STK SEET Environment

The STK SEET Geomagnetic Field component evaluates the magnetic field and performs field-line tracing using several models for a satellite, missile, or launch vehicle. Beyond several Earth radii, the Earth's magnetic field is increasingly distorted by the solar wind interacting with the Earth's magnetosphere; the total magnetic field is therefore modeled primarily as a dipole main-field model, plus an external (magnetospheric) field model.

Flux intensity for energetic protons in the South Atlantic Anomaly (SAA) region is based on data from the Compact Environmental Anomaly Sensor (CEASE) flown onboard the Tri-Service Experiment-5 (TSX-5) satellite from 2000 to 2006 (Ginet et al., 2008). The data resolution is 3 degrees for both latitude and longitude and 50 km in altitude. The data cover the full range of latitudes and longitudes with an altitude range from 400 km through 1700 km.

For additional background information, consult: SEET: Space Environment and Effects Tool for STK (PDF).

Options for STK SEET Environment - Magnetic Field Model

Option Description
Main Field Options are:
  • Fast IGRF - a specially tuned version of the IGRF that returns a field strength estimate accurate to within 1% of the full-IGRF option, but it is significantly faster.
  • IGRF - calculations based on the full harmonic expansion of International Geomagnetic Reference Field model coefficients. The model coefficients at the epoch of interest are linearly interpolated from ICRF coefficient tables, the nodes of which are spaced approximately every five years.
  • Offset Dipole - simple dipole magnetic field model that is offset from the Earth's center.
  • Tilted Dipole - simple dipole magnetic field model tilted ~11 degrees from the rotational axis.
External Field

Options are:

  • None - only the main (core) model is used
  • Olson-Pfitzer - apply the local-time-dependent model due to Olson and Pfitzer (1977)
IGRF Update Rate The time period of the frequency at which IGRF harmonic model coefficients will be re-evaluated from the table of IGRF coefficients (spaced approximately every five years).

Options for STK SEET Environment - South Atlantic Anomaly (SAA)

Option Description
Channel Options for proton threshold-energy level:
  • > 23 MeV
  • > 38 MeV
  • > 66 MeV
  • > 94 MeV
Flux Level

Level of the boundary contour to be displayed:

  • Background + 3 Sigma
  • Half of Peak
  • Tenth of Peak

For reference information, see: Energetic Proton Maps for the South Atlantic Anomaly (PDF).

Outside the altitude range of 400 km through 1700 km, the SAA model returns zero.

Ginet, G.P., D. Madden, B.K. Dichter, D.H. Brautigam (2008), "Energetic Proton Maps for the South Atlantic Anomaly." AFRL-RV-HA-TR-2008_1060, Reprinted from Radiation Effects Data Workshop Record, 2007 IEEE Nuclear and Space Radiation Effects Conference, 23-27 Jul 2007.

Olson, W. P., and K. A. Pfitzer, Magnetospheric magnetic field modeling, Annual Scientific Report, AFOSR Contract No. F44620-75-C-0033, 1977.