Longitude Distributions of the Large Sunspot Groups on the Solar Disk in the Past Three Cycles

The sunspot groups of Types E and F which appeared in the 19th, 20th and 21st cycles are statisticlly analysed in this paper, with the results showing that(1) the distributions of the solar longitudes of the large sunspot groups with time(expressed by the solar rotation period) are "V" and "∧" in shape and(2) there are two peaks in the numbers of the large sunspot groups for cach of the three cycles according to the longitude distribution.