POLAR TIMAS
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SUMMARY PLOTS
These plots provide an overview of high resolution ion pitch angle distributions and net ion
outflow for perigee passes from launch until December 8, 1998.
See also the EJD and PA plot types.
First (top) color panel
- Pitch angle distribution of H+ obtained by integrating over the energy range 0.6 < E/Q < 4.5 keV
- Number flux in units of (cm^2-s-sr-keV/e)^-1 is encoded using the color bar on the right
- All perigee data are from the southern hemisphere, so a pitch angle of 0 degrees corresponds to ions flowing
up the field line from the ionosphere
below.
- Weak or missing fluxes near 0 degrees pitch angle indicate the existesnce of an "ion loss cone" type
distribution.
Second color panel
- Pitch angle distribution of H+ integrated over the energy range 16 < E/Q < 600 eV
- Same format as first color panel
Solid lines between second and third color panels
- Color of upper line indicates source of H+ data
- Color of lower line indicates source of O+ data
- Green indicates data are from PAD data products and therefore have the highest angular resolution (~11 degrees) available from the TIMAS
instrument.
- PAD's (Pitch Angle Data product) are intended to provide the maximum angular resolution attainable from the
TIMAS where it is reasonable to assume the distributions are
gyrotropic in the measurement frame. PADs are again specified independently by detector half and M/Q; however,
they are further specified by the
number of pitch angle elements required and whether or not the data are summed over adjacent energy steps. The
Data Processor uses the MAGAZ and
MAGEL signals provided by the spacecraft to select the 9 detector sector elements that best characterize the
pitch angle distribution for each
detector half in either the first or both spin sectors that intercept the magnetic field vector within the
TIMAS field of view. Each PAD consists
of 63, 126, or 252 energy, pitch-angle elements. See This Page for more
information about onboard acquisition and
processing of data.
- Orange indicates the data are from MRDF data products with medium angular resolution (~22 degrees).
- As with the LRDF described below, the MRDF are defined independently by detector half and M/Q; however,
MRDF are always for a single spin period.
MRDF are generated from the spin buffer by summing over two adjacent detector sectors and summing over two
adjacent spin sectors for the elements
nearest the spin axis, thus producing an array of 104 solid angle elements per detector half. The MRDF may
be specified to be further summed over
adjacent energy steps (i.e. adjacent odd or adjacent even depending on spin). Thus each (of eight possible)
MRDF is a 3-D distribution with
either 728 or 1456 velocity space elements. See This Page for more information
about on board acquisition and
processing of data.
- RED indicates the data are from LRDF data products with low angular resolution (~45 degrees).
- Data from each detector half and each M/Q are treated separately and can be integrated over 2^N spin
periods (0 <= N <= 5), thus 8 separate
LRDF are possible. LRDF are generated from the spin buffer data by summing over adjacent even and/or odd
energy steps, summing over two adjacent
spin sectors, and summing over four adjacent detector sectors except for those nearest to the spin axis which
are summed over 2 sectors. Thus
each LRDF represents a 3-D distribution with 224 velocity space elements (7 energy x 8 spin angles x 4 polar
angles). This resolution is
sufficient to characterize most magnetospheric ion distributions. See This
Page for more information about on board acquisition and
processing of data.
Third color panel
- Pitch angle distribution of O+ obtained by integrating over the energy range 0.6 < E/Q < 4.5 keV
- Same format as the first color panel
Fouth color panel
- Pitch angle distribution of O+ obtained by integrating over the energy range 16 < E/Q < 600 eV
- Same format as the first color panel
Line plots labeled Ion Fluence on the left.
- Upward directed ion fluence in units of cm^2/s for H+ (red), O+ (green), He+ (blue), and the sum of them
(black) derived for each spectra
displayed in the color panels above.
- The data have NOT been normalized to a uniform altitude.
- Intervals with fluxes below 10^5 could be regions with a net downflowing fluence of ions.
- Statistical summaries of the net fluence of ions derived from data such as these can be found in the
following papers:
-
The Seasonal Variation of Auroral Ion Beams, H.L. Collin, W.K. Peterson, O.W. Lennartsson, and J.F. Drake,
Geophysical Research Letters, 25, 4071,
1998.
- Polar/TIMAS Observations
of Suprathermal Ion Outflow During Solar Minimum Conditions, W.K. Peterson, H.L. Collin, A.W. Yau, and
O.W. Lennartsson,
J. Geophys. Res., 106, 6059, 2001.
-
Solar wind control of Earth's H+ and O+ outflow rates in the 15-eV to 33-keV energy range,
O.W Lennartsson, W.K. Peterson, and H.L. Collin, J. Geophys. Res., Vol. 109, No. A12, A12212 10.1029/2004JA010690,
15 December 2004.
-
Quiet time solar illumination effects on the fluxes and characteristic energies of ionospheric outflow,
W.K. Peterson, H.L. Collin, O.W. Lennartsson and A.W. Yau,
J. Geophys. Res., 111, A11S05, doi:10.1029/2005JA011596, 2006.
- Solar-minimum quiet-time ion energization and outflow in dynamic boundary related coordinates,
W.K. Peterson, L. Andersson, B.C. Callahan, H.L. Collin, J.D. Scudder, and A.W. Yau, To appear in J. Geophys.
Res., 2008.
Line and symbol plots labeled Angle of Peak Flux on left and N (density) on the right
- The "angle of the peak flux" is determined as described in Collin et al., 1998 (above).
- Angle of peak flux not detectable in all intervals because of broad quasi-isotropic distributions
- Red diamonds indicate the angle of peak flux for H+. The angle scale is on the left.
- Green X's indicate the angle of peak O+ flux. The angle scale is on the left.
- Blue symbols indicated the angle of peak He+ flux are usually not seen because He+ data were
generally acquired with lower angular resolution
than H+ and O+.
- Density is indicated by the solid colored lines and black dots
- The density scale is on the right
- The red line indicates the H+ density.
- The green line indicates the O+ density.
- A blue line is shown if He+ data were processed for this interval
- The dotted x's indicate the total density derived from TIMAS
- The solid black line indicates the total density inferred from the space
craft potential measurement made by the Polar EFI instrument.
- The line and number panel labeled BCR ICP and E Range on the left
- The solid line gives the Background Counting Rate (BCR) in a log scale. No scale is indicated.
Values near the top of the panel indicate regions where the signal (and therefore the
information in the color panels above) is degraded because of high background counting rates.
- The color of the BCR rate line indicates instrumental status. Green indicates OK. Orange
indicates that caution should be used in applying the data. Red indicates that the data are
not valid.
- The TIMAS mode in use at the time is indicated by its ICP Table #. For a description of
TIMAS modes by ICP table # see the TIMAS Mode description page
- The color of the solid line above the UT information encodes the energy range sampled by
the TIMAS instrument. Green indicates full ( 15 eV < E/q < 33 keV). Orange indicates the
reduced energy range ( 15 eV < E/q < 25 keV ). Red indicates the low energy range ( 15 eV <
E/q < 2 keV ).
- Information about the orbit in tabular format
- UT: Universal time in hours:minutes
- R(Re): Geocentric distance of Polar in units of Earth radii
- L(Re): McIlwain L parameter at the location of Polar
- MLT(Hr): Magnetic Local Time at the location of Polar in decimal hour format
- MagLAT: Geomagnetic Latitude at the location of Polar in degrees.
- InvLat: Invariant Latitude at the location of Polar in degrees.
Prepared by WK (Bill) Peterson, May
2008.