Monday - November 18
Combination Strategies and Issues for TRF / CRF / EOPs
Part1: Combination of station coordinates, velocities, local ties, datum definition, non-linear motion, ... (Altamimi / Boucher / Drewes / Ferland ) Summary: The main focus of this session is to review the current status of the combination of station positions and velocities with an emphasis on the modelling, strategies and datum definition. A particular attention will be given to the current achievement, underlying accuracy level, weaknesses and limitation factors inherent to individual techniques as well as the distribution and quality of collocation sites. Goals and recommendations for future improvements will be discussed. Draft program: | |
| 10:30 | Position Paper (Z. Altamimi, IGN) |
| 10:50 | ITRF WG status/views (K. Larson, Colorado Univ., presented by J. Ray) |
| 11:00 | ITRS-PC status/views (C. Boucher, IGN, presented by Z. Altamimi) |
| 11:10 | Remarks on some general problems in the combination of station coordinate and velocity solutions (H. Drewes, DGFI) |
| 11:20 | TRF combination at NRCan; Status report (R. Ferland, NRC) |
| 11:30 | Discussion |
Part 2: Celestial reference frame issues (Souchay / Ma) Summary: Draft program: | |
| 13:30 | Introduction on the Position paper (J. Souchay) |
| 13:40 | The status of the ICRF (C. Ma) |
| 13:55 | Internal consistency of the celestial reference frame based on time stability (M. Feissel-Vernier) |
| 14:10 | Discussion |
Part 3: Combination / comparison of EOPs (xp, yp, UT1/LOD, nutation), subdaily EOPs, impact of IAU Resolutions (Gambis / Vondrak) Summary: The objective of the session is twofold: first to present the impacts of the IAU Resolutions on IERS products, and in particular those concerning the Earth Orientation Parameters (EOP) and secondly to review the variety of current methods used for combining Earth Orientation Parameters time series (Polar motion, Universal Time and precession-nutation). The different Earth Orientation Parameters (EOP) series obtained by the individual techniques are inhomogeneous in their temporal length, quality, temporal resolutio; this fact supports the concept of equally spaced combined solutions benefitting from the individual contributions at the various time scales. Keywords concerning the critical points of combination procedures include separation of signal/noise, weighting, smoothing, error propagation due to interpolation, detection of outliers, etc.. The limiting factors of the accuracy of combined solutions will be discussed. Draft program: | |
| 14:20 | Position Paper (D. Gambis, J. Vondrak) EOP Combinations: |
| 14:35 | D. Gambis, EOP-PC |
| 14:50 | T. Johnson, Rapid/Prediction Service |
| 15:05 | R. Gross, JPL |
| 15:15 | J. Vondrak, AICAS |
| 15:25 | Discussion |
Part 4: EOP Alignment Campaign, IGS / IVS / ILRS combinations, systematic errors (Nothnagel / Dill) Summary: The session is devoted to EOP combinations with special emphasis on EOP derived on the basis of ITRF2000 station coordinates and velocities. While the IERS EOP Alignment Campaign endeavours to compare EOP series across space geodetic techniques, the services (IDS, IGS, ILRS, IVS) carry out technique related comparisons and combinations. Draft program: | |
| 16:15 | Introduction to session (A. Nothnagel, R. Dill) |
| 16:20 | Comparisons of IGS EOP series contributed to IERS Alignment Campaign (R. Ferland) |
| 16:35 | EOP Combination within IVS: Status and Problems (A. Nothnagel and C. Steinforth) |
| 16:50 | Comparison of EOP series from the IERS analysis campaign to align EOPs to the ITRF2000/ICRF (R. Dill) |
| 17:05 | Evolution of consistency between EOP series and reference frames (D. Gambis, C. Bizouard, T. Carlucci) |
| 17:20 | Discussion |
Tuesday - November 19
Issues of a Rigorous Combination (Coordinates + EOPs (+CRF), and Other Parameter Types)
Part 1: Conventions and models for a rigorous combination, consistency aspects, systematic errors, ... (McCarthy / Petit) Summary: Draft program: | |
| 09:00 | Status and Future of the IERS Conventions (D.D. McCarthy, G. Petit) |
| 09:15 | Impact of IAU Resolutions on EOPs (N. Capitaine) |
| 09:35 | Discussion |
Part 2: Aspects of a rigorous combination, combination of several parameter types, different combination levels (Ray / Zhu) Summary: We survey the current status of product combinations within the IERS, noting some weaknesses and limitations of each. A general feature is that the IERS products are not formed rigorously or self-consistently across the service. This leads to inaccuracies that are in some cases greater than the inherent errors of the observing techniques, unnecessarily limiting the usefulness of the products and obscuring our understanding of important systematic errors which should be addressed. The IGGOS concept of an integrated, comprehensive, global geodetic observing system provides an ambitious objective which the IERS should embrace to better serve users. Doing so will require new approaches to combined product formation, not just in terms of methodology but also in terms of cooperation among the observing techniques and IERS components. We offer a roadmap of proposed actions which are intended to provoke discuss and stimulate change towards the IGGOS goals. Draft program: | |
| 10:30 | Position Paper and discussion (Jim Ray, NGS) |
| 11:00 | Combination of multi-satellite techniques at the observation level (Sheng-Yuan Zhu, GFZ) |
| 11:15 | Program and first results at GRGS in the framework of CRC (Richard Biancale, GRGS) |
| 11:30 | Systematic differences in individiual solutions and IERS products (Zinovy Malkin, IAA) |
| 11:45 | Numerical aspects of combination at the observation equation and normal equation level (Michael Gerstl, DGFI) |
Part 3: SINEX Combination Campaign (Angermann / Thaller / Rothacher) Summary: This session focusses on the combination of daily, weekly or monthly solutions from the SINEX files of different space geodetic techniques (VLBI, SLR, GPS, DORIS, ...) with station coordinates and EOPs (and ICRF) as parameters. The time table and present status of the SINEX Combination Campaign as well as the available data pool and a summary of proposals can be seen at http://tau.fesg.tu-muenchen.de/~iers/. Objectives are the analysis of the individual solutions (and normal equations) regarding possible datum constraints, rang defects, etc. and the assessment of systematic biases between the different techniques. Primary goal is the development of new combination strategies and standards for common modeling and parameterization to provide highly accurate and consistent combined results. Draft program: | |
| 13:30 | Presentation of Position Paper (D. Angermann, D. Thaller) |
| 14:00 | Multi-technique combination of time series of station positions and Earth orientation parameters |
| 14:15 | Combination of loosely constrained solutions (G. Bianco, R. Devoti, V. Luceri) |
| 14:30 | First Results at NRCan for the IERS SINEX Combination Campaign (R. Ferland) |
| 14:45 | Rang defect analysis and variance component estimation for inter-technique combination (R. Kelm) |
| 15:00 | Discussion |
Wednesday - November 20
Global Geophysical Fluids (Part 1)
GGFC Overview (Chao) Summary: | |
Special Bureau for the Atmosphere (Salstein) Summary: The atmosphere has been shown to play an important role in the excitation of Earth rotation including length of day variations and polar motion on a broad range of time scales that involve forcing by weather and climate. A catalogue of such signals can include subdaily, weekly weather patterns, subseasonal fluctuations, semiannual and annual, interannual, (e.g., stratospheric quasi-biennial and El Nino), and decadal. Both the motion of the winds and the mass fluctuations, estimated from atmospheric surface pressures impact the Earth orientation parameters. To better understand the mechanisms of the dynamic interaction between atmosphere and the solid earth, torques, largely related to pressure and winds near the surface, as well as varying mass distribution, are being investigated, though their formulation in atmospheric models and data assimilation systems may not be straightforward. Mechanisms that force the free, Chandler, polar motion mode are being sought as well. The atmospheric mass distribution also impacts the overall changing planetary gravitational signature, as well as loads the crust affecting vertical reference coordinates. The atmosphere physically interacts with the ocean, combining with it to cause the excitations of the fluid envelope. Draft program: (* = presenter) | |
| 09:15 | Update of the SBA (D. Salstein) |
| 09:30 | Atmospheric loading effects on Earth's time-variable gravity (J.-P. Boy and B.F. Chao*) |
| 09:45 | Reliability of atmospheric torque for geodesy (O. de Viron* and V. Dehant) |
| 10:00 | Atmospheric excitations of the Chandler wobble estimated from ECMWF reanalysis datasets (I. Naito, Y. Aoyama*, T. Iwabuchi and N. Yamazaki) |
| 10:15 | Time variable atmospheric and oceanic signals in excitation functions of polar motion (J. Nastula*, D. Salstein, and B. Kolaczek) |
| 10:30 | Discussion |
Special Bureau for the Oceans (Gross) Summary: The oceans have a major impact on Earth rotation dynamics and terrestrial reference frame definition. Nontidal changes in oceanic currents and bottom pressure have been shown to be a major source of polar motion excitation and also measurably change the length of the day. The changing mass distribution of the oceans causes the Earth's gravitational field to change and causes the center-of-mass of the oceans to change which in turn causes the center-of-mass of the solid Earth to change. The changing mass distribution of the oceans also changes the load on the oceanic crust, thereby affecting both the vertical and horizontal position of observing stations located near the oceans. Such effects of the oceans on the Earth's rotation, gravitational field, and station locations will be discussed in this session. Draft program: (* = presenter) | |
| 11:15 | Comparison of Oceanographic Signals with SLR-Derived Gravity Observations (C. Cox* and B.F. Chao) |
| 11:30 | Oceanic Excitation of Polar Motion and Nutation: An Overview (A. Brzezinski) |
| 11:45 | Possible Role of Oceans in Variations of Lenght-of-Day at High Frequencies (T. Johnson) |
| 12:00 | The IERS Special Bureau for the Oceans: Past Progress and Future Plans (R. Gross) |
| 12:15 | Discussion |
Special Bureau for Hydrology (Wilson) Summary: Variations in the load of water on the land surface are poorly known, yet are important in changing earth's rotation, both polar motion and length of day. In addition, the variable load of water affects station positions, the geocenter, and the gravity field. Water loads on land are likely to dominate at long periods because water can be stored permanently in ground water, ice, and other reservoirs. Other geophysical fluids, such as the load of the atmosphere cannot accumulate permanently in the same way. The session will review the state of land surface hydrology models and the data sets available on the Hydrology Bureau website at present. There will be also discussions of forthcoming models and remote sensing capabilities. Draft program: (* = presenter) | |
| 13:45 | SBH goals and the SBH Website (C.R. Wilson) |
| 13:55 | New directions and capabilities in hydrologic land surface models (M. Rodell via C.R. Wilson*) |
| 14:05 | Future plans for satellite remote sensing capabilities of the hydrologic cylce (D.E. Alsdorf via C.R. Wilson*) |
| 14:15 | Using space geodesy to constrain global loads (P. Clarke) |
| 14:30 | Recent hydrology studies at GSFC (B.F. Chao* and A.Y. Au) |
| 14:45 | Discussion |
Special Bureau for Gravity / Geocentre (Watkins / Gruber) Summary: Draft program: (* = presenter) | |
| 15:00 | SBGG status and prospects (M. Watkins via T. Gruber*) |
| 15:15 | Using future observations for time-variable gravity work (T. Gruber) |
| 15:30 | Recent SLR results (C. Cox* and B.F. Chao) |
| 15:45 | Short-time atmosphere and ocean de-aliasing for GRACE (F. Flechtner) |
| 16:00 | Discussion |
Special Bureau for Tides (Richard Ray) Summary: Tidal variations in Earth rotation have been detected for all major tides, long-period, diurnal, and semidiurnal. The Special Bureau for Tides collects model data relevant for predicting these variations. The session will highlight recent advances and some outstanding issues for the Bureau, including how it should interact with other bureaus. Also to be discussed are recent advances in understanding torque mechanisms between fluid tides and the solid earth and in modeling nutations. Tides and nutations are intimately related, and progress in one should advance the other. Draft program: (* = presenter) | |
| 16:45 | Overview of SBT, issues and plans (R. Ray) |
| 17:15 | Recent work on theoretical modeling of nutation (J.M. Ferrandiz Leal) |
| 17:30 | Oceanic tidal torque on the solid earth (O. de Viron*, J.-P. Boy) |
| 17:45 | Discussion |
Thursday - November 21
Global Geophysical Fluids (Part 2)
Special Bureau for Mantle (Chao) Summary: The solid, non-rigid mantle is perpetually in motion. There are motions caused by external forces, including tidal deformation, atmospheric and hydrospheric loading, and occasional meteorite impacts. For internal processes, volcanic eruptions and pre-seismic, coseismic and post-seismic dislocations associated with an earthquake act on short timescales. On longer timescales, present-day post-glacial rebound, surface processes of soil erosion and deposition, and tectonic activity such as plate motion, orogeny, and internal mantle convection, all transport large masses over long distances. As with any geophysical processes that involve mass transports, these large-scale motions produce variations in Earth's rotation, gravity field, and geocenter. Among them, the Special Bureau for Mantle currently presents three topics that have seen considerable investigation and modeling: co-seismic excitation of Earth rotational and gravitational changes, the glacial isostatic adjustment, and mantle convection influences on Earth's true polar wonder. Draft program: (* = presenter) | |
| 08:45 | SB Mantle status and plan (B.F. Chao) |
| 09:00 | On the secular drift component of global Earth deformation (E. Ivins) |
| 09:15 | Co-seismic Excitation of Earth Rotational and Gravitational Changes (B.F. Chao* and R. Gross) |
| 09:30 | Geophysical Inverse Solutions Using Long-Term SLR-Derived Gravity Rates (C. Cox* and B.F. Chao) |
| 09:45 | Discussion |
Special Bureau for the Core (Van Hoolst) Summary: Flow in the fluid outer core, and also motion of the inner core with respect to the outer core and mantle, can result in various geodetic phenomena observable from the Earth's surface or space. The core has been recognized as the major component in explaining the variations of the length of day at decadal time scales since it was shown that the time-variations of parameters describing the geomagnetic field are correlated with the decadal length-of-day variations. The core also influences nutation and polar motion, through coupling torques between the inner core, outer core and mantle, and mass redistributions within the core can cause surface gravity changes, geocenter variations, and surface deformations. Such topics, along with the geodynamo and the topography of the core, will be discussed in this session. Draft program: (* = presenter) | |
| 10:30 | SBC overview (T. Van Hoolst) |
| 10:50 | Core mantle interactions (V. Dehant*, D. Jault, S. Ponsar, T. Van Hoolst) |
| 11:10 | Geodynamo modeling, core-mantle interactions, and Earth rotation variations (W. Kuang) |
| 11:30 | Discussion |
Special Bureau for Loading (Van Dam / Plag) Summary: The rapidly increasing accuracy of space-geodetic observation techniques allows to measure displacements of the Earth surface resulting from surface loads on different spatial and temporal scales. On the one hand, these observations offer the opportunity to validate the geophysical models describing deformations induced by various surface loads, including those due to ocean tides, the atmosphere, and groundwater. On the other hand, in order to improve the results of space geodetic analyses, increasingly complex geophysical models of station motion are required (as emphasised, e.g., in the IERS Conventions). The main purpose of the International Earth Rotation Service (IERS) Special Bureau for Loading (SBL) is to provide reliable, consistent model predictions of loading signals, that have been thoroughly tested and validated. The products will describe at least the surface deformation, gravity signal and geo-centre variations due to the various surface loading processes in reference frames relevant for direct comparison with existing geodetic observing techniques. To achieve these goals, major scientific advances are required with respect to the Earth model, the theory and algorithms used to model deformations of the Earth as well as improvements in the observational data related to surface loading. Draft program: | |
| 13:00 | SBL Introduction (T. van Dam) |
| 13:05 | Status of loading predictions (Earth Model, Model Surface Loads, Theory, Numerical Tools) (P. Gegout) |
| 13:25 | Products of the SBL (Predictions, Research Products, Operational Products (H.-P. Plag) |
| 13:40 | Validation of loading predictions (Intercomparison, comparison with observations) (T. van Dam) |
| 14:00 | Discussion |
Interactions and support (various, all)
IERS Product Centres -- GGFC, CRC-GGFC ( Chao / Rothacher / Zhu )
