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Climate Analysis and Future Scenarios

Acquisition, critical examination and analysis of Italian historical series

Maurizio Maugeri
Institute of General Applied Physics (University of Milan)

We have come to consider that the study of climatic variations in Italy is principally limited by the quality and availability of data. These are the results of the recent National Research Council special project entitled “Reconstruction of the climate in the Mediterranean area in the past” and the recent awareness that has developed in the scientific community on the essential issues relating to the homogeneity and the thoroughness of the historical series of meteorological data.

With this in mind, this research offers an initial phase of acquisition, critical examination and homogenization of data. On the one hand, it will allow for the expansion both of numbers of series and of parameters of the Central Office for Crop Ecology (UCEA) archives, which contain the historical series of the centuries-old meteorological data. On the other, it will allow for data homogenization, using both information relative to the history of the meteorological stations and statistical methods. At the conclusion of the data homogenization phase, archives will be created from an initial series of records with the history of the individual stations and from the homogenization series.

Upon completion of the data revision phase, we will then come to the analysis, considering the following objectives:
  • Calculating spatially averaged series grouped by temperature (minimum, mean and maximum), rainfall and pressure from 1865 up to today and the analysis of such series. These average series will represent climatically homogeneous Italian areas, and their calculations will be made monthly.
  • Locating trends, cycles and change points for all the parameters under consideration in order to evaluate possible climatic changes;
  • Comparing processes observed at the national level and those relative to a larger area, and the analysis of Italian peculiarities;
  • Verifying the presence of certain trends recently emerging in Italy in international publications such as a shortening of the daily temperature range and the increase of the intensity of rainfall;
  • Extending previous results to a longer period (200-250 years) for some sites of particular interest.


The activity of the first year will essentially consist in collecting information and completing data. From there we will be proceed to gathering the necessary information to reconstruct the “history” of all the series to use in this project. This research will be carried out both through a systematic analysis of data annals and research published from 1865, and through the study of correspondence between the Central Office and individual stations. Further, research will be carried out at the UCEA library and at other libraries and archives to identify monographs and local reports with useful news information. The information collected will be used to create information records, station by station, in which all the information that could prove relevant for evaluating the homogeneity of data will be indicated.

Completing the data will consist both in including the UCEA archives of 12 new thermopluviometric series that will be recovered from previous projects, from annals of meteorological data and scientific publications, and complete of all the 26 more than a hundred years old thermopluviometric series, at monthly scale, from the UCEA archives. With the exception of the series that will be recovered from previous projects, this activity will essentially consist in digitizing the data . The data will be mainly recovered from annals (Italian Meteorology, Annals of the Central Office for Crop Ecology and the Annals of the Hydrographic Service) and the original files, which are stored in the UCEA archives, will be used periodically only.

Second year activities will consist in completing the data and in their homogenization. In this context, we will proceed to the completion with 10 daily series of thermopluviometric data. Some of these will extend to the end of the 18th century; others will begin from the last decades of the 19th century. The completion of the database will further include recovering pressure data (monthly average) for 5 series. This activity will essentially consist in digitazing the data. This phase, however, will also proceed daily, and therefore make major use of the original files stored at the UCEA archives.

The homogenization will be done both according to the records relative to the history of individual stations, and through statistical methods based on the comparison of different series and on methodologies already used within the project entitled, “Reconstruction of climate in the Mediterranean area in the past”. At the end of this phase, the data still missing will be estimated with statistical methods. Once this is achieved, the final database will be designed. This will consist of a complete and homogeneous series. The final archives will include an initial series and informational files of individual stations.

Finally, the average series will be calculated (at monthly time-scale) that will be representative of the Italian areas that are climatically homogeneous for temperatures (minimum, mean and maximum), rainfall and pressure from 1865 to today.

Third year activities will consist of data analysis established during the first two years of the research and have the following objectives:
  • Evaluating temperature ranges (minimum, medium and maximum) of rainfall and monthly pressure, both for individual stations as well as for spatially averaged series obtained through groups of stations in order to show the climatic evolutions in various areas of the national territory. The data analysis will aim at identifying the trends, cycles and change points and be based on the methods currently used in the field of the most recent scientific literature.
  • Studying the correlations among the processes of temperature, rainfall and pressure observed in Italy and those relating to vaster areas.
  • Analysing the roles of the forceful external elements (solar constant) and internal (greenhouse gas, volcanic eruptions, El Niño Southern Oscillation (ENSO), North Atlantic Oscillation (NAO), etc.) on the observed processes.
  • Studying the evolution of the behaviour of the daily rainfall of some stations with the aim of verifying if they are at work in the observable tendency influencing the intensity of rainfall.
  • Studying the processes of daily temperature range so as to verify if the tendency recently emerged in international publications toward the shortening of daily thermal change is also present in Italy.

  • Finding necessary information to reconstruct the “history” of all the series to use in the project. Such information will be synthesized in records, station by station, on which all the relevant information in order to evaluate the homogeneity of the data will be indicated.
  • Completion, at monthly time-scale, of all 26, more than a hundred-years old, historical thermopluviometric series from the UCEA archives.
  • Inclusion of the UCEA archives for 12 new thermopluviometric series that will be recovered from the previous projects, from annals of meteorological data and from scientific publications.

One first innovative aspect of the research is that it plans for a wide phase of crucial evaluation and homogenization of data. Such an activity was not carried out when the UCEA archives of the centuries-old series were created, because it is only very recently that the scientific community has fully understood that it is the essential role of this data preparation phase.

The additional innovative aspects are linked with the analysis of parameters that have been studied in Italy up until today only episodically. These include: the monthly averages of pressure and minimum, maximum daily temperatures (and the daily temperature range) and daily values of the temperature and rainfall.

A final innovative aspect consists in applying analytical techniques that, according to what has already been used in other fields, have never been applied to this historical, Italian series.

A first and immediate effects of the project regard the scientific field. In the scientific community today, there is a strong demand for the use of reliable data for the Mediterranean area because there is very limited information regarding as compared to other European areas.

The Italian data are very important because they constitute the basis to understand how climate evolves in this area within an evolution that is present at a larger scale and to locate if such data demonstrate peculiar behaviour.

The identification of the distinct features of a certain geographical zone is very important because the precision of estimating climate evolution obtained by using the general circulation models is reduced when dealing with a smaller spatial resolution . The research results may definitely be used to obtain more trustworthy estimation on the evolution of Italian climate and more in general of the Mediterranean area for the near future. This estimate presents particular economic and social relevance in the areas that are most exposed to various climatic risks (extreme events).

  • Buffoni, L., Maugeri, M. & Nanni, T. 1999: Rainfall in Italy from 1833 to 1996. Theor. Appl. Climatol., 63, 33-40.
  • Brunetti, M., Buffoni, L., Mangianti, F., Maugeri, M. & Nanni, T. 2000a. Urban heat island bias in average northern and central-southern Italian air temperature series. Il Nuovo Cimento, 23C, 423-431.
  • Brunetti, M., Buffoni, L., Maugeri, M. & Nanni, T. 2000b. Trends of minimum and maximum daily temperatures in Italy from 1865 to 1996. Theor. Appl. Climatol., 66, 49-60.
  • Brunetti, M., Mangianti, F, Maugeri, M. & Nanni, T. 2000c. Climate variation in Italy from 1866 to 1995. World Resources Review, 12, 31-43.
  • Brunetti, M., Maugeri, M. & Nanni, T. 2000d. Variations of temperature and rainfall in Italy from 1866 to 1995. Theor. Appl. Climatol., 65, 165-174.
  • Maugeri, M. & Nanni, T. 1998: Surface air temperature variations in Italy: recent trends and an update to 1993. Theor. Appl. Climatol., 61, 191-196.


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