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Metadata Identifier: gov.noaa.ngdc.stp.dmsp:G01123

Aggregation Info | Bands | Citations | Constraints | Coverage Descriptions | Dimensions | Extents | Formats | Geographic Bounding Box
Georectified Information | Georeferenceable Information | Identifiers | Instruments | Mediums | OnlineResources | Operations
Platforms | Process Steps | Range Elements | Reference Systems | Responsible Parties | Series | Sources | Spatial Grids | Temporal Extents

MD_DataIdentification

Count Component Title Abstract
1 DMSP SSM/I- Microwave Imager The SSM/I is a seven-channel, four frequency, linearly-polarized, passive microwave radiometric system which measures atmospheric, ocean and terrain microwave brightness temperatures at 19.35, 22.235, 37.0 and 85.5 GHz. The data are used to obtain synoptic maps of critical atmospheric, oceanographic and selected land parameters on a global scale. The SSM/I archive data set consists of antenna temperatures recorded across a 1,400 km conical scan, satellite ephemeris, earth surface positions for each pixel and instrument calibration. Electromagnetic radiation is polarized by the ambient electric field, scattered by the atmosphere and the Earth's surface and scattered and absorbed by atmospheric water vapor, oxygen, liquid water and ice. The SSM/I instrument consists of an offset parabolic reflector that is 24 x 26 inches fed by a seven- port horn antenna. The reflector and feed are mounted on a drum which contains the radiometers, digital data subsystem, mechanical scanning subsystem and power subsystem. The drum assembly rotates about the axis of the drum. A small mirror and a hot reference absorber are mounted on the assembly. The instrument sweeps a 450 cone around the satellite velocity vector so that the Earth incidence angle is always 540. Data are recorded during the 102.40 of the cone when the antenna beam intercepts the Earth's surface. The channel footprint varies with channel energy, position in the scan, along scan or along track direction and altitude of the satellite. The 85 GHz footprint is the smallest with a 13 x 15 km and the 19 GHz footprint is the largest at 43 x 69 km. Because the 85 GHz footprint is so small, it is sampled twice as often, i.e., 128 times a scan. One data cycle consists of 4 85 GHz scans and 2 scans of the 19, 22 and 37 GHz channels. The complete cycle takes 28 seconds and it must be complete to process the data. The SSM/I processor is queried once a second by onboard computer and the data are placed into the "TS SSP" data field. Data is ingested as sent from AFWA on a T-1 line. At NGDC, the "TS SSP" data are decommutated, deinterleaved, bit flipped, reordered and restructured into orbits beginning with the equatorial crossing as the satellite travels from south to north. Satellite ephemeris are computed using a physically-based, orbital mechanics model. SSM/I pixels are geolocated using the satellite ephemeris and satellite attitude corrections. Antenna temperatures are computed from instrumental counts by a linear equation, i.e., the conversion is reversible. In the decommutation step, we encountered bit reversals that occurred 1.8 - 3.4% of the time and are probably caused by ionospheric scintillation. These are identified through careful checking procedures and corrected. Archive files contain metadata by orbit and geolocated antenna temperatures.
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SV_Identification

none found
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CI_Citation

Count Component Title Date Citation Identifier
1 DMSP Raw Data Records (RDR)
RDR
1 DMSP SSM/I- Microwave Imager
  • 1992-01-01
SSM/I
1 NASA/GCMD Earth Science Keywords
    1 NASA/GCMD Location Keywords
      1 Uncontrolled Keywords
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        CI_Series

        none found
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        CI_ResponsibleParty

        Count Component Individual Organization Position Email Role Linkage
        1 http://www.ngdc.noaa.gov/dmsp/sensors/ssmi.html
        2 DMSP Data Manager DOC/NOAA/NESDIS/NGDC > National Geophysical Data Center, NESDIS, NOAA, U.S. Department of Commerce ngdc.dmsp@noaa.gov pointOfContact
        1 DMSP Data Manager DOC/NOAA/NESDIS/NGDC > National Geophysical Data Center, NESDIS, NOAA, U.S. Department of Commerce ngdc.dmsp@noaa.gov distributor
        1 DMSP Data Manager DOC/NOAA/NESDIS/NGDC > National Geophysical Data Center, NESDIS, NOAA, U.S. Department of Commerce ngdc.dmsp@noaa.gov processor
        1 DOC/NOAA/NESDIS/NGDC > National Geophysical Data Center, NESDIS, NOAA, U.S. Department of Commerce (comp) originator
        2 DOD/USAF/AFWA > Air Force Weather Agency, U.S. Air Force, U.S. Department of Defense originator
        1 Data Manager DOC/NOAA/NESDIS/NGDC > National Geophysical Data Center, NESDIS, NOAA, U.S. Department of Commerce ngdc.dmsp@noaa.gov pointOfContact
        1 National Geophysical Data Center publisher
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        CI_OnlineResource

        Count Component Linkage Name Description Function
        2 http://spidr.ngdc.noaa.gov Spidr interface Download data from Spidr download
        1 http://www.ngdc.noaa.gov/dmsp/sensors/ssmi.html SSM/I- Microwave Imager Home page for the SSM/I sensor information
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        MD_Identifier or RS_Identifier

        Count Component Code
        1 RDR
        1 SSM/I
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        EX_Extent

        Bounding Box Temporal Extent
        Count Component Description West East North South Start End
        1 -180 180 90 -90 1974-04-01
        1 1992-01-01
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        EX_GeographicBoundingBox

        Count Component West East North South
        1 -180 180 90 -90
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        EX_TemporalExtent

        Count Component Start End
        1 1974-04-01
        1 1992-01-01
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        MD_Format

        Count Component Name Version specification
        1 ASCII
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        MD_Medium

        none found
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        MD_Constraints

        Count Component Use Limitation
        1 While every effort has been made to ensure that these data are accurate and reliable within the limits of the current state of the art, NOAA cannot assume liability for any damages caused by any errors or omissions in the data, nor as a result of the failure of the data to function on a particular system. NOAA makes no warranty, expressed or implied, nor does the fact of distribution constitute such a warranty.
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        MD_ReferenceSystem

        none found
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        MD_GridSpatialRepresentation

        none found
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        MD_Georeferenceable or MI_Georeferenceable

        none found
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        MD_Georectified or MI_Georectified

        none found
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        MD_Dimension

        none found
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        MD_CoverageDescription or MI_CoverageDescription

        none found
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        MD_Band or MI_Band

        none found
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        MI_RangeElementDescription

        none found
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        MD_AggregateInformation

        none found
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        LE_Source or LI_Source

        Count Component Title Date Description
        1 DMSP Raw Data Records (RDR) Source Contribution: Used the Raw Data Records Source Type: digital database file
        Unresolved Xlinks
        #RDR at: /gmi:MI_Metadata/gmd:dataQualityInfo[1]/gmd:DQ_DataQuality[1]/gmd:lineage[1]/gmd:LI_Lineage[1]/gmd:processStep[1]/gmi:LE_ProcessStep[1]/gmd:source[1]
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        LE_ProcessStep or LI_ProcessStep

        Count Component DateTime Description
        1 The SSM/I processor is queried once a second by onboard computer and the data are placed into the "TS SSP" data field. Data is ingested as sent from AFWA on a T-1 line. At NGDC, the "TS SSP" data are decommutated, deinterleaved, bit flipped, reordered and restructured into orbits beginning with the equatorial crossing as the satellite travels from south to north. Satellite ephemeris are computed using a physically-based, orbital mechanics model. SSM/I pixels are geolocated using the satellite ephemeris and satellite attitude corrections. Antenna temperatures are computed from instrumental counts by a linear equation, i.e., the conversion is reversible.
        #RDR at Xpath: /gmi:MI_Metadata/gmd:dataQualityInfo[1]/gmd:DQ_DataQuality[1]/gmd:lineage[1]/gmd:LI_Lineage[1]/gmd:processStep[1]/gmi:LE_ProcessStep[1]/gmd:source[1]
        #SSMI at Xpath: /gmi:MI_Metadata/gmd:dataQualityInfo[1]/gmd:DQ_DataQuality[1]/gmd:lineage[1]/gmd:LI_Lineage[1]/gmd:processStep[1]/gmi:LE_ProcessStep[1]/gmi:output[1]
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        MI_Operation

        none found
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        MI_Platform

        none found
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        MI_Instrument

        none found
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