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High Speed Stream
Catalog: M2M_CATALOG
Event Time: 2025-10-28T06:21Z ( ACE: SWEPAM )

All Detecting Spacecrafts:

ACE: SWEPAM

ACE: MAG

DSCOVR: PLASMAG

Activity ID: 2025-10-28T06:21:00-HSS-001 (version 3)
Event End Time:
Peak Solar Wind Speed (km/s): 750.0
Date of first appearance of coronal hole in EUV at east limb: 2025-10-21
Note: Characterized by a steady increase in solar wind speed from about 390 km/s to 520 km/s over the course of several hours. The candidate coronal hole spans from about S10 to S20 and first crossed the central meridian on 2025-10-25. The increase in solar wind speed begins at about 2025-10-28T06:21Z and has so far reached a peak sustained value of about 520 km/s by 2025-10-29T13:09Z; however, the increasing trend in solar wind speed is ongoing. Temperature also exhibits an increasing trend, nearly simultaneous with the increase in speed, starting at about 2025-10-28T06:21Z. Density only shows a slight increase at the start time of this high speed stream at 2025-10-28T06:21Z, but had recently previously exhibited a more notable increase from around 5p/cc to 25p/cc at about 2025-10-27T12:43Z, which is likely attributable to a complex mix of multiple sources, including a glancing blow from CME 2025-10-23T16:38Z modeled to arrive 2025-10-26T13:00Z (+-7 hours), potentially a corotating interactive region (CIR) ahead of the coronal hole whose western edge crossed the central meridian on 2025-10-25, and potentially a solar sector boundary crossing (SSBC) with the pile-up, velocity increase, and phi angle flip from 315 to 135 degrees around 2025-10-27T15:22Z.

Version 1 submitted on 2025-10-29T16:48Z by Hannah Hermann
Version 2 submitted on 2025-10-29T17:10Z by Hannah Hermann
Version 3 submitted on 2025-11-03T18:07Z by Mary Aronne

No Notification has been sent for this activity yet.

All directly linked activities:

2025-10-31T12:05:00-RBE-001

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