Trace¶

Trace Diagram

OTSO.trace ¶

trace(
    coordsys: str = "GEO",
    solar_wind_params: SolarWindParams = {},
    geomagnetic_params: GeomagneticParams = {},
    tsyganenko_params: TsyganenkoParams = {},
    datetime_params: DateTimeParams = {},
    magfield_params: MagFieldParams = {},
    computation_params: ComputationParams = {},
    data_retrieval_params: DataRetrievalParams = {},
    custom_field_params: CustomFieldParams = {},
    integration_params: IntegrationParams = {},
    coordinate_params: CoordinateParams = {},
    grid_params: GridParams = {},
) -> list

Trace magnetic field lines using the OTSO framework.

Traces magnetic field lines across a global grid to visualize the magnetosphere structure. Useful for understanding magnetic connectivity and field line topology. Computation also returns the McIlwain L value for the field line and invariant latitude for the origin location of the field line. Users should be cautious when interpreting low- or high-latitude origin invariant latitudes as they are ill-defined in such locations.

Parameters:

Coordsys (str) –

Coordinate system for field line positions.
datetime_params (DateTimeParams, default: {} ) –
Date/time parameters.

Available keys:
- year (int, default=2024): Year (e.g., 2023)
- month (int, default=1): Month (1–12)
- day (int, default=1): Day (1–31)
- hour (int, default=12): Hour (0–23)
- minute (int, default=0): Minute (0–59)
- second (int, default=0): Second (0–59)
magfield_params (MagFieldParams, default: {} ) –
Magnetic field models.

Available keys:
- internalmag (str, default="IGRF"): "NONE", "IGRF", "Dipole", "Custom Gauss", "CHAOS"
- externalmag (str, default="TSY89c"): "NONE", "TSY87short", "TSY87long", "TSY89a", "TSY96", "TSY01", "TSY01S", "TSY04", "TSY89c", "TSY15N", "TSY15B", "TA16_RBF", "TSY89_refit", "MHD"
- boberg (bool, default=False): Enable Boberg extension
- bobergtype (str, default="EXTENSION"): "EXTENSION", "CONTINUOUS", "DST_DEPENDENT", "DST_MIDPOINT"
- magnetopause (str, default="Kobel"): "NONE", "Kobel", "Sibeck", "Lin", "Sphere", "aFormisano"
- spheresize (float, default=25): Spherical boundary radius (Re)
- AdaptiveExternalModel (bool, default=False): Auto-select external model
- optimise_tsy (bool, default=False): Use the faster implementation of the selected Tsyganenko model (affects externalmag="TSY01", "TSY01S", "TSY04", or "TSY96"; other models are unaffected by this flag). Both settings give numerically identical results (all known bugs are fixed in both); True is just faster
solar_wind_params (SolarWindParams, default: {} ) –
Solar wind parameters. Defaults are quiet-time medians (Kp <= 1) of OMNI data, 1996-2025.

Available keys:
- vx (float, default=-359.4): Solar wind velocity x-component (km/s)
- vy (float, default=0): Solar wind velocity y-component (km/s)
- vz (float, default=0): Solar wind velocity z-component (km/s)
- bx (float, default=0.11): IMF x-component (nT)
- by (float, default=-0.16): IMF y-component (nT)
- bz (float, default=0.58): IMF z-component (nT)
- by_avg (float, default=-0.17): Averaged IMF By over last 30mins (nT)
- bz_avg (float, default=0.59): Averaged IMF Bz over last 30mins (nT)
- density (float, default=4.94): Solar wind density (particles/cm³)
- pdyn (float, default=1.31): Solar wind dynamic pressure (nPa); computed from density and velocity when 0, or when density or velocity is given without pdyn
geomagnetic_params (GeomagneticParams, default: {} ) –
Geomagnetic indices. Defaults are quiet-time medians (Kp <= 1) of OMNI data, 1996-2025.

Available keys:
- Dst (float, default=-4): Dst index (nT)
- kp (float, default=0.7): Kp index (0-9)
- n_index (float, default=0.145): Newell coupling function
- b_index (float, default=0.032): Boynton coupling function
- sym_h_corrected (float, default=-18.07): Corrected SYM-H index (nT)
tsyganenko_params (TsyganenkoParams, default: {} ) –
Tsyganenko model coefficients. Defaults are quiet-time medians (Kp <= 1) of OMNI data, 1996-2025.

Available keys:
- G1 (float, default=0.38): Tsyganenko G1 coefficient
- G2 (float, default=0.12): Tsyganenko G2 coefficient
- G3 (float, default=0.47): Tsyganenko G3 coefficient
- W1 (float, default=0.07): Tsyganenko W1 coefficient
- W2 (float, default=0.06): Tsyganenko W2 coefficient
- W3 (float, default=0.13): Tsyganenko W3 coefficient
- W4 (float, default=0.03): Tsyganenko W4 coefficient
- W5 (float, default=0.05): Tsyganenko W5 coefficient
- W6 (float, default=0.08): Tsyganenko W6 coefficient
grid_params (GridParams, default: {} ) –
Grid configuration parameters.

Available keys:
- latstep (float, default=-5): Latitude step size for grid
- longstep (float, default=5): Longitude step size for grid
- maxlat (float, default=90): Maximum latitude for grid
- minlat (float, default=-90): Minimum latitude for grid
- maxlong (float, default=360): Maximum longitude for grid
- minlong (float, default=0): Minimum longitude for grid
computation_params (ComputationParams, default: {} ) –
Computation settings.

Available keys:
- corenum (int, default=None): Number of CPU cores for multicore processing
- Verbose (bool, default=True): Enable verbose output
data_retrieval_params (DataRetrievalParams, default: {} ) –
Data retrieval.

Available keys:
- serverdata (str, default="OFF"): Server data retrieval from OMNI
- livedata (str, default="OFF"): real-time data retrieval from NOAA
custom_field_params (CustomFieldParams, default: {} ) –
Custom fields.

Available keys:
- g (list, default=None): Gauss g coefficients
- h (list, default=None): Gauss h coefficients
- max_degree (int, default=13): Max degree of spherical harmonic expansion
- MHDfile (str, default=None): MHD simulation file
- MHDcoordsys (str, default=None): MHD coordinate system
- MHDgridtype (str, default="auto"): How the MHD grid is looked up - "auto" detects per-axis spacing automatically, "uniform" forces the fast fixed-spacing path (only correct if every axis really is evenly spaced), "stretched" forces the general path needed for a grid whose resolution varies with position (e.g. finer near Earth)
- MHDinterpolation (str, default="trilinear"): How the field is reconstructed between grid points - "trilinear" is the classic fast corner-blend (kinked gradients at cell boundaries), "tricubic" is a smooth C^1 fit that's far more accurate in smooth field regions but can overshoot near sharp gradients/boundaries, "monotonic" is the same tricubic fit with overshoot limiting (recommended for general use), "divfree" returns the curl of an interpolated vector potential so the field is exactly divergence-free (for long quasi-trapped trajectories; less point-wise accurate than "tricubic"; the gridded field must itself be divergence-free, e.g. an external-only field - a warning is issued otherwise)

Returns:

list ( list ) –
[trace_data, readme_text]
- trace_data: Dictionary with magnetic field line positions
- readme_text: OTSO computation summary

Examples:

   from OTSO import trace

   if __name__ == '__main__':

       # Example using grouped parameters
       trace_results = trace(
           computation_params={"corenum": 4},
           magfield_params={"externalmag":"TSY89c"},
           grid_params={"latstep": -30, "longstep": 180, "maxlat": 60, "minlat": 0},
       )

        # Access the results
        trace_dict, metadata = trace_result