CNR - ISAC, Unit UOS of Padua
Corso Stati Uniti 4, I-35127 Padova - Italy
Tel: +39 049 8295906
"Improved understanding of past climatic variability from early daily European instrumental sources" (IMPROVE)
Coordinator: Dr. D. Camuffo.
Contract N°: ENV4-CT97-0511 funded by the European Commission
programme Environment and Climate.
The Research Project
The EU research project Improved understanding of past climatic
variability from early daily European instrumental sources (IMPROVE) has been 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 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 (It., 1725-present), Milan (It.,
1763-present), Central Belgium (Be., 1767-present, temperature only), Uppsala
(Se., 1722-present), Stockholm (Se., 1756-present), San Fernando/Cadiz (Es.,
1776-present) and St Petersburg, Russia (1743-present). These series have been
augmented with newly-produced series (Central England, UK., 1772-present).
- characterise climate variability and determine teleconnection behaviour across Europe:
high-frequency temperature variability; seasonal temperature extremes;
recurrence intervals; growing seasons.
- 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 book Improved understanding of past climatic variability
from early daily European instrumental sources (Kluwer 2002)
contains all the IMPROVE results and a CD-ROM with the original and the corrected data.
As far as these fundamental questions are concerned, IMPROVE has contributed in a number of ways by:
- producing seven new highly reliable
series, covering a very long time interval, nearly three centuries. Another
important aspect is the high (daily) resolution of the series, which allows
more insight into past variability, as monthly averages smooth out and mask many
important climatic features;
- 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. In actual fact, the long series
are affected by a huge number of problems, and not only casual reading errors.
Reading 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 in the course of time, the changes in measuring
style due to national or international regulations or the simple evolution of
technology, that affected the observations in the same way and simultaneously
in all sites. All homogeneity assessment techniques would perform poorly if all
station time series were affected similarly by common factors, and changes in
measuring style cannot be assessed with statistical analysis, but only with
historical research of all the metadata. Some illustrative case studies
reported in this issue will clarify the situation. The better the quality of
the existing data, the better the response we obtain.
At present, attention is being mainly
devoted to forecasting 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 (e.g. Jones et al., Reviews of Geophysics, 37:2, 173-199,
1999). 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 the field practice. For
instance, in general a first contribution ±0.2°C corresponds to the accuracy of
standard thermometers (WMO Report No.8, Geneva, 1983) but the overall error in the field is
greater. In the sunny countries, the largest error is reached on clear, calm
days, when the screen may over-heat by +2.5°C and on clear nights when it may
under-cool by -0.5°C. The correction based on metadata describing observational
errors and problems requires a long and unrewarding work to improve the quality
of long series. One of the aims of IMPROVE is to encourage critical revision
and improvement of the quality of existing series, while providing, at the same
time, examples of typical errors to be removed and identifying the procedures
needed to amend them.
- The actual warming rate has been proven to be at such a slow rate that temperature changes, over years
(i.e. 0.006°C/yr) and even decades (i.e. 0.06°C/decade), are in most cases
smaller than the instrumental resolution and can hardly be directly detected.
This occurs especially with temperature averages, for which the climate signal is often
below the noise and/or the instrumental limit. However, looking at the frequency
distribution of extreme events, things appear differently. Extreme events
depart so much from the average, that they can be easily detected, and in
computing their signal to noise ratio the observational error becomes less
relevant. IMPROVE has clearly demonstrated that this approach is very
promising. An analysis of the distribution of extreme events has also shown
that recent warming is characterised by an increase in frequency of the hottest
days, in association with a decrease in frequency of the coldest.
Research in cooperation with:
- Dr. Gaston Demarée, Royal Meteorological Institute, Hydrology Session, Brussels, Belgium
- Prof. Erik Thoen, Department of Medieval History, University of Gent, Belgium
- Prof. Trevor Davies and Dr. Phil Jones, Climatic Research Unit, University of East Anglia, Norwich, U.K.
- Dr. Anders Moberg, Department of Physical Geography, Stockholm University, Sweden
- Dr. Hans Bergström, Department of Meteorology, Uppsala Universitet, Sweden
- Prof. Javier Martin-Vide, Department of Physical Geography, Barcelona University, Spain
- Dr. Vincenzo Cocheo, Fondazione Salvatore Maugeri - IRCCS, Centre for Environmental Researches, Padova, Italy
- Dr. Maurizio Maugeri, Applied Physics Department, Milan University, Italy
PAPERS and DATA:
Climatic Change, Vol 53 Nos. 1-3 (2002) IMPROVE (special issue):
- D. CAMUFFO and P JONES / Improved Understanding of Past Climatic Variability from Early Daily European Instrumental Sources - Guest Editorial. 4 p
- D. CAMUFFO / History of the Long Series of the Daily Air Temperature in Padova (1725-1998). 69 p
- C. COCHEO and D. CAMUFFO / Corrections of Systematic Errors and Data Homogenisation in the Daily Temperature Padova Series (1725 - 1998). 24 p
- M. MAUGERI, L. BUFFONI and F. CHLISTOVSKY / Daily Milan Temperature and Pressure Series (1763-1998): History of the Observations and Data and Metadata Recovery. 17 p
- M. MAUGERI, L. BUFFONI, B. DELMONTE and A. FASSINA / Daily Milan Temperature and Pressure Series 1763-1998): Completing and Homogenising the Data. 31 p
- M. BARRIENDOS, J. MARTÍN-VIDE, J.C. PEÑA and R. RODRÍGUEZ / Daily Meteorological Observations in Cádiz - San Fernando. Analysis of the Documentary Sources and the Instrumental Data Content (1786-1996). 20 p
- A. MOBERG, H. BERGSTRÖM, J. RUIZ KRIGSMAN and O. SVANERED/ Daily Air Temperature and Pressure Series for Stockholm (1756-1998). 42 p
- H. BERGSTRÖM AND A. MOBERG / Daily Air Temperature and Pressure Series for Uppsala (1722-1998). 40 p
- P. JONES, and D.H. LISTER / The Daily Temperature Record of St. Petersburg (1743-1996). 14 p
- G.R. DEMARÉE, P.J. LACHAERT, T. VERHOEVE and E. THOEN / The Long-Term Daily Central Belgium Temperature Series (1767-1998) and the Early Instrumental Meteorological Observations in Belgium. 25 p
- D. CAMUFFO / Calibration and Instrumental Errors in Early Measurements of Air Temperature.
- D. CAMUFFO / Errors in Early Temperature Series Arising from Changes in Style of Measuring Time, Sampling Schedule and Number of Observations. 22 p
- Z. YAN, P.D. JONES, T.D. DAVIES, A. MOBERG, H. BERGSTRÖM, D. CAMUFFO, C. COCHEO, M. MAUGERI, G. DEMARÉE, T. VERHOEVE, E. THOEN, M. BARRIENDOS, R. RODRIGUEZ, J. MARTIN-VIDE and C. YANG / Trends of Extreme Temperature in Europe and China Based on Daily Observations. 38 p
Papers in other journals or in other issues:
- Camuffo, D., Cocheo, C. and Enzi, S., 2000: Seasonality of instability phenomena (hailstorms and thunderstorms) in Padova, Northern Italy, from archive and instrumental sources from AD 1300 to 1989. The Holocene, 10:5, 651-658.
- Camuffo, D., Secco, C., Brimblecombe, P. and Martin-Vide, J., 2000: Sea Storms in the Adriatic Sea and the Western Mediterranean During the Last Millennium. Climatic Change, 46, 209-223.
- Moberg, A., Jones, P.D., Bergström, H., Camuffo, D., Cocheo, C., Davies, T.D., Demarée, G., Maugeri, M., Martin-Vide, J. and Verhoeve, T., 2000: Day-to-day Temperature Variability Trends in 160- to 275-year-long European Instrumental Records. J. Geophys. Res. -Atmospheres, 105(D18), 22849-22868.
- Jones P.D., Briffa, K.R., Osborn, T.J., Moberg, A. and Bergström, H., 2002: Relationships between circulation strength and the variability of growing season and cold season climate in Northern and Central Europe. The Holocene, 12:6, 643-656.
- Yan, Z., Jones, P.D., Moberg, A., Bergström, H., Davies, T.D. and Yang, C., 2002: Recent trends in weather and seasonal cycles - An analysis of daily data in Europe and China. J. Geophys. Res., 106(D6), 5123-5138.
- Moberg, M. Barriendos, H. Bergström, D. Camuffo, C. Cocheo, T.D. Davies, G. Demarée, P.D. Jones, J. Martin-Vide, M. Maugeri, R. Rodriguez and T. Verhoeve 2000: "Daily meteorological observations for a quarter of a millennium" Conference Meteorology at the Millennium, Cambridge, 10-14 July 2000.
- D. Camuffo, G. Demarée, T. Davies, P. Jones, A. Moberg, J. Martin-Vide, C. Cocheo, M. Maugeri, E. Thoen, H. Bergström (1998): Improved Understanding Of Past Climatic Variability From Early Daily European Instrumental Sources - (Improve). European Climate Science Conference, Vienna 19-23 October 1998. 7 pp.