WebAMPS  

The polar maps show average ionospheric currents for the most recent solar wind conditions, using the Average Magnetic Field and Polar Current System (AMPS) model. To change output quantity, hemisphere, or external conditions, use the dropdown menus, sliders, or click the time series plot. For more details see below.      

About AMPS

The AMPS model is an empirical model based on magnetic field measurements in low Earth orbit from the CHAMP and Swarm satellites. The model represents the average ionospheric disturbance magnetic field as a function of solar wind speed, interplanetary magnetic field, the tilt angle of Earth's magnetic dipole axis with respect to the Sun, and the F10.7 solar flux index. Ionospheric electric current densities are derived from the magnetic field, assuming that horizontal currents are confined to a spherical shell below the satellites. Here we assume that this shell is at 110 km altitude. Different representations of the ionospheric currents can be chosen in the dropdown menus. You can also choose ground magnetic perturbation components, which represent the corresponding magnetic field inside the current-carrying shell.  

 

Instructions

The dropdown menus allow you to choose which output quantity to display in each map, and which hemisphere to show. When loading the site, the most recent solar wind conditions are used, taken from the NOAA Space Weather Prediction Center. The time series plot shows the conditions during the previous 24 hours. Click the plot to choose a different time. You can also change the external conditions directly by adjusting the sliders or click the compass plot of the interplanetary magnetic field GSM yz-plane. When changing the input values directly, the coastlines disappear. This is because, without a specific time and date, the orientation of the coastlines is ambiguous. To compare different conditions, you can get individual controls for each map by deselecting "shared controls". To get a pdf version of a map, click the download link.

 

Coordinates

The maps are shown in modified apex coordinates, with a reference height of 110 km. This is a magnetic coordinate system that depends on Earth's magnetic field. It is non-orthogonal, which is why the shapes of the coastlines appear slightly different from polar maps in geographic coordinates (also, since Earth's magnetic field changes slowly in time, the coastlines actually change in this coordinate system, as illustrated in this gif: link).

 

More information

Exact information about how the model is defined can be found in the following paper. We kindly ask that you cite this paper if you use the maps in publications. Laundal, K. M., Finlay, C. C., Olsen, N., & Reistad, J. P. (2018). Solar wind and seasonal influence on ionospheric currents from Swarm and CHAMP measurements. Journal of Geophysical Research: Space Physics, 23, 4402–4429. https://doi.org/10.1029/2018JA025387

To get numeric output, or make plots with other settings than offered here, please use the Python forward code for the AMPS model, pyAMPS. pyAMPS allows you to calculate all model output for any set of external conditions, at any coordinate. This page is based on pyAMPS. The code can be found here: https://github.com/klaundal/pyAMPS/  

Credits

This website was produced with support from ESA through Swarm DISC. It was coded by Brage Førland and Karl Laundal.

For questions or comments, please contact Karl Laundal