Data Assimilation for the Earth System

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Series IV: Earth and Environmental Sciences - Val. 26

Data Assimilation for the EarthSystem

edited by

Richard SwinbankMet Oftice,Bracknell, U.K.

Victor ShutyaevInstitute of Numerical Mathematics,Russian Academy of Sciences, Moscow, Russia

and

William Albert LahozData Assimilation Research Cent re,University of Reading, Read ing, U.K.

Springer Science+Business Media, B.V.

Proceedings of the NATO Advanced Study Institute onData Assimilation for the Earth SystemAcquafredda, Maratea, Italy19 May-1 June 2002

A C.I.P. Catalogue record for this book is available from the Library of Congress.

Printed an acid-free paper

AII Rights Reserved© 2003 Springer Science+Business Media DordrechtOriginally published by Kluwer Academic Publishers in 2003Softcover reprint of the hardcover lst edition 2003No part of this work may be reproduced , stored in a retrieval system, or transmitted in anyform or by any means, electronic, mechanical, photocopying, microfilming, recording orotherwise, without written permission from the Publisher, with the exception of anymaterial supplied specif ically for the purpose of being entered and executed on a compu­ter system , for exclusive use by the purchaser of the work.

ISBN 978-94-010-0029-1 (eBook)ISBN 978-1-4020-1953-9DOI 10.1007/978-94-010-0029-1

v

Table of Contents

Preface

List of Contributors

IntroductionR. Swinbank

IX

Xl

Data assimilation: aims and basic concepts 9N.K. Nichols

Bayesian estimation. Optimal interpolation. Statistical linear estimation 210. Talagrand

Variational assimilation. Adjoint equations 370. Talagrand

Control operators and fundamental control functions in data assimilation 55V.Shutyaev

Solvability of variational data assimilation problems and iterative 65algorithmsV.Shutyaev

Fundamental control functions and error analysis 75V.Shutyaev

A posteriori validation of assimilation algorithms 85o Talagrand

Introduction to initialization 97P Lynch

Digital filter initialization 113P. Lynch

Treating model errors in 3-D and 4-D data assimilation 127N.K. Nichols

Observing the atmosphere 137R. Swinbank

Atmospheric modelling 149WA . Lahoz

VI

Operational implementation of variational data assimilation 167P. Gauthier

Quality control: methodology and applications 177P. Gauthier, C Chouinard, B. Brasnett

Statistical assimilation of satellite data: method, algorithms, examples 189OM Pokrovsky

Theoretical impact assessment of satellite data on weather forecasts 20 IOM Pokrovsky

The correlation features of the inverse problem solution in atmospheric 213remote sensingOM Pokrovsky

Assimilation of remote sensing observations in Numerical Weather 225PredictionJ.-N. Thiipaut

Research satellites 241W.A. Lahoz

The structure and evolution of the atmosphere 251A.ONeill

Introduction to atmospheric photochemical modelling 253B. Khattatov, J.F. Lamarque, G. Brasseur, G. Tyndall, J. Orlando

Ozone assimilation 263R.B. Rood

Multivariate chemical data assimilation 279B. Khattatov

Uses of ocean data assimilation and ocean state estimation 289K. Haines

Altimeter covariances and errors treatment 297K. Haines

Assimilation of hydrographic data and analysis of model bias 309K. Haines

Land surface processes 321P.R. Houser

Assimilation ofland surface data 331P.R. Houser

Land data assimilation sys temsP.R. Hous er

ReanalysisR.B. Rood

Index

VII

345

361

373

IX

PREFACE

This book is based on a set of lectures presented at the NATO (North Atlantic TreatyOrganisation) Advanced Study Institute (ASI) on Data Assimilation for the EarthSystem, which was held during late May 2002. The ASI grew out of a long-held concernthat there was little teaching available in data assimilation, even though it has becomecentral to modern weather forecasting, and is becoming increasingly important in arange of other earth science disciplines.

Over recent years a few teaching initiatives have been started, for example a dataassimilation module in the European Centre for Medium-range Weather Forecasts(ECMWF) meteorological training course. However, we still felt that there was acontinuing unfulfilled demand for training in data assimil ation that focused on theapplication of data assimilation techniques to a range of earth sciences.

An additional consideration was the wealth of earth observation satellite data that isnow coming on stream, as outlined elsewhere in this book. Data assimilation is the best,or, arguably, the only feasible technique available to make use of the enormous varietyand volume of data that are being relayed from these satellite instruments.

To meet the need for advanced training in data assimilation, we submitted aproposal to NATO for an Advanced Study Institute on the subject. We are very gratefulto NATO that they accepted our proposal and provided generous financial support. Thenumber of applications to attend the ASI substantially exceeded the number of studentplaces available, confirming the continuing and expanding demand for training in thisfield. A particular feature of the NATO sponsorship agreement was that 40% of thestudents at the summer school came from NATO partner countries and MediterraneanDialogue countries. This meant that a high proportion of the students came fromcountries where data assimilation is still in its infancy. It is our hope that the ASI hashelped the technique to become more established in earth science applications in thosecountries.

Like the ASI, this book is aimed at graduate students and post-doctoral and otherresearchers who are working on data assimilation across a range of earth sciences. Theopening chapters survey the basic theory of data assimilation, forming the theoreticalframework for the remainder of the book. The next set of chapters explores some of themore advanced theory of data assimilation , taking the advanced reader to some of thefrontiers of current research work. In the second half of the book, the applications ofdata assimilation are outlined. For those not familiar with meteorology, atmosphericchemistry, oceanography and land surface processes, some of the basic concepts inthose subject areas are described before moving on to detailed discussions of theapplications.

The ASI could not have taken place without strong support from the organisingcommittee and lecturers . As well as the editors of this volume, the organisingcommittee comprised: Alan oNeill, who is the director of the Data AssimilationResearch Centre (DARC) in Reading; Olivier Talagrand, one of the founding fathers ofmeteorological data assimilation; and Boris Khattatov, a leading expert on assimilationof chemical constituents. We were fortunate to enrol an international team of lecturerswho are each experts in their own particular areas of data assimilation. We would like

x

to thank all the lecturers for presenting their material both in lectures at the ASI, and inwritten form in this book.

In addition to lectures and tutorials presented by the lecturing staff, a keycomponent of the ASI was a set of computer-based practicals. We would like to thankthe three teaching assistants, Matt Huddleston, Amos Lawless and Stefano Migliorini,who assisted students with the computer practicals. Amos played a particularlyimportant role in coordinating the practicals, and presenting some of the practicalexercises. We also thank Andy Heaps, who organised the computers for the ASI andserved as computer manager. As editors, we felt that we could not easily presentmaterial from the computer practicals in this book. However, we encourage interestedreaders to visit the web-site at http://darc.nerc.ac.uklasi_progs, where the relevantcomputer software, and associated documentation has been made available.

We are particularly grateful to all the various organisations which providedfinancial support that made the Advanced Study Institute possible. We have alreadymentioned generous backing by NATO, the main sponsor of the summer school. Inaddition, NASA supported students travel costs; we would particularly like to thank PhilDeCola for securing this generous support. We would like to thank Boris Khattatov andMarilena Stone of the Atmospheric Chemistry Division at the National Center forAtmospheric Research (NCAR), who administered the NASA grant. Centre National dela Recherche Scientifique (CNRS) and Centre National dEtudes Spatiales (CNES) bothprovided grants to support students and teaching assistants at the summer school. Wewould also like to thank the various organisations where the lecturers work, forallowing the lecturers time to prepare the lectures , attend the ASI and write theircontributions to this book. Jan Fillingham, of DARC at the University of Reading,provided essential administrative support, particularly in the months leading up to theASI, and we are especially grateful to her.

We also thank Maria Armiento and the staff of the Hotel Villa del Mare inAcquafredda di Maratea. Their hospitality made a major contribution to the success ofthe ASI. We are particularly grateful for their assistance with two major problems:arranging bus transport when the Italian railways called a strike to coincide with thestart of the ASI, and for arranging rental of replacement computer monitors when theequipment ordered from the UK did not arrive. We also appreciated the social eventsthat they arranged, including the evening soccer match against the hotel staff - whichthe ASI team looked like winning at one point.

Finally, we would like to thank the students for their enthusiastic participation inthe summer school. The awards ceremony, in which the students highlighted specialtalents of some of the lecturers, was particularly memorable. Although the main aim ofthe ASI was to provide advanced teaching to the students, the lecturers also found it avery stimulating experience.

Richard SwinbankVictor ShutyaevWilliam Lahoz

LIST OF CONTRIBUTORS

Dr Pierre GauthierAtmospheric Environment Service,ARMA/SEA (5e Etage) ,2121 Route Transcanadienne,Dorval P.Q.H9P 113,Canadaemail : pierre .gauthier@ec.gc .ca

Dr Paul R. HouserHydrological Services Branch ,Code 974,NASA Goddard Space Flight Center ,Greenbelt MD 20771 ,USAemail: houser@hsb.gsfc.nasa.gov

Dr William A. LahozDARC, Department of Meteorology,PO Box 243,Earley Gate,Reading RG6 6BB,UKemail: wal@met.reading.ac.uk

ProfNancy K. NicholsDepartment of Mathematics,University of Reading,PO Box 220,Reading, Berks RG6 6AX,UKemail: nkn@po.cwru.edu

Dr Oleg M. PokrovskyPrincipal Scientist & Head of Laboratory ,Main Geophysical Observatory,Karbyshev str.7,St.Petersburg, 194021,Russiaemail: pokrovsk@cnrm.meteo.fr

XI

Dr Keith HainesESSC, University of Reading,PO Box 238,Earley Gate,Reading RG6 6AL ,UKemail: kh@maiI.nerc-essc.ac.uk

Dr Boris KhattatovNCAR,P.O. Box 3000,Boulder, CO 80307-3000,USAemail: boris@ucar.edu

Dr Peter LynchAssistant Director,Met Eireann,Glasnevin Hill ,Dublin 9 ,Irelandemail: peter.lynch @met.ie

Prof Alan O'NeillDARC, Department of Meteorology,PO Box 243,Earley Gate,Reading RG6 6BB,UKemail: alan@met.rdg.ac.uk

Dr Richard B. RoodActing Chief, ESDCD,Code 930,NASA Goddard Space Flight Center,Greenbelt MD 20771 ,USAemail: Richard.B.Rood .1@gsfc .nasa.gov

xi i

ProfVictor ShutyaevINM, Russian Academy of Sciences ,Gubkina 8,117951 GSP-I ,Moscow,Russiaemail: shutyaev@inm .ras.ru

Or Olivier TalagrandLMO, Ecole Normale Superieure ,24 Rue Lhomond ,72531 PARIS Cedex 05,Franceemail: talagran@lmd.ens.fr

Or Richard SwinbankNWP , Met Office ,London Road,Bracknel1 RGI2 2S2 ,UKemail: richard.swinbank@metoffice.com

Or Jean-Noel ThepautECMWF,Shinfield Park,Reading RG29AX ,UKemail: jean-noel.thepaut@ecmwfint