Using SSN with PropLab 3

[DanElyea]

Question: On the page “IRI Model Options” how many of the factors listed must have an entry made if all I want to do is compare two different SSN #s?

Does some kind of average entry need to be made for the factors that are unknown (such as A index, etcetera)?

Here’s an example of results that don’t seem correct for the SSNs entered.

Transmission path is Okeechobee, Florida to  Bogota, Columbia.

With SSN of 10 used, reasonable elevation of 10 degrees chosen, hour 02 in February, scanning frequencies of 5 to 16 MHz, the first six frequencies propagate, the rest are lost in space.  MUF from that chart is given as 9.2 MHz.  All well and good.

But changing the SSN to 100, and making the same run, results in an indicated MUF of 9 MHz (lower than with SSN of 10), and sweeping the frequencies, only the first five frequencies make it back to earth.  This is exactly the opposite of what I would expect, and from what many years of operating experience would indicate. 

Suggestions?  I can’t find any detailed information about working with the solar activity input in the documentation.

Thanks,



Dan

[DanElyea]

Is there anyone out there knowledgeable about Proplab-Pro 3 who can help me with my questions about using different levels of SSN?  (see my original message to which I'm responding--yes, apparently talking to myself!)

In brief, when I set up for present conditions and make a run, the results look very reasonable, and fall close to actual observations of present propagation performance.  But when I  want to take a look at what the situation might be when the solar activity cycle goes to more robust levels, the results are couter-intuitive, and I can place no confidence in them. 

Quite possibly, it resolves to something I don't understand about making the entries on the "IRI Model Options" page...

Thanks,

Dan

[BethKatz17582]

Dan -

You're not talking to yourself, it just looks that way. I don't use PropLab 3, so I can't answer your question. I'll see if I can nudge someone who can.

Beth

[Cary]

Our apologies Dan for the delay in looking into this. It actually looks like it might be a bug. And if it is, we'll need to get a patch out ASAP. As I noted to you in my PM, it's odd no one else has noticed this (including ourselves). We haven't had time to delve into that particular problem yet, but will be looking at it in the next week.

Thanks for being so patient. We'll get the problem (whatever it is) resolved. The results you describe do sound buggy - like the system is not recognizing changes in the SSN (which is possible). It might only be reading the current SSN and disregarding any changes you try to make. I'm not sure. But we'll figure it out.

[Cary]

Dan, we have examined the software and can find no error in the code. Here is what we suspect you are doing, and considering it is not mentioned in the manual, it might be a common mistake others are making, so we appreciate you spotting this.

The models primarily use the IG12 index (a relatively new and more accurate measure of the sunspot number, also known as the "effective" sunspot number in some literature) and the running 12-month mean Sunspot Number. Each parameter is used in a different way to help shape the ionospheric layers appropriately. The solar flux value will not have any influence on the global maps and has been included to help quantify the quality of the sunspot number values input into the code. So you can disregard the solar flux.

If you want to see what conditions will be like during the next solar maximum, then when you adjust the values in the Main Options / IRI Options panel, ADJUST BOTH THE RUNNING MEAN 12-MONTH SSN AS WELL AS THE IG12 INDEX TO THE SAME VALUES. Values anywhere from 0 to about 400 can be used for the SSN and values between about -50 (negative 50) and 400 can be used for the IG12.

Since under normal quiet geomagnetic conditions, the IG12 value should be very close to the running 12-month mean SSN value, you can (and should) basically equate the two when making changes to estimate future conditions.

If you do this, you will notice a HUGE difference in both the global maps that are produced, as well as in the ray-traced results. I ran a quick 2.5D simulation using your parameters and was able to reproduce the anomaly you observed when you only changed the SSN. But changing both the SSN and IG12 results in precisely what you are after... a large increase in critical F2-layer frequencies and an attendant increase in useable frequencies on that circuit.

I hope this helps. Again, my apologies for the delay in responding to this.

It's good to know this is not a bug. But we do need to add more clarity in the manual. Thanks for noticing.

[DanElyea]

That  made all the difference in the world, Cary.  Thanks very much.

I'm very relieved now that the SSN changes make sense in terms of the MUF and ray tracing functions. 

When making generic runs (not for the present conditions), do you have any recommendations for the other parameters (such as Ap Index and Kp Index) on that page, perhaps some average value?

Thanks again and 73,  Dan

[Tad]

If you want to see what conditions will be like during the next solar maximum, then when you adjust the values in the Main Options / IRI Options panel, ADJUST BOTH THE RUNNING MEAN 12-MONTH SSN AS WELL AS THE IG12 INDEX TO THE SAME VALUES. Values anywhere from 0 to about 400 can be used for the SSN and values between about -50 (negative 50) and 400 can be used for the IG12.

this is not a bug. But we do need to add more clarity in the manual. Thanks for noticing.

One very basic thing I cannot figure out, and cannot find a reference to it in the manual or any online discussions, is when I enter those values, what next?  There doesn't seem to be any Save function.

[admin]

One very basic thing I cannot figure out, and cannot find a reference to it in the manual or any online discussions, is when I enter those values, what next?  There doesn't seem to be any Save function.

Under the Other Options tab, there is a "Save Configuration..." button. Click that, choose a filename, and it will save ALL of your settings. To load them back, click the Load Configuration... button.

[Tad]

I thought I was saving config info when doing that, such as my email address and any proxy servers.  Since it isn't under the same tab, I guess it wasn't obvious after entering data under IRI Model Options.

Now when I save the config, I should change it back to Proplab.cfg, right?  Or do I save it to the new suggested file name, then load that the next time I use the program?

Thanks.