(Last update: 15/12/2015)
This site is maintained because it has been publicized in various documents
and other web sites, but most of its former contents have been moved to other
sites. Please, update your links and bookmarks:
Current data acquisition is generally either made by automatic means or
routinely entered into computer files, ready to be used for different
applications. But a good wealth of old data remains in original paper support,
and Data Rescue (DARE) activities are needed to ensure their preservation and
digitization in order to extend backwards our knowledge about climate. NMHS
have DARE projects in different degrees of development, and there are several
international initiatives promoting DARE activities worldwide:
- Atmospheric Circulation Reconstructions over the Earth (ACRE)
- International Environmental Data Rescue Organization (IEDRO)
- WMO sponsored Mediterranean climate DAta REscue
- International Surface Temperature Initiative (ISTI)
- Climate of the Carpatian Region (CARPATCLIM)
- NOAA's Climate Database Modernization Program (CDMP)
CDMP 19th Century Forts and Voluntary Observers Database Build Project
- ARPA Sardegna and ARPA Liguria are digitizing thermo-pluviometric series for their regions, rescued from the
Annali Idrologici del Servizio Idrografico, within the Project RESMAR, partly funded by E.U. Operational
Program "Italia-Francia Marittimo"
Data Rescue activities can be seen as composed of a few distinctive steps:
- Imaging of the historic data documents, either by photographing or scanning them
in standard digital computer formats. Any analogue micro-forms must also be
converted to digital files. Afterwards, paper documents must be preserved in adequate
archives, as digital images should be the primary source for the following steps. Conservation of digital
images will include backup copies and a policy of conversion to open emerging formats to
- Digitizing the images obtained in step 1 to allow computer processing of the data.
Scanned typewritten documents can be treated with an OCR (Optical Character Recognition) program;
otherwise human mechanization will be needed, either with
ad hoc input programs or with simple spread sheets. After some basic Quality Controls
on the data, they can be transferred to the preferred database system.
- Data rescue ends here, but before being used for climate analysis, rescued series
must be further quality controlled and homogenized to remove the frequent alterations
due to non-climatic factors. Errors originated during the digitization process must be
corrected, but otherwise the raw series must be kept untouched, since different
homogenization procedures can yield (slightly) different homogenized series.
Homogenized series, however, will be preferred source for climate studies.
According to an old Chinese proverb, an image is worth more than a thousand words,
but it also occupies more space in digital storage! To limit the file size of images,
binary black&white scan modes are often used. But since the price of computer storage is
continuously decreasing, gray or color scale modes are to be preferred, since the black&white threshold
cannot be adapted to the requirements of all pages of a document and therefore information
will be lost in the faintest sheets, where a grey scale image could still be interpretable by a
Additional information can be found at the
WCDMP web page, including the publication Guidelines on Climate Data Rescue
(WMO-Td No. 1210).