Abstract
Solar phenomena have long been suspected to exhibit a form of longitudinal dependence, whereby certain solar events – such as sunspots and flares – tend to form in larger “clusters”. These clusters can persist for several Carrington rotations, with features forming and decaying within the same longitudinal band, typically spanning roughly 20° – 60°. Over the decades, many attempts have been made to detect and explain these clusters, often referred to as active longitudes or nests. Despite extensive research, the topic remains debated.
In this talk, we present a novel approach to demonstrating the longitudinal dependence of sunspots and major solar flares, using observational data spanning more than 10 solar cycles. Our results are validated through comparison with synthetic datasets. In addition, we examine the evolution of these clusters over the course of the solar cycle, offering new insights into their temporal behaviour and potential links to the solar dynamo.