Inside the instrument shelter, the MMCR data system collects radar spectral data and processes these into reflectivity, vertical velocities, and spectral width.

As a result of upgrades to the Millimeter Wave Cloud Radar (MMCR) processors (see http://www.arm.gov/acrf/updates051504.stm#nsammcr) at the ACRF Southern Great Plains (SGP) and North Slope of Alaska (NSA) locales, two MMCR data streams—mmcrcalC1.a1 (calibration data) and mmcrmomentsC1.a1 (spectral “moments” data)—have been combined to produce a new data stream—mmcrmomC1.b1. The data Archive contains the new data stream for SGP as of September 9, 2003, and for NSA as of April 14, 2004. Processor upgrades for the MMCR at the ACRF Tropical Western Pacific (TWP) locale are expected to occur this coming fall and winter. Until then, the TWP MMCRs will continue to generate the mmcrcalC1.a1 and mmcrmomentsC1.a1 data streams.

A data stream represents the output of a single data source (i.e., instrument, instrument group, or algorithm). Overhauling the MMCR processors has brought faster data collection, continuous collection of spectral data, and (currently at NSA only) new modes of data collection intended to improve boundary layer cloud detection. The new mode sequence, with the addition of a polarization mode, is planned to begin running at SGP in July. MMCR data are now being collected approximately every 2 seconds! The new MMCR processors also continuously record spectral data, which is available in a separate data stream—mmcrspecmom. Spectral data from the SGP and NSA are available via the “Power User” option at the Archive.

Although every effort was made to preserve the previous data formats where feasible, a number of changes needed to be made to the field names in the interest of improving the MMCR data product. A field-by-field comparison of the data streams and a sample netCDF header for the new sgpmmcrmomC1.b1 files are available at http://www.gim.bnl.gov/armclouds/mmcr/mmcrMomNewVsOldDataStreams.html. However, the data stream naming convention remains the same; depending on the parameters, the file name identifies the site, time intervals, instrument, type of data collected, facilities, and level of data processing, in that order. Previous mmcrcal and mmcrmoments data are expected to be reprocessed using the new mmcrmom data format.