Weekly Bulletin on Solar and Geomagnetic Activity Highlights on 23 - 27.08.2021, Forecast on 28.08 - 13.09.2021 Carrington Rotation 2247, 2248 (1,1.08, 28,33.08.2021) Earth out of ecliptic (4.5 - 3.8) deg. (S30 - N32 is zone of geoeffectiveness) THE SUNSPOT-FORMING SOLAR ACTIVITY WAS ON VERY LOW, LOW AND MIDDLE LEVELS. THE ESTIMATED MOST LIKELY WEEKLY AVERAGE VALUE OF THE SUNSPOT NUMBER IN THE INTERNATIONAL SYSTEM (old) FOR PERIOD IS W=23+23/-15 (Wn= 38+35/-24). 4 SMALL QUITE SUNSPOT GROUPS ON THE VISIBLE SOLAR DISK, ONE WERE ON NORTH HEMISPHE- RE HAS BEEN OBSERVED. NEXT WEEK SUNSPOT ACTIVITY WILL BE ON LOW AND MIDDLE LEVELS. WEEKLY AVERAGE VALUE OF THE RELATIVE SUNSPOT NUMBER IN THE IN- TERNATIONAL SYSTEM (old) FOR NEXT WEEK IS W=030+20/-10. FLARE ACTIVITY WAS AT MIDDLE AND LOW LEVELS. ONE FLARE OF X- RAY CLASS "M", 14 - CLASS "C", 43 - CLASS "B", 4 SOLAR FILA- MENT EJECTION AND 11 CORONAL MASS EJECTIONS (24-26.08) HAVE BEEN OBSERVED. ------------------------------------------------------------------- FLARES >M1 X-RAY CLASSES to tm te local. Class E(1-8A) AR RII/IV CME X-ray/Ïp J/m-2 DSF to te localization l deg. Fl AR CME/to 23.08 22/1607 23/0143 N52E15L084 40 CME/0648 24.08 0300 0845 NW-limb >10 CMEII/0648 26.08 >0018 >1331 S07W29L004 8 26.08 1754 1812 N27E12L037 7 C3/1F 12859 CMEII/1900 -------------------------------------------------------------------- NEXT WEEK THE FLARE ACTIVITY IS EXPECTED AT VERY LOW AND LOW LEVELS. ON THE VISIBLE SOLAR DISK THE FOLLOWING CORONAL HOLES WERE OBSERVED: --------------------------------------------------------------------- sign N end E end S end W end Sch EE R G Spacecraft CH* - N20L052 N05L057 S05L056 N10L051 1.1% 27.08 R1 SDO,SOHO... * - low geoeffectivity, the substorms with duration <6 h. only. Sch - CH area in % solar hemisphere near the central meridian on https://www.solarmonitor.org/; n/d - no data; R - solar rotations; EE-date of possible geomagnetic disturbance in the Earth's environment. G(0-5)-geoeffectivity in last solar rotation on the middle latitudes. A-active geomagnetic condition. ---------------------------------------------------------------------- AFTER 13.08/06 UT THE EARTH IS IN THE "+" SECTOR OF THE INTERPLANETA- RY MAGNETIC FIELD. AT PERIOD 22/05 TO 23/0745 UT THE SIGN OF SECTOR WAS "-". FOLLOWING SECTOR BOUNDARY "+/-" IT CAN BE EXPECT 28.08. ---------------------------------------------------------------------- AUGUST 23 24 25 26 27 á÷çõóô Wus 014 029 029 047 073 F10.7 078 081 084 084 090 èbcg á8.1 á7.1 ÷1.2 ÷1.3 B1.6 GOES Sp 160 260 240 210 110 msh N 1 1 1 IMF -/+ + + + + DSCOVR Å>2 1.3å+6 1.2å+6 1.3å+6 1.3E+6 1.8E+6 GOES Ie>2 156 143 125 139 161 pfu Ap 4 5 9 6 20 nô Dst nô KIOTO Amsc 3 4 7 4 18 nô IZMIRAN ---------------------------------------------------------------------- Å>2 - Daily Electron Fluency e/(cm2-ster-day) with E>2 MeV. Ie>2 - the maximum intensity of electron flux in geostationary or- bits in days according to GOES-15 in (electrons/cm2.s.sr) for events > 1000 pfu. THE GREATER THAN 2 MeV RECURRENT ELECTRON FLUX AT GEOSYNCHRONOUS ORBIT NO OBSERVED. NEXT WEEK THE GREATER THAN 2 MeV ELECTRON FLUX AT GEOSYNCHRONOUS ORBIT IS NOT EXPECTED - NO GEOEFFECTIVE CORONAL HOLES. THE GEOMAGNETIC CONDITION WAS QUIET AND UNSETTLED ALL DAYS EXCEPT 27.08, WHEN A MINOR MAGNETIC STORM (G1, Ams= 34, dur.=15 h) ACCOR- DING TO THE CENTER IN BULDER DATA AND (G1, Ams= 25, dur.=18 h) AC- CORDING TO IZMIRAN DATA. THE DISTURBATION BECAME A CONSEQUENCE OF THE ARRIVAL TO THE EARTH OF CME FROM SOLAR FILAMENT EJECTA (40 deg) 23.08. THE NEXT WEEK IS MOST PROBABLE A QUIET AND UNSETTLED GEOMAGNETIC CONDITION ALL DAYS. HIGHLIGHT AND FORECAST COMPOSED FROM DATA: NOAA SWPC, BOULDER, USA http://www.swpc.noaa.gov, THE SOLAR INFLUENCES DATA ANALYSIS CENTRE, SIDC, BRUSSELS, BELGIUM http://sidc.oma.be/index.php3, THE IZMIRAN, MOSCOW, TROITSK, RUSSIA http://www.izmiran.ru V. Ishkov