Yesterday I lamented the loss of the Millstone Hill (MIT at Haystack Observatory) Digisonde. For some reason, this morning I woke up and went on one of those “Alice in the Looking Glass” trips through the internet. My general premise was that if I could not get real time ionograms with “www”, I should be able to find the data via FTP. To make a very long story a lot shorter-I found the “Mother of all Propagation” repositories. Near Real Time Ionograms from all operating stations around the world.
In my case I will use Millstone Hill and Dyess AFB data because they are the two stations closest to each end of our daily QSO. I could look for a central location to our QSO but I would have to assume where rays bounce. Primarily, I look for Sporadic E layer stuff at 90-100 Km in height. It shows up as a solid but patchy layer that effectively blocks access to any F layer propagation. We have a very high correlation of difficult HF propagation to incidence of Sporadic E Layer at one end of our QSO or another. However, the whole world data is present at this site and in near real time! Simply pick a station by longitude and latitude and click on the stations blue hyperlink ([URSI]Left side of page not center) and then select Year/Month/Day/Hour. The only disadvantage to this display from the www one on my link at the right side of my “Good Stuff” area on the right side of my blog pages is that that one self refreshes every couple of minutes. On this URL you must use your browser to refresh to the latest plot-a very small price to pay when just yesterday I was thinking I had lost the data entirely.
Several Notes to assist. The altitude axis is along the left and is vertical. It is calibrated in Kms. Frequency is the “X” or horizontal axis and is calibrated in Mhz. Be aware not all stations can transmit on all frequencies so the available frequency ranges are shown with a light black line along and below the bottom of the graph and forbidden frequencies are shown as gaps in the line. There are plenty of informational sites showing digisonde “How To” write-ups. I posted 2 in yesterdays posting.
Along the “Y” axis on the left there are some terms Hams are familiar with. Basically, I look at FOF2. 2.5 times the FOF2 number is a reasonable approximation of MUF. Sometimes it is fun to go through the previous days data by hour to see when Es layers form, if ever, and when FOF2 is present and highest at your location.
I hope you find this data as interesting and educational as I do. Good Hunting!
Thanks for reading my Blog. Best, Chas W7MAP/5