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IMPROVED UNDERSTANDING OF PAST CLIMATIC VARIABILITY FROM EARLY DAILY EUROPEAN INSTRUMENTAL SOURCES

Cover illustration: Calibration of thermometer (steam point) in a Physics laboratory, mid XVIII century. A Florentine, an Amontons, a Drebbel and other thermometers are hung on the wall (after: Jean Antoine Nollet (1748): Le¡ons de Physique Experimentale, Tome quartième, Paris: chez les FrÀres Guerin, courtesy of the Museo della Storia della Scienza, Florence).

IMPROVED UNDERSTANDING OF PAST CLIMATIC VARIABILITY FROM EARLY DAILY EUROPEAN INSTRUMENTAL SOURCES

Edited by

Dario Camuffo and Phil Jones National Research Council, Institute of Atmospheric Sciences and Climate, Padova, Italy Climatic Research Unit, University of East Anglia, Norwich, U.K.

Reprinted from Climatic Change Volume 53, Nos. 1-3, 2002

Kluwer Academic Publishers Dordrecht / Boston / London

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

ISBN 1-4020-0556-3

Published by Kluwer Academic Publishers, P.O. Box 17, 3300 AA Dordrecht, The Netherlands.

Printed on acid-free paper

All rights reserved © 2002 Kluwer Academic Publishers No part of this work can be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, microfilming, recording or otherwise, without written permission from the Publisher, with the exception of any material supplied specifically for the purpose of being entered and executed on a computer system, for exclusive use by the purchaser of the work. Printed in The Netherlands

Contents D. CAMUFFO and P. JONES / Improved Understanding of Past Climatic Variability from Early Daily European Instrumental Sources Guest Editorial

I

1

History and Correction of Long Temperature Series

D. CAMUFFO / History of the long series of the air temperature in Padova (1725 – 1998)

7

C. COCHEO and D. CAMUFFO / Corrections of systematic errors and data homogenisation in the Padova series (1725 – 1998)

77

M. MAUGERI, L. BUFFONI and F. CHLISTOVSKY / Daily Milan Temperature and Pressure Series: History of The Observations and Data And Metadata Recovery

101

M. MAUGERI, L. BUFFONI, B. DELMONTE and A. FASSINA / Daily Milan Temperature And Pressure Series: Homogenising The Data Using Direct Methodologies

119

M. BARRIENDOS, J. MARTIN VIDE, J.C. PEÑA, R. RODRIGUEZ / Daily Meteorological Observations in Cadiz - San Fernando. Analysis of The Documentary Sources and the Instrumental Data Content (17861996)

151

A. MOBERG, H. BERGSTRÖM, J. RUIZ KRIGSMAN and O. SVANERED / Daily Air Temperature and Pressure Series for Stockholm (1756-1998)

171

P. D. JONES AND D. H. LISTER / The Daily Temperature Record for St. Petersburg (1743–1996)

253

G. R. DEMARÉE, P.J. LACHAERT, T. VERHOEVE and E. THOEN / The Long-Term Daily Central Belgium Temperature (CBT) Series (1767–1998) and Early Instrumental Meteorological Observations in Belgium

269

II Typical Problems with Early Thermometers and Measuring Times D. CAMUFFO / Calibration and instrumental errors in early measurements of air temperature,

297

D. CAMUFFO / Errors in early temperature series arising from changes in style of measuring time, sampling schedule and number of observations.

331

III Trends in Extreme Temperatures Z. YAN, JONES, P.D., DAVIES, T.D., MOBERG, A., BERGSTRÖM, H., CAMUFFO, D., COCHEO, C., MAUGERI, M., DEMARÉE, G., VERHOEVE, T., BARRIENDOS, M., RODRIGUEZ, R., MARTINVIDE, J. and YANG, C. / Extreme Temperature Trends in Europe and China Based on Daily Observations

355

IMPROVED UNDERSTANDING OF PAST CLIMATIC VARIABILITY FROM EARLY DAILY EUROPEAN INSTRUMENTAL SOURCES

Guest Editorial

Climatic Change is a journal dedicated to the problem of climatic variability and change in its entirety – its descriptions, causes, implications and interactions. For this reason it welcomes contributions of a multidisciplinary nature, based on extensive research projects which advance our knowledge in a variety of fields. Following Volume 43, No.1, 1999 Climatic Variability in Sixteenth-Century Europe and its Social Dimension, another special issue is published. This time it is dedicated to a related research programme that has involved historical, instrumental, astronomical, statistical and climatic studies with the aim of clarifying key problems that are of concern to the scientific community, policy makers, and citizens. We are presently witnessing a global temperature rise of 0.6 ◦ C over the twentieth century (Jones et al., 1999). Many frequently asked questions are: • Is this warming part of a natural climate change, in part a recovery from cooler conditions in some recent centuries? Is the warming part of a cycle that will begin to reverse soon? • Has the natural warming already come to an end and is the present temperature rise only an effect of anthropogenically-induced changes to the composition of the atmosphere? Will warming rates continue or even enhance in the future? • Are we witnessing the combined effect of both natural and uncontrolled anthropogenic changes? What are the relative weights of the two contributions? These and many related questions have been extensively addressed in the latest IPCC report (Houghton et al., 2001). Models seem to confirm the last hypothesis of a combined effect of natural variability and increases in greenhouse gas concentrations, but much work is still needed to clarify mechanisms and to determine, if possible, future changes on decadal timescales. To achieve this we not only need estimations of future anthropogenic emissions, but also of natural factors that influence the climate system. Long-term instrumental data are vital to place recent changes in as long an historical perspective as possible, and to provide series to develop and validate climate models at the time and space scale we might use for planning. Knowledge of the past is one of the keys to interpreting the present and forecasting the future. The answer is conditioned by the quality of our present information, and this gives rise to three further questions: Climatic Change 53: 1–4, 2002.

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GUEST EDITORIAL

• Is our knowledge based on the best available data? • Can we learn more from the past by utilising new, unexploited data? • Are we really utilising the best strategies to interpret available data? This was the rationale by which the EU research project Improved understanding of past climatic variability from early daily European instrumental sources (IMPROVE) developed with the funding of the European Commission, DG XII. The study involved European regions from the Baltic to the Mediterranean and from the Atlantic to Eastern Europe. IMPROVE’s general objectives were to: • assess correction and homogenisation protocols for early daily instrumental records of air temperature and air pressure; • produce general comments on the case studies to be used as guidelines for the quality-assessment, correction and homogenisation of other early instrumental records of air temperature and pressure; • recover data; produce daily pressure and temperature series for carefully selected examples from European archives, i.e., Padova (Italy, 1725–1998), Milan (Italy, 1763–1998), Central Belgium (1767–1998, temperature only), Uppsala (Sweden, 1722–1998), Stockholm (Sweden, 1756–1998), San Fernando/Cadiz (Spain, 1776–1996) and St. Petersburg (Russia, 1743–1996, temperature only). These series have been augmented with recently-produced daily temperature series (Central England, U.K., 1772–1999); • publish the history of each series, all the original data and metadata, and the final corrected, validated and homogenised series on CD-ROM, along with a detailed explanation of all the steps that were necessary to arrive from the original registers to the final series. The special issue of Climatic Change contains the papers concerning all the above items, except the CD-ROM with the original and the corrected data. The CD-ROM is enclosed in a book, a hardbound version of this issue; • characterise climate variability and determine teleconnection behaviour across Europe, with particular reference to high-frequency temperature variability, seasonal temperature extremes, recurrence intervals and growing season lengths. The series on the CD-ROM can be considered as an Appendix to the papers in this volume explaining in more detail the history of the series and the types of corrections made. Users of the data, therefore, should refer to the appropriate papers in the volume when including analyses of the series in any subsequent papers. Also, each series is different from each other. We have attempted to standardize the formats as much as possible, but the different numbers of observations per day mean that all are different. Readers with particular questions about any one of the series should contact the author(s) of the relevant paper(s) rather than the editors of the volume and CD-ROM. The editors will be happy to deal with general enquiries

GUEST EDITORIAL

3

about the whole IMPROVE project and techniques used to analyse the series as a group. As far as the above fundamental questions are concerned, IMPROVE has contributed in a number of ways by: 1. Producing seven new highly reliable series, extending over nearly three centuries. Another important aspect is the high (daily) resolution of the series, which allows more insight into past variability, particularly extremes. Monthly averages can smooth out and mask many important climatic features. 2. Analysing and correcting errors and inhomogeneities in the long series. Metadata have been considered as important as data, since metadata are fundamental not only to correct, make homogeneous and interpret data, but also to distinguish apparent climatic changes, due to variations in observational methodology, from real climatic changes. This not only helped to produce more accurate series, but also clarified the question of the quality of the existing ones. All long series are affected by a huge number of problems. Measurement errors are mainly randomly distributed and they disappear when the averages of many series are calculated. The real problem is the presence of systematic errors that vary over the course of time, the changes in measuring style due to national or international observational practices or the simple evolution of technology that have affected the observations in the same way. With extensive historical research of all the metadata, most of the problems can be overcome but some may remain because some changes made in the past were not considered important enough to document. Some illustrative case studies reported in this issue will be applicable to all European locations and possibly elsewhere. Some are probably unique to the location and the period considered but they highlight the type of issues that need to be considered. At present, much attention in the climate sciences is devoted to developing future scenarios. To this aim, the quality of data is essential and a number of subjective and relatively objective criteria exist for testing monthly data and sources of inhomogeneity. However, the evaluation of the data quality, as deduced from the statistical analysis of the data, appears more optimistic than the error deduced by looking at the instruments capability and field practices. Corrections based on metadata describing observational errors and biases requires exhaustive studies to improve the quality of long series. One of the aims of IMPROVE is to encourage critical revision and improvement of of existing series, while providing, at the same time, examples of typical errors that need to be removed and identifying the procedures to achieve this. 3. Warming average over the 20th century is about 0.6 ◦ C, but is highly spatially variable. At first glance it might seem that such a rise would be impossible to measure, but the consistent spatial patterns incorporating observations from different countries and from oceanic regions attest to its veracity. To policymaker and the public the issue of climatic change is often perceived through

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GUEST EDITORIAL

extreme events. Analyses of the distribution of extreme events, undertaken using the results from IMPROVE, has shown that recent warming is characterised, for most of the study sites, more by a decrease in frequency of the coldest days, than by increases in frequency of the warmest.

References Houghton, J. T., Ding, Y., Griggs, D. J., Noguer, M., van der Linden, P. J., Dai, X., Maskell, K., and Johnson, C. A.: 2001, Climate Change 2001: The Scientific Basis, IPCC, Cambridge University Press, p. 881. Jones, P. D., New, M., Parker, D. E., Martin, S., and Rigor, I. G.: 1999, ‘Surface Air Temperature and its Changes over the Past 150 Years’, Reviews of Geophysics 37, 173–199. IMPROVE Co-ordinator, Consiglio Nazionale delle Ricerche, Istituto di Scienze dell’Atmosfera e del Clima, I-35127 Padova, Italy University of East Anglia, Climatic Research Unit, NR4 7TJ Norwich, U.K.

DARIO CAMUFFO

PHIL JONES