Sunspot minimum between solar cycles No 23 and 24. Prediction of solar cycle No 24 magnitude on the base of "Waldmeier's rule"

TL;DR

This study determines the solar minimum between cycles 23 and 24 using multiple data sources and predicts the cycle 24 magnitude based on Waldmeier's rule, indicating a relatively weak cycle.

Contribution

It introduces a method combining four data types to accurately identify solar minimum and applies Waldmeier's rule for cycle magnitude prediction.

Findings

Solar minimum occurred on Nov 6, 2008.

Cycle 23 lasted approximately 12.6 years.

Cycle 24 is predicted to be relatively weak.

Abstract

The main purpose of this study is the determination of solar minimum date of the new sunspot cycle No 24. It is provided by using of four types of mean daily data values for the period Jan 01. 2006 - Dec 31. 2009: (1) the solar radioindex F10.7; (2) the International sunspot number Ri; (3) the total solar irradiance index (TSI), and (4) the daily number of X-ray flares of classes from "B" to "X" from the soft X-ray GOES satellite channel (0.1 - 0.8 nm). It is found that the mean starting moment of the upward solar activity tendency (the mean solar minimum) is Nov. 06th, 2008. So, the solar cycle No 23 length is estimated to ~12.6 years. A conclusion for a relatively weak general magnitude of solar cycle No 24 is made. By using of relationship based on the "Waldmeier's rule" a near maximal mean yearly sunspot number value of 72 \pm 27 has been determined.