Manual on sea level measurement and ... - unesdoc - Unesco

Sea Level Measurement and Interpretation1. IntroductionThis is the fourth in the series of IOC <strong>Manual</strong>s on SeaLevel Measurement and Interpretation. It incorporatesthe changes in tide gauge technology and measurementtechniques in the five years since the thirdmanual was written, and includes material from theWorkshop on New Technical Developments in Sea andLand Level Observing Systems (UNESCO, Paris, 14–16October 2003). In addition, it reflects to a great extentthe changes in priorities for tide gauges in a globalnetwork which have taken place in recent years. Forexample, it is inconceivable now that most gaugesinstalled in the GLOSS network will be without a realtimereporting capability and a capacity to provide dataof use to a tsunami warning system.The manual includes some sections of text from theearlier editions, updated as appropriate. However,for reasons of space it does not include some othersections from the earlier versions, even though theyare still valid and useful (e.g. the discussion of dataquality control and filters in Volume III, see the presentAppendix II). The earlier editions continue to be readilyavailable on the web at http://www.pol.ac.uk/psmsl/manuals/.In order to provide a fresh perspective, this volumehas been largely written by new people. A consultant(Dr. Ian Vassie) produced a first draft. Drs. Tilo Schöneand Georg Beyerle of GFZ, Postdam, contributed thetext for section 8. The first drafts were commentedon and edited by the GLOSS Technical Subcommittee(Chair Dr. Begoña Pérez) and the volume was subsequentlyreviewed by members of the GLOSS Groupof Experts and Mr David Meldrum provided additionalcomments on Section 5.The following section provides a brief overview ofsea level variations which may be of general interest,including a discussion of estimation of extreme levelsthat was missing from earlier editions. However, thevolume is largely concerned with tide gauge and datacommunications technologies and aimed at peoplewho work in those fields. These are rapidly developingtopics, and ones in which the sharing of expertiseamong groups is essential. Some readers of this volumemay, therefore, have different perspectives on sea levelmeasurements. Some of these independent views areexpressed in the contributions given in Appendix V.Each of these authors has expressed willingness to provideadvice to others as required.We thank everyone who contributed material for, andadvice on, this volume. In particular, we thank RobertSmith of the Proudman Oceanographic Laboratory forhis technical assistance and Ray C. Griffiths for editorialassistance.Thorkild Aarup(GLOSS Technical Secretary)Mark Merrifield(Chair GLOSS Group of Experts)Begoña Pérez(Chair GLOSS Technical Subcommittee)Ian Vassie(Consultant)Philip Woodworth(Director, Permanent Service for Mean Sea Level)June 2006IOC <strong>Manual</strong>s and Guides No 14 vol IV1