Comparison of latitude distribution and evolution of even and odd sunspot cycles
1Space Physics and Astronomy Research Unit, University of Oulu, POB 3000, 90014, Oulu, Finland
|Online Access:||PDF Full Text (PDF, 2.1 MB)|
|Persistent link:|| http://urn.fi/urn:nbn:fi-fe2020060340327
|Publish Date:|| 2020-06-03
We study the latitudinal distribution and evolution of sunspot areas of Solar Cycles 12 – 23 (SC12–23) and sunspot groups of Solar Cycles 8 – 23 (SC8–23) for even and odd cycles. The Rician distribution is the best-fit function for both even and odd sunspots group latitudinal occurrence. The mean and variance for even northern/southern butterfly wing sunspots are 14.94/14.76 and 58.62/56.08, respectively, and the mean and variance for odd northern/southern wing sunspots are 15.52/15.58 and 61.77/58.00, respectively. Sunspot groups of even cycle wings are thus at somewhat lower latitudes on average than sunspot groups of the odd cycle wings, i.e. about 0.6 degrees for northern hemisphere wings and 0.8 degrees for southern hemisphere wings.
The spatial analysis of sunspot areas between SC12–23 shows that the small sunspots are at lower solar latitudes of the Sun than the large sunspots for both odd and even cycles, and also for both hemispheres.
Temporal evolution of sunspot areas shows a lack of large sunspots after four years (exactly between 4.2 – 4.5 years), i.e. about 40% after the start of the cycle, especially for even cycles. This is related to the Gnevyshev gap and is occurring at the time when the evolution of the average sunspot latitudes crosses about 15 degrees. The gap is, however, clearer for even cycles than odd ones. Gnevyshev gap divides the cycle into two disparate parts: the ascending phase/cycle maximum and the declining phase of the sunspot cycle.
|Type of Publication:||
A1 Journal article – refereed
|Field of Science:||
115 Astronomy and space science
Open access funding provided by University of Oulu including Oulu University Hospital. We acknowledge the financial support by the Academy of Finland to the ReSoLVE Centre of Excellence (project no. 272157).
|Academy of Finland Grant Number:||
272157 (Academy of Finland Funding decision)
The sunspot-group data are downloaded from VizieR database (https://vizier.u-strasbg.fr/viz-bin/VizieR?-source=J/A+A/599/A131&-to=3), and the sunspot area data from RGO-USAF/ NOAA (https://solarscience.msfc.nasa.gov/greenwch.shtml). The dates of cycle maxima were obtained from the National Geophysical Data Center (NGDC), Boulder, Colorado, USA (ftp.ngdc.noaa.gov).
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