No doubling of the Sun's coronal magnetic field during the last 100 years
Abstract
Various authors have conjectured that the interplanetary magnetic field near the Earth (and by inference the Sun's magnetic field) has more than doubled during the last 100 years. The primary evidence for this is a similar increase in the geomagnetic activity index aa. We discuss several lines of independent evidence that all indicate that the aa-index does not have a constant calibration over time. While it certainly is true that different solar cycles show different amounts of geomagnetic activity due to variations of the sun and the interplanetary environment, correcting the calibration of the aa-index strongly suggests that there is no persistent upward trend over the last 100 years. We call for a concerted effort to re-calibrate the aa-index.
- Publication:
-
EGS - AGU - EUG Joint Assembly
- Pub Date:
- April 2003
- Bibcode:
- 2003EAEJA.....7616S