25 CYCLE OF SOLAR ACTIVITY, THE BRANCH OF RISE: THE PHASE OF MINIMUM Weekly Bulletin on Solar and Geomagnetic Activity Highlights on 13 - 19.12.2021, Forecast on 20 - 27.12.2021 Carrington Rotation 2251, 2252 (18,18.11; 15,49.2021) Earth out of ecliptic (-5.0 - -5.5) deg. (S32 - N27 is zone of geoeffectiveness) THE SUNSPOT-FORMING SOLAR ACTIVITY WAS ON LOW AND VERY LOW LEVELS. ESTIMATED MOST LIKELY WEEKLY AVERAGE VALUE OF THE SUNSPOT NUMBER IN THE INTERNATIONAL SYSTEM (old) FOR PERIOD IS W=54+22/-30 (Wn=91+36/ -51). ON VISIBLE SOLAR DISK AT THE 6 SMALL SUNSPOT GROUPS AND 1 MID- DLE HAVE BEEN OBSERVED. NEXT WEEK SUNSPOT ACTIVITY WILL BE ON LOW AND VERY LOW LEVELS. WEEK- LY AVERAGE VALUE OF THE RELATIVE SUNSPOT NUMBER IN THE INTERNATIONAL SYSTEM (old) FOR NEXT WEEK IS W=060+40/-20. FLARE ACTIVITY WAS AT MIDDLE AND LOW LEVELS. 1 FLARE X-RAY CLASS "M", 56-CLASS "C", 52- CLASS "A", ONE SOLAR FILAMENT EJECTION AND 12 CORO- NAL MASS EJECTIONS (13, 15, 16, 18, 19.12) 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 17.12 0039 0056 0051 N19E70L270 M1.2/1F 5.3E-03 12911 DSF (EPL) to te localization l deg. Fl AR CME/to 15.12 0856 0920 S27E47L033 5 C1.6 12907 CME/0948 -------------------------------------------------------------------- NEXT WEEK THE FLARE ACTIVITY IS EXPECTED AT LOW AND (MAY BE) MIDDLE 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 - S23L033 S32L053 S45L053 S24L031 2% 15.12 2 - SDO, HINOTORI CH - N10L320 S05L340 S15L317 S00L305 <8% 22.12 1 - SDO, HINOTORI * - 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. ---------------------------------------------------------------------- 14.12/1840 UT THE EARTH IS IN THE "-" SECTOR OF THE INTERPLANETARY MAG- NETIC FIELD. FOLLOWING SECTOR BOUNDARY "+/-" IT CAN BE EXPECT 25.12. ----------------------------------------------------------------------- DECEMBER 13 14 15 16 17 18 19 DECEMBER Wus 040 040 079 127 119 117 109 F10.7 081 086 103 118 121 121 115 èbcg á4.8 B2.1 B5.0 B4.6 B5.3 ÷4.7 ÷4.0 GOES Sp 040 110 830 650 920 900 740 msh N 2 2 2 IMF + +/- - - - - - DSCOVR Å>2 2.9å+6 1.5E+6 2.0E+5 2.0E+6 1.8å+6 2.8E+6 5.1E+6 GOES Ie>2 354 168 156 169 159 189 477 pfu Ap 7 5 5 3 4 4 14 nô Dst nô KIOTO Amsc 7 5 5 2 4 4 15 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 ELECTRON FLUX AT GEOSYNCHRONOUS ORBIT NO OB- SERVED. NEXT WEEK THE GREATER THAN 2 MeV ELECTRON FLUX AT GEOSYNCHRONOUS ORBIT IS NOT EXPECTED. THE GEOMAGNETIC CONDITION REMAINED QUIET AND UNSETTLED UNTIL THE SE- COND HALF of 19.12, WHEN DISTURBANCE (CME) COME TO THE EARTH FROM THE SOLAR FILAMENT EJECTA AT 15.12 AND A MINOR MAGNETIC STORM (G1, Ams=33, dur.=12 h) ACCORDING TO BOULDER CENTER DATA AND 9-hour G1 SUBSTORM AC- CORDING TO IZMIRAN DATA WAS RECORDED. THE NEXT WEEK IS MOST PROBABLE A QUIET AND UNSETTLED GEOMAGNETIC CONDI- TION, HOWEVER 21 - 22.12, WHEN THE EARTH PASSING A HIGH-VELOCITY STREAM FROM THE EQUATORIAL CORONAL HOLE "-" POLARITY, THE GROWTH OF THE DISTUR- BANCE OF THE GEOMAGNETIC FIELD IS POSSIBLE. THE PROBABILITY OF A MINOR MAGNETIC STORM IS NOT MORE THAN 20%. 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