NCEP ADP ETA / NAM Upper Air Observation Subsets are composed of a
regional synoptic set of upper air reports centered over North
America, operationally collected by the National Centers for
Environmental Prediction (NCEP). These include radiosondes, pibals
and aircraft reports from the Global Telecommunications System (GTS)
and satellite data from the National Environmental Satellite Data
and Information Service (NESDIS). The reports can include pressure,
geopotential height, temperature, dew point depression, wind
direction and speed. Data may be available at up to 20 mandatory
levels from 1000 millibars to 1 millibar, plus a few significant
levels. Report time intervals range from 3 hourly to 12 hourly.
These data are the primary input to the EDAS / NAM Data Assimilation
System (NDAS starting January 23, 2005). DS351.0
[https://rda.ucar.edu/datasets/ds351.0/] provides global data
coverage over the same time period.
This data set is no longer updated.
If you have a need for North American data that is not met by
DS351.0 NCEP ADP Global Upper Air Observational Weather Data,
October 1999 - continuing [https://rda.ucar.edu/datasets/ds351.0/],
contact the RDA for alternatives.