Subject: [IGSMAIL-6128]: Joint GGOS/IAU Science Workshop on Observing and Understanding Earth Rotation
From: "Gross, Richard S (335N)" <[email-masked]>
To: "[email-masked]" <[email-masked]>, "[email-masked]" <[email-masked]>, "[email-masked]" <[email-masked]>
Cc: "Gross, Richard S (335N)" <[email-masked]>
Date: Tue, 13 Apr 2010 16:59:16 -0700

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IGS Electronic Mail      13 Apr 16:59:37 PDT 2010      Message Number 6128
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Author: Richard Gross

Subject: Joint GGOS/IAU Science Workshop on Observing and Understanding Earth Rotation

Dear Colleagues -

The Global Geodetic Observing System (GGOS) of the International Association of Geodesy (IAG) and the International Astronomical Union (IAU) are jointly organizing a workshop on Observing and Understanding Earth Rotation that will be held in Shanghai, China during 25-28 October 2010. A description of the workshop is given below and more information about it can be obtained from the workshop web site at <http://GGOS-C19.shao.ac.cn/ >.

On behalf of the organizers I would like to invite you to participate in this workshop. We are developing a rich program that will cover all aspects of the Earth's rotation including theory, measurement, analysis, excitation, and integration with other geodetic measurements into a global geodetic observing system. I hope that you will be able to join us in Shanghai for this exciting workshop.

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Observing and Understanding Earth Rotation
A Joint GGOS/IAU Science Workshop

October 25b28, 2010
Shanghaio<China

The Earthbs rotation, encompassing both the rate of rotation and the location of the rotation axis with respect to the Earthbs crust, is not constant but changes on all observable time scales from subdaily to decadal and longer. The wide range of time scales on which the Earthbs rotation changes reflects the wide variety of processes that are causing it to change, including external tidal forces, surficial fluid processes involving the atmosphere, oceans, and hydrosphere, and internal processes acting both within the solid Earth itself and between the fluid core and the solid Earth. Knowing the rotational response of the Earth to these global-scale processes allows Earth rotation measurements to be used to study them.

Measurements of the Earthbs time varying rotation have been traditionally provided by optical astrometry and the space-geodetic techniques of satellite and lunar laser ranging (SLR and LLR), very long baseline interferometry (VLBI), global navigation satellite systems (GNSS), and Doppler orbitography and radio positioning integrated by satellite (DORIS). However, the launch of the GRACE twin gravity satellites in March 2002 and the densification of the global GNSS ground receiver network afford new opportunities for studying the Earthbs rotation. GRACE is directly observing the effect of mass redistribution on the Earthbs rotation, and the global network of GNSS ground receivers can be used to infer changes in the load acting on the Earthbs surface and its effect on the Earthbs rotation from observations of changes in the Earthbs shape. Combining independent observations of the Earthbs rotation, gravity, and shape will enable greater insight into the common processes causing them to change.

The Global Geodetic Observing System (GGOS) of the International Association of Geodesy (IAG) provides the geodetic infrastructure necessary for monitoring the Earth system, including changes in its rotation, gravity, and shape. This joint Science Workshop, organized by both GGOS and the  International Astronomical Union (IAU), on Observing and Understanding Earth Rotation will be a forum for assessing our current ability to observe the Earthbs time varying rotation, for assessing our current understanding of the causes of the observed variations, for assessing the consistency of Earth rotation observations with global gravity and shape observations, for exploring methods of combining Earth rotation, gravity, and shape observations to gain greater understanding of the mass load acting on the surface of the solid Earth, and for identifying improvements in the global geodetic observing system needed to further our understanding of the Earthbs variable rotation.

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