Polar Non-Summer Mesospheric Echoes, and backscatter signals.

Interesting to see the mid-latitude winter version of PMSE break out weakly above Wales this afternoon.

Conditions have been mostly quite tough on 12m today, relative to the past week or two, due to the quiet geomagnetic conditions.  But there are periods of good, if weak DX, notably to ZS and PY.  Signals from EA8 are extremely strong, with German and Belgian stations showing a pronounced backscatter reception path. 

The backscatter is worth recording: OS8A (see video) was coming in at -18 to -7dB when I was beaming towards him, but came in at +9dB when I was beaming 220, out into the southern Atlantic.  Similarly, nearly an hour after sunset here, EA9ACD was -17dB in a dying band when beaming 220 degrees, but entirely undetectable on a direct beaming path to him.

Whether or not this is related to the winter echoes is an open question.  There are no signs of the unusual bursts much-discussed on this page in recent months.

Vertical radar profile above Aberystwyth, Wales today.  Vertical lines are data glitches, real echoes are the blue patches from around 08UT onwards at 75-80km altitude.

The precise cause of winter echoes is not understood.  Infrasound from rough seas propagating into the mesosphere is one idea.

Looking back at the past month's MAARSY data from 70 degrees north, there have been quite a number of PMWE breakouts, notably on the 24th October, where the returns were strong and long-lived (top plot; lower plot is lower atmosphere and irrelevant to this subject):

Data courtesy IAP/MAARSY.

In other news, a bloody great big sunspot group has just emerged into view.  More fun to come on the bands, I think!

Courtesy of NASA/SDO and the AIA, EVE, and HMI science teams.