************************************************************************ IERS Message No. 266 January 21, 2015 ************************************************************************ IAG Symposium on Earth Rotation and Geodynamics at IUGG General Assembly Dear Colleagues - As part of the 26th IUGG General Assembly that will be held in Prague, Czech Republic during June 22 to July 2, 2015 there will be an IAG Symposium on Earth Rotation and Geodynamics. The description of the Symposium is given below. On behalf of the conveners I would like to draw your attention to this Symposium and encourage you to participate in it. Besides the regular sessions of the IAG Commission 3 Symposium on Earth Rotation and Geodynamics there will also be special sessions relating to Sub-Commission 3.5 on Tectonics and Earthquake Geodesy (WEGENER) and to Joint Study Group (JSG) 3.1 on Gravity and Height Change Intercomparison. A description of the JSG 3.1 special session is given below. If you would like to submit an abstract to one of the special sessions, please submit it to the Symposium but let one of the conveners know that you would like to present it in one of the special sessions. Otherwise your abstract will be considered for presentation in one of the regular sessions of the Symposium. We hope that you will be able to join us in Prague for the IAG Commission 3 Symposium and special sessions. More information about the IUGG General Assembly 2015 can be obtained from its web site at . Please note that the deadline for submitting abstracts is 31 January 2015. Hope to see you in Prague! Best regards, Richard Gross ........................................................................ G04 Earth Rotation and Geodynamics Convener: Richard Gross (Pasadena, USA), richard.s.gross [at] jpl.nasa.gov Co-conveners: Aleksander Brzezinski (Warsaw, Poland), Manabu Hashimoto (Kyoto, Japan), Matt King (Tasmania, Australia), Haluk Ozener (Istanbul, Turkey), Maik Thomas (Potsdam, Germany) Description The Earth is a dynamic system: it has a fluid, mobile atmosphere and oceans, a continually changing global distribution of ice, snow, and water, a fluid core that is undergoing some type of hydromagnetic motion, a mantle both thermally convecting and rebounding from the glacial loading of the last ice age, and mobile tectonic plates. In addition, external forces due to the gravitational attraction of the Sun, Moon, and planets act upon the Earth. These internal dynamical processes and external gravitational forces exert torques on the solid Earth, or displace its mass, thereby causing the Earth's rotation, gravitational field, and shape to change. Geodetic observing systems, both space-based and ground-based, provide the measurements of the Earth's rotation, gravitational field, and shape that are used to study the response of the Earth to these dynamical forces. This symposium will be a forum for discussing the theory, modeling, and observations of these geodynamical processes and their effect on the Earth's rotation. In particular, contributions are solicited on tidal phenomena; on global and regional crustal deformation including intraplate deformation, the earthquake deformation cycle, aseismic phenomena such as episodic tremor and slip, and volcanic deformation; on loading effects associated with the space-time variation of atmospheric pressure, seafloor pressure, and the hydrological cycle; on the Earth's instantaneous and delayed responses to ice mass changes; and on the integration of space and terrestrial approaches for studying the kinematics and mechanics of tectonic plate boundary zones, and in particular of the Eurasian/African/Arabian boundary zone. Contributions on the theory, modeling, and observations of the Earth's rotation itself are also sought. ........................................................................ JSG 3.1 Special Session Comparison of Ground and Space Gravity with Surface Displacement Measurements Surface deformations are continuously recorded from space or from the ground with increasing accuracy. Vertical displacements and temporal variations of gravity are representative of various deformation mechanisms of the Earth occurring at different spatial and temporal scales. We can quote for instance post-glacial rebound, tidal deformation, hydrologic loading, co-seismic deformation and volcanic deformation. The involved time scales range from seconds to years and the space scales range from millimeters to continental dimension. Large-scale deformations are well monitored by space geodetic measurements from monthly spatially-averaged GRACE measurements while local deformations are precisely monitored by daily GPS solution and sub-daily gravimeter data at a site. Issues that arise when comparing site displacements with gravity measurements are differences in spatial and temporal scales and differences in sensitivity. This session encourages works related to the development and application of standardized procedure and tools to compare surface gravity measurement with space gravity field (e.g. empirical orthogonal functions, wavelets). Theoretical understanding and analysis of the Earth's deformational response to various geophysical processes in relation with its rheology (tidal deformation, co-seismic deformation, volcanic deformation, hydrological loading and ice melting ...) are encouraged. The inter-comparison of the space- and ground-gravity measurements with vertical surface displacements enable to infer more information on the structure, dynamics and evolution of the Earth system, particularly, on the rheological properties of the Earth. ************************************************************************ IERS Messages are edited and distributed by the IERS Central Bureau. If not stated otherwise, the IERS is only the distributor of the message and is not responsible for its content. To submit texts for distribution and to subscribe or unsubscribe, please write to . Archives: http://www.iers.org/Messages/ ************************************************************************