Observed Helicity of Active Region Magnetic Fields in Solar Cycle 21

We report the results of a study of magnetic helicity in solar active regions during solar cycles 21 and 22 from observations with the Marshall Space Flight Center's solar vector magnetograph. Using the force-free parameter a as the proxy for helicity, we calculated an average value of a for each of 91 active regions fiom a total of 683 vector magnetograms that were obtained during the period March 1980 to July 1993. The signs of these average values of alpha were correlated with the latitude of the active regions to test the hemispherical rule of helicity that has been proposed for solar magnetic fields: negative helicity predominant in northern latitudes, positive in the southern ones. We have found that of the 65 regions that were observed in cycle 21,49% obey the hemispherical rule and 51% do not. On the other hand, for the 26 regions in cycle 22,65% do exhibit this correlation.