This ASCII data set (DATSAV3) is produced at the National Climatic
Data Center (NCDC) from a USAF binary set (DATSAV2), a collection of
worldwide surface weather observations from sources such as the the
Global Telecommunications System (GTS) and Automated Weather Network
(AWN). The Air Force Weather Agency (AFWA) decoded most of the
collected observations for the Air Force Combat Climatology Center
(AFCCC) where final decoding, validation, and quality control
Mandatory data includes pressure, temperature, visibility, sky
condition, and wind observation, but there may also be additional
data, data remarks, or data element quality sections.
NCDC provides quarterly updates to DSS, usually with a two-month
delay. The earliest data is for 1901. The earliest years have the
least volume of data, a few hundred megabytes; the volume in the
1950s-early 1960s increased by a factor of 10-20; 1965-1972 shows a
decrease because of a loss of data; beginning in 1973 with about 5
gigabytes of data, volume has gradually increased to about 20
gigabytes per year. There are now about 10,000 active stations.
Similar data sets prepared by the National Centers for Environmental
Prediction (NCEP) are ds464.0
[http://rda.ucar.edu/datasets/ds464.0/] (beginning February 1975),
and ds461.0 [http://rda.ucar.edu/datasets/ds461.0/] (beginning April
This dataset has been superseded by ds463.3 [/datasets/ds463.3/].