winter transatlantic E_s
by Bob Mobile, WA1OUB

For the first time ever (May 1996), 48MHz European video was heard from here via Es during our winter Es season. Unfortunately no European QSOs resulted. however, the VO1ZA beacon was heard on 27 Dec. Here are the dates and times:

This is extremely rare and I thought the timing would be of interest to the 6m DX community. while on the subject of timing, I have plotted the 6m summer diurnal distribution for East Coast to European Es, and used it to try to predict the diurnal distribution for winter Es. The results are interesting:

Summer Transatlantic Es

The first plot (Fig 1) shows UTC times versus QSO rates for each and every transatlantic Es QSO (1502 QSOs) that I have made over the last 10 years. I believed that this plot is the most important of all. The plot covers any QSOs made during the entire summer Es season which runs approx. 1 June through 31 July. The left scale Y axis shows the distribution of contacts in percent, and you can see that the maximum probability is at around 2200z.

Superimposed average solar elevation for 1 July

This plot (Fig. 2) shows the scaled diurnal variation against the corrected average solar elevations of the three equidistant path midpoints between FN43AD and IN80. The three path midpoints are 105km above grids FN95, HN17, and IN34.

Solar elevations were calculated at the ground and raised 10.3 degrees to account for the better 'view' at E-layer height, using a formula that compresses the 'lift' at higher angles. Note that any average elevations that are less than zero are forced to a zero value.

Calculated diurnal variation for trans-Atlantic Es on 27 December 1995.

This may be considered a joke, but not really. The potential solar influence on the summer diurnal for 1 July was estimated using a complex array of polynomials, a Gaussian distribution and interpolation to obtain a 'baseline' formula that fits the summer diurnal nicely. A simple program was written and the results are plotted for 27 Dec 1995. It shows maximum probability occurs around 1800z. I would be interested to It shows how this diurnal compares to the facts. To the best of my knowledge, no 3+ hop winter Es 50MHz QSOs have ever occurred!

UKSMG Six News issue 49, May 1996