International Reference Ionosphere (IRI) Model

Get the International Reference Ionosphere (IRI) output parameters.

Description

Computes the International Reference Ionosphere (IRI), which is an internationally recognized model for various ionospheric properties. I would call it more of a hack than a true IRI implementation as it works by querying the online interface at http://omniweb.gsfc.nasa.gov/vitmo/iri_vitmo.html using the curl command on an operating system terminal. Because of this, it requires an internet connection and is pretty slow, but if high speed is not an important issue for you, this can be an easy way to get IRI data into MATLAB.

An example script for how to use the function is given as iritest.m. This is also the script that generated the attached screenshot. It took a little less than 15 minutes to run on my computer.

As stated, the query is made using the command curl in an operating system terminal. This program is built-in to Unix (and Mac I believe) but not Windows. Windows users can download cURL from http://curl.haxx.se/download.html. You'll have to download the appropriate executable for your operating system, and I recommend putting it in the same directory as iri.m.

Acknowledgements

This file inspired Msis E 90.

• Required Products: MATLAB
• MATLAB release: MATLAB 7.5 (R2007b)
• Other requirements: curl.exe (can be downloaded at http://curl.haxx.se/download.html if not included in your operating system).

[Derek]

Drew, thank you! That fixed my problems! Thanks again for this awesome code!

[Drew Compston]

Derek, there were some problems in some of the time sweeps (unrelated to number of points) which I just fixed and uploaded. Longitude sweeps can also be tricky: First of all, they only work for altitude = 100, and something like [-2 -1 0 1 2] will not work because the negative numbers wrap around to near 360, resulting in a big gap. Please feel free to post any other specific examples where maybe it should calculate a linear sweep but doesn't.

[Derek]

Actually, I retract my statement saying "I believe this is because sweepstop = min([sweep(end) + sweepstep/10, sweepmax]); should be sweepstop = [sweep(end) + sweepstep/10, sweepmax];"

[Derek]

Thank you for submitting this code and updating it. On that note, I believe there is an issue with sweeping linear arrays greater than 500 elements. The program should enter into case {1 2 3 4 5 6 7} however, it instead moves to case 8. If the adjustment is made to force the program into case {1 2 3 4 5 6 7}, sweeping still fails. I believe this is because sweepstop = min([sweep(end) + sweepstep/10, sweepmax]); should be sweepstop = [sweep(end) + sweepstep/10, sweepmax];

[Brandon]

On line 496 in iri.m, there is a conversion from time into hours (in decimal form), and I think there is a mistake. The conversion divides seconds by 360 when I think it should be 3600.

[Drew Compston]

Krishna, as you pointed out, there was a bug in my geocentric coordinate conversion which might have caused your confusion. Look at it when the new version I just uploaded gets approved. When the input COORD is 'geoc', input LATITUDE is elevation, input LONGITUDE is azimuth, and input ALTITUDE is range.

[Krishna Prasad]

Hi This is a great piece of code.But I have a small doubt.When the input is geocentric coordinate system we need azimuth,elevation and range to convert it to geodetic coordinates your code converts does this conversion but where does you give elevation,azimuth and range as input.And there is minor bug in the code where you used sph2cart function.Have a look at it.May be I am wrong I am not sure.But this is really awesome stuff it helped me a lot..
Thanks

[Allen Kummer]

 

[Allen Kummer]

 

[Allen Kummer]

For robustness, I would suggest updating the definition for endcmd at line 386 with below. As written, if your path has a space in it, curl gets confused, so adding quotes around the path name helps.

Otherwise the file seems to work great!

Also, for your information, at least my mac has curl built in.

endcmd = [Rz12 IG12 tec_hmax ...
'&ne_top=' ne_top ...
'&imap=' fpeak ...
'&ffof2=' storm ...
'&ib0=' bottom ...
'&probab=' f1prob ...
'&dreg=' d_reg ...
'&tset=' Te_top ...
'&icomp=' ioncomp ...
sprintf('&nmf2=%g.', f2peak_N) ...
sprintf('&f2=%g.', f2peak_M) ...
sprintf('&vars=%i', 11:50) ...
'" http://omniweb.gsfc.nasa.gov/cgi/vitmo/vitmo_model.cgi > "' ...
fullfile(fpath, 'temp.html"')];