Magnetic Field Boundaries in Cassini Plasma Spectrometer Data

This dataset consists of:

• get_files.sh - a bash script to download ELS data (.DAT and .LBL) files.
• crossing_events_urls.txt - a text file containing URLs for each of the ELS
  data files. get_files.sh reads this file directly.
• crossing_events.txt - a text file containing the list of crossing events
  with associated data, obtained by processing Table S1 in [1].
• labels.zip - a zip file containing directory with events for each DAT file,
  in YAML format.
• plotter.py - a plotting script in Python.
• requirements.txt - a file indicating dependencies for the plotting script.

Data

This dataset spans 1259 observations from CAPS ELS, each with a .LBL file and a
.DAT file. Together, these take 128 GB of space. To download these files, do:

./get_files.sh

in a Bash shell/terminal. The files are stored in the 'data/' folder (created if
not present) in the current directory.

ELS data files are obtained from NASA's Planetary Data System at
https://pds-ppi.igpp.ucla.edu/search/view/?f=yes&id=pds://PPI/CO-E_J_S_SW-CAPS-3-CALIBRATED-V1.0/DATA/CALIBRATED

For help in understanding the ELS data files, see the CAPS User Guide at
https://pds-ppi.igpp.ucla.edu/ditdos/download?id=pds://PPI/COCAPS_1SAT/DOCUMENT/CAPS_USER_GUIDE/CAPS_PDS_USER_GUIDE_V1_00.PDF.

Labels

Unzipping the labels.zip file will create a labels/ folder in the current
directory, requiring 28MB of space.

Within labels/:

• bs/ - includes bow shock crossing events.
• mp/ - includes magnetopause crossing events.
• dg/ - includes known data-gap events. See [1].
• sc/ - includes unreliable data events. See [1].
• valid/ - union of all files in bs/ and mp/.
• all/ - union of all files in bs/, mp/, dg/ and sc/.

Within the labels/bs/ and labels/mp/ folders:

• in/ - crossing events with the transition direction as inward.
• out/ - crossing events with the transition direction as outward.
• all/ - union of all files in in/ and out/.

Each label file is a YAML file containing a 'change_points' field. The entries
under this field each indicate the time of a transition event. The other fields
('bimodality' and 'negative_ions') are not relevant for this dataset.

Plotting the Data (and Labels)

To help visualize the data and labels, we supply a plotting script
plotter.py, in Python (version 2.7). First, install dependencies with:

pip install -r requirements.txt

and then run:

./plotter.py -h

to see the available options. Example usage (after downloading data and
unzipping labels):

./plotter.py data/ELS_200418018_V01.DAT -l labels/mp/all/ELS_200418018_V01.yaml --interpolated -f max_filter -fsize 100 --title "An Observation from CAPS ELS" 

will open up a new window with a plot of the data.
To directly save to a file, use the '-o savefilename' option. For example,

./plotter.py data/ELS_200418018_V01.DAT -l labels/mp/all/ELS_200418018_V01.yaml --interpolated -f max_filter -fsize 100 --title "An Observation from CAPS ELS" -o ELS_200418018_V01.png

References

[1] Jackman, C. M., Thomsen, M. F., & Dougherty, M. K. (2019). Survey of
Saturn's magnetopause and bow shock positions over the entire Cassini mission:
Boundary statistical properties and exploration of associated upstream
conditions. Journal of Geophysical Research: Space Physics, 124, 8865– 8883.
https://doi.org/10.1029/2019JA026628

The original table of magnetopause and bow shock crossing events can be found at
https://agupubs.onlinelibrary.wiley.com/action/downloadSupplement?doi=10.1029%2F2019JA026628&file=jgra55251-sup-0001-Table_SI-S01.txt

Grants

• NASA Contract through JPL with South West Research Institute. Grant Number: 1243218
• Science and Technology Facilities Council. Grant Number: ST/L004399/1
• NASA. Grant Number: 1243218
• Diamond Jubilee Fellowship
• STFC. Grant Number: ST/L004399/1