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Global Historical Climatology Network - Daily

Description - Coverage

GHCN-Daily contains over 75000 stations, approximately 20000 of which are regularly updated with observations from within the last month. While most of the sites report precipitation, daily maximum and minimum temperatures are also available from more than 25,000 sites, and many stations in North America also report snowfall and snow depth. Snow depth observations for stations outside of the United States originate from the synoptic reports in the Global Summary of the Day.

The interval covered by GHCN-Daily station records varies from less than one year up to over 175 years, with the average temperature record spanning about 36 years and the average precipitation record lasting about 33 years. Currently, the earliest observation in the dataset is a daily precipitation total recorded on January 1, 1832 at Parramatta, Australia (GHCN-Daily ID = ASN00066046; total = 0.0 mm). The earliest maximum and minimum temperature measurements are from January 2, 1833 at Uccle, Belgium (GHCN-Daily ID = BE000006447; maximum temperature = -1.4°C and minimum temperature = -4.8°C). Uccle, a GCOS Surface Network station, is still active and provides the longest daily station record in the dataset.

Maps indicating the density of stations that have at least 10 years of precipitation or temperature records during successive 30-year intervals starting in 1861 are provided below.









Like GHCN-Monthly, the concentration of stations with observations of temperature or precipitation in GHCN-Daily is denser over North America and Eurasia than over Africa, Antarctica, and South America. In the case of GHCN-Daily, however, the densest historical station networks come from the United States, Canada and Australia--a reflection of the comprehensive contributions from these countries. Nevertheless, Brazil, India, and South Africa have also contributed records from very dense national precipitation networks.

The temporal evolution of the station network is such that daily summaries are available from a relatively small number of stations before 1890 when the number of stations reporting maximum and minimum temperature (precipitation) is about 2.5% (8.9%) of the peak number. The total number, spatial distribution, and temporal completeness generally increase through time for all variables, although both the temperature and precipitation networks attain their maximum density in the 1960s. For the periods of record of individual stations and elements, see the GHCN-Daily inventory.
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Last Updated Thursday, 10-Sep-2009 10:59:38 EDT by
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