Space Weather

Space Weather

Space weather describes changing environmental conditions in near-Earth space. Magnetic fields, radiation, particles and matter, which have been ejected from the Sun, can interact with the Earth’s upper atmosphere and surrounding magnetic field to produce a  variety of effects.

Image courtesy of NASA/SDO and the AIA, EVE, and HMI science teams

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Aurora forecasts

Northern Hemisphere

There is a diminishing chance of G1/Minor Storm intervals through the next 24 hours, which may lead to some minor enhancements of the auroral oval at higher latitudes at first this working week.

Southern Hemisphere

There is a diminishing chance of G1/Minor Storm intervals through the next 24 hours, which may lead to some minor enhancements of the auroral oval at higher latitudes at first this working week.

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Forecast overview

Space Weather Forecast Headline: G1/Minor Geomagnetic Storms becoming less likely.

Analysis of Space Weather Activity over past 24 hours 

Solar Activity: Solar activity was very low over the past 24 hours, although there was a rising trend in background X-ray flux and occasional sub-common class flare activity. There remains one sunspot region on the sun in the southeastern quarter. This region has been dynamic in the period, with significant proliferation and spreading visible in its trailing portion, with some minor decay in its leader. This group retains its large vertical span on the sun, which lends itself to shear from differential rotation (often meaning increased activity from contorting the magnetic field lines), although this has yet to manifest as significant flaring.

A large, slow Coronal Mass Ejection (CME) was visible on satellite imagery in the period, with a gradual emergence starting around 18/0600TC. The source region is not certain from the limited imagery available, however it may be from a slow 'prominence eruption' over the northwestern horizon seen during the UTC morning. This CME has yet to be analysed, however it appears to lead Earth in its orbit and is angled mostly above the ecliptic plane. No other CMEs were evident in available imagery.

Solar Wind / Geomagnetic Activity: Earth is considered likely to be experiencing the fast solar wind emanating from a large southern hemisphere 'coronal hole', although the connection is perhaps intermittent given periodic dips in solar wind speed, perhaps signalling occasional departure from a pure coronal hole-like environment.

The solar wind speed showed a level trend during the first half of the period, easing away through the afternoon before finding a new lower (but still elevated) level in the UTC evening. Measurement of the number of particles comprising the solar wind was somewhat erratic but mostly slightly above background, with a discontinuity at 18/1300UTC. This was roughly coincident with the onset of the decline in solar wind speed and a rising trend in the magnetic field associated with the particles in the solar wind. Meanwhile the north-south component of the field again with a slight negative bias as in recent days (anti-aligned with Earth's field).

The net effect of the preceding solar wind measures was for geomagnetic activity narrowly below G1 Minor Storm bookending the UTC day, with quieter intervening activity.

Energetic Particles / Solar Radiation: No solar radiation storms observed.

Four-Day Space Weather Forecast Summary

Solar Activity: Solar activity is expected to be low in the period, given the increased complexity of the sole sunspot on the facing side of the sun. This may be bolstered by a possible new region expected over the eastern horizon early in the four-day period, although this does not yet impact on flare probabilities, pending analysis.

Solar Wind / Geomagnetic Activity: There are no Earth-directed CMEs in the forecast.

Earth is currently connected to the fast wind of a large coronal hole, with solar wind speeds only gradually declining through the period, giving a Slight and decreasing chance of G1/Minor Storm intervals. Mainly quiet geomagnetic activity should predominate by midweek, with a possible uptick at the end of the four days due to a smaller high speed stream from another coronal hole, perhaps offering a chance of G1 on Thursday 22 April.

Energetic Particles / Solar Radiation: No solar radiation storms are forecast.

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Solar imagery

SDO AIA-193

This channel highlights the outer atmosphere of the Sun - called the corona - as well as hot flare plasma. Hot active regions, solar flares, and coronal mass ejections will appear bright here. The dark areas - called coronal holes - are places where very little radiation is emitted, yet are the main source of solar wind particles.

SDO AIA-304

This channel is especially good at showing areas where cooler dense plumes of plasma (filaments and prominences) are located above the visible surface of the Sun. Many of these features either can't be seen or appear as dark lines in the other channels. The bright areas show places where the plasma has a high density.

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