DescriptionRadiosondes are balloon-borne instruments that are carried aloft to measure soundings of wind, temperature, moisture and geopotential height at different atmospheric pressure levels. The synoptic observing programs of the United States and other WMO countries typically provide one to four soundings per day from stations spaced approximately 250 km apart over large land areas and 1000 km over sparsely populated and oceanic regions. The average continental U.S. station separation is currently 315 km, and two observations are scheduled daily (valid at 0000 and 1200 UTC).
The MADIS radiosonde dataset provides data from all stations in North America, as well as observations from many other stations around the globe.
Geographic CoverageThe geographic coverage is global.
Data ScheduleRadiosonde data are processed in 3-hour chunks. For HH = 00, 03, ..., 21; the processing is run and data made available every 10 minutes from HH + 4 minutes, through HH + 124 minutes; and a final processing run is made at HH + 12 hours + 4 minutes. The data are segmented into hourly files. The vast majority of the observations are at the synoptic times of 0000 and 1200. Most of the North American data can be found in those files, although some stations report during hours 1100 and 2300. Stations outside North America also tend to report on this 12 hour schedule, but a lot of these reports go into the 1100 and 2300 files. About 40% of all reports for hour HH are available at HH + 54 minutes, with most of the rest available by HH + 94 minutes.
VolumeTypical daily volume for all MADIS datasets can be seen here.
This handbook prescribes federal standards for taking radiosonde observations; for processing the observations; and for encoding, telecommunicating, and archiving the data. This is a good source of technical details concerning how these observations are created.
The home page of the NWS branch responsible for U.S. radiosonde operations.
This page, from Michigan Technical University, is a useful collection of links to other radiosonde-related pages.