Solar Wind: IMF Bz
Solar Wind: Flow Speed
Solar Wind: Particle Density
ITM: Planetary Magnetic K-Index
ITM: Poker Magnetometer H-Component
ITM: SuperDARN Cross-Polar-Cap Potential
Solar: 1-8 Angstrom X-Ray Flux
Solar: Proton Flux >10 MeV
Solar: 10.7 cm Radio Flux


The spiral plots displayed above show various parameters that are relevant for studies of space weather. Current time should be at the top and in the horizontal center of each spiral. Time runs backward from this location — age increases anti-clockwise around the spiral and inward toward the center. Up to five cycles of the spiral are shown. The cycle period is 27 days.

The reason for the 27-day periodicity is because this is the approximate rotation period for geoeffective latitudes on the Sun. This means that disturbances produced by long-lived solar features (such as coronal holes) may persist for several solar rotations, and thus appear on these plots at similar phases (clock angles) over several cycles of the spiral. If such features can be identified, they can be considered when making space weather forecasts over look-ahead periods longer than the few days that it takes for the solar wind to travel to Earth from the Sun. A minor secondary benefit is that the length of the "x-axis" in this format is much greater than the size of the figure itself, which allows a long time series to be visualized in a plot with approximately 1:1 aspect ratio.

For comparison, the same data are re-plotted below the spirals, using a conventional Cartesian format instead.

Data Sources:

All source data were obtained from, except for the Poker Flat magnetic delta-H component, which was provided by the University of Alaska Geophysical Institute, and the SuperDARN cross-polar-cap potential difference, which was provided by Evan Thomas at Dartmouth College.