Date: 17 February 2024

Title: 

Data for reconstruction analysis of global ionospheric outflow patterns

Authors: 

Michael W. Liemohn, Jorg-Micha Jahn, Raluca Ilie, Natalia Y. Ganushkina, Daniel T. Welling, Heather A. Elliott, Meghan Burleigh, Kaitlin Doublestein, Stephanie Colon-Rodriguez, Pauline Dredger, and Philip W. Valek

Contact: 

Mike Liemohn (liemohn@umich.edu)

Acknowledgment and Supporting Grants:

The authors thank the University of Michigan and Southwest Research Institute for support of this project. The authors would like to thank the University of Michigan for its financial support, Southwest Research Institute for its financial support, and the US government, in particular research grants from NASA (specifically, grant numbers 80NSSC19K0077, 80NSSC21K1127, and 80NSSC21K1405) and NSF (specifically, grant AGS-1414517). MB was supported by the Office of Naval Research. All authors listed have made a substantial, direct, and intellectual contribution to the work and approved it for publication. The simulations were conducted by DTW and analyzed by DTW and MWL. An undergraduate student, Joshua Adam, also contributed to the plots and calculations.

Key Points of the Study:

-- A simulation study is conducted to determine the number of spacecraft needed for accurate reconstruction of 2D ionospheric outflow patterns
-- Determining the global pattern of ionospheric outflow is needed to understand the geospace system, especially during geomagnetic storms
-- A potential ionospheric outflow mission concept is defined that could address this unresolved key issue of space physics and space weather

Research Overview:

Earth’s upper atmosphere above 500 km altitude constantly loses charged particles to outer space in a process called ionospheric outflow. This outflow is important for the dynamics of the near-Earth space environment (“space weather”) yet is poorly understood on a global scale. A mission is needed to observe the global patterns of ionospheric outflow and its relation to space weather driving conditions. The science objectives of such a mission could include not only the reconstruction of global outflow patterns but also the relation of these patterns to geomagnetic activity and the spatial and temporal nature of outflow composition. A study is presented to show that four well-placed spacecraft would be sufficient for reasonable outflow reconstructions.

Methodology:

Several example high-latitude outflow spatial patterns from a magnetohydrodynamic (MHD) numerical simulation of Earth's magnetosphere were used as the "true observations" of ionospheric outflow. From these, values were extracted along satellite tracks and then used within a spline fitting routine to recreate the original spatial pattern. Many aspects of the satellite trajectories were varied, resulting in tens of thousands of reconstructions. Quantitative comparisons were conducted to assess what orbital settings provide an optimal reconstruction. 

Instrument and/or Software specifications:

The analysis and plotting code is provided in Python. The resulting plot files were then combined into the multi-panel figures for the paper using Adobe Illustrator.

Files contained here:

-- Analyze_results.py: set up code for the 4-sat case and plot output as a function of orbit parameter settings

-- cPickle.pyi: code of functions and procedures needed to run the other codes, in particular opening files

-- Create_reconstructions.sh: a script to run sat_analysis.py many times for different sat configurations and append the output to log.txt

-- ExHail.py: code of functions and procedures needed to run the other codes

-- extract_and_reconstruct.py: a file for reading in the MHD output, creating the satellite orbit trajectories, extracting values on the trajectories, doing the reconstruction, and making plots. This is the big one.

-- gmoutflow.py: code of functions and procedures needed to run the other codes, in particular the MHD output

-- Sat_analysis.py: code to make the 3-panel plots of original, extracted, and reconstructed outflow.

-- Shell_r300_northward.dat: the Tecplot-formatted MHD model output for northward IMF

-- Shell_r300_southward.dat: the Tecplot-formatted MHD model output for southward IMF

-- Six_circle_plot.py: python code to make the 6-plot comparison of the outflow reconstruction as a function of number of satellites

-- Results_foursats_incl05_lin.zip: many plots of linear reconstruction with 4 satellites and an 85˚ inclination (5˚ from purely polar), with different S/C spread and different LT of crossover

-- northward_results_##sats_inclxx.zip: these are zipped folders that each contain 250 plots of reconstruction results for a northward IMF (interplanetary magnetic field, a key upstream driving condition) outflow (i.e., quiet time outflow) with the Hermite cubic interpolation, with "##" indicating the number of satellite tracks used in the process (1 – 6) and the "xx" indicating the magnetic inclination of the crossing point of the satellite trajectories. The 250 plots, named fig00yyy.png where "yyy" is the plot number between 000 and 249, are the full combination of local times and maximum local time separations. The final file in each subfolder, named results_#sats.txt with "#" the same as the number of satellites for the folder, is a listing of error metrics between the reconstructed outflow spatial pattern and the original.

-- southward_results_##sats_inclxx.zip: these are folders like the "northward" zipped files, except for a southward IMF upstream condition.

Order of running these codes:

-- Load and run cPickle, ExHail, extract_and_reconstruct, and gmoutflow, so the functions within them are usable by the other codes.

-- Run the shell script create_reconstructions.sh as a Python subprocess (please look this up as it depends your Python installation; this runs sat_analysis.py many times, for 1 through 6 satellites and for inclinations 1 degree through 25 degrees.

-- You can then run one or more of the post-processing codes, Analyze_results and Six_circle_plot, to make additional plots from the output.

Related publication:

Liemohn, M. W., Jörg-Micha Jahn, Raluca Ilie, Natalia Y. Ganushkina, Daniel T. Welling, Heather Elliott, Meghan Burleigh, Kaitlin Doublestein, Stephanie Colon-Rodriguez, Pauline Dredger, & Philip Valek (2024). Reconstruction analysis of global ionospheric outflow patterns. Journal of Geophysical Research Space Physics, 129, e2023JA032238. https://doi/org/10.1029/2024JA032238

Use and Access: 
This data set is made available under a Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0).

To Cite Data: 
Liemohn, M. W., et al. (2024). Data for Reconstruction analysis of global ionospheric outflow patterns. University of Michigan Deep Blue Data Repository. https:TBD. University of Michigan Deep Blue Data Repository. https:TBD.