About SWICS-SWIMS Level 2 Data



Sensor Full Name Measured Species Measured Quantities Typical Energy (KeV/Q) Measurement Technique

SWICS

 Solar Wind Ion Composition Spectrometer 1 ≤ Z ≤ 30 M, Q, E 0.5 - 100 E/Q
TOF - E

SWIMS

 Solar Wind Ion Mass Spectrometer 2 ≤ Z ≤ 30 M, E/Q 0.5 - 20 E/Q
TOF - E

The SWICS and SWIMS Instruments on ACE

The Solar Wind Ion Composition Spectrometer (SWICS) and the Solar Wind Ion Mass Spectrometer (SWIMS) on ACE are instruments optimized for measurements of the chemical and isotopic composition of solar and interstellar matter. SWICS determines uniquely the chemical and ionic-charge composition of the solar wind, the temperatures and mean speeds of all major solar-wind ions, from H through Fe, at all solar wind speeds above 300 km/s (protons) and 170 km/s (Fe+16), and resolves H and He isotopes of both solar and interstellar sources. SWICS measures the distribution functions of both the interstellar cloud and dust cloud pickup ions up to energies of 100 keV/e. SWIMS measures the chemical and isotopic and charge state composition of the solar wind for every element between He and Ni. Each of the two instruments uses electrostatic analysis followed by a time-of-flight and, as required, an energy measurement.

For more information about the SWICS and SWIMS instruments, visit the SWICS and SWIMS Home Page, at the University of Michigan.

SWICS-SWIMS Data Description

August 2014 update - The SWICS data set has been recalibrated using an improved instrument forward model and a more rigorous ion identification scheme. Version 4 data that will be released in Sept. 2014 include recalibrated versions of all data products currently available on the ACE Science Center, which cover the time range 1998 - Aug 2011, as well as several charge state ratios and the average Fe charge state from Aug 2011 through present day, and proton data from 1998-present. In Oct. 2014, Additional data products will be provided, including average charge states of Si and Mg prior to Aug 2011, and elemental abundance ratios from Aug. 2011-present. Researchers are encouraged to use the recalibrated data as soon as it is released.

July 2013 update - The SWICS instrument on ACE is out of calibration since day 225 of 2011, due to a hardware issue with the TOF. The SWICS team is working on new data analysis methods for providing science data products since this hardware issue, but these data have not yet been released.
The SWICS instrument team is performing a comprehensive review of its elemental abundance and charge state estimation methods. This review has revealed that the current ion species assignment method suffers from a lack of robustness when less abundant species overlap heavily with more abundant ones. A more robust method is currently being implemented and will form the basis of an upcoming major new SWICS data release.
For details, see the release notes for SWICS-SWIMS level 2 data - provided by the instrument team. All users of SWICS-SWIMS data should read these notes.

April 2012 update - a new version of the SWICS-SWIMS level 2 2hr and daily-averaged data has been released. See the release notes for SWICS-SWIMS level 2 data - provided by the instrument team. All users of SWICS-SWIMS data should read these notes.

November 2011 update - the SWICS instrument is out of calibration since 2011-225, due to a hardware issue with the TOF. The instrument team is investigating this issue.

Sept 2005 update - an entirely new version of the SWICS-SWIMS level 2 data has been released. Read this paper for full details.

A groupware site has been established, to keep users up to date on issues related to SWICS/SWIMS level 2 data. This site has announcements, discussion of current data issues and investigation schedules. It extends the functionality of the former announcement mailing list. To subscribe, send mail to Jim Raines (jraines@umich.edu) with subject 'subscribe SWICS/SWIMS LV2'.

Time Data
All level 2 data records for all ACE instruments contain timing information in the same format. The format of the timing information is described here.

SWICS-SWIMS Data Quality Flags are described in the Release notes for SWICS-SWIMS level 2 data - please read the release notes and do not ignore the data quality flags!

SWICS-SWIMS level 2 data are organized into yearly files. The data-collection cycle of the instruments is 12 minutes, and the level 2 data are provided as time-averages, as follows: