[TangerineSDR] Fwd: another 24hour RM3100 run and comparison with Fredericksburg
Julius Madey
hillfox at fairpoint.net
Tue Sep 15 12:43:14 EDT 2020
The Z axis reading is high relative to the Z axis value of 48,032.0nT
from the World Magnetic Model for that day for my specific location of
42deg 15min 41.24sec North, 73deg 32min 32.43sec West, 1220 ft elevation.
Hyomin, have you had time to complete the solenoid coil measurement of
the RM3100?
Jules - K2KGJ
On 9/15/2020 11:58 AM, Kim, Hyomin wrote:
> Just to add to Phil's comments, what I see from the Z axis (if I am
> not wrong), is that there is a drift (whether real or not) in our Z
> axis data: for example, Bz in the USGS mag began at ~0 nT and ended at
> ~0 nT whereas ours began at ~49980 nT and ended at 50000 nT, which is
> a 20 nT increase.
>
>
>
> 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 <mailto: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 11:53 AM Phil Erickson
> <phil.erickson at gmail.com <mailto: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
> <mailto: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 <mailto: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 <mailto: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!!
>
>
> 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 <mailto: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
> <mailto: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 <mailto: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
>
> 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 <mailto: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
> <mailto: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
> <mailto: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
> <mailto: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
> <mailto: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
> <mailto: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
> <mailto:hmkim at njit.edu>>,
> David Witten
> <wittend at wwrinc.com
> <mailto:wittend at wwrinc.com>>,
> Dr. Nathaniel A. Frissell
> Ph.D.
> <nathaniel.frissell at scranton.edu
> <mailto:nathaniel.frissell at scranton.edu>>,
> Dave Larsen
> <kv0s.dave at gmail.com
> <mailto: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
> --
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>
>
>
> --
> ----
> Phil Erickson
> phil.erickson at gmail.com
> <mailto:phil.erickson at gmail.com>
>
>
>
> --
> ----
> Phil Erickson
> phil.erickson at gmail.com
> <mailto:phil.erickson at gmail.com>
> --
> TangerineSDR mailing list
> TangerineSDR at lists.tapr.org
> <mailto:TangerineSDR at lists.tapr.org>
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>
>
>
> --
> ----
> Phil Erickson
> phil.erickson at gmail.com
> <mailto:phil.erickson at gmail.com>
>
>
>
> --
> ----
> Phil Erickson
> phil.erickson at gmail.com <mailto:phil.erickson at gmail.com>
>
>
>
> --
> ----
> Phil Erickson
> phil.erickson at gmail.com <mailto:phil.erickson at gmail.com>
>
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