The June 21, 2001 Total Solar Eclipse

On Thursday, June 21, 2001, a total eclipse of the Sun was visible from within a narrow corridor crossing the Southern Hemisphere, beginning in the South Atlantic, crossing southern Africa and Madagascar, and terminating in the Indian Ocean. A partial eclipse could be seen throughout eastern South America and mid/south Africa. For a detailed description of the eclipse path, see Fred Espenak’s 2001 Total Eclipse web site.

On May 19, 2001, we started an MHD computation of the solar corona, in preparation for our prediction of what the solar corona would look like during this eclipse. We used photospheric magnetic field data from Carrington rotation 1975 (corresponding to the dates April 9 – May 6, 2001) from the National Solar Observatory at Kitt Peak. On June 10, 2001 we updated this prediction by running another MHD simulation in which we evolved the photospheric magnetic field to match data from Carrington rotation 1976 (corresponding to the dates May 6 – June 2, 2001). On June 14, 2001 we attempted to update the photospheric magnetic field once again to match data from Carrington rotations 1976+1977 (corresponding to the dates May 18 – June 14, 2001), but, for technical reasons, this simulation was not successful. The eclipse prediction shown below is thus based on the data from CR1976. A comparison of the coronal predictions for the two simulations based on CR1975 and CR1976 is on the original comparison page.

Predicted polarization brightness, terrestrial north up — Predicted polarization brightness (pB) in the solar corona for the eclipse expected on June 21, 2001 at 13:10 UT (corresponding to totality in Lusaka, Zambia). The state of the solar corona was computed using a 3D magnetohydrodynamic (MHD) simulation. The pB signal is produced by white light scattered off electrons in the coronal plasma. The image has been radially detrended to account for the fall-off of coronal brightness with distance from the Sun. Vertical (top) is terrestrial (geocentric) north. This is the view of the Sun that would be seen by an observer on Earth with a camera aligned so that vertical is toward the Earth’s north pole. Views aligned with solar north are on the original solar-north page.

Predicted polarization brightness with photospheric field contours — Predicted polarization brightness (left) together with traces of the magnetic field lines in the solar corona (right) for the eclipse expected on June 21, 2001 at 13:10 UT (with terrestrial north up). The Sun’s surface shows color contours of the radial component of the measured photospheric magnetic field from Kitt Peak National Solar Observatory, showing the location of active regions (strong magnetic fields).

Traces of the magnetic field lines with photospheric field contours — Predicted polarization brightness (left) together with traces of the magnetic field lines in the solar corona (right) for the eclipse expected on June 21, 2001 at 13:10 UT (with terrestrial north up). The Sun’s surface shows color contours of the radial component of the measured photospheric magnetic field from Kitt Peak National Solar Observatory, showing the location of active regions (strong magnetic fields).

Comparison with an Eclipse Photograph Taken in Zambia

Composite eclipse image from Zambia by Wendy Carlos and Jonathan Kern — In the figures above we compare our MHD model prediction with a photograph taken in Lusaka, Zambia. The eclipse image is a computer composite and optimization from several negatives taken by Wendy Carlos, merged with images taken with radially graded filters by Jonathan Kern. The images have terrestrial (geocentric) north vertically upward. *Eclipse Image: © 2001 Wendy Carlos and Jonathan Kern – All Rights Reserved. For details, see wendycarlos.com/eclipse.html.

MHD model prediction of polarization brightness — In the figures above we compare our MHD model prediction with a photograph taken in Lusaka, Zambia. The eclipse image is a computer composite and optimization from several negatives taken by Wendy Carlos, merged with images taken with radially graded filters by Jonathan Kern. The images have terrestrial (geocentric) north vertically upward. *Eclipse Image: © 2001 Wendy Carlos and Jonathan Kern – All Rights Reserved. For details, see wendycarlos.com/eclipse.html.

Evolution of the Photospheric Magnetic Field

The photospheric magnetic field maps we use for our calculations are built up from daily observations of the Sun during a solar rotation. These maps give a good approximation of the Sun’s magnetic flux if the large-scale flux is not changing much throughout a rotation. Previously, we have computed coronal models for an eclipse during the declining phase of the last solar cycle (November 3, 1994), for two eclipses during solar minimum (October 24, 1995 and March 9, 1997), one eclipse during the early rising phase of solar cycle 23 (February 26, 1998), and one eclipse approaching solar maximum (August 11, 1999). The June 21, 2001 eclipse, which occurred at the peak of solar maximum, presented a challenge. The photospheric magnetic field was evolving more rapidly, making synoptic magnetic field data a less reliable approximation to the true state of the photospheric magnetic field. The complexity of coronal structures required high resolution runs (approximately 1,500,000 grid points in our calculation).

Photospheric magnetic field map for CR1975 — These figures show the photospheric magnetic field maps for three Carrington rotations, CR1975, CR1976, and CR1976+1977, as measured by the National Solar Observatory at Kitt Peak. The maps show the measured photospheric magnetic field as a function of latitude (vertical axis) and Carrington longitude (horizontal axis). Red shows outward directed magnetic flux, and blue shows inward directed flux. These maps are considerably more complex than maps during solar minimum.

Photospheric magnetic field map for CR1976 — These figures show the photospheric magnetic field maps for three Carrington rotations, CR1975, CR1976, and CR1976+1977, as measured by the National Solar Observatory at Kitt Peak. The maps show the measured photospheric magnetic field as a function of latitude (vertical axis) and Carrington longitude (horizontal axis). Red shows outward directed magnetic flux, and blue shows inward directed flux. These maps are considerably more complex than maps during solar minimum.

Movies

We have made a movie of the polarization brightness from our MHD simulation of the solar corona during Carrington rotation 1975 (April 9 – May 6, 2001). This illustrates visually how rapidly the solar corona changes as a result of solar rotation during the maximum phase of the solar cycle.

Polarization Brightness(Carrington Rotation 1975)

Publications

For technical details about our model, please see the publications:

Z. Mikić, J. A. Linker, D. D. Schnack, R. Lionello, and A. Tarditi, “Magnetohydrodynamic Modeling of the Global Solar Corona,” Physics of Plasmas, 6, 2217 (1999).
Z. Mikić, J. A. Linker, P. Riley, and R. Lionello, “Predicting the Structure of the Solar Corona During the 11 August 1999 Total Solar Eclipse,” in The Last Total Solar Eclipse of the Millennium, Proceedings of the Conference held in Istanbul, Turkey, 13–15 August, 1999 (W. Livingston and A. Ozguc, eds.), ASP Conference Series, Vol. 205, p. 162 (2000).

Other Web Resources for the Eclipse

Fred Espenak’s 2001 Total Solar Eclipse web site (a great resource for the eclipse, including lots of information and links to other sites).
Eclipse information from NASA’s Goddard Space Flight Center.
Sky and Telescope Magazine.
MrEclipse.com.

Archived prediction, converted from the original 2001 page. The movie originally offered as an MPEG/QuickTime download is embedded above.