Coastal Altimetry

567 Pages·2011·38.613 MB·English

by  J. Benveniste (auth.), Stefano Vignudelli, Andrey G. Kostianoy, Paolo Cipollini, Jérôme Benveniste (eds.)

Coastal Altimetry
Stefano Vignudelli • Andrey G. Kostianoy
Paolo Cipollini • Jérôme Benveniste
(Editors)
Coastal Altimetry
Stefano Vignudelli Paolo Cipollini
Consiglio Nazionale delle Ricerche National Oceanography Centre
Istituto di Biofisica European Way
Area Ricerca CNR SO14 3ZH, Southampton
Via Moruzzi 1 United Kingdom
56124 Pisa [email protected]
Italy
[email protected]
Jérôme Benveniste
European Space Agency/ESRIN
Andrey G. Kostianoy Directorate of Earth Observation
P.P. Shirshov Institute of Oceanology Programmes, EO Science
Russian Academy of Sciences Applications and Future
36, Nakhimovsky Pr. Technologies Department
Moscow, 117997 Via Galileo Galilei
Russia Frascati (Roma) 00044
[email protected] Italy
[email protected]
ISBN: 978-3-642-12795-3 e-ISBN: 978-3-642-12796-0
DOI: 10.1007/978-3-642-12796-0
Springer Heidelberg Dordrecht London New York
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Preface
“I consider this the most successful ocean experiment of all times”
Walter Munk of Scripps Institution of Oceanography, University of California at San Diego
speaking about the TOPEX/Poseidon altimetry mission in front of the U.S. Commission on Ocean
Policy, in April 2002.
The above statement, a tribute from one of the fathers of modern oceanography and a pio-
neer of revolutionary techniques to sample the sea, is a convincing summary of the
immense impact that satellite radar altimetry is having on our knowledge of the oceans.
The TOPEX/Poseidon mission (funded by NASA and CNES), its successors Jason-1 and
Jason-2, the altimeters on board ESA’s ERS-1/2 and Envisat missions and the U.S. Navy’s
Geosat Follow-On have started and are sustaining one of the most impressive observa-
tional records in geophysics, both for its length (currently almost two decades), its synop-
ticity, and its accuracy. The importance of altimetry in capturing the dynamics of the
oceans, the intended primary application of the missions, is now paralleled by its role as a
global sea level gauge – an application that has become ever more prominent in times
of climate change. The by-products of the technique – wind speed and significant wave
height – are important variables for climate research and for the independent validation of
measurements from other sources. Altimetry’s exceptional progress has been made possi-
ble by the dedication of many scientists and engineers. Their first-class research on orbit
determination and instrumental, atmospheric and surface effects’ corrections has improved
the precision of the altimetric measurements to levels that were almost unthinkable of at
the beginning (~2 cm from a 1,335-km orbit, i.e., slightly more than one part in one hun-
dred million) and ensures accuracy and long-term stability that allow the rate of global sea
level rise to be measured with a resolution accuracy better than 1 mm/y. The excellent
body of research behind altimetry is comprehensively reviewed in Fu and Cazenave’s
book Satellite Altimetry and Earth Sciences (2001), whose many chapters, authored by
some of the leading experts in the field, also illustrate several of the applications of altim-
etry. Some simple statistics will confirm the impact of altimetry on the oceanographic
community: the ISI (Institute for Scientific Information) online library of refereed journals
and major conference proceedings cites more than 6,000 papers on ocean altimetry; a
search for “TOPEX” on Google Scholar yields more than 15,000 hits (including reports
and similar grey literature). A measure of this enormous impact is also the widespread use
of altimetry within the modelling community: nowadays, altimetric data are routinely
v
vi Preface
assimilated into ocean models, both in near-real time for operational forecasting and in
delayed time for hindcasts and reanalysis that greatly improve our understanding of many
ocean processes. It is not a surprise that GCOS has included Sea Level in its list of Essential
Climate Variables (ECVs) required to support the work of the UNFCCC and the IPCC.
Ensuring continued support to altimetry is, now more than ever, at the centre of the general
political debate on sustaining climate research.
Therefore, altimetry is mature, and is a great success story for satellite-based Earth
Observation. At this point the casual reader might conclude that all the technical hurdles
have been reasonably overcome, and the future is rosy. Forthcoming techniques (like the
delay-Doppler technique) will just bring in more excitement, with their promise to push
further the capability of altimeters, and make the picture described in the above paragraph
even sharper.
While the above might be true for open-ocean altimetry, there is an important domain
where altimetry remains grossly underexploited. This domain coincides, crucially, with
the region where changing circulation, sea level and sea state have by far the largest
impact on human society: the coastal zone. Altimetric data gathered over this coastal
strip (up to a few tens of kilometers from the coast) remain unused in the archive, mainly
as they are flagged as “bad” or “not reliable” due to contamination of the altimetric wave-
forms, inadequate corrections, or poorly understood surface effects. The information in
the coastal altimetry records ends up being corrupted, and for a long time many satellite
oceanographers simply used to throw those records away. But that information would be
invaluable for studies of coastal circulation, sea level change and impact on the coastline.
And we would have, already, almost two decades of data in the archives. Is that informa-
tion completely unrecoverable? Many researchers believe this is not the case. They
believe that not only coastal altimetry would be very useful, but also, and crucially, that
it is to a large extent feasible, and so must be done! This book is an account of their val-
iant efforts.
The path to coastal altimetry crosses two crucial territories: improvement of the radar
measurement retrieval algorithms (retracking) and of the geophysical corrections. First
of all, the radar return signals (known as waveforms) are archived, so their conversion to
geophysical measurements can be revisited by fitting models of the waveforms (which
is what is called retracking) optimized for the coastal zone: this is expected to improve
the estimation of height, significant wave height and wind speed, or indeed to make that
estimation possible where it was previously not possible at all employing open-ocean
waveform models. Then, the other aspects of the whole processing chain from sensor to
product, including the various corrections and the quality control, can be largely
improved integrating local knowledge; one simple example is the use of local accurate
models for the correction of the high-frequency atmospheric pressure effects on the sea
level.
The process of extending altimetry to the coastal zone has begun with some early papers
(e.g. Crout 1997; Anzenhofer et al. 1999; Vignudelli et al. 2000) around the turn of the
century, when several researchers around the world were starting to come up with new
ideas and to explore some of the techniques necessary to make it work. A small but signifi-
cant mark in the history of coastal altimetry was the launch of the ALBICOCCA program
Preface vii
on 2001; this was the precursor of the European INTAS ALTICORE project (2007–2008)
where this book had its genesis. Since 2006 there has been a dramatic increase in the
research effort on this novel topic, and the coming together of an active international com-
munity of researchers who are exchanging ideas at regular Coastal Altimetry workshops
(Silver Spring 2008; Pisa 2008; Frascati 2009; Porto 2010 – see http://www.coastalt.eu)
and have contributed a “Community White Paper” on the role of altimetry in Coastal
Observing Systems at the recent OceanObs’09 conference (Cipollini et al. 2010). The
major space agencies and funding agencies have recognized the importance of the topic
and are supporting it via a series of projects (e.g. COASTALT, PISTACH, RECOSETO
and some OSTST projects). This book builds on many of the research efforts in the afore-
mentioned projects and across the whole community, with the aim of presenting the cur-
rent status in this new, challenging and exciting topic.
This peer-reviewed book brings together 20 chapters addressing a wide range of issues
in processing and exploiting satellite altimetry from the open ocean to the coasts. The
chapters presented describe the state of the art, recent developments on specific issues and
practical experience. Chapter 1 gives a historic perspective and shows the current status of
satellite altimetry missions. This is immediately followed in Chapter 2 by the illustration
of a successful case in which coastal altimetry data have gone from research to operation.
Chapter 3 discusses the user requirements for the new coastal altimetry products, i.e. what
the users expect to get. The bulk of chapters from Chapter 4 to 9 deals with data processing
aspects, particularly those concerning re-tracking and corrections for improving altimeter
data, including editing strategy. These are the techniques that truly make coastal altimetry
a reality. Chapter 10 extends the content of the book to data dissemination and services.
Chapter 11 illustrates the clear link of calibration and validation to coastal altimetry.
Following this introduction of how altimeter data are processed and managed is a series of
Chapters (12 to 19) that show the gamut of applications in some regional seas (Mediterranean,
Black, Caspian, White, Barents), around coasts of some countries (North America, China,
Australia) and even lakes that have similar processing challenges. Finally, Chapter 20
explores novel technologies of forthcoming satellite altimetry missions and their expected
impact on data retrieval in the coastal zone.
We intend this book for a wide audience of students, researchers, data-integrators with
interest in the Coastal Zone who seek a unique, research-centred, up-to-date reference to
Coastal Altimetry. Finally, we hope that this book will inspire both young and more expe-
rienced researchers, and we hope that it will be seen both as a stimulus to exploit Coastal
Altimetry and an invitation to explore further the intricate details of technology, algo-
rithms, processing, in a field that promises to bring significant and long-lasting societal
benefits.
Stefano Vignudelli,
Andrey G. Kostianoy,
Paolo Cipollini,
Jérôme Benveniste
August 2010
viii Preface
References
Anzenhofer M, Shum CK, Rentsh M (1999) Costal altimetry and applications, Tech. Rep.
n. 464, Geodetic Science and Surveying, The Ohio State University Columbus, USA
Cipollini P, Benveniste J, Bouffard J, Emery W, Gommenginger C, Griffin D, Høyer J,
Madsen K, Mercier F, Miller L, Pascual A, Ravichandran M, Shillington F, Snaith H,
Strub T, Vandemark D, Vignudelli S, Wilkin J, Woodworth P, Zavala-Garay J (2010) The
role of altimetry in Coastal Observing Systems, in Proceedings of OceanObs’09: Sustained
Ocean Observations and Information for Society (Vol. 2), Venice, Italy, 21-25 September
2009, Hall, J., Harrison, D.E. & Stammer, D., Eds., ESA Publication WPP-306.
doi:10.5270/OceanObs09.cwp.16
Crout R L (1997) Coastal currents from satellite altimetry. Sea Technology 8:33–37
Fu LL, Cazenave A (eds) (2001) Satellite altimetry and earth sciences: a handbook of
techniques and applications. Academic Press, San Diego, 463 pp
Vignudelli S, Cipollini P, Astraldi M, Gasparini GP, Manzella GMR (2000) Integrated use
of altimeter and in situ data for understanding the water exchanges between the
Tyrrhenian and Ligurian Seas. J Geophys Res 105:19,649–19,000
Abbreviations
ALBICOCCA A Ltimeter-Based Investigations in COrsica, Capraia and
Contiguous Areas
ALTICORE Value added satellite ALTImetry for COastal REgions
CNES Centre National d’Études Spatiales
COASTALT ESA Development of COASTal ALTimetry
ERS European Remote Satellite
ESA European Space Agency
GCOS Global Climate Observing System
INTAS International Association for the promotion of co-operation with
scientists from the New Independent States of the former Soviet Union
IPCC Intergovernmental Panel on Climate Change
ISI Institute for Scientific Information
NASA National Aeronautics and Space Administration
OSTST Ocean Surface Topography Science Team
PISTACH CNES Development of “Prototype Innovant de Système de
Traitement pour les Applications Côtières et l’Hydrologie”
RECOSETO REgional COastal SEa level change and sea surface Topography
from altimetry, Oceanography, and tide gauge stations in Europe
UNFCCC United Nations Framework Convention on Climate Change
Editorial Note and Acknowledgements
Each chapter in the book underwent rigorous peer-reviewing. The editors identified a mini-
mum of two external reviewers for each chapter, selected on the basis of experience and
knowledge of the subject. Each leading author received the formal anonymous reviews
from the reviewers plus additional editorial comments, and was asked to improve or cor-
rect each one of the points raised or explain rebuttal. In some cases, where appropriate, the
editorial process involved more than one review round, and this hopefully will have helped
to guarantee the high quality of the final book.
The editors, also on behalf of the authors, would like to express gratitude to Springer-
Verlag for the timely interest to the Coastal Altimetry topic and for supporting our efforts.
The financial support of the European Space Agency and Centre National d’Etudes Spatiales
(France) for publishing and disseminating the book is also gratefully acknowledged.
A sincere “thank you” from the editors goes to the chapter authors, who have played a
crucial role in creating the book, for their patience during the lengthy review rounds but
also for having responded in such a constructive manner to the editorial and reviewing
feedback. The editors are particularly indebted to the 44 external reviewers for their invalu-
able help, suggestions, corrections and insights. Here is the list (including current affilia-
tions) of those anonymous reviewers who agreed to be acknowledged here:
Arbic B., Florida State University, Tallahassee, USA
Callahan P., NASA Jet Propulsion Laboratory, Pasadena, USA
Chang X., Chinese Academy of Surveying and Mapping, Beijing, China
Cripe D., Group on Earth Observations, Geneva, Switzerland
Dinardo S., SERCO/ESRIN, Frascati, Italy
Fairhead D., University of Leeds/GETECH, Leeds, UK
Fanjul E., Puertos del Estado, Madrid, Spain
Font J., Institut de Ciències del Mar, Barcelona, Spain
Fouks V., St. Petersburg State University, St. Petersburg, Russia
Francis O., University of Luxembourg, Luxembourg
Francis R., European Space Agency, Noordwijk, The Netherlands
Gòmez-Enri J., Universidad de Cádiz, Cadiz, Spain
Heron M., James Cook University, Townsville, Australia
Jeansou E., NOVELTIS SA, Ramonville-Saint-Agne, France
Kosarev A., Moscow State University, Moscow, Russia
Le Traon P. Y., Institut Francais de Recherche pour l’Exploitation de la Mer, Brest, France
ix
x Editorial Note and Acknowledgements
Liu Y., University of South Florida, St. Petersburg, USA
Martinez-Benjamin J. J., Technical University of Catalonia, Barcelona, Spain
Marullo S., ENEA, Frascati, Italy
Mercier F., Collecte Localisation Satellites (CLS), Toulouse, France
Maharaj A., Macquarie University, Sydney, Australia
Mertikas S., Technical University of Crete, Chania, Greece
Perosanz F., Centre National d’Etudes Spatiales, Toulouse, France
Roca M., IsardSAT, Barcelona, Spain
Sandwell D., University of California, San Diego, USA
Scozzari A., Consiglio Nazionale delle Ricerche, Pisa, Italy
Seyler F., Institut de Recherches pour le Développement, Toulouse, France
Soares A., World Meteorological Organization, Geneva, Switzerland
Stanichny S., Marine Hydrophysical Institute, Sevastopol, Ukraine
Sychev V., State Hydrometeorological University, St. Petersburg, Russia
Tuzhilkin V., Moscow State University, Moscow, Russia
Vazzana S., European Space Agency, Frascati, Italy