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

Tue Sep 15 11:53:32 EDT 2020

Hi David,

  When I say "secular change", I meant the time scale of the change.
Secular = long term, in this case relative to the time scales of a magnetic
disturbance.  For example, storm time current variations might occur on a
few minute to hour or two scale, but would not last for 24 hours.  The
latter is what I was referring to and indicates a more long term drift.  If
you saw that drift for example from day to day, that is now climatology
(not weather) and you would have to see whether that is reasonable
geophysically.

73
Phil

On Tue, Sep 15, 2020 at 11:50 AM David Witten <wittend at wwrinc.com> wrote:

> Phil, Hyomin,
>
> I believe that I understand your comments, but to be sure, may I ask
> exactly what is meant by 'secular change'.  I do not want to make incorrect
> assumptions about a term of art.
>
> Dave
>
> On Tue, Sep 15, 2020 at 10:45 AM Phil Erickson <phil.erickson at gmail.com>
> wrote:
>
>> If it is picking up a 10 nT level secular change, that is fabulous for a
>> reasonable cost sensor!  Maybe Jules has a ground induced current nearby?
>> Anyhow, temperature sensitivity at a more precise level is I'm sure all
>> part of the calibration needs, so we'll find out later...
>>
>> Phil
>>
>> On Tue, Sep 15, 2020 at 11:40 AM Kim, Hyomin <hmkim at njit.edu> wrote:
>>
>>> 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
>>>>
>>>
>>
>> --
>> ----
>> Phil Erickson
>> phil.erickson at gmail.com
>>
>

-- 
----
Phil Erickson
phil.erickson at gmail.com
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