OF THE 14TH INT. SYMPOSIUM ON EARTH TIDES (ETS2000)
14th International Symposium on Earth Tides (ETS2000) was successfully
held in Mizusawa, Japan, during the period from August 28 to September
1, 2000. 137 participants from 21 countries reported fully on their
results of continuing researches on Earth tides and thus contributed
to the progress of further research of Earth and Planetary Tides.
Officers of the Commission
President of the IAG Commission V (Earth Tides) was elected by the
Council of IAG at the IUGG/IAG General Assembly held in Birmingham,
UK, in July 1999.Before the opening session of the ETS2000, the
President consulted opinion of the National Representatives of the
Commission on proposal to ask Jacques Hinderer and Olivier Francis to
continue their office until the next IUGG/IAG General Assembly to be
held in Sapporo, Japan, in July 2003, and obtained their approval.
the opening session of ETS2000, the Commission elected J. Hinderer as
Vice-President and Francis as Secretary without a dissenting voice.
Congratulation to Jacques Hinderer and Olivier Francis, and the best
wishes for their future work.
the ETC Homepage can be seen through the following address,
2nd ETC Medal
ETC steering committee decided to award the 2nd ETC Medal (ETC Medal
2000) to the late Prof. Hans-Georg Wenzel for his outstanding
contribution to international cooperation in earth tide research. His
contribution to gravity and Earth tides researches is so well known
through the papers more than 150. He is famous by development of a new
tidal potential catalogue, a worldwide synthetic gravity tides model,
and the Earth tides data processing package so called ETERNA. With
grateful appreciation for the numerous services rendered by Prof.
Hans-Georg Wenzel during his lifetime, all participants of ETS2000
paid one-minute's tribute to him with deepest sympathy. The ETC
awarded the 2nd ETC Medal to Ms Marion Wenzel at the Opening Session
of ETS2000 on August 28 2000 at Mizusawa, Japan.
ETC Working Groups
the opening session of ETS2000, chairpersons of following Working
Groups reported their activities,
Group 4 "Calibration of Gravimeters", (M.van Ruymbeke),
Group 5 "Global Gravity Monitoring", (B. Richter),
Group 6 "Earth Tides in Geodetic Space Techniques, (H. Schuh),
Group 7 "Analysis of Environmental data for the interpretation of
gravity measurements", (G. Jentzsch).
Earth Tide Commission thanks all members and chairpersons of WGs which
have been active during the last period, for their fruitful work.
accepted the conclusions of the reports of the Working Groups and
decided according to their wishes:
close Working Group 4 (Calibration of Gravimeters, Chairperson: M.van
close Working Group 5 (Global Gravity Monitoring, Chairperson: B.
extend for another 4 year term the activities of the Working Group 6
(Earth Tides in Geodetic Space Techniques) under the new
extend for another 4 year term the activities of the Working Group 7
(Analysis of Environmental data for the interpretation of gravity
measurements) under the new chairperson-ship.
create Working Group 8 on "Gravitational Physics" under the
chairperson-ship of Prof. Lalu Manshinha to tackle among others the
following scientific problems: The Problem of Aberration: Modern tidal
position catalogs assume that the true position of the tide causing
body is responsible for the tidal forces, rather than the apparent
position, as in optical astronomy. The problem may have consequences,
as it may imply relative velocities between the gravity and optical
signals. This is a case for experts in Celestial Mechanics and in
Earth Tides. The Gravitational Shielding:There is currently no
accepted theory of gravity that incorporates or predicts gravitational
shielding. The problem is possibly different from the absorption of
gravitational radiation by matter. The Earth Tide community should
think about, and search for, the consequences of shielding.
Directing Board of the International Center for Earth Tides (ICET)
ICET Directing Board (S.Takemoto (Chair), B.Ducarme, T.F.Baker,
D.Crossley, H.T.Hsu and O. Francis (Non-voting member)) met together
on August 29, 2000 at the Z-hall in Mizusawa. The main subject for
discussion was "Future activity of ICET and re-organization of
the IAG services". ICET-DB discussed on the GFFS (Gravity Field
and Figure of the Earth Service) proposed by Prof. F. Sanso, which is
a new Service including activities of BGI, IGeS and ICET.
of a restriction of time, ICET-DB could not draw a conclusion at
Mizusawa and decided to continue our discussion by E-mail. ICET-DB
will draw a conclusion not later than the end of October 2000.
RESOLUTIONS adopted by the Earth Tide Commission
Earth Tide Commission has adopted the following resolutions at the
closing session of the 14th International Symposium on Earth Tides,
August 28 - September 1, 2000, Mizusawa, Japan.
Recognizing the importance of the observation of tidal effects and of
the determination of tidal parameters by space geodetic techniques,
continue this observational effort;
compare the results obtained by different space geodetic techniques
between each other and with the results of ground based tidal
Recognizing the importance of the new international services on space
WG6 establishes or intensifies the cooperation with the analysis
coordinators of these international services concerning the tidal
Considering the new fields of tidal research in lunar and planetary
the tidal community should take an active part in space missions
related to lunar and planetary geodesy ;
a proper archiving of the data and metadata acquired during those
missions and normal access to the world-wide geodetic community.
Considering the increasing interest of the tidal community to lunar
and planetary researches
a session on tides on the planets should be included in the future
earth tides symposia.
Recognizing the importance of a global Earth coverage with
the study of weak geophysical signals,
the determination of the liquid core resonance parameters,
the study of the polar motion effects on gravity,
the intercomparison of the load vectors derived from recent ocean
the study of global and regional gravity changes to validate the
results of the dedicated satellite missions,
extend the GGP observation period for an additional 6 year period
starting July 2003, to maintain the existing sites and to encourage
the installation of new GGP stations especially in the Southern
hemisphere and in polar regions.
Recognizing the fact that presently the calibration of the
superconducting gravimeters participating to the world-wide GGP
project is not homogeneous
systematic calibration campaigns with absolute gravimeters should be
planned and realized before the end of the current GGP observation
period, through an international cooperative effort.
Recognizing the importance to keep in operation several calibration
techniques for gravimeters to allow a mutual accuracy control,
inertial calibration platforms and moving mass calibration devices
should continue to be developed or maintained besides more usual
calibration methods such as intercomparison with absolute or
well-calibrated relative instruments.
Recognizing the importance of environmental data for the
interpretation of tidal measurements the ETC recommends:
to record the following parameters:
The barometric pressure, temperature, precipitation, and ground water
level. The sampling rate for the recording of environmental parameters
should correspond to the sampling rate of the geodynamic data
observed. A sufficient resolution and accuracy of the measurements of
the environmental parameters should be granted.
Although the difficulties of monitoring soil moisture are recognized,
its is recommended to undertake efforts to realize a continuous
monitoring of this parameter.
The monitoring of wind is also recommended because wind might produce
short-period noise as well as long-period modulations.
to correct gravity data in long term studies for local (diameter 100
km), regional (diameter 2000 km), and global atmospheric pressure
signals as all three produce significant effects.
to develop correction models for gravity, tilt, and strain related to:
ground water table variations
snow, rain and soil moisture
stress resulting from temperature variations
Noting the importance for tidal measurements of accurate error
appreciating that such estimates can be made only if the power
spectral density of the noise is known
show noise spectra as Power Spectral Density expressed in unit 2/
On behalf of all participants of the 14th International Symposium on
Earth Tides, the ETC thanks the Japanese National Committee for
Geodesy, the Science Council of Japan, the Geodetic Society of Japan,
the National Astronomical Observatory of Japan, the City of Mizusawa
and the Iwate Prefecture for their generous support to the Symposium.
ETC thanks the Local Organising Committee : Masatsugu Ooe (Chairman),
Tadehiro Sato (Secretary) , Jiro Segawa (President of Geodetic Society
of Japan) and the staff, for their wonderful welcome and their many
efforts in making the 14th International Symposium on Earth Tides a
great scientific success.
IAG Travel Awards
following 5 persons are winners of IAG Travel Award.
Kopaev, (Moscow, Russia), Janusz Bogusz, (Warsaw, Poland), Carla
Braitenberg, (Trieste, Italy), Sun He-Ping (Wuhan, P.R. China), Zhigen
Yang (Shanghai, P.R. Chin)
Publication of the ETS2000
of scientific papers will be published as a special issue of the Jour.
Geod. Soc. Japan. Other Report on the ETS2000 including the list of
participants will be appeared in the next issue of BIM
the ETS2000, Canadian Colleagues (Profs. D. Smylie, L. Mansinha and S.
Pagiatakis) kindly offered to have the next (15th) International
Symposium on Earth Tides in Canada in 2004. The Earth Tide Commission
acknowledges the receipt of this invitation.