From Liisa.Juusola@fmi.fi Fri Dec 20 11:18:59 2024
Date: Fri, 20 Dec 2024 10:18:55 +0000
From: "Juusola Liisa (FMI)" <Liisa.Juusola@fmi.fi>
To: Maria Hamrin <Maria.Hamrin@space.umu.se>
Subject: VS: VS: Question about equivalent currents

Hi Maria,

yes, the code can just as well be used for the North American network, but the
grid resolution should probably be corser. You may need to do some testing. I
can't think of any particulat caveats, except for the most obvious: don't trust
the results in areas where there are no observations and don't trust the
patterns when the amplitude is very weak (less than 50 A/km). Also, I would
recommend to place the telluric current layer just below the ground surface. As
far as I can remember, in the code the value is set to 20 km depth. I'd change
this to 1 m depth. 

Kind regards,
Liisa

________________________________________________________________________________
Lähettäjä: Maria Hamrin <Maria.Hamrin@space.umu.se>
Lähetetty: perjantai 20. joulukuuta 2024 11.28
Vastaanottaja: Juusola Liisa (FMI) <Liisa.Juusola@fmi.fi>
Aihe: Re: VS: Question about equivalent currents  

Hi Liisa,


Thanks for your answer, and no worries. I know that this time of the year can be
stressful and it is really stupid that they put the proposal season at the same
time as the Christmas season. 


And as for our proposal, Juan's was unfortunately not granted but mine was, so
I'm presently looking for a PhD student to study heavy ion transport in the
magnetotail together with me, Timo Pitkänen and others.


Good to know that we can run the code ourselves. I'm not sure yet what the study
will look like, if we will study many or just a few events. It depends on the
student and on the events themselves...


I just opened the Matlab file and it looks quite straight forward though, so I
guess the student should be able to run that for selected events. 


I guess also that this code can be used for magnetometers in North America, just
by feeding with correct input data. It could be good to do all computations
in-house and by the same method and person so it will be easier to compare
results from Scandianvia and from North America.


Are there any known issues or caveats with using the code and computing the
currents? Other than selecting the base line for the magnetic field data?


Merry Christmas!



/Maria

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Maria Hamrin                     Email: maria.hamrin@space.umu.se
Associate Professor              Phone: +46 (0)70 325 80 38
Docent in space physics
Department of Physics
Umeå University
Linnaeus väg 24, 901 87 Umeå, Sweden
https://www.umu.se/personal/maria-hamrin/
https://www.umu.se/en/research/groups/space-plasma-physics-group/
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On 12/20/24 09:04, Juusola Liisa (FMI) wrote:
      Hi Maria,

sorry for taking so long to reply, but I have been, indeed, having far too
much work before Christmas. The Research Council of Finland decided that
an optimal time for project application DLs is right after the holidays.
In practise this means that the application must be submitted before the
school holiday starts. But now mine has been sent. I'm sorry to hear that
yours wasn't successful this time. Better luck next round!

The equivalent current web page has been made by Max van de Kamp. If you
like, you can ask him about accessing the data (max.van.de.kamp@fmi.fi),
but I suspect it won't be straightforward.

Do you know how much data you're going to need? If it's a handful of days
only, I'm happy to calculate the data and send it to you. On the other
hand, if you need large amounts of data, then your student may need to
download the magnetic field data and learn to run the code (available as a
supplement to
https://link.springer.com/chapter/10.1007/978-3-030-26732-2_2). In case
you only plan on calculating differential equivalent currents, you need
not worry about the baseline (except for the necessary cleaning of the
data), otherwise you'll also need a baseline method.

I'm happy to either send you the data or help in case your student needs
assistance with the code.

Kind regards,
Liisa

________________________________________________________________________________
Lähettäjä: Maria Hamrin <Maria.Hamrin@space.umu.se>
Lähetetty: keskiviikko 18. joulukuuta 2024 12.28
Vastaanottaja: Juusola Liisa (FMI) <Liisa.Juusola@fmi.fi>
Aihe: Question about equivalent currents  
Hi Liisa,

I hope you are fine and not having too much work before Christmas.

I'm contacting you right now because I will be supervising a master
student this spring and he will look into equivalent currents and
especially differential equivalent current using both IMAGE data and
THEMIS GBO data. The student's study will be inspired by ideas from
Schillings et al., 2023, on which you were co-author
(https://doi.org/10.1051/swsc/2023018).

My question to you is what is the easiest way to compute the
differential equivalent currents from IMAGE data. I notice from your
IMAGE web that one can play around with the base line time, and that my
work for estimating the differential currents. But is there any way we
can download also the data (not only as plots) from the web? And do you
have any other recommendations for us computing the differential
equivalent currents? Btw, we have also been in contact with James
Weygand for the same thing using THEMIS GBO data.

If the student's work is promising, we'll try to make a paper from it
but I cannot promise that yet. But if we succeed, you will of course be
offered to be co-author!

Moreover, very recently, we go to know that Juan Carlos' proposal rom
last year was not granted this time. However, we will try again in the
next round. :-)

Merry Christmas!

--
/Maria

-----------------------------------------------------------------
Maria Hamrin                     Email: maria.hamrin@space.umu.se
Associate Professor              Phone: +46 (0)70 325 80 38
Docent in space physics
Department of Physics
Umeå University
Linnaeus väg 24, 901 87 Umeå, Sweden
https://www.umu.se/personal/maria-hamrin/
https://www.umu.se/en/research/groups/space-plasma-physics-group/
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