Propagation News – 30 August 2015

The predicted drop in the solar wind failed to materialise this week as it is still being driven by coronal holes on the sun. These are areas of weaker magnetic fields that let plasma escape from the sun’s surface. The Kp index has hit six at times, bringing very unsettled geomagnetic storm conditions and poor HF DX in general, apart from auroral conditions on the higher bands.

There have been a few glimmers of better autumnal HF conditions, but there have also been some very noisy bands at times, completely devoid of signals. The outlook for the next seven days is likely to be similar. Sunspot region 2403 will be rotating out of view and the rest of the sun is virtually spotless.

NOAA says we can expect the solar flux index to be in the range 100-115 next week, but high-speed solar wind effects from coronal holes may continue, with a high K index at times. Scientists say that coronal holes are a feature of where we are in the current sunspot cycle and are long-lived as they form near the solar equator.

We could be in for more of the same over the coming months, so take the chance to work any DX as and when you hear it.

VHF and up propagation news

Last week saw almost daily 10GHz rain scatter propagation over the Channel and North Sea and, once again, the coming week is likely to be dominated by low pressure at first. Since we are still getting some very warm days, there is scope for large showers and thunderstorms to develop, which raises the prospect of more rain scatter conditions on the upper GHz bands.

Later in the week, high pressure moves in towards the western side of the country and could bring slightly enhanced tropo conditions. But the flow underneath the high is not especially moist, which is the preferred condition for VHF DX.

If you do notice lift conditions, please try the simplex channels and multimode options on SSB and CW, rather than risk co-channel interference by accessing distant repeaters.

Sporadic-E is even more sporadic once we move into September, so don’t expect much, but if you are searching then the best things to look for are strong jet streams on the upper air weather charts on the RSGB forum.

We are back to random meteor scatter propagation on the lower VHF bands and for EME operators losses are low this week, with moon windows getting longer as the week goes on.

Category: GB2RS Propagation News