Supporting Van Allen Probes science with the TS07D magnetic field model: Nowcasting electron intensities, global magnetic field distribution, and magnetic field ephemeris December 4 th, 2015: Van Allen Probes SWG Telecon Grant Stephens and Sasha Ukhorskiy

2 Classic vs. New Generation of Models TS07DTS05vs.  TS07D is free of restrictions intrinsic to earlier models  This allows for realistic topology and temporal evolution of storm-time equatorial currents  Spatial resolution of equatorial currents are bounded by available magnetometer data  This makes it agreeable for scientific studies  Such as to study storms with different solar wind drivers: CMEs [Sitnov et al. 2008] and CIRs [Sitnov et al. 2010]  And different convection modes such as SMC [Stephens et al. 2013]

3 Using TS07D  Model link is on Van Allen Probes Science Gateway  du/ du/  Tsyganenko’s Geopack link  TS07D link, including source code, static shielding coefficients, and dynamic model coefficients

4 TS07D: New data products!  We will be providing several new TS07D derived data products that will be placed on the Van Allen Probes science gateway  The model will be precomputed and written out to cubes for easier use and will eventually cover the whole Van Allen probes timespan  Additional cubes of other magnetic field derived quantities, such as the magnetic vector potential, Euler potentials, and empirical plasma pressure will be precomputed  Using these cubes, we will produce magnetic ephemeris files including the computation of L*  Using these cubes and particle flux data, and making simple adiabatic assumptions, we will nowcast the electron intensities into 3D data product

5 TS07D: Gridded field values  We will provide precomputed cubes of magnetic field vectors  Cubes will be in the VTK binary format  Simple tri-linear interpolation can be used to evaluate the field within the cube  FORTRAN readers and evaluators are available  Much much faster (500-1,000 times!) than full-evaluation of the model and less error prone  Cubes are ~21 MB Z-GSM X-GSM Y-GSM +16 dx=dy=dz = 0.2 RE

6 TS07D: Gridded magnetic vector potential  Additional, cubes of the magnetic vector potential will also be precomputed: allowing for efficient computation of such quantities as:  The electric field  And the magnetic flux  Which for a drift shell defines the third adiabatic invariant  Other useful magnetic field derived parameters, such as Euler potentials or force-balance plasma pressure, could also be precomputed onto cubes

7 TS07D: Gridded field values and magnetic ephemeris  Initially, magnetic and vector potential cubes will be processed for a ‘trial’ selection of events  e.g. March 2013, March 2015, and June 2015 geomagnetic storms on a 10 min cadence  Once vetted, the cubes will be expanded to encompass the whole of the Van Allen probes mission  We will additionally provide magnetic Ephemeris files for the Van Allen Probes mission using the TS07D model  This is meant to supplement the magnetic ephemeris files being produced by ECT for other models  Will include, B field, L*, etc… Z-GSM X-GSM Y-GSM +16 dx=dy=dz = 0.2 RE

8 TS07D: Nowcasting electron intensities  Using simple adiabatic assumptions, we have developed a 3D nowcasting model of intensities of the electron radiation belts  Model output from a variety of electron energies from RBSPICE, MagEIS, an REPT will be provided in a 3D data format  Science studies such as this are often overly simplified (dipole field approximation) or are limited in scope due to computational constraints  Utilizing precomputed magnetic field grid significantly speeds up calculations while still having a realistic magnetic field

9 TS07D: Nowcasting electron intensities MagEIS MeV spin averaged electrons