The latitudinal distribution of solar wind magnetic holes

Abstract

Using the fast latitude scan period of the Ulysses spacecraft, the occurrence of magnetic holes in the solar wind is investigated from -80° to +80° helio-latitude. Near the ecliptic, the large average value and the large variations of the hole count rate appear to be correlated with interaction regions. It is found, however, that at 30°north and south latitude, approximately, the hole count rate drops to about 10% of that in the low latitude region and stays constant at this level to near the poles. The small but non-zero hole count rate at high helio-latitudes indicates that these holes were formed by processes other than the large scale dynamic solar wind features operating in the ecliptic region. Copyright 2000 by the American Geophysical Union.