Work Description

Title: Model results for "Modeling study of geospace system response to the solar wind dynamic pressure enhancement on March 17, 2015"
Authors: Dogacan Su Ozturk, Shasha Zou, Aaron J. Ridley, James A. Slavin
Date generated: 19 February 2018
Contact: dcsoztrk@umich.edu
Grant no: NSF Grant - AGS1203232

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Research Overview:
The global magnetosphere-ionosphere-thermosphere (M-I-T) system is intrinsically coupled and susceptible to external drivers such as solar wind dynamic pressure enhancements. In order to understand the large-scale dynamic processes in the M-I-T system due to the compression from the solar wind, the 17 March 2015 sudden commencement was studied in detail using global numerical models. This storm was one of the most geoeffective events of the solar cycle 24 with a minimum Dst of -222 nT. The Wind spacecraft recorded a 10 nPa increment in the solar wind dynamic pressure, while the IMF Bz became further northward. The University of Michigan Block Adaptive Tree Solarwind Roe Upwind Scheme (BATS-R-US), global MHD code was utilized to study the generation and propagation of perturbations associated with the compression of the magnetosphere system. In addition, the high-resolution electric field potential and auroral power output from the MHD model was used to drive the Global Ionosphere Thermosphere Model (GITM) to investigate the I-T system response to pressure enhancement. During the compression, the electric field potentials and convection patterns in the polar ionosphere were significantly altered when the PI and MI FACs moved from dayside to nightside. As a result of enhanced frictional heating, plasma and neutral temperatures increased at the locations where the flow speeds were enhanced, whereas the electron density dropped at these locations. In particular, the region between the PI and MI FACs experienced the most significant heating with 1000 K ion temperature increase and 20 K neutral temperature increase within 2 minutes. Comparison of the simulation results with the Poker Flat Incoherent Scatter Radar (PFISR) observations showed reasonable agreements despite underestimated magnitudes.

Key Points:
- Shock induced compression significantly alters the high-latitude convection patterns.
- Large convection speed at locations between PI and MI FACs and polar cap caused significant frictional heating.
- The simulation results in general reproduce observations despite lower magnitudes.

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Methods:

We used the Global Magnetosphere (GM), Inner Magnetosphere (IM) and Ionospheric Electrodynamics (IE) modules of the Space Weather Modeling Framework (SWMF) (Toth et al., 2005). The global MHD code Block Adaptive Tree Solar Wind Roe Upwind Scheme (BATS-R-US) was used in the GM region to solve for the ideal MHD equations and was coupled with the IM and IE components (Powell et al., 1999; Toth et al., 2012; Ridley et al., 2016). The IE component was the Ridley Ionosphere Model (RIM) (Ridley et al., 2004), which was driven by the FACs and auroral power computed from the GM component and estimated the ionospheric electric potential based on FACs and conductance. The potential solution was then mapped out to the GM inner boundary at 2.5 Re where it was used to drive the motion of the magnetic field lines in BATS-R-US. We used the Comprehensive Ring Current Model (CRCM) (Fok et al., 2001; Glocer et al., 2013) to represent the IM component, which was two-way coupled with the GM component and received the ionospheric electric potential solution from IE.

The results obtained from the coupled GM-IM-IE modules including convection and auroral precipitation were used to drive the Global Ionosphere Thermosphere Model (GITM) (Ridley, et al., 2006). GITM is a three-dimensional, parallel, spherical code that uses a stretched altitude grid and allows non-hydrostatic solutions (Ridley et al., 2006). The model self-consistently solves the electron, ion and neutral temperatures (Zhu & Ridley, 2016). For this study, we used a spatial resolution of 4 degree in longitude to 1 degree in latitude for the region between ~100 km to ~600 km. The GITM simulation was also driven by the same solar wind and IMF conditions that was used to run SWMF, to specify the ionospheric potentials according to the Weimer model (2005) and the auroral power according to the Ovation model (2002), from 15/03/2015-0000 UT, i.e., two days before the event, to 17/03/2015-0405 UT, i.e., ~40 minutes before the compression. From 0405 UT onwards, we used the electric potentials and auroral powers obtained from the MHD simulation to drive the GITM model, updating the electrodynamic patterns every 10 seconds to better capture the temporal and spatial variations associated with the solar wind drivers.

The simulation data were generated through the use of the following models: the Block Adaptive Tree Solarwind Roe Upwind Scheme (BATS-R-US), Comprehensive Ring Current Model (CRCM), Ridley Ionosphere Model (RIM) and the Global Ionosphere Thermosphere Model (GITM). The simulations were performed on the Yellowstone and Cheyenne Supercomputer Clusters provided by National Center for Atmospheric Research (NCAR) Computational and Information Systems Laboratory, sponsored by the National Science Foundation.

File Inventory:
This repository contains:
- Two 3D Tecplot binary files from coupled SWMF simulations (GM/IM-CRCM/IE-RIM) at 04.46 and 04.47 UT
- Four 3DALL files from GITM simulations for 04.45, 04.46, 04.47 and 04.48 UT
- One 3DION file from GITM simulations at 04.30 UT
- Five 2D ascii files from IE/RIM component at 04.30, 04.45, 04.46, 04.47 and 04.48 UT
- Five 2D ascii files from virtual magnetometers in the SWMF simulations at 04.30, 04.45, 04.46, 04.47, 04.48 UT
- One ascii text file, peak_pkr_madrigal_virtual.txt for the extracted values at the location of Poker Flat Incoherent Scatter Radar (PFISR)
- Two movie files in mp4 format, that shows the time evolution of global system, ms01, and Field-Aligned Currents, ms02.
- Readme file

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Definition of Terms and Variables:

The global magnetosphere-ionosphere-thermosphere (M-I-T) system is intrinsically coupled and susceptible to external drivers such as solar wind dynamic pressure enhancements. In order to understand the large-scale dynamic processes in the M-I-T system due to the compression from the solar wind, the 17 March 2015 sudden commencement was studied in detail using global numerical models. This data set is comprised of the simulation data generated from these models.

Contents of 3d__mhd_7_t00040200_n00006371.plt and similar files
MHD - vars: X Y Z rho Ux Uy Uz Bx By Bz P Jx Jy Jz

X: x coordinate
Y: y coordinate
Z: z coordinate
rho: density
Ux: x-component of velocity
Uy: y-component of velocity
Uz: z-component of velocity
Bx: x-component of magnetic field
By: y-component of magnetic field
Bz: z-component of magnetic field
P: pressure
Jx: x-component of the current
Jy: y-component of the current
Jz: z-component of the current

Contents of it150317_043000_000.tec and similar files
"Theta [deg]","Psi [deg]"
"SigmaH [S]","SigmaP [S]"
"JR [`mA/m^2]","PHI [kV]"
"E-Flux [W/m^2]"
"Ave-E [eV]"
"RT 1/B [1/T]","RT Rho [amu/cm^3]","RT P [Pa]"
"JouleHeat [mW/m^2]"
"IonNumFlux [/cm^2/s]"
"conjugate dLat [deg]"
"conjugate dLon [deg]"

Contents of mag_grid_e20150317-043000.out and similar files
Lon Lat dBn dBe dBd dBnMhd dBeMhd dBdMhd dBnFac dBeFac dBdFac dBnHal dBeHal dBdHal dBnPed dBePed dBdPed

Lon: Magnetic longitude
Lat: Magnetic latitude
dBn: N-component of total magnetic perturbation (north)
dBe: E-component of total magnetic perturbation (east)
dBd: D-component of total magnetic perturbation (horizontal)
Mhd: Contribution from magnetospheric currents
Fac: Contribution from FAC currents
Hal: Contribution from Hall currents
Ped: Contribution from Pedersen currents

Contents of 3DALL_t150317_050100.bin and similar files

Altitude: Altitude from the surface of the planet (m)
Ar: Argon density (m-3)
Ar Mixing Ratio: Argon mixing ratio
CH4 Mixing Ratio: Methane mixing ratio
Conduction: Heat conduction
EuvHeating: EUV Heating rate
H: Hydrogen density (m-3)
H!U+!N: H+ density (m-3)
H2 Mixing Ratio: Molecular Hydrogen mixing ratio
HCN Mixing Ratio: Hydrogen Cyanide mixing ratio
He: Helium density (m-3)
He!U+!N: He+ density (m-3)
Heaing Efficiency: Heating efficiency
Heat Balance Total: Heat balance total
Latitude: Geographic latitude (degrees)
Longitude: Geographic longitude (degrees)
N!D2!N: N2 density (m-3)
N!D2!U+!N: N+2
density (m-3)
N!U+!N: N+ density (m-3)
N(!U2!ND): N(2D) density (m-3)
N(!U2!NP): N(2P) density (m-3)
N(!U4!NS): N(4S) density (m-3)
N2 Mixing Ratio: Molecular nitrogen mixing ratio
NO: Nitrious Oxide density (m-3)
NO!U+!N: NO+ density (m-3)
O!D2!N: O2 density (m-3)
O!D2!U+!N: O+2
density (m-3)
O(!U1!ND): O(1D) density (m-3)
O(!U2!ND)!U+!N: O(2D) density (m-3)
O(!U2!NP)!U+!N: O(2P) density (m-3)
O(!U3!NP): O(3P) density (m-3)
O 4SP !U+!N: O(4SP)+ density (m-3)
RadCooling: Radiative Cooling rate
Rho: Neutral density (m-3)
Temperature: Neutral temperature (K)
V!Di!N (east): Ion velocity towards geographic East (m s-1)
V!Di!N (north): Ion velocity towards geographic North (m s-1)
V!Di!N (up): Vertical ion velocity (m s-1)
V!Dn!N (east): Neutral velocity towards geographic East (m s-1)
V!Dn!N (north): Neutral velocity towards geographic North (m s-1)
V!Dn!N (up): Vertical neutral velocity (m s-1)
V!Dn!N (up,N!D2!N): Vertical N2 velocity (m s-1)
V!Dn!N (up,N(!U4!NS)): Vertical N(4S) velocity (m s-1)
V!Dn!N (up,NO): Vertical NO velocity (m s-1)
V!Dn!N (up,O!D2!N): Vertical O2 velocity (m s-1)
V!Dn!N (up,O(!U3!NP)): Vertical O(3P) velocity (m s-1)
e-: electron density (m-3)
eTemperature: electron temperature (K)
iTemperature: ion temperature (K)
time: Universal time

Note: Time shift is 16 minutes in between simulation and PKR magnetometer data.

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Use and Access:

The data provided in this repository is open to public access. Anyone can download and reuse the data. Restrictions apply for publishing with the data presented here.
Please contact, author Dogacan Ozturk (dcsoztrk@umich.edu) for further information and permission.

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