A Year of Uninterrupted Solar Magnetic Field Observations from MDI on
**J.T. Hoeksema**, R.I. Bush, P.H. Scherrer
W.W. Hansen Experimental Physics Laboratory,
HEPL Annex B213, Stanford University, Stanford, CA 94305-4085
C. Heck, N. Hurllburt, A. Title
Lockheed Martin Palo Alto Research Laboratory
91-30/252, 3251 Hanover St., Palo Alto, CA 94304
The Solar Oscillations Investigation Michelson Doppler Imager (SOI/MDI)
on SOHO has measured the solar photospheric magnetic field with 4"
resolution over the whole disk nearly every 96 minutes since April
1996. This unprecedented continuous sequence of frequent, uniform
quality magnetograms provides a striking view of the continuous
emergence and evolution of flux over the visible surface of the
Sun near solar minimum. Since evolving solar magnetic fields drive the
variations of the corona and solar wind that affect the
solar-terrestrial environment, knowledge of the rapidly evolving
photospheric field provides a crucial input for forecasting conditions
in the corona, heliosphere, and geospace.
A few magnetic images are available each day within hours of observation
through the SOHO web site at http://sohowww.nascom.nasa.gov/.
These are used for planning and forecasting purposes. The remainder
are generally available within a couple of weeks. From time to time
intensive magnetic campaigns are run that provide observations as often
as once each minute for up to 8 hours. These can be taken with either
the full disk resolution or with 0.6" pixels in a limited region near
the center of the disk. The SOI project welcomes collaborations.
More information can be found at http://soi.stanford.edu/.