This site provides two types of meteorological data: (1) surface data, and (2) upper air data.

Surface data are meteorological data that are measured at the earth’s surface (technically, somewhere between the ground level and 10m). This data contains physical parameters that are measured directly by instrumentation, such as temperature, dew point, wind direction, wind speed, cloud cover, cloud layer(s), ceiling height, visibility, current weather, and precipitation amount. Surface data are reported by the National Weather Service for each hour.

Upper air data are meteorological data that are measured in the vertical layers of the atmosphere. Upper air data are usually measured by twice daily radionsonde soundings, taken at 00 and 12Z (Greenwich time). There are other collection methods for gathering upper air data, though radiosonde soundings are the method usually employed for local-scale dispersion modeling.

Surface Databases

• SCRAM Surface Archived Data (TD-1440)
  SCRAM Archived Data (TD-1440) are compressed WBAN Hourly Surface Observations (TD-1440) format data, provided through compressed data files containing 1984-1992, with all 9 years in a single file. Although this database is no longer supported by NCDC and is not Y2K compliant, some meteorological processors, such as PCRAMMET, MPRM, and AERMET, can accept this format.

• SAMSON (Solar and Meteorological Surface Observation Network) Exit
  Data containing U.S. surface and solar data for 1961-1990. This dataset contains all of the observed data parameters taken at 1st order National Weather Service locations, as well as solar data as provided by the National Renewable Energy Laboratory (NREL). NCDC provides this data on 3 CDs.

• HUSWO (Hourly Surface Weather Observations) Exit
  These data contain all observed U.S. surface data for 1990-1995 taken at 1st order National Weather Service locations. These data are a follow-up to the SAMSON data (partially funded by EPA), but do not contain solar data. NCDC provides this data on 1 CD.

• Precipitation Database (TD-3240) Exit
  A precipitation ONLY database, where data is compiled from cooperative station information, with a station number based on the cooperative network. There are 2 formats available, fixed and variable length, which most models readily accept. TD-3240 data is provided by NCDC on 2 CDs, and contains data January 1948 through June 1998, although some data starting in 1900 are available.

Upper Air Databases

• NOAA/ESRL Radiosonde Database Exit
  This is a standard upper air database containing 1946-1997 data, provided by NCDC on 4 CDs in the original FSL (Forecast Systems Laboratory) format. Upper air data for 1998 - Present are also available.

• Integrated Global Radiosonde Archive (IGRA) dataset Exit
  IGRA is the largest and most comprehensive dataset of quality-assured radiosonde observations freely available for 1948 - present.

• SCRAM Mixing Height Archived Data
  Hourly mixing heights for 1984-1991, computed by NCDC using a program based on the original mixing height documentation by Holzworth (1972). The SCRAM Mixing Height Program will provide similar results. Each file, designated by State, contains multiple mixing height files for upper air sites across the U.S. for 1984-1991. (1992 mixing heights not available).