What are Level I data?
Level I data are the raw time series data received by the Receiver/Signal Processor (RSP) and subsequently processed to generate Level II data. Separate files are generated for each elevation in a volume scan. The Level I data are not used operationally, but are useful for algorithm development and verification. Unlike Level II and III data, this data is not collected regularly or disseminated in real time. Level I data is only collected for specific cases when the Radar Operations Center determines the data will be useful. Priority is placed on collecting data for newer VCPs or atmospheric conditions which have not been collected in previous data sets. All collected data are sent to the National Centers for Environmental Information (NCEI) for archiving. This includes event data from operational and testbed radar sites.

The interface control document describing the NEXRAD Level I data format is available at: https://www.roc.noaa.gov/WSR88D/PublicDocs/ICDs/26200076.pdf

Event data which has been archived is available for download from the National Centers for Environmental Information (NCEI) here: https://www.ncei.noaa.gov/access/search/data-search/nexrad-level-1-event-data

The NCEI Level I data page can be found here: https://www.ncei.noaa.gov/metadata/geoportal/rest/metadata/item/gov.noaa.ncdc:C01597/html