NCEI uses a standalone Java version that only depends on the Apache Commons Compress library. Several decoders are available for the BZip2 block compression, including decoders integrated into the Unidata NetCDF-Java library and Department of Energy (DOE) PyART. The files in the NCEI archive do not use the BZip2 block compression and exist in the uncompressed Message-1 or Message-31 format, with Gzip compression applied to the entire file. The format of the volume scan files is unique and will not decompress with standard BZip2 decompression tools. Full volume scan files are created by linking together blocks and arranging them based on scanning order . The data sections are compressed using BZip2. These blocks include header and data sections. The real-time Next Generation Weather Radar (NEXRAD) Level-2 data transmission uses several blocks of data per sweep. Several free and currently supported decoders are available, including the following programs: Level-2 NEXRAD BZip2 Block Decoder Radar data needs to be decoded with special software before it can be opened.
