Daily Report

(last updated 15 Sep 2024 23:30 UT)

SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT ISSUED AT 2330UT/15 SEPTEMBER 2024 FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE SUMMARY FOR 15 SEPTEMBER AND FORECAST FOR 16 SEPTEMBER - 18 SEPTEMBER STATUS INDICATORS SOL:** RED ** MAG:** RED ** ION: GREEN ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx ----------------------------------------------------------- 1A. SOLAR SUMMARY Activity 15 Sep: R0 Flares: none. Observed 10.7 cm flux/Equivalent Sunspot Number for 15 Sep: 173/127 1B. SOLAR FORECAST 16 Sep 17 Sep 18 Sep Activity R1, chance R2/R3 R1, chance R2/R3 R1, chance R2/R3 Fadeouts Probable Probable Probable 10.7cm/SSN 175/129 170/124 170/124 COMMENT: Solar activity on UT day 15-Sep was at the R0 level with multiple C-class flares. There are currently five numbered sunspot regions visible on the solar disk and one unnumbered region. AR3825 (S15E41, gamma) is the largest and most significant group on the solar disk, however it underwent some spot decay over the UT day and lost its delta spot. AR3824 (S04W20, beta-gamma) developed over the UT day. An unnumbered region has recently rotated onto the solar disk at around S25E75 with alpha magnetic complexity and appears stable. All other sunspot regions are either stable or in decay. Solar activity is expected to be at the R1 level over 16-18 Sep, with a chance of R2-R3 events. The >10MeV solar proton flux was elevated over the UT day but did not cross the S1 threshold. S0 conditions, with a chance of S1 are expected over 16-18 Sep. No CMEs were observed over the UT day. The solar wind speed on UT day 15-Sep was steady but choppy, ranging from 426 to 570 km/s and is currently near 440 km/s. The peak total interplanetary field strength (IMF, Bt) was 9 nT and the north-south IMF component (Bz) range was +6 to -8 nT. A significant increase in wind speed is expected on 16-Sep due to an anticipated impact from a fast halo CME, first observed on 14-Sep, around the middle of the UT day. This is expected to combine with a possible glancing impact from a CME first observed on 13-Sep and high speed wind stream effects from coronal holes in the northern and southern hemisphere. The solar wind speed is expected to continue to be elevated on 17-Sep, with a decline towards background levels possible on 18-Sep ----------------------------------------------------------- 2A. MAGNETIC SUMMARY Geomagnetic field for Australian Region 15 Sep: G0 Estimated Indices 15 Sep : A K Australian Region 11 23323322 Cocos Island 7 23222221 Darwin 10 23323222 Townsville 13 23323333 Learmonth 12 23333322 Alice Springs 10 23323222 Gingin 12 23323332 Canberra 10 13313223 Kennaook Cape Grim 12 13323333 Hobart 14 23423333 Estimated Antarctic Regional K Indices 15 Sep : Macquarie Island 25 34535432 Casey 17 44433223 Mawson 29 34534454 Observed Regional daily pc3 Indices 15 Sep : Darwin 0 (Quiet) Townsville 0 (Quiet) Learmonth 0 (Quiet) Alice Springs 0 (Quiet) Gingin 8 (Quiet) Canberra 11 (Quiet) 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 15 Sep : A Fredericksburg 17 Planetary 20 Observed AFr/Ap Indices 14 Sep : A K Fredericksburg 22 Planetary 23 3325 5433 2B. MAGNETIC FORECAST Date Ap Conditions 16 Sep 65 G3, chance of G4 17 Sep 25 G0-G1, chance of G2 18 Sep 15 G0, chance of G1 COMMENT: ASWFC Geomagnetic Warning 55 was issued on 14 September and is current for 15-17 Sep. G0 geomagnetic conditions were observed in the Australian region on UT day 15-Sep. Mostly G1 geomagnetic conditions were observed in the Antarctic region with G0 conditions observed at Casey. G3 geomagnetic conditions, with a chance of G4 are expected on 16-Sep, due to an anticipated impact from a halo CME first observed on 14-Sep, combined with a possible glancing impact from a CME first observed on 13-Sep and high speed wind stream effects from coronal holes in the northern and southern hemispheres. G0-G1 geomagnetic conditions, with a chance of G2 are expected on 17-Sep and G0 conditions, with a chance of G1 are expected on 18-Sep, due to ongoing CME and coronal hole high speed wind stream effects. ----------------------------------------------------------- 3A. GLOBAL HF PROPAGATION SUMMARY Latitude Band Date Low Middle High 15 Sep Poor-normal Fair-normal Fair-normal PCA Event : No event. 3B. GLOBAL HF PROPAGATION FORECAST Latitude Band Date Low Middle High 16 Sep Poor Poor Poor 17 Sep Fair Fair Fair-poor 18 Sep Normal Normal Normal-fair COMMENT: HF radio communication conditions on UT day 15-Sep were mostly poor at high latitudes and fair at mid to low latitudes until around 1200UT when conditions eased to mostly normal at all latitudes. Degraded conditions are likely in the second half of 16-Sep due to anticipated geomagnetic activity. Possible S1 solar proton conditions may also cause degradations to HF conditions at high latitudes. Conditions are expected to remain degraded on 17-Sep, with a recovery to mostly normal conditions expected on 18-Sep. Shortwave fadeouts are probable. ----------------------------------------------------------- 4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY Date T index 15 Sep 125 Observed Australian Regional MUFs Cocos Island Region: Enhanced by 15% during local day. Enhanced by 45% during local night. Niue Island Region: Enhanced by 35% during local day. No data available during local night. Northern Australian Region: Mostly near predicted monthly values. 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 Aug 159 Sep 117 Oct 116 4B. AUSTRALIAN REGION IONOSPHERIC FORECAST Date T index MUFs 16 Sep 100 Depressed 5 to 20%/near predicted monthly values 17 Sep 130 Near predicted monthly values 18 Sep 130 Near predicted monthly values COMMENT: ASWFC Preliminary HF Communications Warning 102 was issued on 14 September and is current for 16-17 Sep. Maximum usable frequencies (MUFs) in the northern Australian region on UT day 15-Sep were near predicted monthly values. MUFs in the southern Australian region were near predicted monthly values to depressed by up to 20%, with the strongest depressions observed during local night hours. Spread F was observed at Hobart throughout the day, and at Perth, Canberra and Brisbane during local night. MUFs on 16-Sep are expected to be near predicted monthly values for the first part of the day. Following expected geomagnetic activity in the middle of the day, depressions of up to 20% are expected particularly in the southern Australian region. MUFs are expected to continue to be depressed on 17-Sep, with a recovery towards near predicted monthly values possible on 18-Sep. Shortwave fadeouts are probable. ----------------------------------------------------------- 5. SPACE ENVIRONMENT SUMMARY GOES satellite data for 14 Sep Daily Proton Fluence >1 MeV: 2.0E+06 Daily Proton Fluence >10 MeV: 6.6E+04 Daily Electron Fluence >2 MeV: 2.40E+07 (normal fluence) Electron Fluence Daily Deep Dielectric Discharge Probability: 4% Fluence (flux accumulation over 24hrs)/ cm2-ster-day. X-ray background: C2.5 DSCOVR Satellite Solar Wind Day Averaged Data for 14 Sep Speed: 420 km/sec Density: 2.4 p/cc Temp: 66800 K Bz: -2 nT (Courtesy Space Weather Prediction Center, Boulder USA) -----------------------------------------------------------