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NAMMA High Altitude MMIC Sounding Radiometer (HAMSR) Table of Contents
Introduction HAMSR is a microwave atmospheric sounder, a small but accurate instrument that is well suited for hurricane and tropical storm studies. It provides measurements that can be used to infer the 3-D distribution of temperature, water vapor, and liquid water in the atmosphere, even in the presence of clouds. Parameters related to scattering from ice particles aloft as well as precipitation can also be inferred. During the NAMMA experiment, HAMSR flew on the NASA DC-8 research aircraft. CampaignThese data files were generated during support of the NASA African Monsoon Multidisciplinary Analyses (NAMMA) campaign, a field research investigation sponsored by the Science Mission Directorate of the National Aeronautics and Space Administration (NASA). This mission was based in the Cape Verde Islands, 350 miles off the coast of Senegal in west Africa. Commencing in August 2006, NASA scientists employed surface observation networks and aircraft to characterize the evolution and structure of African Easterly Waves (AEWs) and Mesoscale Convective Systems over continental western Africa, and their associated impacts on regional water and energy budgets. For more information about the NAMMA Campaign, go to the NAMMA web site: http://namma.nsstc.nasa.gov/ Instrument DescriptionHAMSR is a 25-channel microwave atmospheric sounder operating as a cross-track scanner. It operates in three frequency bands centered around 53, 118 and 183 GHz. HAMSR functionality is similar to AMSU-A/B, but with additional channels. There are three bands: an 8-channel band near 50-GHz, used for primary temperature sounding; a 10-channel band near 118 GHz, used for secondary temperature sounding and assessment of scattering; and a 7-channel band near 183 GHz, used for water vapor (humidity) sounding. The instrument is continuously self-calibrating using internal calibration targets. Radiometric sensitivity at the composite sampling cells provided in the archive is typically 0.1 K and ranges up to 0.25 K for the stratospheric channels. Calibration accuracy is estimated at better than 1 K for temperature sounding and better than 2 K for water vapor sounding. Temperature weighting function peaks are distributed between the surface and the flight altitude. The scan mirror makes a full revolution in a little more than 1 second, for a temporal resolution of one cross-track scan set every 10.4 seconds. During that period it obtains a number of overlapping spatial samples of the scene below and several views of two internal calibration targets. From an altitude of 20 km the scan width is about 40 km wide on the ground with a single field of view of 2 km at nadir. Sampling intervals are 1 km cross-track. Additional information about the HAMSR instrument may be found in the PDF document Hurricane Studies With HAMSR. Data ProductsThe primary derived measurements are vertical profiles of temperature, water vapor and liquid water, from the surface to 100 mb in 2-4 km layers. The data provider has supplied an excel spreadsheet that shows the status and quality of the data from each frequency band during each DC-8 mission: NAMMA_instrument_status_HAMSR.xls Data Format and File NamingData are in HDF format. There is one data file for each DC-8 flight (mission). The File naming convention for the data files is:
where namma identifies the campaign , hamsr identifies the instrument, yyyymmdd is the year, month and day, nnnn is the number of data records, and the file extension is hdf for HDF format files. There are quicklook browse image files which look like:
where namma identifies the campaign, hamsr identifies the instrument, fff is the frequency in gigahertz, yyyymmdd is the year, month and day, hhMMss is the hour, minute and second (first is start time and second is stop time), and the file extension is jpg which is the type of browse file. For additional information about these data files, refer to: HAMSR HDF Data Description. The HDF format may be read using any common HDF reader. More information about HDF may be found at the HDF Group homepage. Contact InformationThe data producer is:
To order these data or for further information, please contact:
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