheric water vapor (integrated water vapor and precipitable water vapor profiles). Together with ground based GPS, spaceborne GPS occultation measurements are beginning to have a major impact on space weather, meteorology and climate studies. Use of GPS on buoys for water level measurements represents another innovative use of GPS. GPS reflection or GPS altimeter measurements, which are being tested (e.g., using CHAMP), represents another new space technology to be potentially promising. Synthetic Aperture Radar interferometry (InSAR) is continuing to be studied as another cutting-edge space geodetic technology. Special Commission and SSGs under Section II have made progress in studying in each of these new space geodetic techniques. IGS has grown significantly during 1999-2003. New services now include IVS and ILRS. Potential new services such as the International DORIS Service (IDS) and the International Altimeter Service (IAS) are being considered. The near future challenges include the smooth integration of current Section II elements efficiently into the new IAG structure.

Conferences

During 1999-2003, Section II contributed to various scientific conferences including the following partial list:

• ION GPS/GNSS 2003, Portland, Oregon, USA, September 9-12, 2003.
• IUGG Symposia, Sapporo, Japan, June 30-July 11, 2003.
• GNSS 2003, Graz, Austria, 22-25 April, 2003.
• GNSS Workshop, Wuhan, China, November 6-8, 2002.
• Weikko A. Heiskanen Symposium In Geodesy: Celebrating 50 years in Geodetic Science at the Ohio State University, Ohio State University, Columbus, Ohio, USA, 1-5 October 2002.
• ION GPS 2002, Portland, Oregon, USA, September 24-27, 2002.
• International Workshop on Satellite Altimetry, Wuhan, China, September 8-13, 2002.
• Joint EGS-AGU-EGU General Assembly, Nice, France, April, 2002.
• American Geophysical Union Fall Meeting, San Francisco, California, USA, December 2002.
• American Geophysical Union Spring Meeting, Washington DC, USA, June 2002.
• 27th General Assembly of the EGS in Nice, France, April, 2002.
• ION GPS 2001, Salt Lake City, Utah, USA, September 11-14, 2001.
• American Geophysical Union Fall Meeting, San Francisco, California, USA, December 2001.
• IAG Scientific Assembly, Vistas for Geodesy in the New Millennium, Budapest, Hungary, September 2-7, 2001.
• American Geophysical Union Spring Meeting, Boston, Massachusetts, USA, June 2001.
• Fifth Symposium on Integrated Observing Systems, American Meteorological Society Symposium, Albuquerque, New Mexico January 15-19, 2001.
• 26th General Assembly of the EGS in Nice, France, March 25-30, 2001.
• GNSS-2001, Sevilla, Spain, 2001.
• American Geophysical Union Fall Meeting, San Francisco, California, USA, December, 2000.
• ERS-ENVISAT Symposium, Gothenbury, Sweden, October 2000.
• COSPAR Symposia, Taipei, Taiwan, Sept., 2000.
• 14 th International Symposium on Earth Tides, Mizusawa, Japan, August 8-Septemeber 1, 2000.
• IAG International Symposium on Gravity, Geoid, and Geodynamics 2000, July 31-August 4, Canada, 2000.
• COSPAR Symposia, Warsaw, Poland, July 16-23, 2000.
• IGARSS 2000, Honolulu, July 2000.
• Spring AGU Meeting, Washington D.C. May 30-June 3, 2000.
• ERIM 2000, Remote Sensing for Marine and Coastal Environments, Charleston, May 1-3, 2000.
• Pacific Islands Conference on Climate Change, Rarotonga, Cook Islands, April 2-7, 2000.
• 25th General Assembly of the EGS in Nice, France, April 24-29, 2000.
• ISRSE, Cape Town, 27-31 March 2000.
• 6th International Conference on Applications of High-Performance Computers in Engineering, 26-28 January, 2000, Maui, Hawaii, 2000.
• American Geophysical Union Spring meeting, Washington, USA, 2000.
• TOPEX/POSEIDON/Jason-1 Science Working Team Meeting, Miami, USA, 2000.
• ION GPS 2000, Salt Lake City, Utah, USA, 2000.
• Sixth International Symposium on Land Subsidence,volume CNR, 2000.
• Fall AGU Meeting, San Francisco, December 13-17, 1999.
• Second International Workshop on ERS SAR Interferometry, `FRINGE99', Belgium, 10-12 Nov 1999.
• TOPEX side B altimeter calibration campaigns, Jason SWT Meeting, St. Raphael, France, October 25-27, 1999.
• EGS' First Vening Meinesz Conference on Global and Regional Sea-Level Changes and the Hydrological Cycle, Loiri-Porto San Paolo, Sardinia, Italy, October 4-7, 1999.
• GPS99 meeting, Tsukuba, Japan, October, 1999.
• IUGG Symposia, Birmingham, UK, July, 1999.
• EGS 24th General Assembly, The Hague, The Netherlands, April 1999.
• ALT-B Calibration Workshop, Goddard Space Flight Center, Greenbelt, Maryland, USA, 1999.
• The Ocean Observing System for Climate, OCEANOBS 99, St Raphael, France, 1999.

Conclusions

On the eve of the evolution of the IAG structure, Section II would be in its last 4-year term under the current organization. While mathematics and technology may considered by many as the foundation of Geodesy, the new IAG structure would reflect the prominence of applications and services in terms of Commissions (Reference Frame, Gravity Field, Earth Rotation and Geodynamics, and Positioning and Applications). It is envisioned that the development and studies of space technologies, while no long would be at the highest level of the IAG new structure, would and should still be playing a critical part in its evolved role to continue to contribute as one of the foundations of contemporary geodesy.