Can't let go of this yet.
If you think about the inverse problem of deriving the sea surface
elevation from the heave you would have to account for the latency of
ship motion relative to the sea-surface. A? wave passing under a ship
induces motions that are not instantaneous either in attack or decay.
J.
On 5/25/18 20:42, John Helly wrote:
>
> I believe it's a synonym within the oceanographic community for the
> vertical motion of an ocean-going platform.
>
> https://en.wikipedia.org/wiki/Ship_motions
>
> Could just be jargon but it strike me as more complex: nonetheless a
> vertical position relative to a datum, but the buoyancy, stability and
> momentum of the platform are implied as part of the dynamics.? It
> seems that the datum is not a geophysical one alone but confounded
> with the 'normal' waterline for a platform so it may be relative to
> the water level in which the platform is embedded.? That's a tough
> one.? Two different platforms on the same sea surface would have
> different 'heave', for example.
>
> J.
>
>
> On 5/25/18 19:54, Jim Biard wrote:
>> Hi.
>>
>> I get and endorse the need for pitch, roll, and yaw, but I remain
>> perplexed about heave. How is a time series of 'heave' different from
>> a time series of height relative to some vertical datum? I've yet to
>> see a proposed definition that convinces me that this is a uniquely
>> different quantity.
>>
>> Grace and peace,
>>
>> Jim
>>
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>>
>>
>> On Fri, May 25, 2018 at 7:28 AM, Lowry, Roy K. <rkl at bodc.ac.uk
>> <mailto:rkl at bodc.ac.uk>> wrote:
>>
>> Dear All,
>>
>>
>> I agree with Nan that definitions of pitch roll and yaw would
>> improve the existing Standard Name definitions. I also agree with
>> using the existing orientation Standard Names?for ADCPs and that
>> the 'platform' definition wording could make this clearer.
>> However, such an enhancements should be submitted as a separate
>> proposal and not be considered as part of Steve's proposal.
>>
>>
>> Cheers, Roy.
>>
>>
>> I am retiring on 31/05/2018 but will continue to be active
>> through an Emeritus Fellowship using this e-mail address.
>>
>>
>>
>> ------------------------------------------------------------------------
>> *From:* CF-metadata <cf-metadata-bounces at cgd.ucar.edu
>> <mailto:cf-metadata-bounces at cgd.ucar.edu>> on behalf of Nan
>> Galbraith <ngalbraith at whoi.edu <mailto:ngalbraith at whoi.edu>>
>> *Sent:* 25 May 2018 14:46
>> *To:* cf-metadata at cgd.ucar.edu <mailto:cf-metadata at cgd.ucar.edu>
>> *Subject:* Re: [CF-metadata] Platform Heave
>> I'd really like to see pitch, roll and yaw defined in the CF
>> standard
>> name table; currently
>> the definitions only say 'Standard names for platform describe the
>> motion and orientation
>> of the vehicle from which observations are made e.g. aeroplane,
>> ship or
>> satellite.'
>>
>> Also, not to get too far into the weeds, but many of the platform
>> terms
>> are important
>> for instruments like ADCPs, so I'd just like to confirm that these
>> definitions - and
>> the names themselves - can be used to describe instruments, not just
>> vehicles
>> 'e.g.? aeroplane, ship or satellite'. We already use pitch roll and
>> yaw for these
>> instruments on surface moorings, and I hope (and assume) this is
>> legal.
>>
>> Thanks - Nan Galbraith
>>
>>
>> On 5/25/18 8:53 AM, Lowry, Roy K. wrote:
>> >
>> >
>> > Dear Steve,
>> >
>> >
>> > One of the reasons I was interested in your definitions was your
>> > perspective on the datum (i.e. zero value) for heave. The datum
>> > 'mean_sea_level' is well used?in CF, but with the definition 'time
>> > mean of sea surface elevation at a given location over an
>> arbitrary
>> > period sufficient to eliminate the tidal signals.' This is
>> obviously
>> > not appropriate for platform heave which doesn't take any
>> account of
>> > the state of the tide and so I would exclude 'mean_sea_level'
>> from the
>> > Standard Name.
>> >
>> >
>> > I think my preference would be to keep the term 'heave' as we
>> already
>> > have 'pitch', 'yaw' and 'roll', giving:
>> >
>> >
>> > platform_heave (m)
>> >
>> >
>> > Standard names for platform describe the motion and orientation
>> of the
>> > vehicle from which observations are made e.g. aeroplane, ship or
>> > satellite. "Heave" is a term used to describe the vertical
>> > displacement of the platform above?its position when not moving.
>> >
>> >
>> > tendency_of_platform_heave (m s-1)
>> >
>> >
>> > Standard names for platform describe the motion and orientation
>> of the
>> > vehicle from which observations are made e.g. aeroplane, ship or
>> > satellite. "Tendency_of_X" means derivative of X with respect
>> to time.
>> > "Heave" is a term used to describe the vertical displacement of
>> the
>> > platform above its position when not moving.
>> >
>> >
>> > What do you think?
>> >
>> >
>> > Cheers, Roy.
>> >
>> >
>> > I am retiring on 31/05/2018 but will continue to be active
>> through an
>> > Emeritus Fellowship using this e-mail address.
>> >
>> >
>> >
>> >
>> ------------------------------------------------------------------------
>> > *From:* CF-metadata <cf-metadata-bounces at cgd.ucar.edu
>> <mailto:cf-metadata-bounces at cgd.ucar.edu>> on behalf of
>> > Hamilton, Steve <sj.hamilton at fugro.com
>> <mailto:sj.hamilton at fugro.com>>
>> > *Sent:* 25 May 2018 08:51
>> > *To:* cf-metadata at cgd.ucar.edu <mailto:cf-metadata at cgd.ucar.edu>
>> > *Subject:* Re: [CF-metadata] Platform Heave
>> >
>> > All,
>> >
>> > Thanks for all the comments, I have tried to capture as below -
>> >
>> > *Parameter Name***
>> >
>> >
>> >
>> > *Standard Name*
>> >
>> >
>> >
>> > *Definition*
>> >
>> >
>> >
>> > *Canonical Units*
>> >
>> > ???????? Platform Heave
>> >
>> >
>> >
>> > Platform_Height_above_mean_sea_Level
>> >
>> >
>> >
>> > ??????? Standard names for platform describe the motion and
>> > orientation of the vehicle from which observations are made e.g.
>> > aeroplane, ship or satellite. Height above mean sea Level is the
>> > linear vertical (up/down) distance of the platform in respect
>> to the
>> > mean sea level.
>> >
>> >
>> >
>> > ??????? m
>> >
>> > ?????? Platform Heave Rate
>> >
>> >
>> >
>> > Tendency_of_Platform_Height_above_mean_sea_Level
>> >
>> >
>> >
>> > ??????? Standard names for platform describe the motion and
>> > orientation of the vehicle from which observations are made e.g.
>> > aeroplane, ship or satellite. "tendency_of_X" means derivative
>> of X
>> > with respect to time. Height above mean sea Level is the linear
>> > vertical (up/down) distance of the platform in respect to the
>> mean sea
>> > level.
>> >
>> >
>> >
>> > ??????? m s-1
>> >
>> > Please let me know if you have further comments
>> >
>> > Thanks
>> >
>> > Steve
>> >
>> > *From:*Steven Emmerson <emmerson at ucar.edu
>> <mailto:emmerson at ucar.edu>>
>> > *Sent:* 21 May 2018 19:18
>> > *To:* Hamilton, Steve <sj.hamilton at fugro.com
>> <mailto:sj.hamilton at fugro.com>>
>> > *Cc:* cf-metadata at cgd.ucar.edu <mailto:cf-metadata at cgd.ucar.edu>
>> > *Subject:* Re: [CF-metadata] Platform Heave
>> >
>> > Whatever name you come up with, the canonical unit of the heave
>> rate
>> > shouldn't be "ms-1", but rather one of the following:
>> >
>> >???? m s-1
>> >
>> >???? m/s
>> >
>> >???? m.s-1
>> >
>> > I favor "m/s".
>> >
>> >
>> > Regards,
>> >
>> > Steve Emmerson
>> >
>> > On Mon, May 21, 2018 at 6:32 AM, Hamilton, Steve
>> > <sj.hamilton at fugro.com <mailto:sj.hamilton at fugro.com>
>> <mailto:sj.hamilton at fugro.com>> wrote:
>> >
>> >???? Hi
>> >
>> >???? I am trying to find the CF name for heave of a vessel or
>> >???? platform.? platform_roll_angle and platform_pitch_angle already
>> >???? exist but nothing on heave
>> >
>> >???? Would be the following be acceptable
>> >
>> >???? Platform_heave (m)
>> >
>> >???? Platform_heave_rate (ms-1)
>> >
>> >???? Standard names for platform describe the motion and
>> orientation of
>> >???? the vehicle from which observations are made e.g.
>> aeroplane, ship
>> >???? or satellite.
>> >
>> >???? Kind Regards,
>> >
>> >???? Steve
>> >
>> >
>>
>>
>> --
>> *******************************************************
>> * Nan Galbraith??????? Information Systems Specialist *
>> * Upper Ocean Processes Group Mail Stop 29 *
>> * Woods Hole Oceanographic Institution??????????????? *
>> * Woods Hole, MA 02543 (508) 289-2444 *
>> *******************************************************
>>
>>
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>
> --
> John Helly, University of California, San Diego / San Diego Supercomputer Center / Scripps Institution of Oceanography / 760 840 8660 mobile /http://www.sdsc.edu/~hellyj
> ORCID ID: orcid.org/0000-0002-3779-0603
--
John Helly, University of California, San Diego / San Diego Supercomputer Center / Scripps Institution of Oceanography / 760 840 8660 mobile / http://www.sdsc.edu/~hellyj
ORCID ID: orcid.org/0000-0002-3779-0603
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