EarthRef.org Reference Database (ERR)
Development and Maintenance by the EarthRef.org Database Team

Detailed Reference Information
Mursula et al. 2002
Mursula, K., Hiltula, T. and Zieger, B. (2002). Latitudinal gradients of solar wind speed around the ecliptic: Systematic displacement of the streamer belt. Geophysical Research Letters 29: doi: 10.1029/2002GL015318. issn: 0094-8276.

We study the effective latitudinal gradients of the solar wind (SW) speed in the two magnetic hemispheres around the heliographic equator by comparing observations at the Earth's orbit in Spring and Fall since 1964. We find that there is a large, statistically significant effective gradient of about 10 km/s/deg in the southern magnetic hemisphere around each solar minimum. However, no statistically significant effective gradient is found in the northern magnetic hemisphere. This difference implies a systematic displacement of the minimum speed locus of the streamer belt toward the northern magnetic hemisphere. We note that at least during one minimum the streamer belt and the heliospheric current sheet seem to have been oppositely displaced. We also show that the average SW speeds from the two magnetic hemispheres are roughly equal. Therefore, the earlier reported annual variation in SW speed at 1 AU is due to the displacement of the streamer belt and not due to different speeds from coronal holes of opposite polarity. The displacement of the streamer belt implies a new, persistent north-south asymmetry related to the solar magnetic cycle which needs to be explained by realistic solar dynamo models.

BACKGROUND DATA FILES

Abstract

Keywords
Interplanetary Physics, Solar wind plasma, Interplanetary Physics, Solar cycle variations, Solar Physics, Astrophysics, and Astronomy, Solar activity cycle
Journal
Geophysical Research Letters
http://www.agu.org/journals/gl/
Publisher
American Geophysical Union
2000 Florida Avenue N.W.
Washington, D.C. 20009-1277
USA
1-202-462-6900
1-202-328-0566
service@agu.org
Click to clear formClick to return to previous pageClick to submit