Daily Report

(last updated 23 May 2025 23:30 UT)

SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT ISSUED AT 2330UT/23 MAY 2025 FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE SUMMARY FOR 23 MAY AND FORECAST FOR 24 MAY - 26 MAY STATUS INDICATORS SOL:** YELLOW ** MAG:GREEN ION: ** YELLOW ** ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx ----------------------------------------------------------- 1A. SOLAR SUMMARY Activity 23 May: R0 Flares: none. Observed 10.7 cm flux/Equivalent Sunspot Number for 23 May: 122/75 1B. SOLAR FORECAST 24 May 25 May 26 May Activity R0-R1 R0-R1 R0-R1 Fadeouts Possible Possible Possible 10.7cm/SSN 120/72 120/72 130/84 COMMENT: Solar activity on UT day 23-May was at the R0 level, with no significant flaring activity. There are currently eight numbered sunspot regions visible on the solar disk. AR4087 (N17W61, alpha) is the largest region on the disk and is stable. AR4098 (S04W22, beta) has exhibited spot development over the UT day. All other sunspot regions are either stable or in decay. Solar activity is expected to be at R0-R1 levels over 24-26 May. No Earth-directed CMEs have been observed. A halo CME was observed, visible in LASCO C2 coronagraph imagery from 23/1700UT. This CME is considered to be a farside event and not geoeffective. The solar wind speed on UT day 23-May declined, ranging from 425 to 520 km/s and is currently near 425 km/s. The peak total interplanetary magnetic field strength (IMF, Bt) was 8 nT and the north-south IMF component (Bz) range was -5 to +7 nT. The solar wind speed is expected to decline over 24-26 May due to waning coronal hole high speed wind stream effects. ----------------------------------------------------------- 2A. MAGNETIC SUMMARY Geomagnetic field for Australian Region 23 May: G0 Estimated Indices 23 May : A K Australian Region 4 22221101 Cocos Island 2 11111100 Darwin 7 2------- Townsville 5 22221112 Learmonth 5 22222201 Alice Springs 3 21211200 Gingin 5 22212201 Canberra 3 11221101 Kennaook Cape Grim 3 11221101 Hobart 5 22212102 Estimated Antarctic Regional K Indices 23 May : Macquarie Island 4 11122201 Casey 10 33332211 Mawson 16 34432323 Observed Regional daily pc3 Indices 23 May : Darwin 60 (Unsettled) Townsville 0 (Quiet) Learmonth 0 (Quiet) Alice Springs 0 (Quiet) Gingin 11 (Quiet) Canberra 17 (Quiet) Hobart 21 (Quiet to unsettled) Pc3 pulsations are high frequency (10-45 second period) variations of the Earths magnetic field. Daily pc3-indices are the daily sum of 20 minute pc3-indices for that station and have been shown to be well correlated with rejection of high resolution aeromagnetic survey flight-line data. NOTE: Indices may have been generated from data obtained in cooperation with the following organisations: Geoscience Australia, University of Newcastle Space Physics Group, Australian Government Antarctic Division and International Center for Space Weather Science and Education, Japan. Estimated AFr/Ap Indices 23 May : A Fredericksburg 7 Planetary 8 Observed AFr/Ap Indices 22 May : A K Fredericksburg 6 Planetary 0 2221 2122 2B. MAGNETIC FORECAST Date Ap Conditions 24 May 8 G0 25 May 5 G0 26 May 6 G0 COMMENT: G0 geomagnetic conditions were observed in the Australian and Antarctic regions on UT day 23-May. G0 geomagnetic conditions are expected over 24-26 May. ----------------------------------------------------------- 3A. GLOBAL HF PROPAGATION SUMMARY Latitude Band Date Low Middle High 23 May Normal Normal-fair Fair PCA Event : No event. 3B. GLOBAL HF PROPAGATION FORECAST Latitude Band Date Low Middle High 24 May Normal Normal Normal-fair 25 May Normal Normal Normal 26 May Normal Normal Normal COMMENT: HF radio propagation conditions on UT day 23-May were normal to fair. HF radio propagation conditions are expected to be normal to fair over 24-26 May. Shortwave fadeouts are possible. ----------------------------------------------------------- 4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY Date T index 23 May 83 Observed Australian Regional MUFs Cocos Island Region: Near predicted monthly values during local day. Depressed by 15% during local night. Niue Island Region: Near predicted monthly values during local day. Northern Australian Region: Depressed by 15% during local day. Depressed by 30% during local night. Southern Australian Region: Near predicted monthly values during local day. Depressed by 20% during local night. Antarctic Region (Casey/Davis/Mawson): Near predicted monthly values over the UT day. Monthly T index: Month T index Apr 123 May 113 Jun 111 4B. AUSTRALIAN REGION IONOSPHERIC FORECAST Date T index MUFs 24 May 85 Depressed 15%/near predicted monthly values 25 May 85 Depressed 15%/near predicted monthly values 26 May 85 Depressed 15%/near predicted monthly values COMMENT: ASWFC HF Communications Warning 51 was issued on 23 May and is current for 23-25 May. Maximum usable frequencies (MUFs) in the Australian region on UT day 23-May were near predicted monthly values to 15-30% depressed. Spread F was observed at Hobart during local night hours. MUFs are expected to be near predicted monthly values to 15% depressed over 24-26 May. Shortwave fadeouts are possible. ----------------------------------------------------------- 5. SPACE ENVIRONMENT SUMMARY GOES satellite data for 22 May Daily Proton Fluence >1 MeV: 1.5E+05 Daily Proton Fluence >10 MeV: 1.6E+04 Daily Electron Fluence >2 MeV: 6.90E+07 (normal fluence) Electron Fluence Daily Deep Dielectric Discharge Probability: 8% Fluence (flux accumulation over 24hrs)/ cm2-ster-day. X-ray background: B4.7 DSCOVR Satellite Solar Wind Day Averaged Data for 22 May Speed: 506 km/sec Density: 2.0 p/cc Temp: 194000 K Bz: 0 nT (Courtesy Space Weather Prediction Center, Boulder USA) -----------------------------------------------------------