Quicklook Data from Ulysses SWICS

Snapshot data are available on a near-daily basis. A text file of the data set is available via electronic mail to interested parties. If you wish to be placed on this mailing list, please contact
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The snapshot data set contains the following information:

Predicted trajectory information, derived from the Ulysses Reference Trajectory Characteristics Document, JPL 628-53, Rev. E, Nov. 29, 1990. This information is printed out once per day of data and consists of the heliocentric range of the spacecraft in astronomical units (AU), the heliographic latitude of the spacecraft in degrees (SMEQ - sun mean equator and equinox of 1950), and the solar longitude with respect to earth in degrees (the earth-sun-s/c angle projected onto the sun's equatorial plane, where the current earth-sun line is defined as longitude = 0.0 degrees).

Time of data, given as DD-MMM-YY HH.

Solar Wind Proton Bulk Speed [kilometers per second], given in the spacecraft frame of reference. The proton speed is derived once per instrument E/Q scan (typically 13-minutes is required to perform one energy-per-charge scan). The value given here is an hourly average based on a simple fitting procedure to an assumed Maxwellian distribution function.

Oxygen Ionization Temperature [degrees Kelvin], derived from the calculated abundance ratio of Oxygen ionic charge state +7 to Oxygen ionic charge state +6, assuming the equilibrium ionization rates of Arnaud and Rothenflug (Astron. and Astrophys. Suppl. Ser., 60, 425, 1985 ).

IMPORTANT NOTE: A simplified, fast calculation technique is used for determining the solar wind speed and oxygen charge state abundances; therefore these data should be considered "browse quality" and are not citable. If a value cannot be calculated, it is given a "fill" value of zero.

By using the solar wind speed and ionization temperature information, one can often identify the type of solar wind flow that has been encountered. For example:

Solar Wind from Coronal Holes is typically characterized by an increase in speed with a slow recovery (the peak speed is usually high, above 500 km/sec, however this depends on the particular hole), and low O+7/O+6 ionization temperatures (typically 1.1-1.4 million K). Sample of a coronal hole-associated solar wind flow:

Solar Wind from Transient Events (such as the interplanetary manifestation of a Coronal Mass Ejection) may be preceded by a shock (showing an abrupt increase in speed) and turbulent sheath region. The event proper is typically associated with initially high speeds with a gradually decaying profile exhibiting low variance, and high O+7/O+6 ionization temperatures (typically rising above 2 million K). Sample of a CME-related solar wind:

Quiet or Interstream Solar Wind (such as associated with helmet streamers) is typically associated with low speeds (typically < 450 km/sec) and modest O+7/O+6 ionization temperatures (typically ~ 1.4-1.7 million K). Sample of Quiet solar wind:
For a clear identification of solar wind flow type, other data sets should also be consulted (e.g., the interplanetary magnetic field, and solar wind electron and plasma parameters). The signatures described above are often observed, but are neither unique nor always present.


This page prepared by Toni Galvin, galvin@umdsp.umd.edu

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