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  <Version>2.3.1</Version>

  <Instrument>

    <ResourceID>spase://CNES/Instrument/CDPP-AMDA/TIMED/SEE</ResourceID>

    <ResourceHeader>
      <ResourceName>SEE</ResourceName>
      <AlternateName>Solar EUV Experiment</AlternateName>
      <ReleaseDate>2019-05-20T21:10:13Z</ReleaseDate>
      <Description>One of the fundamental TIMED mission objectives is to understand the energetics in the mesosphere, 
        lower thermosphere and ionosphere (MLTI). Solar radiation below 200 nm is completely absorbed in the Earth’s 
        mesosphere and thermosphere. Changes in the amount of solar radiation, which range from 20% at the longer wavelengths 
        to factors as much as 1000 at the shorter wavelengths, result in corresponding changes in the photochemistry, 
        dynamics, and energy balance of the upper atmosphere. A detailed quantitative understanding of atmospheric radiative 
        processes, including changes in the solar ultraviolet irradiance arising from flares, solar rotation (27 day), or 
        the 11 year solar cycle, is fundamental to the TIMED investigations. The daily measurement of the full-disk solar 
        vacuum ultraviolet (VUV) irradiance by the SEE directly supports the TIMED mission requirement to measure the 
        sources of energy into the MLTI.

The primary science objectives for SEE are to accurately and precisely determine the solar VUV absolute irradiance and 
variability during the TIMED mission, to study the solar-terrestrial relationships utilizing atmospheric models, and to 
improve proxy models of the solar VUV irradiance. The VUV range of 0 to 200 nm includes the soft x-ray (XUV) from 0 to 30 nm, 
the extreme ultraviolet (EUV) from 0 to 120 nm, and the far ultraviolet (FUV) from 120 to 200 nm.

Solar irradiance data will be provided to the TIMED science team and the solar-terrestrial community in general, and will be 
integrated into the NCAR Thermosphere-Ionosphere-Mesosphere-Electrodynamics General Circulation Model (TIME-GCM) for 
solar-terrestrial studies. The primary SEE data product is its Level 3 data product which includes a solar irradiance 
spectrum in 1 nm intervals on 0.5 nm centers and the irradiance of the brighter 52 emissions in the solar VUV spectrum.

For normal operations, SEE observes the Sun for about 3 minutes 
every orbit (97 minutes), which usually gives 14-15 measurements 
per day. The SEE Level 3 data are time averaged over the entire 
day, after applying corrections for atmospheric absorption, 
degradation, flare removal, and to 1-AU. A suborbital (sounding 
rocket) payload is flown approximately once a year for TIMED SEE 
absolute calibrations.  The first SEE suborbital calibration flight was 
on Feb. 8, 2002, the second was on Aug. 12, 2003, the third was
on Oct. 15, 2004, the fourth was on Oct. 28, 2006, and the final
SEE calibration flight was on Apr. 14, 2008.  There are also three
SDO EVE calibration flights used for checking SEE degradation trends -
May 3, 2010, Mar. 23, 2011, June 23, 2012, Oct 21, 2013, and 
June 1, 2016.
</Description>
      <Contact>       

        <PersonID>spase://CNES/Person/T.Woods</PersonID>

        <Role>PrincipalInvestigator</Role>
      </Contact>
      <InformationURL>
        <Name>SEE home</Name>
        <URL>http://lasp.colorado.edu/home/see/documents/instrument</URL>
      </InformationURL>
    </ResourceHeader>
   <InstrumentType>Photometer</InstrumentType>
    <InvestigationName/>
    <ObservatoryID>spase://CDPP/Observatory/AMDA/TIMED</ObservatoryID>
  </Instrument>
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