Winter Es breaks out again!

Some very good DX appeared from about 09:30UT this morning, and continued into the afternoon.

Although it's actually very common to reach into the Indian Ocean on 12m, even at this dead state of the solar cycle, I was amazed to see FR4OO reporting reception of my 25W from the 3 ele LFA at a whopping +16dB!  That's almost certainly the strongest report I've ever had from the Indian Ocean since FT8 began.

Spectacular report from FR4OO.

A few minutes later, the propagation drops to almost nothing, but then recovered.

Sadly, there were absolutely no stations active in VK, and ZS took a while to wake up to the ongoing situation.  Eventually, I managed a couple of QSOs with ZS.


The afternoon looks likely to produce transatlantic openings at 12m.

Up at 10m, I was hearing 3B8CW, but with only a delta loop and being much too far north, my chances of reaching him were not good.  But there were plenty of strong European stations to be worked.

The Es seems to have been sparked locally over Europe by a strong front running across the middle of the continent.  Very unusually for this time of year, thunderstorms were active along and around that front, and were even seen here in north Wales last evening.

Strong front with thunderstorms over central Europe.

All the 10m reports were to the south of a thunderstorm front covering most of central Europe.

These storm disturbances, which propagate all the way up to mesosphere height, may well have provided the link from northern Europe to more southerly Es patches, and then on to the Indian Ocean.

Or it could have been another instance of the proposed propagation mechanism of the north-south teleconnection that was discussed here, and developed further here.

Update on the higher-HF bands DX of December 01, 2019.

On December 1st, there was a remarkable set of solar minimum openings on 12 and 10m from Europe into the antipodes.

A day later, I commented that this unusual and rare propagation could be related to the approaching austral midsummer.

NLC seen from Dunedin, NZ, on the same day as unusual upper HF DX opened up.  (C) Mirko Harnisch

A few days after the event, I learn from Spaceweather.com that noctilucent clouds were definitively seen from Dunedin, New Zealand - at a latitude of 45 degrees south - on the same day as the propagation event.  This is the only known sighting of NLC so far from the south pole; the equivalent position in the north encompasses, for example, southern France and northern Italy.  NLC are also being seen further from the north pole in the northern hemisphere.

The rather sensationalist claims by the media about the planetary waves boosting NLC are a bit silly.  Planetary waves have been known about for many decades, and are well understood to modulate NLC with various periodicities of one to several days.  The 5-day wave mentioned in the article is one of the strongest and most-easily detected planetary waves.
  
The fact of the unusual EU-VK propagation at higher HF and the sighting of the very extensive NLC from ZL is almost certainly not a coincidence, given that Es, PMSE and related phenomena can all arise from the same underlying mechanism.

That mechanism is one of a warming midsummer troposhere yielding a strongly cooling mesosphere owing to upwelling and gravity wave activity.  NLC form around meteor debris, and the debris-ice particles, just nanometers across, are highly charged surfaces - which is where the radio propagation relationship comes in.

UPDATE (2): Non-summer mesospheric echoes appeared over central Wales today (06/12/2019), as seen by the MST radar near Aberystwyth.  The radar isn't quite working at optimum settings at the moment, but the winter echoes are certainly there, roughly between 10UT and 14UT:

In the northern hemisphere, summer 50MHz propagation from Europe to JA is often seen, and has also been related to NLC/PMSE.

The data from AIM satellite confirms the very northerly extent of part of the NLC formation.  On 08/12/2019, the NLC was continuing to appear at near 50 degrees south.

Winter mesospheric echoes drift by...

I was glad I checked the MST radar site in mid-Wales today because, if you look on the extreme left hand side, you can see some weak, but coherent polar non-summer mesospheric echoes, or simply winter echoes, were present early morning to mid-afternoon yesterday.

There are no singificant meteor showers at present, and it's a month since the Quadrantids peaked in early January.  So the explanation is interesting to think about.  I don't think anybody really understands these winter echoes, beyond those that arise in association with meteor showers which is, in itself, not a perfect correlation.

One possibility is that a modest-sized bolide entered somewhere over the planet recently, leaving a trail of charged debris behind it.

I'm not able to check data from the MST archive this morning, but a fascinating visual phenomenon that occurred over Wales four days after the Chelyabinsk bolide entry in February 2013 was this stratospheric layer; it's ablated fine dust from the meteorite's passage through the atmosphere.  It travelled eastwards, the 'long way' around, before first being spotted (only once, with no photo) from Alaska, then once in Ireland (with photos) and Wales: