Long Period Magnetotelluric signals
These are long-period MT data collected in Tibet in 1995. Note the daily variation
produced as the earth rotates within the solar wind.
At day 12 a sharp step in Bx (north-south manetic field)occurs. This was generated by a change in the solar wind caused by a small magnetic storm. The low frequency content of this step gave resolution to a depth of several hundred kilometres.
The strength of long-period MT signals varies with the sunspot cycle. Solar Cycle 24 began officially in January 2008, but the increase in the number of sunspots has been unusually slow.
Sunspot predictions
See the latest sunspot prediction from the Solar Influences Data analysis Center (SIDC) hereMore about space weather at SolarCycle24.com
K-indices
The K-indices are a common way to measure the strength of long-period geomagnetic activity. Recent K-index data is complied by the NOAA at the Space Weather Prediction Centre