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

Tue Sep 15 12:00:24 EDT 2020

@Phil,

Thanks for the explanation.
I was guessing secular = local.  Important distinction.

Dave Witten, KD0EAG

On Tue, Sep 15, 2020 at 10:53 AM Phil Erickson <phil.erickson at gmail.com>
wrote:

> 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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