Dear Abdur Rauf,

You should set end time or stop as 21 because 24 is the same as 00 for next day

Dear Sergii V. Panasenko,

Your suggestion solve my problem. Here i have chosen one fix date i.e 12 July. I do not konw that using [00 24] will repeat the ap index value in the same day or it will continue to the next day. If it repeats the value in the same day then i think the ap index should be same at 00 and 24. But, from the third figure you can see different values at 00 and 24. Your comment will be appreciated.

Thanks

I have checked 3h-ap for three adjacent days and noted that ap values for 24 UT and 00 UT (next day) are not the same. But I have detected that ap values for 21 UT and 24 UT are always the same. So, maybe they are repeated for uniformity.

Dear Sergii V. Panasenko,

Thank you very much for spending your precious time to help me. Also, i wish you tell me that, is the value at '00' means the ap value in the time range [00 03]?.

The IRI reads their indices from reference files here: http://irimodel.org/indices/apf107.dat

The file is organized as follows: year, month, day, 8 ap values, daily mean ap, etc...

As for the issue you mention above (regarding the repeating indices), the IRI uses the ap at an hour to define the ap for the next three hours (e.g. the ap at 00UT is used for everything between 0UT and 2:59UT). The 24UT value is the same as the 21UT value because the IRI treats individual days separately. In this way, it has no way of knowing what the ap is at 00UT the next day, so it treats the 24UT value as an extension of the 21UT 3-hour block.

Also, if you are just looking for Kp and ap, you can get Kp and ap values directly from the following ftp: ftp://ftp.ngdc.noaa.gov/STP/GEOMAGNETIC_DATA/INDICES/KP_AP

The format of that file is given in the kp_ap.fmt file.

Dear David R. Themens ,

Got it.

I am not native speaker, so i do not know whether i have used ' Got it' in a correct way or not. But, what i actually mean is that i understand it now. Also, if possible then kindly share the reference literature. I want to read this in more detail.

Thanks

I'm afraid that the IRI reference literature has not been updated in quite a long time and does not include information regarding some of the finer details of the auxiliary model outputs like ap, kp, F10.7, etc... I merely know this from my familiarity with the model code, which you can consult here: http://irimodel.org/IRI-2016/

I hope this helps.

Thank you sir.

Dear David R. Themens ,

While downloading the index values from IRI model, i meet another problem. I have checked the 3-hour ap and kp values on 12-13 July of 2004 and 2005. Each time i ran the model, it gave me value '0' for 3-hour kp indices. The details are given in the attach file.If you have some information then kindly share with me.

Also, sir if you know then kindly tell me about downloading the 3-hour K-index and a-index of one specific observatory. Because, i am not interested in the planetary indices.

Thanks

The ap values are correct. The Kp is wrongly put as zero; however, the IRI does not record or use Kp, so it's understandable. Likely, that option should be removed from the model output list. In general, I would recommend not using the IRI to generate your indices; instead, use the world data centers (see the ftp I listed in my first response).

As for local disturbance indices, I would look at getting in touch with magnetometer operators. Without knowing what region you're interested in and for what purpose you wish to use this information, it is difficult for me to provide further information.

Sir, actually i want to investigate the effect of local indices on some parameters from EISCAT radar located in Tromsø ( Norway ). So is this useful to use the indices from Tromsø geophysical observatory (TGO)? You can find the indices in the attach file.

Also, i checked the kp_ap.fmt file, but i do not understand how to find the indices of my interest e.g. on 12 July 2004. If possible the kindly give me some hints to find the required indices.

Thanks

This is all detailed in the fmt file (note: these files are planetary indices, one for every year). As for local indices, it might make the most sense to use the actual magnetometer data, if you are trying to identify physical mechanisms or look at a particular physical phenomenon.

4 7 12333 32320272323132023173 9 7 12 9 9 5 7 9 80.52 17 84.00

year, month,day, cycle#, rotation#, day within cycle, 8 3-hour Kp indices: 2320272323132023, daily summed Kp, 8 3-hour ap indices

Dear David R. Themens ,

Following your comment, i checked the the kp_ap.fmt file again. I meet two questions. Firstly, i do not find information about cycle# you have mentioned in your comment. Secondly, it is clear from the FORMAT FOR RECORDS OF SELECTED GEOMAGNETIC AND SOLAR ACTIVITY INDICES that the column # 13-14 represents the Kp or PLANETARY 3-HOUR RANGE INDEX for 0000 - 0300 UT. Kp-index values ranges from 0 - 9. But, when i checked column # 13-14, i found a value 33 in the first row of the attached file. If possible then kindly comment on these questions.

Thanks

The Kp values are recorded in the traditional method (e.g. in thirds of a unit). For example 3-, 3, 3+ mean 2.7, 3.0, and 3.3, respectively.

Divide the value you find recorded in the file by ten to arrive at the true Kp value.

The Bartels/cycle information is irrelevant for your purposes.

Thank you sir.

Dear David R. Themens ,

Could you please suggest some literature to understand solar and geomagnetic indices in detail.

Thanks

https://omniweb.gsfc.nasa.gov/form/dx1.html please visit this web page you can select all types of solar and geomagnetic data

@ Mustafa Ulukavak , Thanks