The surface station temperature record consists of a collection of daily thermometer readings from locations all around the world, with the record going back up to over 150 years in some locations. The longest data record is 'Central England Temperature' (CET), which goes back to 1659. Most records are far shorter, with the most extensive coming from the continental U.S. These temperature recordings are used as inputs into or validation against some climate models. If the records are combined into annual average temperatures, they can be used to show changes in temperature over time. It is generally accepted in the climate community that the world has warmed about .8 degrees Celsius in the past century with relative warming until the late 1930s, cooling until the 1970s, and then warming again afterward.
Surface station records require various adjustments before they can be used as measurements of temperature change over time, such as the TOB and UHI bias adjustments (see Time of Observation Bias (TOB) and Urban Heat Island (UHI)).
Surface Station Auditing
The National Oceanographic and Atmospheric Administration (NOAA) is responsible for the operation, documentation and upkeep of the United States Historical Climatological Network (USHCN) set of weather stations. In 1997 a National Research Council panel expressed concerns about the state of the network and its ability to acquire data suitable for climate monitoring. Despite continuing complaints for ten years, no systematic efforts were made even to document the condition of the network. Finally, in 2007 after discovering several stations totally out of compliance with published standards, meteorologist Anthony Watts organized a grassroots effort with a network of hundreds of volunteers to survey and photograph all 1221 stations in the USHCN. This project, currently in progress, led to the creation of the surfacestations.org http://www.surfacestations.org/ website. Because very little current physical site condition data exists in the public domain, the goals of the project are:
To provide a standardized method for site survey and reporting so that interested individuals can gather site survey data, pictures, and anecdotal history of climate recording sites worldwide, and upload for screening.
To provide a repository for screened and approved qualitative and quantitative site survey data, pictures, and anecdotal history.
To provide a searchable database of such information for USHCN and GHCN climate station sites.
To photographically document good sites that have been well preserved and maintained through their history.
To photographically document poor examples of sites that may introduce biases and errors through faulty siting, encroachments, or maintenance issues, and to identify specific issues when possible.
As of November 2007 about one third of the USHCN station sites had been surveyed. Preliminary analysis of the data show a substantial number of stations are compromised by nearby structures, vegetation, asphalt parking lots, and unnatural heat sources such as air conditioning exhaust, automobiles, and barbeque grills. These "microsite" problems have been assessed using [french study] that ranks the station quality on a scale of 1 (high quality) to 5 (low quality). Using the currently surveyed USHCN stations, only four percent qualify as "1" and only nine percent qualify as "2". [Include position of GISS on this matter (microsite bias and how problematic it is post-adjusting)].