CDPP / CNES

Commit fa9cdd2b531566df58193f7a6565de7a1140858d

Authored by Elena.Budnik
1 parent e74bdf82
Exists in master and in 12 other branches amdadev, aschulz, autocommit, bepi_master, bepi_update, branch_q, cleanup_registry, cleanup_registry_master, cleanup_registry_merged, juice_jdc, juno_jade, soar

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Instrument/AMDA/IMP8/PLS.xml
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4 4 <Instrument>
5 5 <ResourceID>spase://CDPP/Instrument/AMDA/IMP8/PLS</ResourceID>
6 6 <ResourceHeader>
7   - <ResourceName>IMP 8 Solar Plasma Faraday Cup</ResourceName>
  7 + <ResourceName>MIT</ResourceName>
8 8 <AlternateName>IMP 8 PLS</AlternateName>
9 9 <AlternateName>IMP 8 PLA</AlternateName>
10 10 <AlternateName>1973-078A-02</AlternateName>
11 11 <ReleaseDate>2010-02-04T12:34:56.789</ReleaseDate>
12   - <Description>A modulated split-collector Faraday cup, perpendicular to the spacecraft spin axis, was used to study the directional intensity of positive ions and electrons in the solar wind, transition region, and magnetotail. The collector plate split is perpendicular to the spacecraft spin axis in order to measure the flow angle of the ions in a meridional plane; the flow angle in the spacecraft equatorial plane is determined from the fluxes measured as the spacecraft rotates.
13   - Electrons are measured using 21 logarithmically-spaced energy windows covering the energy/charge range between 23 and 1935 volts. Positive ions are studied using 24 energy windows covering the range between 50 and 7000 volts.
14   - The instrument has three operating modes. The tracking mode yields the best time resolution which is about 1 minute. A single energy window is used during a spacecraft rotation. The ion spectrum is obtained in eight spacecraft revolutions using a subset of the energy windows that track the peak of the solar wind. In this mode, fluxes are measured during 11.25-degree sectors of the spacecraft spin while the instrument is looking within the 90 degree sector centered on the sun direction and during 45 degree sectors for the remainder of the rotation. The other modes yield a spectrum using all 24 windows (with the same angular sectors described above) or a spectrum that results from integrating the observed fluxes over 45 degree sectors for the entire spacecraft rotation.
15   - Electron data are obtained in all modes, but are not usually analyzed.
16   - Parameters derived on a routine basis are proton velocity, number density, and temperature (most probable thermal speed). Those parameters are obtained from a non-linear, least-squares fit to the observed fluxes using a convected, isotropic Maxwellian model.
17   - Key Parameters for the Plasma instrument are computed at MIT using Level Zero data that are staged to the ISTP/CDHF approximately two weeks after being received on Earth. Thus the plasma instrument's Key Parameters lag real time by something greater than 2 weeks, but less than four.</Description>
  12 + <Description>
  13 + MIT data are taken from nssdcftp.gsfc.nasa.gov//spacecraft_data/imp/imp8/plasma_mit/sw_msheath_min
  14 +
  15 + MIT Team notes:
  16 + The parameter values: MIT 'better' parameters are under 'mit_BestFit'. 'mit_Raw' are parameters usually derived from taking moments of the distributions. As can be seen easily by eye, there is some discrepancy between moments and MIT best parameters; moments are definitely less accurate.
  17 + Use moment values with caution, and PLEASE request assistance or clarification. For the moment parameters, changes in value are more trustworthy than absolute values, but nothing is guaranteed to be accurate. A value of 9999.0 means that we couldn't calculate that parameter. All parameters are based on a convected, isotropic Maxwellian model. We recommend that, in the absence of data other than moment values, you try to obtain the IMP 8 LANL experiment plasma values as well at http://nssdc.gsfc.nasa.gov/ftphelper/imp8_lanl_2m.html
  18 + Speeds and thermal speeds are given in km/s. Effects due to the orbital motion of Earth are removed from the better parameters, but not from the moment parameters
  19 + Thermal speed is the most probable thermal speed (i.e., the square root of [2kT/m(proton)]). To convert thermal speed to temperature in eV, multiply 0.0052 by the square of the thermal speed; to convert to temperature [K], multiply the square of the thermal speed by 60.5 . This is probably the most inaccurate moment parameter, since moments tend to underestimate the temperature in cold distributions.
  20 + The angles are in degrees. Azimuth is E/W, meaning bulk flow from the East or the West side of the Sun respectively, while flow elevation is from North or South of the s/c spin plane (almost identical to the plane of the ecliptic). For signs, positive azimuth angle means flow from the W; positive elevation angle means flow from the S. If we don't get good angles, there won't be get any velocity components; speeds are available in some such cases. The aberration in velocity due to Earth's motion around the Sun has been removed from the best values, but not from the moment values "Threshsp" values are determined from currents greater than a threshold value, below which we are not confident about the contribution of noise. Dr. Joseph King (GSFC) has looked at 27-day averages of OMNIWeb data from 1984-1994. He finds (and we agree) that there is an offset of about +2 degrees (from the South) in the N/S angle and an annual variation of that angle with an amplitude of about 1 degree. We believe that the annual variation is due to a tilt of the s/c spin axis. He found the mean flow longitude in that study to be -0.3 degrees with no obvious annual variation.
  21 + The moment values, for angles and for the speed, do NOT have aberration corrections included. This means that the total speeds are slightly too low, and that the angles are not really correct. In particular, the azimuthal (E/W) angle is about 4 degrees too positive; this can clearly be seen where both nonlinear and moment angles are available.
  22 + For papers and presentations using these data, please acknowledge that you received them from the MIT Space Plasma Physics Group. Please feel free to contact us if you have questions about any parameters.
  23 + Please send us a copy of papers, presentations, et cetera using these data.
  24 + If you have any questions, please contact Ms. Pamela A. Milligan pam@space.mit.edu Dr. Alan J. Lazarus ajl@space.mit.edu Dr. John Richardson jdr@space.mit.edu
  25 +
  26 +
  27 + ADDITIONAL COMMENTS
  28 + IMP 8 spins with a period of approximately 2.7s. The Faraday Cup (FC) instrument scans the solar wind distribution stepping through a contiguous set of energy windows, one step per spacecraft spin. The FC instrument divides the spin into thirty-two, 11.25 degree angular sectors and integrates the measured currents over different angular sectors depending upon the Mode in which the instrument is operating. The border between two of the 11.25 degree angular sectors lies on the Sun-spacecraft line.
  29 + The FC sensor collector plate is divided into two, semi-circular halves; the division line is parallel to the spacecraft spin plane which is approximately parallel to the ecliptic plane. The split collector allow determination of the bulk plasma flow relative to the spin plane; North/South angles refer to flows coming from above or below the spin plane respectively (flows from the South are designated as having a positive N/S angle). The bulk flow angle in the spin plane is determined from the measurements of current vs. rotation angle. The currents telemetered to the ground are the sums of currents for the two half-collectors ("A" and "B"} and, for the TMS and AQM modes, also the current for the half-collector "B". Electrons are measured except for the eight angles near the Sun.</Description>
18 30 <Contact>
19 31 <PersonID>spase://SMWG/Person/Alan.J.Lazarus</PersonID>
20 32 <Role>PrincipalInvestigator</Role>
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NumericalData/AMDA/IMP-8/MIT/imp-mit-k0.xml
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4 4 <NumericalData>
5 5 <ResourceID>spase://CDPP/NumericalData/AMDA/IMP-8/MIT/imp-mit-k0</ResourceID>
6 6 <ResourceHeader>
7   - <ResourceName>IMP 8 MIT Full Resolution Definitive Interplanetary Plasma Data</ResourceName>
  7 + <ResourceName>best fit</ResourceName>
8 8 <AlternateName>IMP 8 Solar Wind Plasma Faraday Cup Data</AlternateName>
9 9 <ReleaseDate>2015-10-16T16:25:59Z</ReleaseDate>
10 10 <Description>The MIT Faraday cup experiment on IMP 8 measures
... ... @@ -86,7 +86,7 @@ which you accessed the data.&lt;/Acknowledgement&gt;
86 86 <ObservedRegion>Heliosphere.NearEarth</ObservedRegion>
87 87 <ObservedRegion>Earth.Magnetosheath</ObservedRegion>
88 88 <Parameter>
89   - <Name>Proton density fit</Name>
  89 + <Name>density</Name>
90 90 <ParameterKey>imp_mit_nfit</ParameterKey>
91 91 <Description>(Better, from fits) Proton number density</Description>
92 92 <Ucd>phys.density;phys.atmol.ionStage</Ucd>
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107 107 </Particle>
108 108 </Parameter>
109 109 <Parameter>
110   - <Name>V fit</Name>
  110 + <Name>v_bulk</Name>
111 111 <ParameterKey>imp_mit_vfit</ParameterKey>
112 112 <Description>(Better, from fits) Ion Flow Velocity (aberration corrected)</Description>
113 113 <Ucd>phys.veloc;phys.atmol.ionStage</Ucd>
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132 132 </Particle>
133 133 </Parameter>
134 134 <Parameter>
135   - <Name>Proton V thermal fit</Name>
  135 + <Name>v_thermal</Name>
136 136 <ParameterKey>imp_mit_vthfit</ParameterKey>
137 137 <Description>(Better, from fits) Proton most-probable thermal
138 138 speed (aberration corrected). Thermal speed is the most probable thermal
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158 158 </Particle>
159 159 </Parameter>
160 160 <Parameter>
161   - <Name>E/W flow angle best</Name>
  161 + <Name>flow angle e/w</Name>
162 162 <ParameterKey>imp_mit_velewfit</ParameterKey>
163 163 <Description>(Best, from fits) Proton East/West flow angle
164 164 (aberration corrected). Azimuth is E/W, meaning bulk flow from the East
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185 185 </Particle>
186 186 </Parameter>
187 187 <Parameter>
188   - <Name>N/S flow angle best</Name>
  188 + <Name>flow angle n/s</Name>
189 189 <ParameterKey>imp_mit_velnsfit</ParameterKey>
190 190 <Description>(Best, from fits) Proton North/South flow angle
191 191 (aberration corrected). Azimuth is N/S, meaning bulk flow from the North
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