Solar wind prediction for Uranus near opposition in 2024

1. Model

We use a 3-D magnetohydrodynamic model that predicts solar wind conditions between 1 and 40 AU using time-dependent boundary conditions implemented in the adaptive mesh refinement framework of Multi-scale Fluid-kinetic Simulation Suite (MS-FLUKSS), which is a numerical toolkit designed primarily for modeling flows of partially ionized plasma. See Kim et al. (2016) and Lamy et al. (2017) for details.

Simulation domain: 1-40 AUSimulation grid: 4,320 x 720 x 36 (r, phi, theta)Grid size: dr = 0.009 AU, dphi = 0.5 deg, dtheta = 5 deg

At 1 AU, the solar wind boundary conditions are derived from OMNI data at low latitudes and fit to Ulysses data at middle to high latitudes (e.g., Kim et al. 2016, 2017; Zirnstein et al. 2022, 2024).

At 40 AU, the interstellar neutral hydrogen atom parameters are:

Number density = 0.115 cm^3 (Swaczyna et al. 2020; Swaczyna et al. 2025)Flow speed = 22 km/s (Lallement et al. 2005)Temperature = 10,000 K.

2. Data

The simulation data file ("uranus2024_ms-flukss.dat") consists of a header and 22 columns of numerical values in the following order:

(1) time (fractional year)

(2) distance (AU)

(3) MS-FLUKSS longitude (rotated by ~180 degrees from HGI longitude in degrees)

(4) MS-FLUKSS latitude (same as heliographic latitude in degrees)

(5) solar wind proton number density (cm^-3)

(6) solar wind Vr (km/s)

(7) solar wind Vphi (km/s)

(8) solar wind Vtheta (km/s)

(9) thermal pressure of solar wind and interstellar pickup ion mixture (picodyne/cm^2)

(10) Br (microgauss)

(11) Bphi (microgauss)

(12) Btheta (microgauss)

(13) interstellar hydrogen atom number density (cm^-3)

(14) interstellar hydrogen Vr (km/s)

(15) interstellar hydrogen Vphi (km/s)

(16) interstellar hydrogen Vtheta (km/s)

(17) interstellar hydrogen atom thermal pressure (picodyne/cm^2)

(18) tracking parameter for the heliospheric current sheet 

(19) solar wind and interstellar pickup proton temperature (K)

(20) fractional day of year 2024

(21) interplanetary magnetic field strength (nT)

(22) solar wind dynamic pressure (nPa)

3. Figure

The figure shows the model predictions of interplanetary magnetic field, solar wind dynamic pressure, radial velocity, and proton number density at Uranus from 2024-09-01 to 2024-11-30.