SILSO, the World Data Center for the production, preservation and dissemination of the international sunspot number, has issued its monthly report for July 2024. The provisional sunspot number for last month is 196.5, which is the highest monthly value since December 2001, i.e. near the maximum of solar cycle 23 (SC23 - SILSO table). The highest daily value was recorded on 18 July (290), a value not seen since 27-29 July 2002 when the daily sunspot numbers varied between 290 and 310. The SILSO graph underneath shows the daily, monthly, and smoothed monthly sunspot numbers since mid-2011. The forecasts (dashed lines) now give a smoothed maximum for SC25 of 137-144 during the May-September 2024 timeframe. With the number of sunspots already observed so far in August, this maximum may turn out to be even higher.
The observed sunspot activity has been driven by a plethora of active regions in the southern hemisphere. This domination over the northern hemisphere only started a few months ago, and continued into August. The comparison underneath (SDO/HMI) shows the Sun's appearance in white light a year ago (20 July 2023 - left) and currently (6 August 2024 - right). This domination (aka hemispheric asymmetry) can last for years as shown in these plots at SILSO and the STCE's SC25 tracking page.
The domination of the southern solar hemisphere is also visible in other parameters, such as the number of solar flares (M- and X-class). The graph underneath clearly shows how -in 2023- most of the flares were produced in the northern solar hemisphere, whereas from early 2024 onwards the southern hemisphere has taken over with the largest monthly number of flares so far this solar cycle. In May, no less than 143 M- and X-class flares have been recorded, 99 of which in the southern solar hemisphere and -mostly- courtesy of the super group NOAA 3664. Interestingly, the last data point is only for the first 4 days of August and far from complete. Yet, the flare numbers are already close to some of the monthly flare numbers in the northern hemisphere for an entire month!... Impressive.
