Daily Report

(last updated 26 Sep 2021 23:31 UT)

SUBJ: SWS DAILY SOLAR AND GEOPHYSICAL REPORT ISSUED AT 2330UT/26 SEPTEMBER 2021 BY Space Weather Services FROM THE AUSTRALIAN SPACE FORECAST CENTRE SUMMARY FOR 26 SEPTEMBER AND FORECAST FOR 27 SEPTEMBER - 29 SEPTEMBER STATUS INDICATORS SOL:GREEN MAG:** RED ** ION: GREEN ----------------------------------------------------------- 1A. SOLAR SUMMARY Activity 26 Sep: Low Flares: none. Observed 10.7 cm flux/Equivalent Sunspot Number for 26 Sep: 86/29 1B. SOLAR FORECAST 27 Sep 28 Sep 29 Sep Activity Low Low Low Fadeouts None expected None expected None expected 10.7cm/SSN 86/29 86/29 84/26 COMMENT: Solar activity was low on UT day 26 September. Currently there are 7 numbered regions on the visible solar disk. AR2873 (N26W85) produced a C1 flare at 0631 UT and AR2871 (S28W28) produced a C1.6 flare at 1124 UT. There was a weak narrow CME towards the southwest in Lasco and Stereo-A images around 26/03 UT, that appears to have been produced by region 2874 (S23W78) in SDO304 images. There was another weak narrow CME towards the southwest in Lasco and Stereo-A images around 26/1236 UT. Further analysis is needed to determine if these CMEs have an Earth directed component. There were no other CMEs observed in the available coronagraph data. Solar activity is expected to be low on UT days 27-29 September. On UT day 26 September, the solar wind speed followed a decreasing trend from 480 km/s down to 385 km/s. The total IMF (Bt) peaked at 4 nT and the north-south IMF (Bz) component varied between 3 nT and -2 nT. The solar wind speed may increase from slightly enhanced to moderately enhanced levels on UT days 27-29 September due to the combined effects of an extension of a northern polar coronal hole, plus glancing blows from the 23 September CMEs caused by two M-class flares and the 24 September filament eruption CME. ----------------------------------------------------------- 2A. MAGNETIC SUMMARY Geomagnetic field for Australian Region 26 Sep: Quiet Estimated Indices 26 Sep : A K Australian Region 1 11100001 Cocos Island 0 01100000 Darwin 1 11100001 Townsville 1 11000011 Learmonth 1 11100000 Alice Springs 1 11000001 Gingin 1 11100000 Canberra 1 10000011 Hobart 1 10000011 Estimated Antarctic Regional K Indices 26 Sep : Macquarie Island 0 00000000 Casey 6 33311001 Mawson 4 22001023 Observed Regional daily pc3 Indices 26 Sep : Darwin 0 (Quiet) Townsville 0 (Quiet) Learmonth 0 (Quiet) Alice Springs 0 (Quiet) Gingin 0 (Quiet) Canberra 0 (Quiet) Hobart 2 (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 26 Sep : A Fredericksburg 4 Planetary 4 Observed AFr/Ap Indices 25 Sep : A K Fredericksburg 7 Planetary 6 2221 1112 2B. MAGNETIC FORECAST Date Ap Conditions 27 Sep 25 Quiet to active with possible minor to major storms 28 Sep 12 Mostly quiet to unsettled with possible active periods 29 Sep 10 Quiet to Unsettled COMMENT: SWS Geomagnetic Warning 29 was issued on 25 September and is current for 26-27 Sep. On UT day 26 September, geomagnetic conditions in the Australian region were quiet. In the Antarctic region, quiet to unsettled levels were observed. Quiet to active conditions with possible minor to major storm periods are expected for UT day 27 September. This disturbance is due to combined coronal hole plus CME effects. Then on UT day 28 September, mostly quiet to unsettled conditions with possible active periods are expected. On UT day 29 September quiet to unsettled conditions are expected as coronal hole and CME effects fade. Auroras may be visible on the local night of 27 September in Tasmania. ----------------------------------------------------------- 3A. GLOBAL HF PROPAGATION SUMMARY Latitude Band Date Low Middle High 26 Sep Normal Normal Normal-fair PCA Event : No event. 3B. GLOBAL HF PROPAGATION FORECAST Latitude Band Date Low Middle High 27 Sep Fair Fair Fair-poor 28 Sep Normal Normal-fair Fair 29 Sep Normal Normal Normal-fair COMMENT: Mildly degraded HF propagation conditions are possible on UT days 27-28 September, due to the expected increase in geomagnetic activity. Then mostly normal HF propagation conditions are expected on UT day 29 September. Auroras may be visible on the local night of 27 September in Tasmania. ----------------------------------------------------------- 4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY Date T index 26 Sep 26 Observed Australian Regional MUFs Cocos Island Region: Enhanced by 15% during local day. Depressed by 15% during local night. Niue Island Region: No data available. Northern Australian Region: Near predicted monthly values. Southern Australian Region: Near predicted monthly values. Antarctic Region (Casey/Scott Base/Davis/Mawson): Near predicted monthly values. Monthly T index: Month T index Aug 14 Sep 27 Oct 30 4B. AUSTRALIAN REGION IONOSPHERIC FORECAST Date T index MUFs 27 Sep 20 Near predicted monthly values/depressed 10 to 20% 28 Sep 15 Near predicted monthly values/depressed 10 to 20% 29 Sep 20 Near predicted monthly values COMMENT: MUFs in the Australian region on UT day 26 September were mostly near predicted monthly values, with some mild depressions in the Cocos Island region during the local night. Some mild MUF depressions are possible on UT days 27-28 September, due to the expected increase in geomagnetic activity. Mostly normal HF propagation conditions are expected on UT day 29 September. ----------------------------------------------------------- 5. SPACE ENVIRONMENT SUMMARY GOES satellite data for 25 Sep Daily Proton Fluence >1 MeV: 5.7E+04 Daily Proton Fluence >10 MeV: 4.3E+04 Daily Electron Fluence >2 MeV: 3.60E+06 (normal fluence) Electron Fluence Daily Deep Dielectric Discharge Probability: 1% Fluence (flux accumulation over 24hrs)/ cm2-ster-day. X-ray background: B1.5 DSCOVR Satellite Solar Wind Day Averaged Data for 25 Sep Speed: 514 km/sec Density: 7.0 p/cc Temp: 258000 K Bz: 1 nT (Courtesy Space Weather Prediction Center, Boulder USA) -----------------------------------------------------------