Global Historical Climatology Network

The Global Historical Climatology Network (GHCN) is a data set of temperature, precipitation and pressure records managed by the National Climatic Data Center (NCDC), Arizona State University and the Carbon Dioxide Information Analysis Center.

The aggregate data are collected from many continuously reporting fixed stations at the Earth's surface.

Some examples of monitoring variables are the total daily precipitation and maximum and minimum temperature.

Its purpose is to create a global base-line data set that can be compiled from stations worldwide.

[3] This first version, known as Version 1 was a collaboration between research stations and data sets alike to the World Weather Records program and the World Monthly Surface Station Climatology from the National Center for Atmospheric Research.

After this map was created, version 4 of GHCN was released and increase the number of reported stations to over 24,000.

While V1 was the prominent collection of climate data throughout the 1990s, its flaws were slowly appearing and was soon replaced by Version 2 (V2).

V4 is currently made up of 25,000 land-based stations which has become one of the largest collectors of monthly and daily climate data around the world.

[4] Additionally, V4 accounted for previously large issues, such as uncertainties, differences in scale, as well as the aforementioned homogenization.