Daily Report

(last updated 26 Apr 2025 23:31 UT)

SUBJ: ASWFC DAILY SOLAR AND GEOPHYSICAL REPORT ISSUED AT 2330UT/26 APRIL 2025 FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE SUMMARY FOR 26 APRIL AND FORECAST FOR 27 APRIL - 29 APRIL STATUS INDICATORS SOL:GREEN MAG:GREEN ION: GREEN ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx ----------------------------------------------------------- 1A. SOLAR SUMMARY Activity 26 Apr: R0 Flares: none. Observed 10.7 cm flux/Equivalent Sunspot Number for 26 Apr: 156/110 1B. SOLAR FORECAST 27 Apr 28 Apr 29 Apr Activity R0, chance R1 R0, chance R1 R0, chance R1 Fadeouts None expected None expected None expected 10.7cm/SSN 155/109 150/105 145/99 COMMENT: Solar activity on UT day 26-Apr was at the R0 level, with several low level C-class flares observed. There are currently ten numbered sunspot regions visible on the solar disk. AR4064 (N11W54, beta) is the largest region on the disk and has shown decay in its intermediate spots. AR4072 (N06E52, beta) has exhibited mild growth in its trailer spots. All other sunspot regions are either stable or in decay. Solar activity is expected to be at the R0 level over 27-29 Apr, with a chance of R1. Several CMEs were observed, but none are considered geoeffective. The solar wind speed on UT day 26-Apr declined, ranging from 395 to 490 km/s and is currently near 400 km/s. The peak total interplanetary magnetic field strength (IMF, Bt) was 9 nT and the north-south IMF component (Bz) range was -5 to +6 nT. The solar wind speed may moderately increase over 27-28 Apr, then decline on 29-Apr. ----------------------------------------------------------- 2A. MAGNETIC SUMMARY Geomagnetic field for Australian Region 26 Apr: G0 Estimated Indices 26 Apr : A K Australian Region 4 21121111 Cocos Island 3 22111110 Darwin 4 22121111 Townsville 5 22121112 Learmonth 4 21221110 Alice Springs 3 11121101 Gingin 4 21122110 Canberra 4 12032101 Kennaook Cape Grim 4 11132101 Hobart 5 21132101 Estimated Antarctic Regional K Indices 26 Apr : Macquarie Island 6 11043000 Casey 11 44322111 Mawson 11 33222224 Observed Regional daily pc3 Indices 26 Apr : Darwin 0 (Quiet) Townsville 0 (Quiet) Learmonth 0 (Quiet) Alice Springs 0 (Quiet) Gingin 0 (Quiet) Canberra 11 (Quiet) Hobart 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 26 Apr : A Fredericksburg 7 Planetary 7 Observed AFr/Ap Indices 25 Apr : A K Fredericksburg 5 Planetary 0 ---- ---- 2B. MAGNETIC FORECAST Date Ap Conditions 27 Apr 15 G0 28 Apr 12 G0 29 Apr 8 G0 COMMENT: G0 geomagnetic conditions were observed in the Australian and Antarctic regions on UT day 26-Apr. G0 geomagnetic conditions are expected over 27-29 Apr. ----------------------------------------------------------- 3A. GLOBAL HF PROPAGATION SUMMARY Latitude Band Date Low Middle High 26 Apr Normal Normal Normal PCA Event : No event. 3B. GLOBAL HF PROPAGATION FORECAST Latitude Band Date Low Middle High 27 Apr Normal Normal Normal-fair 28 Apr Normal Normal Normal-fair 29 Apr Normal Normal Normal-fair COMMENT: HF radio propagation conditions on UT day 26-Apr were mostly normal. HF radio propagation conditions are expected to be mostly normal over 27-29 Apr with fair conditions at times for high latitudes. ----------------------------------------------------------- 4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY Date T index 26 Apr 123 Observed Australian Regional MUFs Cocos Island Region: Near predicted monthly values during local day. Enhanced by 35% during local night. Niue Island Region: Near predicted monthly values. Northern Australian Region: Near predicted monthly values during local day. Enhanced by 25% during local night. Southern Australian Region: Near predicted monthly values. Antarctic Region (Casey/Davis/Mawson): Near predicted monthly values over the UT day. Monthly T index: Month T index Mar 126 Apr 115 May 113 4B. AUSTRALIAN REGION IONOSPHERIC FORECAST Date T index MUFs 27 Apr 125 Near predicted monthly values 28 Apr 125 Near predicted monthly values 29 Apr 125 Near predicted monthly values COMMENT: Maximum usable frequencies (MUFs) in the Australian region on UT day 26-Apr were near predicted monthly values to 25% enhanced in northern Australian regions. Spread F was observed at Hobart during local night hours. Ionospheric scintillation was observed at Darwin and Weipa over the interval 26/1121-1510UT. MUFs are expected to be near predicted monthly values over 27-29 Apr. ----------------------------------------------------------- 5. SPACE ENVIRONMENT SUMMARY GOES satellite data for 25 Apr Daily Proton Fluence >1 MeV: 6.4E+05 Daily Proton Fluence >10 MeV: 1.5E+04 Daily Electron Fluence >2 MeV: 3.90E+07 (normal fluence) Electron Fluence Daily Deep Dielectric Discharge Probability: 6% Fluence (flux accumulation over 24hrs)/ cm2-ster-day. X-ray background: B9.0 DSCOVR Satellite Solar Wind Day Averaged Data for 25 Apr Speed: 490 km/sec Density: 1.5 p/cc Temp: 150000 K Bz: 4 nT (Courtesy Space Weather Prediction Center, Boulder USA) -----------------------------------------------------------