HF News
Over the last week we have had a fair sprinkling of sunspots, along with some enormous coronal holes, including one almost rectangular hole, the output from which was due to impact the Earth last week.
Coronal holes are lower energy areas on the Sun with open magnetic field lines, allowing solar plasma to flow out.
Geomagnetic conditions have mainly been settled, with the Kp index hitting a maximum 3.67 over the past five days.
Over the same period we had a long-duration M1.3 solar flare at 04:15hrs UTC (Mar 28th) and an X1.5 class solar flare on March 30th. Active region 4405 erupted at 03:18hrs UTC and launched a halo coronal mass ejection (CME) into space that should have hit the Earth around April 1st.
Meanwhile, the solar flux index has remained above 140 for a few days, which bodes well for HF propagation.
Next week, NOAA predicts that the solar flux index will start at 145 at the beginning of next week, falling to 112 by Saturday the 11th. Geomagnetic conditions are set to be unsettled on April 9th to the 12th, with a potential Kp index of five or even six. If this comes to pass expect lower MUFs and disrupted HF conditions, especially on polar paths.
HF DX to look out for this week includes T31TTT Central Kiribati, which is active until April 14th; FO/F6BCW French Polynesia, which is active until April 10th; CE0Y/DJ4EL, Easter Island until April 11; and TJ1GD/P on Mondoleh Island, Cameroon, from April 4th to the 20th.
Meanwhile, have a good Easter and good HF DX!
VHF and up
The equinoxes are a time of the year when the Atlantic jet stream typically blows across the UK as it migrates north from the Mediterranean in winter to near Iceland in summer.
The period of weather through to the end of next week is going to see a succession of lows driven by the Atlantic jet stream crossing the country with bands of rain and scattered blustery showers. These may represent chances of some rain scatter for those on the upper GHz bands, but this pattern suggests limited Tropo options.
The prospects for meteor scatter are no better since we remain some way short of the next major meteor shower in late April. In these situations, your best chances are from random meteors, which tend to peak in the early pre-dawn hours. The equinox also gets credit as being a preferred time for auroras since there is a better coupling between the Earth’s magnetic field and the solar wind.
Lastly, a mention of Sporadic-E for completeness, however this is too early in the year for much to happen, but keep a check on the foEs graphs on www.propquest .co.uk for signs of brief upticks. Incidentally, some maintenance work is currently under way on the website, so apologies for any interruptions.
For EME operators, Moon declination is now negative, reaching its minimum (most negative) on Wednesday the 8th. At this point the Moon is only up for six hours and only gets to nine degrees elevation in the UK. The Moon is also furthest away, (apogee) on April 7th so path losses are at their highest. 144 MHz sky noise starts low but quickly climbs to a high of more than 2700 Kelvin on the 8th.