venerdì 21 luglio 2017

Propagation News – 23 July 2017

Last week, space weather was dominated by sunspot number 2665 that was twenty times larger than any recent sunspot—the largest since number 2529 in April 2016. It disappeared on Wednesday as the Sun’s rotation took it out of our view. Solar flux held at 92 before fading back to the low seventies.

Conditions were unsettled due to C2 and C3 flares. Strong geomagnetic storms occurred. The south-pointing Bz component of the interplanetary magnetic field reached a maximum negative value of minus 23 nanotesla.
Maximum useable frequencies rose briefly to just over 24MHz for the longer paths. Stations in Japan were worked from Europe around midday on 18MHz. European and Russian activity was plentiful on 28MHz for most days in the week. Many stations in the International Beacon Project network were copied on 14 and 18MHz. It is always worth listening on their spot frequencies as indicators of conditions. At 2300UTC on Thursday, the 14 and 18MHz bands were still open to USA. The W1AW Morse practice runs were copied on both bands. South America produced a contact from Peru on 14MHz at 2330.

NOAA is forecasting more of the very low solar activity we have become used to. Propagation we may enjoy is likely to be disrupted by further flares. Moderate geomagnetic storms continue to threaten. At the closing of this HF report there are no visible sunspots on our side of the sun and the solar flux is 70.

VHF and up:

Last week saw record breaking tropo from south-west UK down to the Canary Islands with 144MHz and 432MHz QSOs and a claimed new 1.3GHz Region 1 record of 2662km. At this time of year, fortunately placed stations in the south-west can couple in to the ducts caused by the Azores High giving some super DX. The rest of the country did not fare as well but next week there may be some brief spells with a ridge of high pressure near to southern areas, but not looking like a strong feature. Tropo is an option, but relatively weak and typically found overnight and first half of the morning, before the sunshine warms out any overnight temperature inversion. A weak area of low pressure covers much of Britain at first with some scattered showers, possibly heavy and thundery will give options for more rain scatter on the GHz bands.

Sporadic E has found new legs recently with some good openings across Europe and beyond. It is still within the prime time for Es and should provide days of activity well into August. As usual the best times are late morning, late afternoon and early evening.

Moon declination is positive but falling and goes negative on Friday, with losses increasing as the week progresses. We are still a week or more away from apogee so use the early part of the week for best results on EME.