Modeling the evolution of CMEs from the Sun and through interplanetary space
As seen in Space Weather
OSPREI is a model for the Sun-to-Earth (or elsewhere) evolution of CMEs that combines three different CME models (ForeCAT, ANTEATR, and FIDO) into one fully connected suite. OSPREI is designed to run fast enough for real time predictions (including ensemble simulations) and has tools for automatically processing the results into standardized graphics.
Deflection and Rotation
ForeCAT was the first component developed within the OSPREI suite. When CMEs erupt, the do not always follow a radial path through the corona. Instead, they can deflect and rotate. Observations show that these motions tend to follow the background magnetic energy gradients. Accordingly, ForeCAT simulates the coronal deflection and rotation of CMEs based on the magnetic forces from the solar background. It represents the CME flux rope as a rigid torus and calculates the external magnetic tension and magnetic pressure gradients. These forces cause a change in the latitude and longitude of the CME and the net torque causes a rotation.
Interplanetary Evolution
ANTEATR simulates the interplanetary propagation of a CME and was developed to connect ForeCAT and FIDO. It began by just using a simple, 1D drag model for the change in the bulk velocity combined with using the 3D torus shape to determine the time of impact. Since this first iteration several large updates have been made including the addition of realistic deformation and expansion from internal forces, the ability to generate a CME-driven sheath, and interplanetary rotation from interacting with a structured background solar wind. It now also simlates the evolution of the internal properties including the magnetic field, temperature, velocity, and density.
Synthetic in situ Profiles
FIDO was designed to take the position and orientation of a CME from ForeCAT, combine it with a flux rope model, and generate in situ profiles of the CME as it passes over a synthetic satellite. Originally FIDO only did the magnetic field vector and ran after ForeCAT/ANTEATR but it has now been integrated to run simultaneous to ANTEATR as the CME makes contact and produces profiles for the full magnetic field and plasma properties.
A (Mostly) Empirical High Speed Stream Model
MEOW-HiSS is a companion to the OSPREI suite. It creates a time-dependent background solar wind with an embedded high speed stream (HSS) that can be coupled with ANTEATR and FIDO. MEOW-HiSS is essentially a set of simple equations and associated scaling coefficients derived from MHD simulations of a HSS. It very accurately reproduces the MHD results but runs essentially instantaneously. It also compares well to HSS observed in situ at 1 AU.