[TangerineSDR] Fwd: another 24hour RM3100 run and comparison with Fredericksburg

Tue Sep 15 11:40:09 EDT 2020

Ah, yes I agree - the secular change seems to be a little off. I paid more
attention to the small scale variations which look to be similar. This is a
mystery to me. Maybe our sensor is not so precisely calibrated, say, to
ambient temperature or something? Or we found another magnetic anomaly near
where Jules lives!!

[image: NJIT logo] <https://www.njit.edu/> *Hyomin Kim*
Assistant Professor
Physics
Center for Solar-Terrestrial Research
Institute for Space Weather Sciences
hmkim at njit.edu • (973) 596-5704
https://web.njit.edu/~hmkim/
104 Tiernan Hall, 161 Warren Street, Newark, NJ 07102

On Tue, Sep 15, 2020 at 11:34 AM Phil Erickson <phil.erickson at gmail.com>
wrote:

> Hi Hyomin,
>
>  You have a more expert eye than I do, so I read your statements as
> "uncalibrated axes", which of course is entirely correct for this RM3100
> data.  I just don't know how to separate the geophysical (latitudinal
> difference) from the instrumental (positional axes are not exactly the
> same).  I was reacting mostly to the 24 hour secular change in each
> component.  Is it reasonable to assume that is much less sensitive for
> horizontal vs vertical components?
>
> 73
> Phil
>
> On Tue, Sep 15, 2020 at 11:27 AM Kim, Hyomin <hmkim at njit.edu> wrote:
>
>> Hi Phil,
>> At a first glance I thought the Z traces matched well as the relative
>> values appear to be similar in that axis. If I am not wrong, Bz is oriented
>> toward the center of the earth for the USGS mags. I believe the USGS mag is
>> quite precisely oriented whereas our mag is not. Thus any slight offset in
>> orientation can be seen noticeably as Bz has the biggest values? Also, the
>> latitudinal difference between his place and Fredericksburg could be
>> another factor?
>>
>> Hyomin
>>
>> [image: NJIT logo] <https://www.njit.edu/> *Hyomin Kim*
>> Assistant Professor
>> Physics
>> Center for Solar-Terrestrial Research
>> Institute for Space Weather Sciences
>> hmkim at njit.edu • (973) 596-5704
>> https://web.njit.edu/~hmkim/
>> 104 Tiernan Hall, 161 Warren Street, Newark, NJ 07102
>>
>>
>> On Tue, Sep 15, 2020 at 10:39 AM Phil Erickson via TangerineSDR <
>> tangerinesdr at lists.tapr.org> wrote:
>>
>>> Hi Dave,
>>>
>>>   The X and Y traces return after 24 hours to nearly the same relative
>>> value in both the reference and RM3100 traces.  The Z trace does not.
>>> Ionospheric currents flowing in the E region should not affect Z exclusive
>>> of X and Y under most any geometry I can think of, so I wondered whether
>>> the uncalibrated RM3100 was likely causing this.  (I have never
>>> professionally calibrated a magnetometer, so Hyomin might need to comment
>>> here.). In other words, I always assume there is some measurement
>>> systematic until it has been completely ruled out before assigning it to
>>> geophysical variation.
>>>
>>> 73
>>> Phil W1PJE
>>>
>>>
>>>
>>> On Tue, Sep 15, 2020 at 10:34 AM David Witten <wittend at wwrinc.com>
>>> wrote:
>>>
>>>> @Phil,
>>>>
>>>> Correlation is great, and surely some further calibration issues may
>>>> remain.  But these sensors are NOT colocated - (200-300+ mi apart?) .
>>>> Wouldn't it be suspicious if they did correlate perfectly?  If they did,
>>>> shouldn't  we ask if we do really need an extensive array of these
>>>> sensors?  Presumably there will always be some local variation at this
>>>> scale?  (don't know, just asking)
>>>>
>>>> Dave Witten, KD0EAG
>>>>
>>>> On Tue, Sep 15, 2020 at 7:21 AM Phil Erickson <phil.erickson at gmail.com>
>>>> wrote:
>>>>
>>>>> Hi all,
>>>>>
>>>>>   There appears to be a 10 nT drift in the Z component for the RM3100
>>>>> that is not in the Fredericksburg traces.  Is that slow systematic bias
>>>>> expected?  Maybe things are not calbrated over that time frame quite yet?
>>>>>
>>>>> 73
>>>>> Phil W1PJE
>>>>>
>>>>> On Mon, Sep 14, 2020 at 10:49 PM David Witten via TangerineSDR <
>>>>> tangerinesdr at lists.tapr.org> wrote:
>>>>>
>>>>>> I don't believe that my previous post carried the file K2KGJ provided.
>>>>>>
>>>>>> ---------- Forwarded message ---------
>>>>>> From: Julius Madey <hillfox at fairpoint.net>
>>>>>> Date: Mon, Sep 14, 2020 at 4:26 PM
>>>>>> Subject: another 24hour RM3100 run and comparison with Fredericksburg
>>>>>> To: Kim, Hyomin <hmkim at njit.edu>, David Witten <wittend at wwrinc.com>,
>>>>>> Dr. Nathaniel A. Frissell Ph.D. <nathaniel.frissell at scranton.edu>,
>>>>>> Dave Larsen <kv0s.dave at gmail.com>
>>>>>>
>>>>>>
>>>>>> All,
>>>>>> I was hoping to record a relatively short term event but missed one
>>>>>> about 10 days ago.  However, there was a good run on the 12th with an ~30nT
>>>>>> excursion on the Y axis lasting about an hour.  In the attached pdf, the
>>>>>> three axes of the RM3100 again track the Fredericksburg magnetometer
>>>>>> station data quite closely.  The RM3100 plotted data points are simple
>>>>>> running 60second averages and not the more complex filtering algorithm used
>>>>>> by Intermagnet stations for their 1 minute data points.
>>>>>>
>>>>>> The vertical axes scales on all plots are as close as I could match
>>>>>> them by eye in cutting and pasting.
>>>>>>
>>>>>> I believe the value to the right on the Intermagnet plot is the mean
>>>>>> for the 24 hour period.  I did not try to compute a 24 hour mean.
>>>>>>
>>>>>> One of the products for the future for general interest would be a
>>>>>> running plot like those available on Intermagnet.org.  I guess we can dream
>>>>>> a bit.
>>>>>>
>>>>>> Jules - K2KGJ
>>>>>> --
>>>>>> TangerineSDR mailing list
>>>>>> TangerineSDR at lists.tapr.org
>>>>>> http://lists.tapr.org/mailman/listinfo/tangerinesdr_lists.tapr.org
>>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> ----
>>>>> Phil Erickson
>>>>> phil.erickson at gmail.com
>>>>>
>>>>
>>>
>>> --
>>> ----
>>> Phil Erickson
>>> phil.erickson at gmail.com
>>> --
>>> TangerineSDR mailing list
>>> TangerineSDR at lists.tapr.org
>>> http://lists.tapr.org/mailman/listinfo/tangerinesdr_lists.tapr.org
>>>
>>
>
> --
> ----
> Phil Erickson
> phil.erickson at gmail.com
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.tapr.org/pipermail/tangerinesdr_lists.tapr.org/attachments/20200915/4c6ecb58/attachment-0001.html>