Weekly Report

(last updated 18 Dec 2025 00:51 UT)

SUBJ: ASWFC WEEKLY GEOPHYSICAL REPORT ISSUED ON 18 DECEMBER 2025 FROM THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE ASWAS SCALE DESCRIPTION: https://bit.ly/3lmaMBx 1. SUMMARY (09 DECEMBER - 17 DECEMBER) K indices are in UT (0-24). For conversion to local time: AEST = UT + 10 hours; ACST = UT + 9.5 hours; AWST = UT + 8 hours Australian Region* Date K-INDICES A 09 Dec 1011 1112 3 10 Dec 2231 2345 16 11 Dec 4322 2552 20 In the BOM magnetometer data for 11 Dec, a weak (24nT) impulse was observed at 1500UT. 12 Dec 3334 4355 26 13 Dec 3222 3322 10 14 Dec 1212 1121 4 15 Dec 1122 3111 5 16 Dec 3222 2322 9 17 Dec 3222 3233 11 *estimated from real time 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. In the Australian region G1 periods were observed on 10-Dec, 11-Dec and 12-Dec. Indistinct glancing CME arrivals were observed over 10-11 Dec with a possible corotating interaction region on 12-Dec prior to the Earth entering a coronal hole high speed wind stream. Planetary conditions briefly reached G2 on 10-11 Dec and reached G1 on 12,13 and 18-Dec. G0 conditions were observed on other days of the week. 2. FORECAST (18 DECEMBER - 17 JANUARY) Disturbed Periods: 18 Dec, 21-24 Dec, 26-27 Dec, 30-31 Dec, 7-8 Jan. Best Quiet Periods: 4-5 Jan, 10-11 Jan. 3. FORECAST FOR HIGH RESOLUTION AEROMAGNETIC SURVEYS Northern Australian Regions: Mildly Disturbed Periods: 22-23 Dec. Best Quiet Periods: 18-20 Dec, 28-30 Dec, 03-11 Jan, 14-16 Jan. Central Australian Regions: Disturbed Periods: 22-23 Dec Mildly Disturbed: 21-Dec, 24-27Dec, 31-Dec to 02-Jan, 09-10 Jan, 12-13 Jan. Best Quiet Periods: 19-Dec, 29-30 Dec, 04-07 Jan, 14-15 Jan. Southern Australian Regions: Disturbed Periods: 21-27Dec, 31-Dec to 02-Jan, 09-10 Jan, 12-13 Jan. Best Quiet Periods: 19-Dec, 29-Dec, 04-07 Jan, 14-15 Jan. 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. PLEASE NOTE: Geomagnetic activity can frequently be determined by short timescale solar events that cannot be forecast a week in advance, particularly at solar maximum.