Journal of Geodesy (2001) 75: 234±240

IAG Newsletter Ole Baltazar Andersen IAG Central Bureau, Department of Geophysics, Juliane Maries vej 30, DK-2100 Copenhagen é, Denmark e-mail: [email protected]; Fax: +45 3536 5357; URL: http://www.gfy.ku.dk/iag/

The IAG Newsletter is under the editorial responsibility of the IAG Central Bureau. It is an open forum and contributors are welcome to send material (preferably in electronic form) to the IAG Central Bureau. These contributions should complement information sent by IAG ocials or by IAG symposia organizers (reports and announcements). Each IAG Newsletter includes several of the following topics: I. general information II. reports of IAG symposia III. reports by commissions, special commissions or study groups IV. symposia announcements V. book reviews VI. fast bibliography Meeting Announcements IAG Scienti®c Assembly Budapest, Hungary 3±7 September, 2001 Second and third circular and information: http://www.sztaki.hu/conferences/iag2001 Int. Symp. on Recent Crustal Movements (SRCM), Helsinki, Finland, 27±31.8.2001 Website: http://www.fgi.®/SRCM/ Books for review are the responsibility of: Christian Tiberius TU Delft, Faculty of CEG Dept. of Mathematical geodesy and positioning P.O. Box 5030 NL 2600 GA Delft The Netherlands Fax: (+31) 15 27 83 711 e-mail: [email protected]

Meeting Reports IAG/IAPSO Joint Working Group on Geodetic E€ects of Nontidal Oceanic Processes Meeting held on March 29, 2001 in Nice, France in conjunction with the XXVI General Assembly of the European Geophysical Society (EGS) during which presentations were given by R. Gross, T. Sato, B. Chao, and A. Brzezinski. The oceans have a major impact on global geophysical processes of the Earth. Nontidal changes in oceanic currents and ocean-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 ®eld to change and causes the center-ofmass 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 a€ecting both the vertical and horizontal position of observing stations located near the oceans. Recognizing the important role that nontidal oceanic processes play in Earth rotation dynamics, an IAG/ IAPSO Joint Working Group on Geodetic E€ects of Nontidal Oceanic Processes was formed at the XXII General Assembly of the IUGG in Birmingham. The objective of this IAG/IAPSO Joint Working Group is to investigate the e€ects of nontidal oceanic processes on the Earths rotation, deformation, gravitational ®eld, and geocenter, and to foster interactions between the geodetic and oceanographic communities in order to promote greater understanding of these e€ects. R. Gross described the International Earth Rotation Service (IERS) Special Bureau for the Oceans (SBO). The IERS Special Bureau for the Oceans is one of seven Special Bureaus of the IERS Global Geophysical Fluids Center (GGFC) which was established on January 1, 1998 in order to help relate dynamical properties of the

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atmosphere, oceans, mantle, and core to motions of the Earth, including its rotation. In particular, the IERS Special Bureau for the Oceans is responsible for collecting, calculating, analyzing, archiving, and distributing data relating to nontidal changes in oceanic processes a€ecting the Earth's rotation, deformation, gravitational ®eld, and geocenter. The oceanic products available through the IERS SBO are produced primarily by general circulation models of the oceans that are operated by participating modeling groups and include oceanic angular momentum, center-of-mass, bottom pressure, and torques. Through the IERS SBO web site at http://euler.jpl.nasa.gov/sbo, oceanic data can be downloaded and a bibliography of publications pertaining to the e€ect of the oceans on the solid Earth can be obtained. Currently, two di€erent oceanic angular momentum data sets are available. The IERS SBO is one possible source of data that can be used by the IAG/IAPSO Joint Working Group in their investigations on the geodetic e€ects of nontidal oceanic processes. T. Sato discussed the e€ect of sea surface height variations on superconducting gravimeter measurements. Good agreement with gravity measurements at 3 di€erent sites were obtained using results from both an ocean model and from TOPEX/POSEIDON measurements which had been corrected for the steric changes in sea surface height that have no gravitational signature. This study of the results of gravity observations clearly shows that gravity measurements from satellites and on the ground have an important role to play when studying the e€ects of oceanic variability on the local and global geophysical processes of the Earth. He then presented plans for deploying ocean- bottom pressure recorders o€ the coast of Japan at TOPEX and Jason-1 crossover points. As the mission scientist for the GRACE Mission Oce, B. Chao discussed the use of oceanic general circulation models to dealias GRACE gravitational ®eld measurements. The GRACE project is currently planning on producing gravitational ®eld solutions at monthly intervals. Since the distribution of mass within the oceans changes more rapidly than this, the gravitational e€ect of this rapid oceanic mass movement will be aliased in the monthly solutions unless it is modeled and removed from the GRACE measurements. A barotropic, or perhaps a baroclinic, ocean model driven by either NCEP or ECMWF surface winds and ¯uxes will likely be operated by the GRACE project in order to model and remove the high frequency variations in oceanic mass distribution that will not be sampled by the GRACE monthly gravitational ®eld solutions. Since this scheme will most likely not be able to perfectly remove the aliased signals, the user community should be cognizant of the uncertainties that will be introduced by this procedure. Similar aliasing e€ects are also expected to occur due to rapid atmospheric, hydrologic, and ocean-tidal mass movement, and the GRACE project is also planning to use

atmospheric and ocean tide models to similarly remove these e€ects. A. Brzezinski summarized the results on the oceanic excitation of the Chandler wobble that he and J. Nastula presented at the 33rd COSPAR Scienti®c Assembly held in Warsaw, Poland during July 16±23, 2000 (to appear in Advances in Space Research). Using the POLE98 polar motion series, the NCEP/NCAR reanalysis atmospheric angular momentum series obtained from the IERS Special Bureau for the Atmosphere, and the 11-yearlong oceanic angular momentum (OAM) series of Ponte et al. (J. Geophys. Res., vol. 104, pp. 23393±23409, 1999) obtained from the IERS SBO, they demonstrated that the OAM series is highly coherent with the lacking non-atmospheric excitation of the observed Chandler wobble signal. In terms of the excitation power, the combined e€ect of the atmosphere and ocean explains about 80% of the free wobble, which agrees to within 1sigma uncertainty with the result recently published by R. Gross (Geophys. Res. Lett., vol. 27, pp. 2329±2332, 2000). The next meeting is scheduled to be held in conjunction with the XXVII General Assembly of the EGS that will be held in Nice, France during April 22±26, 2002. The exact date and time of this meeting will be announced later. In order to receive announcements of this and all future meetings, please contact Richard Gross at [email protected]. R. Gross First International Symposium on Robust Statistics and Fuzzy Techniques in Geodesy and GIS, Zurich, Switzerland, March 12±16, 2001 The `First International Symposium on Robust Statistics and Fuzzy Techniques in Geodesy and GIS' took place at the Swiss Federal Institute of Technology (ETH) in Zurich, Switzerland, from March 12±16, 2001. It was initiated by the members of the Special Study Group (SSG) 4.190 of the International Association of Geodesy (IAG) on `Non-probabilistic assessment in geodetic data analysis'. It was organized by Prof. A. Carosio, ETH Zurich., and Dr. H. Kutterer, DGFI Munich, chairman of the SSG. Nearly 60 participants from 15 countries attended the symposium. The program of the meeting consisted of applications of robust statistics and fuzzy theory, mainly in the ®elds of geodetic engineering, deformation analysis, geographic information systems, satellite-based positioning (GPS), and photogrammetry. Therefore ®ve technical sessions and a panel discussion were organized. In advance, two tutorials were given on robust statistics (A. Carosio) and on fuzzy logic (H. Kutterer, S. SchoÈn) on monday, March 12. The symposium was opened on tuesday, March 13, with a welcome address by Prof. B. Heck, University of Karlsruhe, president of the IAG section IV. Two invited lectures followed. The ®rst one was presented by Prof.

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F. Hampel, ETH Zurich, who considered both the historical development of robust statistics and recent mathematical problems. The second one was given by Prof. R. Viertl, Technical University of Vienna, who motivated the non-precision approach and showed the application of statistical methods to non-precise data based on the extension principle of fuzzy theory. H. Kutterer gave the last lecture in this session on a general viewpoint of uncertainty assessment. In the technical session on geodetic engineering four talks were focussed on robust statistics: kinematic positioning (Y. Yang), the BIBER estimator (F. Wicki), and the reliability of robust estimators (M. Berber, S. Hekimoglu). One talk considered the use of interval mathematics for the measurement uncertainties (S. SchoÈn). L. Soukup discussed `least squares without minimization'. The second technical session on deformation analysis showed a variety of di€erent assessment methods: a conic ®tting algorithm (O. Akyilmaz), inference on deformation measures like strain tensors (J. Cai), fuzzy deformation analysis (K. Heine), Plucker coordinates (R. Jurisch), arti®cial neural networks (J. B. Miima), modelling alternatives in deformation measurements (D. Rossikopoulos), and maximum correlation adjustment (F. Neitzel). The third session which was on Geographic Information Systems (GIS) consisted of four talks, three using fuzzy logic (G. Joos, S. Keller, E. Stefanakis) and one on robust estimation techniques (E. Kanani). The following session was dedicated to GPS data processing and analysis: real-time prediction of failures (C. Dacheng), robust techniques (A. Wieser, Y. Yang), and fuzzy methods (S. Leinen, H. Kutterer). The last technical session of the symposium was on photogrammetry, remote sensing, and image processing. F. Sanso discussed the Wiener-Kolmogorov prediction problem with the application to digital terrain models. L. Mussio considered semantic ambiguity questions for pattern recognition. M. Scaioni showed the use of the LMS estimator for outlier rejection in automatic aerial triangulation. The last day of the symposium started with an introductory talk by F. Sanso on the challenges for the IAG in data analysis in the ®elds of geodesy and GIS, especially regarding the modelling of uncertainty by probabilistic and non-probabilistic techniques. A panel discussion on data analysis within IAG closed the symposium. The proceedings of the symposium are published as Report No. 295 of the Institute of Geodesy and Photogrammetry of the Swiss Federal Institute of Technology Zurich (ETH). Further information can be found on the website of the IAG SSG 4.190. The address is www.dg®.badw.de/ssg4.190. Last but not least a warm thanks goes to the local committee around A. Carosio at the ETH Zurich for the excellent organization of the symposium. H. Kutterer

Book Review

title: authors:

Shape and Shape Theory D.G. Kendall, D. Barden, T.K. Carne and H. Le publisher: John Wiley & Sons, Ltd ± Chichester ISBN: 0-471-96823-4 year: 1999 price: GB£ 60 pages: 306 size: 15.5 ´ 23.5 cm details: hard cover Statistics and geometry have been two of the fundamental foundations in geodesy and geomatic engineering. The importance of statistics in geodesy and geomatic engineering has long been fully recognized ever since the invention of the least squares method by Gauss or Legendre, while the usefulness of di€erential geometry has been substantially studied in connection with the gravity ®eld of the earth by our great geodesists Marussi and Hotine. However, as no exception as in other ®elds of science, geodesy and geomatic engineering have been dealing with the statistics of random scalar, vectorial, matrical and tensorial quantities. With the advance of computing machines at a tremendously rapid pace, geodesists and geo-informatic engineers have started working with imagery/icons as a whole object, as in the case of electrical engineering, in particular. The study of imagery/icons as a whole object/ quantity strongly demands further development of

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statistics and geometry. Accordingly, shape and shape theory is emerging as a new study area of statistics and geometry and may be said to start taking shape in the late 1970s, when the works by Bookstein, Kendall (the ®rst author of this book) and Ziezold were published. Since then, many papers on shape and shape theory have been published, scattering in a number of journals. Thus the publication of this book, together with a few other books on the same topic published recently, is very timely for the promotion of further theoretical development and practical applications. This book is written by four experts on shape and shape theory, led by D.G. Kendall ± one of the pioneers in this new ®eld of study. The theory of shape in this book is basically presented following the lines of Kendall's pioneer work in 1977, as stated by the authors. The book may be classi®ed into six parts: (i) de®nitions and representations of shape and shape spaces (chapter 1, pages 1±22); (ii) topological and geometrical structures and properties of shape spaces (chapters 2 to 7, pages 23± 156); (iii) probabilistic and statistical aspects of shapes (chapters 8 and 9, pages 157±229); (iv) visualisation in shape spaces (chapter 10, pages 231±247); (v) extension of the theory of shape to that of shape and size (chapter 11, pages 249±281); and ®nally (vi) the appendix of 9 pages, the bibliography of 5 pages and the index of 8 pages. The ®rst part de®nes the basic concepts for shape and shape theory, in particular, the pre-shape, the shape, the pre-shape space and the shape space. Here also de®ned is the distance between two shape spaces. The shape determined by the labelled points can be represented in matrix notation as well. Since shape spaces are very new and have not been studied before, the authors have put a lot of ink on topological and geometrical structures and properties of shape spaces in the second part. Chapters 2 to 5 discuss the global description of shape spaces. Chapter 6 is focused on geodesics in shape spaces, including the distance between shapes, the set of geodesics between two shapes and the non-uniqueness of minimal geodesics. The last chapter of this part deals with the Riemannian structure of shape spaces. Since the shape can be represented in matrix notation, singular value decomposition has also been shown to be very useful in decomposing shape space. The ®rst chapter of the third part discusses induced shape measures or probabilistic aspects of shapes. Given a joint distribution for con®gurations represented by labelled points, the induced probabilistic measure for shapes may be said to be the joint distribution of the point set after removing the e€ect of translation, rotation and scaling. The other chapter of this part is to discuss statistical measures for shapes. Three di€erent de®nitions for mean shapes have been presented. None of these de®nitions are necessarily unique. It is also shown that in certain situations, the computed mean shape can be out of the shape space and thus lose its meaning as a mean shape. However, the FreÂchet mean shape can be uniquely de®ned for a broad class of shape measures. The last two parts of the main body of the book treat the visualisation of shape spaces and the extension of shape and shape theory to include the component of size.

Although this book is well written and organized, it is the impression of the reviewer that the book is directed more to mathematicians than to users. Nevertheless, considering its rich content and keeping in mind that geodesists and geo-informatic engineers urgently need to know and apply the shape theory in the immediate future, I would like to conclude this review by strongly recommending that geodesists and geo-informatic engineers have this book on desk within the ready reach of hands for reference. Peiliang Xu Kyoto University/Japan Fast Bibliography The fast bibliography consists of a listing of papers relevant to Geod. that has been collected by the IAG bibliographic service since previous issue of the fast bibliography (JG74/10). The IAG bibliographic service is based on the literary data bank GEOPHOKA, which is maintained by IfAG at the Branch Oce Leipzig, Leipzig Zentrale technisch ± wissenschaftliche Angelegenheiten, Bibliothek, Karl ± Rothe-Strasse 10-14, 04105 Leipzig, Germany. The IAG bibliographic service can be reached at the following Internet address: http://www.leipzig.ifag.de. The bibliographic services are furthermore reachable through the homepage of IAG. Agatza-Balodimou, A., Antonopoulos, A. Adjusting sea level measurements at the port of Alexandroupolis, Survey rev., Vol. 36, 2001, No. 279, pp. 35±43, London, 2001. Alsalman, A. E€ects of electric power lines on the accuracy of GPS positioning, Survey rev., Vol. 36, 2001, No. 279, pp. 54±61, London, 2001. Altamini, Z., Sillard, P., Boucher, C. Quality analysis of some IGS weekly combined solutons with respect to ITRF, International Association of Geodesy Symposia; 120, pp. 93±95, Berlin, 2000. Angermann, D., Klotz, J., Reigber, C. Geodetic datum de®nition of the SAGA network, International Association of Geodesy Symposia; 120, pp. 122±125, Berlin, 2000. Atkinson, N., Allan, A. Back to basics (21: least squares statistics and all that, Survey rev., Vol. 36, 2001, No. 279, pp. 62±71, London, 2001. Barkin, Y. About global rotation of the lithosphere, International Association of Geodesy Symposia; 120, pp. 234±237, Berlin, 2000. Barlik, M. Determination of the separation between geoid and quasigeoid using vertical gravity gradient observations along the gravimetric baseline in the meridian of Astro-geodetic Observatory of Warsaw University of Technology at Jozefoslaw, Rep. geod., Nr. 2(50), pp. 53±59, Warszawa, 2000. Barlik, M. Gradientometric corrections to the geoidal heights levelling, Rep. geod., Nr. 2(50), pp. 9±17, Warszawa, 2000. Barlik, M. Investigation of the local covariance function of vertical gravity gradient anomalies, Rep. geod., Nr. 2(50), pp. 61±69, Warszawa, 2000. Barlik, M. On statistical prediction of the geoidal heights using vertical gravity gradient anomalies and other gravity ®eld characteristics in the geodetic test ®eld at Grybow, Rep. geod., Nr. 2(50), pp. 31±35, Warszawa, 2000. Barlik, M. On the contribution of the vertical gravity gradient anomalies to the separation between the geoid and Molodensky's quasigeoid (basing on the example of the geodetic test ®eld near Grybow), Rep. geod., Nr. 2(50), pp. 37±52, Warszawa, 2000. Barlik, M. On the determination of plumb-line defelctions using vertical gravity gradient anomalies in the geodetic test ®eld near Grybow, Rep. geod., Nr. 2(50), pp. 19±29, Warszawa, 2000.

238 Beutler, G., Reigber, C., Drewes, H., Rummel, R. Space techniques and their coordination within IAG at present and in future, International Association of Geodesy Symposia; 120, pp. 22±32, Berlin, 2000. Bogusz, J., Figurski, M., Kruczyk, M., Kujawa, L., Kurka, W., Pfeil, M., Rogowski, J. Contribution of Astro-geodetic Observatory in Jozefoslaw to the CEI international projects, Rep. geod., Nr. 6(52), pp. 103±110, Warszawa, 2000. Bogusz, J., Kujawa, L., Kurka, W., Rogowski, J., Szolucha, M., Korcz, M., Leszczynski, W. Studies on di€erent application of Real-Time Kinematic GPS, Rep. geod., Nr. 6(52), pp. 173±179, Warszawa, 2000. Bosch, W., Wagner, C., Klokocnik, J., Kostelecky, J. Geosat and ERS-1 datum o€set relative to Topex/Poseidon estimated simultaneoisly with geopotential corrections from multi-satellite crossover altimetry, International Association of Geodesy Symposia; 120, pp. 96-98, Berlin, 2000. Brkic, M., Basic, T. Racunanjhe korekcijhe reljhefa u prostornojh i spektralnojh domeni, Geod. list, 54, 4, pp. 259±273, Zagreb, 2000. Cao, Y. GPS leveling experiment for long transit gas pipeline in moutain areas, Geotech. invest. survey., 6,167, pp. 55±57, 54, Peking, 2000. Cefalo, R., Manzoni, G., Pagurut, R., Plasil, J., Sluga, T. DGPS and WAAS experiments with di€erent RTCM radio sources in the CEI area, Rep. geod., Nr. 6(52), pp. 63±69, Warszawa, 2000. Costa, S., Pereira, K., Beattie, D. The integration of Brazilian geodetic network into SIRGAS ± preliminary results -, International Association of Geodesy Symposia; 120, pp. 99±102, Berlin, 2000. Costes, M., Vincent, P. DORIS: contribution of an orbit determination system to accurate and long term altimetry from space, International Association of Geodesy Symposia; 120, pp. 150±153, Berlin, 2000. Craymer, M., Snag, R., Ferland, R. Realization and uni®cation of NAD83 in Canada and the U.S. via the ITRF, International Association of Geodesy Symposia; 120, pp. 118±121, Berlin, 2000. Devoti, R., Ferraro, C., Paciene, R., Fermi, M., Lanotte, R., Rutigliano, P., Nardi, A., Luceni, V., Bianco, G., Sciaretta, C. Height time series of the Italian GPS ®ducial network compared with VLBI and SLR estimations, International Association of Geodesy Symposia; 120, pp. 130±133, Berlin, 2000. Devoti, R., Luceri, V., Bianco, G., Fermi, M., Nardi, A., Vespe, F., Ferraro, C., Peciene, R., Lanotte, R., Sciaretta, C. Earth orientation parameters measured by space geodesy techniques, International Association of Geodesy Symposia; 120, pp. 177± 179, Berlin, 2000. Dolgopolow, A., Kozlowski, Z., Turczyn, T., Wolski, A. Increase in ship safety during port manoeuvres by the DGPS system, Rep. geod., Nr. 6(52), pp. 191±195, Warszawa, 2000. Domingo Preciado, A. Metodos alternativos de ajuste para observaciones fotogrametricas, Topogr. cartogr., Vol. 17, Nr. 100, pp. 62±66, Madrid, 2000. Drewes, H., Tremel, H., Fortes, L., Kaniuth, K., Hernandez, J., Seemueller, W., Hoyer, M., Pereira, K., Stuber, K., Wildermann, E. Monitoring the continental reference frame in South America, International Association of Geodesy Symposia; 120, pp. 134±137, Berlin, 2000. E, D., Liu, J., Ye, S. Using post-processing WADGPS methods to process Arctic GPS data, J. Wuhan Techn. Univ. Survey. Mapp., 25, 5, pp. 396-399, Wuhan, 2000. Elango, K., Rameskchandra, S., Soma, P., Rangarajan, S. ISRO initiatives for space geodesy and geodynamics in India, International Association of Geodesy Symposia; 120, pp. 248±249, Berlin, 2000. Favre, C. Nivellement de puits par la methode GPS au Niger, Vermess. Photogramm. Kulturtech., 98, 11, pp. 662±666, Villmergen, 2000. Felner, A., Grzegorzewski, M., Jafernik, H., Sledzinski, J., Ziolkowski, J. Future navigation system ± FANS, Rep. geod., Nr. 6(52), pp. 207±216, Warszawa, 2000.

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