DescriptionSurface land and maritime observing stations report various meteorological variables that describe the current weather. These variables include basic measurements such as temperature, relative humidity, wind, precipitation, etc., as well as various types of weather occurrences such as hail, fog, and thunder.
The MADIS meteorological surface dataset includes reports from many observing networks run by different "providers". Through the MADIS API, the user can select only a subset of the total by specifying which providers to include or exclude. Most national-scale networks in North America that report surface conditions are included. Over land, this includes all stations that report standard METARs (ASOS, AWOS, non-automated stations) or SAOs (Canadian stations), the National Mesonet/UrbaNet mesonet, as well as reports from climate networks such as the Climate Reference Network (CRN), the U.S. Historical Climatology Network - Modernization (USHCN-M), and the New England Pilot Project (NEPP). Maritime reports are also available, including the Coastal Marine Automated Network (C-MAN), fixed and drifting buoys, and ship reports.
The MADIS meteorological surface dataset also contains a unique collection of thousands of mesonet stations from local, state, and federal agencies, and private firms.
The "High Frequency METAR" dataset consists of experimental 5-minute observations from select Automated Surface Observing System (ASOS) stations, and from Automated Weather Observing System (AWOS) stations. These stations are also included in the standard METAR dataset, which has mostly hourly reports. The stations report an "AWOS Format Weather Message" each minute to the distributed FAA AWOS Data Acquisition System (ADAS). The data from all the ADAS units are then conglomerated at the FAA William J. Hughes Technical Center near Atlantic City, NJ, where they will be routed to MADIS. Currently, MADIS is receiving about 440 stations via a feed courtesy of the Massachusetts Institute of Technology Lincoln Laboratory (click here, to see a map of the station locations).
The National Mesonet/UrbaNet mesonet and some of the other mesonets are restricted. Click here for details.
- Integrated Mesonet Data Providers and Station Counts
- National Mesonet/UrbaNet Data Providers and Station Counts
- Total Meteorological Surface Station Counts
Geographic CoverageThe geographic coverage is densest over North and Central America, plus Hawaii (METAR, maritime, CRN, mesonet, SAO - Canada only). Global datasets include maritime and METAR, along with some mesonets: APRSWXNET has a significant number of global observations, and the PCDINPE mesonet is in Brazil.
Data ScheduleData arrive on a continuous, asynchronous schedule, and the current and previous hour's data are processed every 5 minutes. In order to get regularly-scheduled hourly reports from the standard national data sources (METAR, SAO, and maritime) these files contain data starting 15 minutes before the hour and ending 44 minutes after the hour (e.g., the 0000 file covers 2345 - 0044). With the other surface datasets, the data are segmented into hourly files, with the file for hour HH containing data for HH00 through HH59. The most complete data for a given hour is available a little after 2 hours following the file time. The user should also understand that some of the mesonet networks aren't as timely as the national data sources. The lag time of these reports (lag = time available from MADIS - observation time) ranges from about 8 to 45 minutes, and can sometimes be longer.
Data that arrive after 2 hours following the time of the observation are processed in a "data recovery" mode, where once a day batch processing is performed to reprocess data that are 35 day's, 7 day's old, and 1 day old. These data are available with all communications methods supported by MADIS except for ldm.
VolumeTypical daily volume for all MADIS datasets can be seen here.
Most of the mesonets have all of the basic meteorogical variables (e.g., air temperature, relative humidity and/or dewpoint temperature, wind speed and direction, pressure), but only a subset of mesonets have variables such as soil temperature, etc. Also, different kinds of precipitation measurements are taken by the different mesonets.
This is the definitive United States standard for the Aviation Routine Weather Report/Aviation Selected Special Weather Report (METAR/SPECI) code formats.
The NWS ASOS home page.
The home page of the NWS center responsible for data buoys and C-MAN stations.
Links to the various surface network providers.