Measures of Solar Activity

Solar Magnetic Mean Field - Space Based Observations

Solar Heliospheric Observatory (SOHO) was launched on December 5, 1995. One of the twelve instruments is the Michelson Doppler Imager (MDI). The optical design is shown to the right.
The top diagram shows solar mean field MDI observations with one minute temporal resolution from March 1999 to August 2000.

The bottom diagram shows mean field data for a 7 hour period (16.00 to 22.59) during May 16, 1999.