[CF-metadata] Platform Heave

From: Kenneth Kehoe <kkehoe>
Date: Fri, 3 Aug 2018 12:56:16 -0600

Thanks Jim. This is a good bit of work. I initially tried to come up
with a system to define positive but ran into issues with roll because I
needed more than one word. For example I was using "starboard up" to
indicate what part of the platform is moving "up". But I think you have
a better method by using a rotation word not a linear direction word for
rotational movement. I would prefer to expand the attribute "positive"
to recycle terms instead of making a new one. Also that term is fairly
self explanatory. But if we don't want to mess with COARDS I understand.
Maybe use "positive_direction". I like the idea for linear movement with
surge, sway and heave but I think we need to stick with the clockwise
category of "the direction of positive values". In that case the better
term for surge, sway and heave would be "forward" or "backward". Overall
I feel like using this new attribute will reduce the confusion greatly
for I would also use it with radial instrument data with "toward" or
"away". Pulling the direction of positive out of standard_name as Nan
suggest should make definitions easier to agree on and work with
historical data that was not assuming a positive direction of travel. If
we do pull direction of travel out we will need to decide which one
overrides the other when both are used. My preference is to let the new
attribute override the direction of positive in the standard_name since
the positive direction definition would be in the file while the
standard name requires looking up.

Now the 800 lb gorilla in the room... How to explain what we mean by
clockwise, forward, toward. I feel like we keep stating that a "Google
image search shows" so maybe we should look into a picture to solve our
issue. The old idiom a picture is worth a thousand words
<https://en.wikipedia.org/wiki/A_picture_is_worth_a_thousand_words> may
be more true with this than ever. Plus it should help with English as a
second language speaking users. Could CF host some images that would be
tied to standard names so we can reference them when we need to describe
the reference frame. Cf/Radial
<http://www.ral.ucar.edu/projects/titan/docs/radial_formats/CfRadialDoc.pdf>
uses a picture to describe the reference frame for aircraft in its
document. Once the reference frame is well described the terms x-axis
and clockwise are obvious. Using this example
<https://www.grc.nasa.gov/WWW/K-12/rocket/Images/rotations.gif> is there
any confusion on the positive direction for roll, pitch, yaw (ignore the
actual positive direction, I'm just asking about the clarity of the
image to convey direction of positive travel)?

Have a wonderful weekend,

Ken



On 2018-8-3 08:41, Jim Biard wrote:
>
> I freely admit that I picked direction on sway arbitrarily. In my
> experience, part of the variation that arises in the definitions of
> the different motions arises from different thoughts about their use,
> particularly whether someone is thinking the values are used to
> transform into the platform body frame vs transform from it. Or maybe
> they just aren't worrying about consistency. Like as not, choices have
> often been made in attempts to make the values have the signed-ness
> that felt right to people, and we can't keep to conventions like the
> right hand rule and make it all work consistently. We want a positive
> pitch to be nose up. We want a positive yaw to be nose right. We want
> positive heave to be up. My natural tendency is to think of "roll
> right" as positive and "sway right" as positive, but that isn't what
> other people think of.
>
> As I read what I wrote, I realize I didn't use a consistent approach
> to position and look direction when assigning clockwise and
> anticlockwise to roll, pitch, and yaw. I need to regularize that.
>
> Reading the Conventions about vertical coordinates, it says they must
> all have a "positive" attribute with a value of "up" or "down". I
> don't see a problem with having the definitions back off of declaring
> a specific directionality and add an attribute declaring
> directionality. We could call the attribute "direction" so as not to
> step on the "positive" attribute, and say that if the attribute is not
> present that the user should not assume which direction is correct.
>
> If we declare that X is positive forward, that Y is positive left,
> that Z is positive up, and that we use the right-hand rule for angle
> directions, the direction attribute values could be:
>
> * roll: "clockwise" for positive right side up and "anticlockwise"
> for positive right side down.
> * pitch: "clockwise" for positive nose up and "anticlockwise" for
> positive nose down.
> * yaw: "clockwise" for positive nose right and "anticlockwise" for
> positive nose left.
> * surge: "positive" for positive forward and "negative" for positive
> backward.
> * sway: "positive" for positive left and "negative" for positive right.
> * heave: "positive" for positive up and "negative" for positive down.
>
> Thoughts?
>
> BTW, I'll be out until August 13.
>
> Grace and peace,
>
> Jim
>
> On 8/2/18 12:58 PM, Kenneth Kehoe wrote:
>> Thanks Nan and Roy for the positive direction information. I did the
>> Google search as Roy suggested and I found more images with Jim's
>> definition of positive with starboard down, but there are enough with
>> starboard up to think it's not a standard. This does point out my
>> main concern with putting positive direction in the standard name.
>> Would we then need to create a new standard name with the only
>> difference being the positive direction? I'm OK with doing this but I
>> worry about the increase of names. I think this needs to be a
>> different discussion, but putting the positive direction in an
>> attribute makes the most logical sense to me. I did take a stab at
>> trying to define a standard at this and it was not great.
>>
>> So at this time I'm proposing that if we define roll, sway we need to
>> define them twice to get both positive directions defined and
>> available for use. I don't think CF should force a convention on the
>> data, the user should be free to represent the data as it is produced
>> by the instrument.
>>
>> FYI a very quick search of the data products we produce:
>>
>> * pitch with nose up positive: 6
>> * roll with right side down positive: 6
>> * yaw with clockwise positive: 1
>> * sway with toward left side positive: 1
>> * surge with toward bow positive: 1
>> * heave with up positive: 1
>>
>>
>> Ken
>>
>>
>>
>> On 2018-8-2 09:29, Nan Galbraith wrote:
>>> Thank you, Jim, well done.
>>>
>>> My only concern is that platform_orientation is describing the same
>>> angle
>>> as yaw, and maybe should be deprecated.? The web is full of
>>> references to
>>> 'platform orientation', and a very quick check tells me they
>>> (mainly) refer to
>>> all 3 axes.
>>>
>>> I tried to check the sign of roll for ADCPs, since this is a
>>> variable that's output
>>> by the Teledyne-RDIs that we use, but I don't have the time to do a
>>> thorough job
>>> at this point. If different communities define this differently,
>>> Maybe we'll need to
>>> consider using an attribute.
>>>
>>> Cheers - Nan
>>>
>>> On 8/2/18 5:01 AM, Lowry, Roy K. wrote:
>>>>
>>>> Dear All,
>>>>
>>>>
>>>> You're not going to believe this, but try Googling 'pitch roll yaw'
>>>> and look through the images at the?roll sign convention. This
>>>> reveals some inconsistency on whether?positive roll is clockwise
>>>> when looking forward (Jim's definition)?or looking backward (Ken's
>>>> definition).
>>>>
>>>>
>>>> My personal experience from going to sea was that positive roll was
>>>> port to?starboard?- i.e. clockwise when looking forward. I'm pretty
>>>> sure the roll data?streams we handle (Autosub and gliders)
>>>> also?conform to this convention, but will ask somebody to check.
>>>>
>>>>
>>>> Could I suggest that Ken also?check his definition sources and data
>>>> streams.
>>>>
>>>>
>>>> Cheers, Roy.
>>>>
>>>>
>>>>
>>>> ------------------------------------------------------------------------
>>>>
>>>> *From:* CF-metadata <cf-metadata-bounces at cgd.ucar.edu> on behalf of
>>>> Kenneth Kehoe <kkehoe at ou.edu>
>>>> *Sent:* 01 August 2018 22:51
>>>> *To:* cf-metadata at cgd.ucar.edu
>>>> *Subject:* Re: [CF-metadata] Platform Heave
>>>> Sounds good to me except the platform_roll positive direction seems
>>>> to be opposite of what we have been describing. I typically have
>>>> platform roll positive for right-hand side rising.
>>>>
>>>> Ken
>>>>
>>>>
>>>> On 2018-8-1 13:55, Jim Biard wrote:
>>>>>
>>>>> Hi.
>>>>>
>>>>>
>>>>> Here is my proposal for a self-consistent and generic set of
>>>>> definitions for roll, pitch, yaw, surge, sway, heave, course, and
>>>>> orientation. I've tried to avoid lots of reference frame or vector
>>>>> terms, basing everything on the vertical direction and the nominal
>>>>> forward motion direction, which are two things all the moving
>>>>> platforms we are concerned with have, and which I think are easy
>>>>> enough to extrapolate to a stationary platform. I haven't bothered
>>>>> to do the *_rate definitions, since they are simple extrapolations
>>>>> of these definitions.
>>>>>
>>>>> I have taken the liberty of removing the redundant word "angle"
>>>>> from the definitions of roll, pitch, and yaw. It is like using
>>>>> "latitude angle" for latitude or "course angle" for course. We can
>>>>> make the redundant formulations aliases of the proper ones.
>>>>>
>>>>>
>>>>>
>>>>> *
>>>>>
>>>>> platform_roll: Roll is a rotation about an axis (the X axis) that
>>>>> is perpendicular to the local vertical axis (the Z axis) and is
>>>>> coplanar with the nominal forward motion direction for the
>>>>> platform. The rotation is positive clockwise about that axis when
>>>>> seen from behind the platform looking towards it (e.g. right-hand
>>>>> side falling), and relative to the ?at rest? rotation of the
>>>>> platform with respect to the X axis. Platform is a structure or
>>>>> vehicle that serves as a base for mounting sensors. Platforms
>>>>> include, but are not limited to, satellites, aeroplanes, ships,
>>>>> buoys, ground stations, and masts.
>>>>>
>>>>> **
>>>>>
>>>>> *
>>>>> *
>>>>>
>>>>> platform_pitch: Pitch is a rotation about an axis (the Y axis)
>>>>> that is perpendicular to both the local vertical axis (the Z axis)
>>>>> and the nominal forward motion direction for the platform. The
>>>>> rotation is positive clockwise about that axis when seen from the
>>>>> left of the platform looking towards it (e.g. front end rising),
>>>>> and relative to the ?at rest? rotation of the platform with
>>>>> respect to the Y axis. Platform is a structure or vehicle that
>>>>> serves as a base for mounting sensors. Platforms include, but are
>>>>> not limited to, satellites, aeroplanes, ships, buoys, ground
>>>>> stations, and masts.
>>>>>
>>>>> **
>>>>>
>>>>> *
>>>>> *
>>>>>
>>>>> platform_yaw: Yaw is a rotation about the local vertical axis (the
>>>>> Z axis). The rotation is positive clockwise about that axis when
>>>>> seen from above the platform looking towards it (e.g. front end
>>>>> turning to the right), and relative to the ?at rest? rotation of
>>>>> the platform with respect to the Z axis. Platform is a structure
>>>>> or vehicle that serves as a base for mounting sensors. Platforms
>>>>> include, but are not limited to, satellites, aeroplanes, ships,
>>>>> buoys, ground stations, and masts.
>>>>>
>>>>> **
>>>>>
>>>>> *
>>>>> *
>>>>>
>>>>> platform_surge: Surge is a displacement along an axis (the X axis)
>>>>> that is perpendicular to the local vertical axis (the Z axis) and
>>>>> is coplanar with the nominal forward motion direction for the
>>>>> platform. The displacement is positive for motion of the platform
>>>>> in the nominal forward motion direction (e.g. forward motion), and
>>>>> relative to the ?at rest? position of the platform with respect to
>>>>> the X axis. The ?at rest? position of the platform may change over
>>>>> time. Platform is a structure or vehicle that serves as a base for
>>>>> mounting sensors. Platforms include, but are not limited to,
>>>>> satellites, aeroplanes, ships, buoys, ground stations, and masts.
>>>>>
>>>>> **
>>>>>
>>>>> *
>>>>> *
>>>>>
>>>>> platform_sway: Sway is a displacement along an axis (the Y axis)
>>>>> that is perpendicular to both the local vertical axis (the Z axis)
>>>>> and the nominal forward motion direction for the platform. The
>>>>> displacement is positive for motion of the platform to the right
>>>>> of the nominal forward motion direction when seen from behind the
>>>>> platform looking towards it (e.g. rightward motion), and relative
>>>>> to the ?at rest? position of the platform with respect to the Y
>>>>> axis. The ?at rest? position of the platform may change over time.
>>>>> Platform is a structure or vehicle that serves as a base for
>>>>> mounting sensors. Platforms include, but are not limited to,
>>>>> satellites, aeroplanes, ships, buoys, ground stations, and masts.
>>>>>
>>>>> **
>>>>>
>>>>> *
>>>>> *
>>>>>
>>>>> platform_heave: Heave is a displacement along the local vertical
>>>>> axis (the Z axis). The displacement is positive for upward motion
>>>>> of the platform, and relative to the ?at rest? position of the
>>>>> platform with respect to the Z axis. The ?at rest? position of the
>>>>> platform may change over time. Platform is a structure or vehicle
>>>>> that serves as a base for mounting sensors. Platforms include, but
>>>>> are not limited to, satellites, aeroplanes, ships, buoys, ground
>>>>> stations, and masts.
>>>>>
>>>>> **
>>>>>
>>>>> *
>>>>> *
>>>>>
>>>>> platform_course: Course is the clockwise angle with respect to
>>>>> North of the nominal forward motion direction of the platform.
>>>>> Platform is a structure or vehicle that serves as a base for
>>>>> mounting sensors. Platforms include, but are not limited to,
>>>>> satellites, aeroplanes, ships, buoys, ground stations, and masts.
>>>>>
>>>>> **
>>>>>
>>>>> *
>>>>> *
>>>>>
>>>>> platform_orientation: Orientation is the clockwise angle with
>>>>> respect to North of the longitudinal (front-to-back) axis of the
>>>>> platform, which may be different than the platform course (see
>>>>> platform_course).*Platforms include, but are not limited to,
>>>>> satellites, aeroplanes, ships, buoys, ground stations, and masts.*
>>>>>
>>>>> *
>>>>> Grace and peace,
>>>>>
>>>>> Jim
>>>>>
>>>>> On 7/31/18 3:29 AM, Lowry, Roy K. wrote:
>>>>>>
>>>>>> On second thoughts removing the underscores is more elegant
>>>>>> correction than adding 'platform'.
>>>>>>
>>>>>>
>>>>>> Cheers, Roy.
>>>>>>
>>>>>>
>>>>>> I have now retired 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 Lowry, Roy
>>>>>> K. <rkl at bodc.ac.uk> <mailto:rkl at bodc.ac.uk>
>>>>>> *Sent:* 30 July 2018 18:49
>>>>>> *To:* Kenneth Kehoe
>>>>>> *Cc:* CF Metadata List
>>>>>> *Subject:* Re: [CF-metadata] Platform Heave
>>>>>>
>>>>>> Hi Ken,
>>>>>>
>>>>>>
>>>>>> You're absolutely right - should have been platform_yaw_angle.
>>>>>> Getting the detail spot on in these things isn't easy, which is
>>>>>> why we have discussion lists!
>>>>>>
>>>>>>
>>>>>> With the way I'm currently seeing things?I don't agree that pitch
>>>>>> and roll affect the definition of heave. They are only factors
>>>>>> that come into account with the coupling of heave into the next
>>>>>> level of the CRS hierarchy.
>>>>>>
>>>>>>
>>>>>> Cheers, Roy.
>>>>>>
>>>>>>
>>>>>> I have now retired 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 Kenneth
>>>>>> Kehoe <kkehoe at ou.edu> <mailto:kkehoe at ou.edu>
>>>>>> *Sent:* 30 July 2018 18:39
>>>>>> *Cc:* CF Metadata List
>>>>>> *Subject:* Re: [CF-metadata] Platform Heave
>>>>>> I agree with John the (keel to top of mast) statement is
>>>>>> incorrect when the platform is tilted. I only inserted that to
>>>>>> help describe the Z-axis. But I don't think it's helping. I think
>>>>>> John is also right on point with this since I can't find a
>>>>>> definition of heave that discusses the orientation of the
>>>>>> platform and how it relates to the measurement of heave. That is
>>>>>> why I'm suggesting we not try to tackle that issue. From an
>>>>>> instrument perspective I don't think the organization writing the
>>>>>> measurement to file actually know all the details of how the
>>>>>> values are derived or the full reference frame. I tell people to
>>>>>> not use the standard_name definitions unless they are positive it
>>>>>> matches exactly, and without all the information I don't think
>>>>>> people will be able to use a too specific definition. A less
>>>>>> specific definition would allow the use now, and a more specific
>>>>>> definition can be added later if needed.
>>>>>>
>>>>>> I did like Roy's definition of platform_yaw_angle and
>>>>>> platform_yaw_rate. My only suggestion is to remove the underscore
>>>>>> in "yaw_angle" in the definition of platform_yaw_rate, or use the
>>>>>> full term "platform_yaw_angle". Otherwise it appears like a
>>>>>> reference to a different term.
>>>>>>
>>>>>> Ken
>>>>>>
>>>>>>
>>>>>>
>>>>>> On 2018-7-30 10:52, John Graybeal wrote:
>>>>>>> 1) Now that we have another platform_heave comment, could we
>>>>>>> please create a new thread for the discussion on
>>>>>>> pitch/roll/heading? ?Maybe starting without all the historical
>>>>>>> points, at least the heave-related ones? Both are difficult
>>>>>>> conversations to follow in sequence.
>>>>>>>
>>>>>>> 2) I have a concern about the last two heave definitions.
>>>>>>> ? a) "Heave is the linear motion along the vertical Z-axis (e.g.
>>>>>>> keel to top of mast) with positive values representing upward
>>>>>>> motion.?
>>>>>>>
>>>>>>> I like the thrust of this definition, it?s simple to understand.
>>>>>>> However I don?t think it?s measured in the direction of keel to
>>>>>>> top of mast of the current or recent vessel position, is it? I
>>>>>>> rather assume it is perpendicular to a nominally level service,
>>>>>>> possibly in the direction of the gravity vector. The dictionary
>>>>>>> definition "Heaving is the linear motion along the vertical
>>>>>>> Z-axis? with the positive values coda seems closer.
>>>>>>>
>>>>>>> ? b) "upwards vertical displacement of a platform over a
>>>>>>> measurement time interval?
>>>>>>>
>>>>>>> I can?t tell how to parse ?over? here. ?An upwards vertical
>>>>>>> displacement is relative to another position, and in this case I
>>>>>>> think that ?original? position is being measured (at least
>>>>>>> conceptually) during another time interval. It just needs a few
>>>>>>> words, something like ?of a platform when compared to its
>>>>>>> average vertical position over a corresponding time interface?.
>>>>>>>
>>>>>>> But I guess the fundamental issue is I can?t tell (and don?t
>>>>>>> actually know) what heave is determined with respect to. If my
>>>>>>> last 11 positions relative to average seas are 0, 1, 2, 2, 1, 4,
>>>>>>> 1, 2, 2, 1, 0 (think hilly!), I have no idea if the heave at the
>>>>>>> peak (?4?) is 4 or something else ? it just depends on when and
>>>>>>> how long the baseline measurement is, doesn?t it? ?(Or to put it
>>>>>>> another way, is the heave at the 7th point a negative number,
>>>>>>> since the ship just went down 3 units?) ?If someone can answer
>>>>>>> that then our best definition might be more obvious.
>>>>>>>
>>>>>>> John
>>>>>>>
>>>>>>> ---------------------------------------
>>>>>>> John Graybeal
>>>>>>> jbgraybeal at mindspring.com <mailto:jbgraybeal at mindspring.com>
>>>>>>>
>>>>>>>> On Jul 29, 2018, at 04:29, Lowry, Roy K. <rkl at bodc.ac.uk
>>>>>>>> <mailto:rkl at bodc.ac.uk>> wrote:
>>>>>>>>
>>>>>>>> Dear All,
>>>>>>>>
>>>>>>>> Giving it some thought over the weekend I realise that where we
>>>>>>>> lost the plot in this discussion was when we encountered
>>>>>>>> 'direction of travel'. Jim succinctly described platform motion
>>>>>>>> with the phrase 'nested co-ordinate systems'. What I failed to
>>>>>>>> realise - and I'm guessing I'm not alone - is that the pitch,
>>>>>>>> roll, heave etc. family of terms for platform motion refer
>>>>>>>> SOLELY to the innermost co-ordinate reference in that nest and
>>>>>>>> that the 'zero' for these measurements is 'platform at rest'.
>>>>>>>> This innermost co-ordinate reference comprises three orthogonal
>>>>>>>> axes that intersect at the platform's centre of gravity. Two of
>>>>>>>> these are horizontal (Ken's longitudinal X-axis and transverse
>>>>>>>> Y-axis) and the third vertical (Ken's vertical Z-axis). Others
>>>>>>>> make?no attempt to treat these parameters in the same way as
>>>>>>>> zenith, and I now realise?CF shouldn't be any different.
>>>>>>>>
>>>>>>>> Having come to terms with this, Ken's definition elements hve a
>>>>>>>> beautiful simplicity that?can be slotted into Alison's compound
>>>>>>>> definitions. My only problem is the inclusion of nautical terms
>>>>>>>> like 'bow' and 'stern', but these can easily be replaced by
>>>>>>>> generic equivalents such as 'front' and 'back'. I would also
>>>>>>>> make it clearer is that zero is platform at rest.
>>>>>>>>
>>>>>>>> For example the definition pair for yaw become:
>>>>>>>>
>>>>>>>> platform_yaw_angle
>>>>>>>> "yaw _angle"?is the amount of rotation from the rest
>>>>>>>> position?around the vertical Z-axis with positive values
>>>>>>>> resulting in clockwise motion?when viewed from above.?The
>>>>>>>> vertical?Z axis, also known as the "yaw axis", is an imaginary
>>>>>>>> line running vertically through the platform's?centre of
>>>>>>>> gravity. Standard names for "platform" describe the motion and
>>>>>>>> orientation of the vehicle from which observations are made.
>>>>>>>> Platforms include, but are not limited to, satellites,
>>>>>>>> aeroplanes, ships, instruments and buoys.
>>>>>>>>
>>>>>>>> platform_yaw_rate
>>>>>>>> "platform_yaw_rate" is the change per unit time of "yaw_angle".
>>>>>>>> "yaw _angle"?is?the amount of rotation from the rest
>>>>>>>> position?around the vertical Z-axis with positive values
>>>>>>>> resulting in clockwise motion?when viewed from above.?The
>>>>>>>> vertical Z axis, also known as the "yaw axis", is an imaginary
>>>>>>>> line running vertically through the platform's centre of
>>>>>>>> gravity. Standard names for "platform" describe the motion and
>>>>>>>> orientation of the vehicle from which observations are made.
>>>>>>>> Platforms include, but are not limited to, satellites,
>>>>>>>> aeroplanes, ships, instruments and buoys.
>>>>>>>>
>>>>>>>> How does that work for people?
>>>>>>>>
>>>>>>>> Cheers, Roy.
>>>>>>>>
>>>>>>>> I have now retired 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 Kenneth
>>>>>>>> Kehoe <kkehoe at ou.edu <mailto:kkehoe at ou.edu>>
>>>>>>>> *Sent:*27 July 2018 16:49
>>>>>>>> *To:*cf-metadata at cgd.ucar.edu <mailto:cf-metadata at cgd.ucar.edu>
>>>>>>>> *Subject:*Re: [CF-metadata] Platform Heave
>>>>>>>> All,
>>>>>>>>
>>>>>>>> Sorry for joining this conversation late. This is an important
>>>>>>>> discussion for my group and finding a resolution would be very
>>>>>>>> helpful. For my purposes I only need a good definition, which
>>>>>>>> might coincide with the nautical definitions. For examplethis
>>>>>>>> reference
>>>>>>>> <https://urldefense.proofpoint.com/v2/url?u=https-3A__www.wartsila.com_encyclopedia_term_ship-2Dmotions&d=DwMFaQ&c=qKdtBuuu6dQK9MsRUVJ2DPXW6oayO8fu4TfEHS8sGNk&r=Vm7o2ZGxPkkqRuPs8nVMVQ&m=J2x5E3dUpn954rPN8-v-TFQOZiyobvfd2MaoRgJ8_Zg&s=GnqNqW163_p5PcNhTjRgd0qwnu6cR6JuDeQvE2qaBGQ&e=>would
>>>>>>>> suffice for most of my needs except for the missing definition
>>>>>>>> of positive direction. I've asked about defining a positive
>>>>>>>> direction in the past using the "positive" attribute and it was
>>>>>>>> decided to not expand that attribute. If we can define the
>>>>>>>> positive direction in all the platform standard names that
>>>>>>>> would be great, but it should be universally existent for all
>>>>>>>> current and future platform definitions.
>>>>>>>>
>>>>>>>> I would prefer to not get into the details of how a value is
>>>>>>>> derived in the definition as that is more of the cell_methods
>>>>>>>> domain. Also I find that confusing as heave on an ocean going
>>>>>>>> ship is not always measured as the difference between two GPS
>>>>>>>> points but could be an integration of a speed or acceleration.
>>>>>>>> This would result in two different measurements that depend on
>>>>>>>> the method, but both are correct.
>>>>>>>>
>>>>>>>> I next attempted to come up with some definitions but I ended
>>>>>>>> up going down a wormhole of different reference frames only to
>>>>>>>> realize in the end my definitions will never match with the
>>>>>>>> values from the vendor supplied data values because my
>>>>>>>> definitions were becoming too specific. I can't find a
>>>>>>>> definition of heave that takes into account tides, large waves
>>>>>>>> (water or atmospheric), or orientation of the platform. They
>>>>>>>> all seem to be relative to the platform position some x time
>>>>>>>> ago. So here is my attempt at the definitions:
>>>>>>>>
>>>>>>>> platform_heave =? Heave is the linear motion along the vertical
>>>>>>>> Z-axis (e.g. keel to top of mast) with positive values
>>>>>>>> representing upward motion.
>>>>>>>>
>>>>>>>> platform_sway = Sway is the motion along the transverse Y-axis
>>>>>>>> (e.g. port to starboard) with positive values towards the
>>>>>>>> right-hand side the platform (starboard) when oriented towards
>>>>>>>> leading edge of the platform.
>>>>>>>>
>>>>>>>> platform_surge = Surge is the motion along the longitudinal
>>>>>>>> X-axis (e.g. stern to bow) with positive values indicating
>>>>>>>> motion towards the leading edge of the platform (bow).
>>>>>>>>
>>>>>>>> platform_roll_angle = Roll is a rotation around a longitudinal
>>>>>>>> X-axis with positive values resulting in counter clockwise
>>>>>>>> motion (e.g. right-hand side rising) when oriented towards
>>>>>>>> leading edge of the platform.
>>>>>>>>
>>>>>>>> platform_pitch_angle = Pitch is a rotation around the
>>>>>>>> transverse Y-axis with positive values resulting in counter
>>>>>>>> clockwise motion (e.g. leading edge of the platform rising).
>>>>>>>>
>>>>>>>> platform_yaw_angle = Yaw is a rotation around the vertical
>>>>>>>> Z-axis with positive values resulting in clockwise motion of
>>>>>>>> the forward section (bow) when viewed from above.
>>>>>>>>
>>>>>>>> platform_roll_rate = Roll rate is rotation change per unit time
>>>>>>>> around a longitudinal X-axis with positive values resulting in
>>>>>>>> counter clockwise motion (e.g. right-hand side rising) when
>>>>>>>> oriented towards leading edge of the platform.
>>>>>>>>
>>>>>>>> platform_pitch_rate = Pitch rate is rotation change per unit
>>>>>>>> time around the transverse Y-axis with positive values
>>>>>>>> resulting in counter clockwise motion (e.g. leading edge of the
>>>>>>>> platform rising).
>>>>>>>>
>>>>>>>> platform_yaw_rate = Yaw rate is rotation change per unit time
>>>>>>>> around the vertical Z-axis with positive values resulting in
>>>>>>>> clockwise motion of the forward section (bow) when viewed from
>>>>>>>> above.
>>>>>>>>
>>>>>>>> I know these differ from the current definitions, but I'm not
>>>>>>>> completely understanding how the definitions are created. Is
>>>>>>>> platform_orientation always prepended? Is a rate always defined
>>>>>>>> with the same as the angle definition but with a final sentence
>>>>>>>> explaining it's actually a rate?
>>>>>>>>
>>>>>>>> Thanks,
>>>>>>>>
>>>>>>>> Ken
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> On 2018-7-25 09:50, Jim Biard wrote:
>>>>>>>>> Alison,
>>>>>>>>> It's a lovely nested reference frames problem, isn't it? Roll,
>>>>>>>>> pitch, and yaw are usually defined relative to a center of
>>>>>>>>> motion (CM) reference frame defined using the (mean) direction
>>>>>>>>> of motion and the up direction. In my (satellite-based)
>>>>>>>>> experience, the Y axis unit vector is defined by the
>>>>>>>>> normalized cross-product of the up unit vector with the
>>>>>>>>> direction of motion unit vector (Z x X). The X axis unit
>>>>>>>>> vector is then defined by the cross-product of the Y unit
>>>>>>>>> vector and the up unit vector (Y x Z). This means of forming
>>>>>>>>> the CM reference frame decouples orientation from motion. The
>>>>>>>>> X axis is not necessarily identical to the direction of
>>>>>>>>> motion. The vehicle reference frame may have fixed offsets in
>>>>>>>>> x, y, z, roll, pitch, and yaw relative to the CM reference
>>>>>>>>> frame, but in my limited experience those offsets have been zero.
>>>>>>>>> Platforms that aren't moving are an even more entertaining
>>>>>>>>> case, for sure!
>>>>>>>>> In the end, I'd tend towards referring to a CM or geospatial
>>>>>>>>> reference frame with the Z direction defined as "up" if I'm
>>>>>>>>> going to try and get detailed about it, as opposed to 'mean
>>>>>>>>> orientation'. But I only have experience with satellites (and
>>>>>>>>> a bit with airplanes).
>>>>>>>>> Grace and peace,
>>>>>>>>> Jim
>>>>>>>>>
>>>>>>>>> On 7/25/18 9:37 AM, Alison Pamment - UKRI STFC wrote:
>>>>>>>>>> Hi Roy and Jim,
>>>>>>>>>>
>>>>>>>>>> Thanks for your quick comments on the definitions. I have
>>>>>>>>>> just been looking again at the suggested text for yaw_angle:
>>>>>>>>>> 'Platform yaw angle is the angle between the platform's
>>>>>>>>>> longitudinal/X axis and the direction of travel. Zero yaw
>>>>>>>>>> angle means the longitudinal axis is aligned with the
>>>>>>>>>> direction of travel, or a reference direction if the platform
>>>>>>>>>> is stationary. The usual sign convention is that yaw angle is
>>>>>>>>>> measured positive when the front or leading edge of the
>>>>>>>>>> platform is rotated clockwise from its orientation (which has
>>>>>>>>>> the standard name platform_orientation).'
>>>>>>>>>>
>>>>>>>>>> The problem is how to describe the reference direction which
>>>>>>>>>> the angle is calculated relative to. I started out by talking
>>>>>>>>>> about 'direction of travel' and later referred to
>>>>>>>>>> 'platform_orientation'. The definition of
>>>>>>>>>> platform_orientation says 'The platform orientation is the
>>>>>>>>>> direction in which the "front" or longitudinal axis of the
>>>>>>>>>> platform is pointing (not necessarily the same as the
>>>>>>>>>> direction in which it is travelling, called
>>>>>>>>>> platform_course).' I've realised my new definition doesn't
>>>>>>>>>> really make sense if direction of travel and orientation
>>>>>>>>>> aren't the same (and clearly they can be different). Also, if
>>>>>>>>>> 'orientation' is the instantaneous direction of the
>>>>>>>>>> longitudinal axis, then presumably it includes yaw angle, so
>>>>>>>>>> it isn't the right reference for measuring yaw.
>>>>>>>>>>
>>>>>>>>>> I've revised the text as follows:
>>>>>>>>>> 'Platform yaw angle is the angle between the platform's
>>>>>>>>>> longitudinal/X axis and the platform's mean orientation (i.e.
>>>>>>>>>> its orientation not including high frequency variations due
>>>>>>>>>> to swaying and rocking motions, for example, ship motions
>>>>>>>>>> caused by the passing of sea surface waves). Zero yaw angle
>>>>>>>>>> means the longitudinal axis is aligned with the mean
>>>>>>>>>> orientation. The usual sign convention is that yaw angle is
>>>>>>>>>> measured positive when the front or leading edge of the
>>>>>>>>>> platform is rotated clockwise from its mean orientation
>>>>>>>>>> (which has the standard name platform_orientation).
>>>>>>>>>>
>>>>>>>>>> Does it sound okay to refer to a 'mean orientation' in this
>>>>>>>>>> way? I'm having trouble thinking of a better wording!
>>>>>>>>>>
>>>>>>>>>> Best wishes,
>>>>>>>>>> Alison
>>>>>>>>>>
>>>>>>>>>> ------
>>>>>>>>>> Alison Pamment Tel: +44 1235 778065
>>>>>>>>>> NCAS/Centre for Environmental Data Archival
>>>>>>>>>> Email:alison.pamment at stfc.ac.uk
>>>>>>>>>> <mailto:alison.pamment at stfc.ac.uk>
>>>>>>>>>> STFC Rutherford Appleton Laboratory
>>>>>>>>>> R25, 2.22
>>>>>>>>>> Harwell Oxford, Didcot, OX11 0QX, U.K.
>>>>>>>>>>
>>>>>>>>>> -----Original Message-----
>>>>>>>>>> From: CF-metadata<cf-metadata-bounces at cgd.ucar.edu>
>>>>>>>>>> <mailto:cf-metadata-bounces at cgd.ucar.edu> On Behalf Of Alison
>>>>>>>>>> Pamment - UKRI STFC
>>>>>>>>>> Sent: 25 July 2018 13:12
>>>>>>>>>> To: Hamilton, Steve<sj.hamilton at fugro.com>
>>>>>>>>>> <mailto:sj.hamilton at fugro.com>;cf-metadata at cgd.ucar.edu
>>>>>>>>>> <mailto:cf-metadata at cgd.ucar.edu>
>>>>>>>>>> Subject: Re: [CF-metadata] Platform Heave
>>>>>>>>>>
>>>>>>>>>> Dear Steve, Nan, et al,
>>>>>>>>>>
>>>>>>>>>> Thank you for proposing new standard names for platform_heave
>>>>>>>>>> and improved definitions for existing names for platform
>>>>>>>>>> pitch, roll and yaw. Thank you also to all those who
>>>>>>>>>> submitted comments about these names.
>>>>>>>>>>
>>>>>>>>>> Regarding Steve's proposals for new names, the discussion
>>>>>>>>>> seems to have reached consensus on the quantities themselves.
>>>>>>>>>>
>>>>>>>>>> Until now, our usual explanatory sentence for 'platform' has
>>>>>>>>>> said 'Standard names for platform describe the motion and
>>>>>>>>>> orientation of the vehicle from which observations are made
>>>>>>>>>> e.g. aeroplane, ship or satellite.' Nan has suggested
>>>>>>>>>> extending the list of possible platforms, which seems fair
>>>>>>>>>> enough, so we would now have 'Standard names for platform
>>>>>>>>>> describe the motion and orientation of the vehicle from which
>>>>>>>>>> observations are made. Platforms include, but are not limited
>>>>>>>>>> to, satellites, aeroplanes, ships, instruments, and buoys.'
>>>>>>>>>> I've added this into the definitions of Steve's names,
>>>>>>>>>> leading to:
>>>>>>>>>>
>>>>>>>>>> platform_heave (m)
>>>>>>>>>> 'Standard names for "platform" describe the motion and
>>>>>>>>>> orientation of the vehicle from which observations are made.
>>>>>>>>>> Platforms include, but are not limited to, satellites,
>>>>>>>>>> aeroplanes, ships, instruments, and buoys. "Heave" means the
>>>>>>>>>> vertical displacement of a platform (positive upwards) over a
>>>>>>>>>> measurement time interval.'
>>>>>>>>>>
>>>>>>>>>> platform_heave_rate (m s-1)
>>>>>>>>>> 'Standard names for "platform" describe the motion and
>>>>>>>>>> orientation of the vehicle from which observations are made.
>>>>>>>>>> Platforms include, but are not limited to, satellites,
>>>>>>>>>> aeroplanes, ships, instruments, and buoys "Heave" means the
>>>>>>>>>> vertical displacement of a platform (positive upwards) over a
>>>>>>>>>> measurement time interval. "Heave rate" means the rate of
>>>>>>>>>> change of vertical displacement of the platform over a
>>>>>>>>>> measurement time interval.'
>>>>>>>>>>
>>>>>>>>>> These two names are accepted for publication in the standard
>>>>>>>>>> name table and will be added in the next update, planned for
>>>>>>>>>> 6th August.
>>>>>>>>>>
>>>>>>>>>> We have six existing platform pitch, roll and yaw names:
>>>>>>>>>> platform_pitch_angle (degree)
>>>>>>>>>> platform_pitch_rate (degree s-1)
>>>>>>>>>> platform_roll_angle (degree)
>>>>>>>>>> platform_roll_rate (degree s-1)
>>>>>>>>>> platform_yaw_angle (degree)
>>>>>>>>>> platform_yaw_rate (degree s-1)
>>>>>>>>>>
>>>>>>>>>> Nan has suggested the following definitions, based
>>>>>>>>>> onhttps://en.wikipedia.org/wiki/Ship_motions
>>>>>>>>>> <https://urldefense.proofpoint.com/v2/url?u=https-3A__en.wikipedia.org_wiki_Ship-5Fmotions&d=DwMDaQ&c=qKdtBuuu6dQK9MsRUVJ2DPXW6oayO8fu4TfEHS8sGNk&r=Vm7o2ZGxPkkqRuPs8nVMVQ&m=fsDk1eg5rM-so0h_XCTK_Pl1w5MGnQK88vuvHcbhUUI&s=gxXkUfvVSqtWNEzxwyAeuKgEMzADzXWv2OOZtOBRAao&e=>.
>>>>>>>>>> (A quick search of other online sources yields definitions
>>>>>>>>>> consistent with these).
>>>>>>>>>> Pitch
>>>>>>>>>> The up/down rotation of a platform about its transverse/Y
>>>>>>>>>> axis. The transverse/Y axis, lateral or pitch axis is an
>>>>>>>>>> imaginary line running horizontally across the platform and
>>>>>>>>>> through its center of gravity. A pitch? motion is an
>>>>>>>>>> up-or-down movement of the bow and stern of the platform.
>>>>>>>>>>
>>>>>>>>>> Roll
>>>>>>>>>> The tilting rotation of a platform about its longitudinal/X
>>>>>>>>>> axis. The longitudinal/X axis, or roll axis, is an imaginary
>>>>>>>>>> line running horizontally through the length of the platform,
>>>>>>>>>> through its center of gravity, and parallel to the waterline.
>>>>>>>>>> A roll motion is a side-to-side or port-starboard tilting
>>>>>>>>>> motion of the superstructure around this axis.
>>>>>>>>>>
>>>>>>>>>> Yaw
>>>>>>>>>> The turning rotation of a platform about its vertical/Z axis.
>>>>>>>>>> The vertical/Z axis, or yaw axis, is an imaginary line
>>>>>>>>>> running vertically through the platform and through its
>>>>>>>>>> center of gravity. A yaw motion is a side-to side movement of
>>>>>>>>>> the bow and stern of the ship.
>>>>>>>>>>
>>>>>>>>>> These are useful and concise definitions. I suggest that we
>>>>>>>>>> don't refer anywhere to 'ship', 'bow' or 'stern', since we
>>>>>>>>>> want the definitions to apply to all possible platforms. I'm
>>>>>>>>>> thinking also that 'port' and 'starboard' may apply to ships
>>>>>>>>>> and aeroplanes, but perhaps not to a satellite, so are
>>>>>>>>>> probably best avoided. Similarly, 'waterline' only applies to
>>>>>>>>>> maritime platforms. I suggest the following amendments to
>>>>>>>>>> make the definitions as generic as possible:
>>>>>>>>>>
>>>>>>>>>> Pitch
>>>>>>>>>> "Pitch" means rotation of the platform in the vertical plane
>>>>>>>>>> about its transverse/Y axis. The transverse/Y axis, also
>>>>>>>>>> known as the "lateral axis" or "pitch axis", is an imaginary
>>>>>>>>>> line running horizontally across the platform and through its
>>>>>>>>>> center of gravity. In pitch motion, the leading edge of the
>>>>>>>>>> platform moves vertically upwards while the rear moves
>>>>>>>>>> vertically downwards, and vice versa.
>>>>>>>>>>
>>>>>>>>>> Roll
>>>>>>>>>> "Roll" means rotation of the platform in the vertical plane
>>>>>>>>>> about its longitudinal/X axis. The longitudinal/X axis, also
>>>>>>>>>> known as the "roll axis", is an imaginary line running
>>>>>>>>>> horizontally through the length of the platform and through
>>>>>>>>>> its center of gravity. In roll motion, the platform tilts
>>>>>>>>>> such that one side moves vertically upwards while the other
>>>>>>>>>> moves vertically downwards, and vice versa.
>>>>>>>>>>
>>>>>>>>>> Yaw
>>>>>>>>>> "Yaw" means rotation of the platform in the horizontal plane
>>>>>>>>>> about its vertical/Z axis. The vertical/Z axis, also known as
>>>>>>>>>> the "yaw axis", is an imaginary line running vertically
>>>>>>>>>> through the platform and through its center of gravity. In
>>>>>>>>>> yaw motion, the platform rotates clockwise or counter
>>>>>>>>>> clockwise in the horizontal, relative to its orientation,
>>>>>>>>>> which has the standard name platform_orientation.
>>>>>>>>>>
>>>>>>>>>> Are these okay?
>>>>>>>>>>
>>>>>>>>>> For names such as platform_view_angle and
>>>>>>>>>> platform_zenith_angle we also describe how the angle itself
>>>>>>>>>> is measured. We should do the same for pitch, roll and yaw
>>>>>>>>>> angles while we are in the process of updating the
>>>>>>>>>> definitions. I have come up with the following:
>>>>>>>>>>
>>>>>>>>>> Pitch angle
>>>>>>>>>> Platform pitch angle is the angle between the local
>>>>>>>>>> horizontal and the platform's longitudinal/X axis. Zero pitch
>>>>>>>>>> angle means the longitudinal axis is horizontal. The usual
>>>>>>>>>> sign convention is that pitch angle is measured positive when
>>>>>>>>>> the front or leading edge of the platform is elevated above
>>>>>>>>>> the horizontal, negative when it is below the horizontal.
>>>>>>>>>>
>>>>>>>>>> Roll angle
>>>>>>>>>> Platform roll angle is the angle between the local horizontal
>>>>>>>>>> and the platform's lateral/Y axis. Zero roll angle means the
>>>>>>>>>> lateral axis is horizontal. The usual sign convention is that
>>>>>>>>>> roll angle is measured positive when the right hand edge of
>>>>>>>>>> the platform (when viewing towards the orientation direction
>>>>>>>>>> or "front" of the platform) is elevated above the horizontal,
>>>>>>>>>> negative when it is below the horizontal.
>>>>>>>>>>
>>>>>>>>>> Yaw angle
>>>>>>>>>> Platform yaw angle is the angle between the platform's
>>>>>>>>>> longitudinal/X axis and the direction of travel. Zero yaw
>>>>>>>>>> angle means the longitudinal axis is aligned with the
>>>>>>>>>> direction of travel, or a reference direction if the platform
>>>>>>>>>> is stationary. The usual sign convention is that yaw angle is
>>>>>>>>>> measured positive when the front or leading edge of the
>>>>>>>>>> platform is rotated clockwise from its orientation (which has
>>>>>>>>>> the standard name platform_orientation).
>>>>>>>>>>
>>>>>>>>>> Just so we can see a couple of examples of pulling all this
>>>>>>>>>> together, I've written out the full revised definitions of
>>>>>>>>>> platform platform_pitch_angle and platform_pitch_rate below.
>>>>>>>>>>
>>>>>>>>>> platform_pitch_angle (degree)
>>>>>>>>>> 'Standard names for "platform" describe the motion and
>>>>>>>>>> orientation of the vehicle from which observations are made.
>>>>>>>>>> Platforms include, but are not limited to, satellites,
>>>>>>>>>> aeroplanes, ships, instruments and buoys. "Pitch" means
>>>>>>>>>> rotation of the platform in the vertical plane about its
>>>>>>>>>> transverse/Y axis. The transverse/Y axis, also known as the
>>>>>>>>>> "lateral axis" or "pitch axis", is an imaginary line running
>>>>>>>>>> horizontally across the platform and through its center of
>>>>>>>>>> gravity. In pitch motion, the leading edge of the platform
>>>>>>>>>> moves vertically upwards while the rear moves vertically
>>>>>>>>>> downwards, and vice versa. Platform pitch angle is the angle
>>>>>>>>>> between the local horizontal and the platform's
>>>>>>>>>> longitudinal/X axis. Zero pitch angle means the longitudinal
>>>>>>>>>> axis is horizontal. The usual sign convention is that pitch
>>>>>>>>>> angle is measured positive when the front or leading edge of
>>>>>>>>>> the platform is elevated above the horizontal, negative when
>>>>>>>>>> it is below the horizontal.'
>>>>>>>>>>
>>>>>>>>>> platform_pitch_rate (degree s-1)
>>>>>>>>>> 'Standard names for "platform" describe the motion and
>>>>>>>>>> orientation of the vehicle from which observations are made.
>>>>>>>>>> Platforms include, but are not limited to, satellites,
>>>>>>>>>> aeroplanes, ships, instruments and buoys. "Pitch" means
>>>>>>>>>> rotation of the platform in the vertical plane about its
>>>>>>>>>> transverse/Y axis. The transverse/Y axis, also known as the
>>>>>>>>>> "lateral axis" or "pitch axis", is an imaginary line running
>>>>>>>>>> horizontally across the platform and through its center of
>>>>>>>>>> gravity. In pitch motion, the leading edge of the platform
>>>>>>>>>> moves vertically upwards while the rear moves vertically
>>>>>>>>>> downwards, and vice versa. The quantity with standard name
>>>>>>>>>> platform_pitch_rate is the change per unit time in the
>>>>>>>>>> quantity with standard name platform_pitch_angle.'
>>>>>>>>>>
>>>>>>>>>> The roll and yaw definitions would be constructed similarly.
>>>>>>>>>>
>>>>>>>>>> The pitch/roll/yaw names are still under discussion. I'd
>>>>>>>>>> welcome further comments on these.
>>>>>>>>>>
>>>>>>>>>> Best wishes,
>>>>>>>>>> Alison
>>>>>>>>>>
>>>>>>>>>> ------
>>>>>>>>>> Alison Pamment Tel: +44 1235 778065
>>>>>>>>>> NCAS/Centre for Environmental Data Archival
>>>>>>>>>> Email:alison.pamment at stfc.ac.uk
>>>>>>>>>> <mailto:alison.pamment at stfc.ac.uk>
>>>>>>>>>> STFC Rutherford Appleton Laboratory
>>>>>>>>>> R25, 2.22
>>>>>>>>>> Harwell Oxford, Didcot, OX11 0QX, U.K.
>>>>>>>>>>
>>>>>>>>>> -----Original Message-----
>>>>>>>>>> From: CF-metadata<cf-metadata-bounces at cgd.ucar.edu>
>>>>>>>>>> <mailto:cf-metadata-bounces at cgd.ucar.edu> On Behalf Of
>>>>>>>>>> Hamilton, Steve
>>>>>>>>>> Sent: 11 July 2018 10:52
>>>>>>>>>> To:cf-metadata at cgd.ucar.edu <mailto:cf-metadata at cgd.ucar.edu>
>>>>>>>>>> Subject: Re: [CF-metadata] Platform Heave
>>>>>>>>>>
>>>>>>>>>> Hi Nan,
>>>>>>>>>>
>>>>>>>>>> I agree expanding on the existing standard name descriptions
>>>>>>>>>> does make sense and standardising for _rate and _angle
>>>>>>>>>>
>>>>>>>>>> What you suggest below seems acceptable
>>>>>>>>>>
>>>>>>>>>> Thanks
>>>>>>>>>>
>>>>>>>>>> Steve
>>>>>>>>>>
>>>>>>>>>> -----Original Message-----
>>>>>>>>>> From: CF-metadata<cf-metadata-bounces at cgd.ucar.edu>
>>>>>>>>>> <mailto:cf-metadata-bounces at cgd.ucar.edu> On Behalf Of Nan
>>>>>>>>>> Galbraith
>>>>>>>>>> Sent: 10 July 2018 17:39
>>>>>>>>>> To:cf-metadata at cgd.ucar.edu <mailto:cf-metadata at cgd.ucar.edu>
>>>>>>>>>> Subject: Re: [CF-metadata] Platform Heave
>>>>>>>>>>
>>>>>>>>>> Hi Alison, Steve, and all -
>>>>>>>>>>
>>>>>>>>>> Since we have a little time to finalize this, could we also
>>>>>>>>>> consider updating the definitions of platform_pitch_angle,
>>>>>>>>>> platform_roll_angle and platform_yaw_angle?
>>>>>>>>>>
>>>>>>>>>> Currently, these all say 'Standard names for platform
>>>>>>>>>> describe the motion and orientation of the vehicle from which
>>>>>>>>>> observations are made e.g. aeroplane, ship or satellite.'
>>>>>>>>>>
>>>>>>>>>> John Helly pointed to the helpful Wikipedia page for ship
>>>>>>>>>> motion,https://en.wikipedia.org/wiki/Ship_motions
>>>>>>>>>> <https://urldefense.proofpoint.com/v2/url?u=https-3A__en.wikipedia.org_wiki_Ship-5Fmotions&d=DwMDaQ&c=qKdtBuuu6dQK9MsRUVJ2DPXW6oayO8fu4TfEHS8sGNk&r=Vm7o2ZGxPkkqRuPs8nVMVQ&m=fsDk1eg5rM-so0h_XCTK_Pl1w5MGnQK88vuvHcbhUUI&s=gxXkUfvVSqtWNEzxwyAeuKgEMzADzXWv2OOZtOBRAao&e=>.
>>>>>>>>>> The suggestions below are merged from different sections of
>>>>>>>>>> that page, and might be a little ... long, but I'd also like
>>>>>>>>>> to append something like 'Platforms include but are not
>>>>>>>>>> limited to satellites, aeroplanes, ships, instruments, and
>>>>>>>>>> buoys.'
>>>>>>>>>>
>>>>>>>>>> Pitch
>>>>>>>>>> The up/down rotation of a platform about its transverse/Y
>>>>>>>>>> axis. The transverse/Y axis, lateral or pitch axis is an
>>>>>>>>>> imaginary line running horizontally across the platform and
>>>>>>>>>> through its center of gravity. A pitch? motion is an
>>>>>>>>>> up-or-down movement of the bow and stern of the platform.
>>>>>>>>>>
>>>>>>>>>> Roll
>>>>>>>>>> The tilting rotation of a platform about its longitudinal/X
>>>>>>>>>> axis. The longitudinal/X axis, or roll axis, is an imaginary
>>>>>>>>>> line running horizontally through the length of the platform,
>>>>>>>>>> through its center of gravity, and parallel to the waterline.
>>>>>>>>>> A roll motion is a side-to-side or port-starboard tilting
>>>>>>>>>> motion of the superstructure around this axis.
>>>>>>>>>>
>>>>>>>>>> Yaw
>>>>>>>>>> The turning rotation of a platform about its vertical/Z axis.
>>>>>>>>>> The vertical/Z axis, or yaw axis, is an imaginary line
>>>>>>>>>> running vertically through the platform and through its
>>>>>>>>>> center of gravity.
>>>>>>>>>> A yaw motion is a side-to side movement of the bow and stern
>>>>>>>>>> of the ship.
>>>>>>>>>>
>>>>>>>>>> And we had something like this for heave:
>>>>>>>>>> platform_heave (m) = upwards vertical displacement
>>>>>>>>>>
>>>>>>>>>> I suppose these could also be applied to platform_*_rates.
>>>>>>>>>>
>>>>>>>>>> Regards -
>>>>>>>>>> Nan
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> On 7/4/18 4:47 AM, Alison Pamment - UKRI STFC wrote:
>>>>>>>>>>
>>>>>>>>>>> Dear Steve,? > > Thank you for your message and apologies
>>>>>>>>>>> for not
>>>>>>>>>>> having processed
>>>>>>>>>> ? > your proposals as yet. I have been working on the CMIP
>>>>>>>>>> names, but > they are reaching a conclusion and I will
>>>>>>>>>> shortly be looking through > the many other proposals that
>>>>>>>>>> have been waiting for attention. > > A quick look through the
>>>>>>>>>> discussion of your names shows they are > pretty much agreed.
>>>>>>>>>> You need take no further action at this time - I > will check
>>>>>>>>>> that the names and definitions are clear and consistent >
>>>>>>>>>> with existing names and get back to you on the list with any
>>>>>>>>>> final > comments or questions. Version 56 of the standard
>>>>>>>>>> name table will be > published later today - I think we can
>>>>>>>>>> probably finalise your names > in time for version 57. > >
>>>>>>>>>> Best wishes, Alison
>>>>>>>>>>> ________________________________
>>>>>>>>>>> From: Hamilton, Steve<sj.hamilton at fugro.com>
>>>>>>>>>>> <mailto:sj.hamilton at fugro.com>
>>>>>>>>>>> Sent: 03 July 2018 09:12
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> Please can you advise if this standard name has now been
>>>>>>>>>>> accepted and
>>>>>>>>>>> when it will be included in the CF Standard Names
>>>>>>>>>>>
>>>>>>>>>>> If there is something else to do please let me know
>>>>>>>>>>>
>>>>>>>>>>> Thanks
>>>>>>>>>>>
>>>>>>>>>>> Steve
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> ________________________________
>>>>>>>>>>> From: Jim Biard <jbiard at cicsnc.org
>>>>>>>>>>> <mailto:jbiard at cicsnc.org><mailto:jbiard at cicsnc.org>
>>>>>>>>>>> <mailto:jbiard at cicsnc.org>>
>>>>>>>>>>> Sent: 01 June 2018 22:56
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> Nan,
>>>>>>>>>>> Thanks for pulling things back in. I very much like the idea
>>>>>>>>>>> of keeping technology or specific methods out of the
>>>>>>>>>>> definition if at all possible, so I like your proposal. I
>>>>>>>>>>> expect we should include platform in the definition, as well
>>>>>>>>>>> as an indication that this is dynamic (over time). How about
>>>>>>>>>>> these definitions?
>>>>>>>>>>> platform_heave (m) = upwards vertical displacement of a
>>>>>>>>>>> platform over
>>>>>>>>>>> a measurement time interval platform_heave_rate (m s-1) =
>>>>>>>>>>> upwards rate
>>>>>>>>>>> of change in vertical displacement of a platform over a
>>>>>>>>>>> measurement time interval They leave out some detail but
>>>>>>>>>>> capture the relative nature of the quantities.
>>>>>>>>>>> (In my mind, the primary detail being left out is the 'net
>>>>>>>>>>> zero'
>>>>>>>>>>> nature of the quantities, which gets back to defining the
>>>>>>>>>>> 'moving-mean' sea level reference point.) Grace and peace,
>>>>>>>>>>>
>>>>>>>>>>> Jim
>>>>>>>>>>> On 6/1/18 11:23 AM, Nan Galbraith wrote:
>>>>>>>>>>> Hi all -
>>>>>>>>>>>
>>>>>>>>>>> The latest version is confusing to me. The term 'a platform
>>>>>>>>>>> that is
>>>>>>>>>>> nominally at rest' does not apply to many platforms for
>>>>>>>>>>> which heave is
>>>>>>>>>>> calculated; the original version of that, 'a moving object
>>>>>>>>>>> above the
>>>>>>>>>>> vertical level of that object when stationary' was maybe a
>>>>>>>>>>> little more clear... if also a little wordy.
>>>>>>>>>>>
>>>>>>>>>>> And, the term? 'vertical displacement determined by integrating
>>>>>>>>>>> vertical accelerations' may also not apply - I've been
>>>>>>>>>>> looking at the
>>>>>>>>>>> different ways heave is calculated, and there are a few:
>>>>>>>>>>> 'Heave can be
>>>>>>>>>>> computed from GPS RTK height measurements and from vertical
>>>>>>>>>>> accelerations measured by linear accelerometers'
>>>>>>>>>>>
>>>>>>>>>>> Why? not keep it simple: platform_heave (m) = upwards vertical
>>>>>>>>>>> displacement?? Do we need to be more specific than that?
>>>>>>>>>>>
>>>>>>>>>>> Thanks - Nan
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> From: Lowry, Roy K.
>>>>>>>>>>> Sent: 30 May 2018 21:37
>>>>>>>>>>>
>>>>>>>>>>> An afterthought. Heave is conventionally positive upwards so
>>>>>>>>>>> to make this clear I would add the word 'upwards' thus:
>>>>>>>>>>>
>>>>>>>>>>> platform_heave (m) = upwards vertical displacement
>>>>>>>>>>> determined by integrating vertical accelerations of a
>>>>>>>>>>> platform that is nominally at rest.
>>>>>>>>>>>
>>>>>>>>>>> platform_heave_rate (m s-1) = upwards vertical velocity
>>>>>>>>>>> determined by integrating vertical accelerations of a
>>>>>>>>>>> platform that is nominally at rest.
>>>>>>>>>>>
>>>>>>>>>>> Cheers. Roy.
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> ----------------------------------------------------------------------
>>>>>>>>>>>
>>>>>>>>>>> --
>>>>>>>>>>>
>>>>>>>>>>> From: Lowry, Roy K. <rkl at bodc.ac.uk
>>>>>>>>>>> <mailto:rkl at bodc.ac.uk><mailto:rkl at bodc.ac.uk>
>>>>>>>>>>> <mailto:rkl at bodc.ac.uk>
>>>>>>>>>>> Sent: 30 May 2018 21:02
>>>>>>>>>>>
>>>>>>>>>>> Thanks Jim,
>>>>>>>>>>>
>>>>>>>>>>> That work for me.
>>>>>>>>>>>
>>>>>>>>>>> Cheers, Roy.
>>>>>>>>>>>
>>>>>>>>>>> ----------------------------------------------------------------------
>>>>>>>>>>>
>>>>>>>>>>> --
>>>>>>>>>>>
>>>>>>>>>>> From: Jim Biard<jbiard at cicsnc.org> <mailto:jbiard at cicsnc.org>
>>>>>>>>>>> Sent: 30 May 2018 18:39
>>>>>>>>>>>
>>>>>>>>>>> Roy,
>>>>>>>>>>>
>>>>>>>>>>> So, heave is integrated vertical acceleration? How about
>>>>>>>>>>>
>>>>>>>>>>> platform_heave (m) = vertical displacement determined by
>>>>>>>>>>> integrating vertical accelerations of a platform that is
>>>>>>>>>>> nominally at rest.
>>>>>>>>>>>
>>>>>>>>>>> platform_heave_rate (m s-1) = vertical velocity determined
>>>>>>>>>>> by integrating vertical accelerations of a platform that is
>>>>>>>>>>> nominally at rest.
>>>>>>>>>>>
>>>>>>>>>>> Jim
>>>>>>>>>>>
>>>>>>>>>>> On 5/27/18 5:38 AM, Lowry, Roy K. wrote:
>>>>>>>>>>>
>>>>>>>>>>> ????? Hi Jim,
>>>>>>>>>>>
>>>>>>>>>>> ????? Does
>>>>>>>>>>>
>>>>>>>>>>> ?????????? "Heave" is a term used to describe the vertical
>>>>>>>>>>> displacement
>>>>>>>>>>> ????????? of a moving object above the vertical level of
>>>>>>>>>>> that object
>>>>>>>>>>> ????????? when stationary.
>>>>>>>>>>>
>>>>>>>>>>> ????? help by getting rid of the semantically-loaded word
>>>>>>>>>>> 'height'?
>>>>>>>>>>> ????? If not, what would?
>>>>>>>>>>>
>>>>>>>>>>> ????? I think the confusion is because you are thinking of
>>>>>>>>>>> heave in
>>>>>>>>>>> ????? terms of position within a reference frame. To think
>>>>>>>>>>> of it as the
>>>>>>>>>>> ????? vertical displacement between a real platform and a
>>>>>>>>>>> massless
>>>>>>>>>>> ????? platform is misleading- such considerations are part
>>>>>>>>>>> of the
>>>>>>>>>>> ????? derivation of wave height from high frequency heave
>>>>>>>>>>> measurements,
>>>>>>>>>>> ????? which isn't relevant to a discussion of the raw
>>>>>>>>>>> measurement. It's
>>>>>>>>>>> ????? also worth bearing in mind that whilst the debate has
>>>>>>>>>>> focused on
>>>>>>>>>>> ????? platforms floating on the sea surface, the concept of
>>>>>>>>>>> heave could
>>>>>>>>>>> ????? in theory be applied to objects in the atmosphere.
>>>>>>>>>>>
>>>>>>>>>>> ????? In practice, heave is measured by accelerometers that
>>>>>>>>>>> are usually
>>>>>>>>>>> ????? combined with tilt sensors that give pitch, roll and
>>>>>>>>>>> yaw. Hence,
>>>>>>>>>>> ????? it is totally decoupled from any reference outside the
>>>>>>>>>>> platform.
>>>>>>>>>>>
>>>>>>>>>>> ????? To answer your last muse, to get heave from a high
>>>>>>>>>>> frequency
>>>>>>>>>>> ????? height relative to datum time series the method would
>>>>>>>>>>> need to
>>>>>>>>>>> ????? determine the height of the object when 'stationary'.
>>>>>>>>>>> In the case
>>>>>>>>>>> ????? of objects on the sea, 'stationary' is considered to
>>>>>>>>>>> be a flat
>>>>>>>>>>> ????? calm sea (i.e. no waves), which can be approximated by
>>>>>>>>>>> averaging
>>>>>>>>>>> ????? the raw time series. So, heave could be approximated by
>>>>>>>>>>> ????? differencing the raw and averaged data. However, I
>>>>>>>>>>> can't think why
>>>>>>>>>>> ????? anybody would want to do that.
>>>>>>>>>>>
>>>>>>>>>>> ????? Cheers, Roy.
>>>>>>>>>>>
>>>>>>>>>>> ----------------------------------------------------------------------
>>>>>>>>>>>
>>>>>>>>>>> --
>>>>>>>>>>>
>>>>>>>>>>> ????? From:Jim Biard<jbiard at cicsnc.org>
>>>>>>>>>>> <mailto:jbiard at cicsnc.org><mailto:jbiard at cicsnc.org>
>>>>>>>>>>> <mailto:jbiard at cicsnc.org>
>>>>>>>>>>> ????? Sent: 26 May 2018 23:18
>>>>>>>>>>>
>>>>>>>>>>> ????? My biggest concern is that the standard name
>>>>>>>>>>> definition makes it
>>>>>>>>>>> ????? clear in some fashion or other that this is a measure of
>>>>>>>>>>> ????? deviations from some lower frequency (or low-pass
>>>>>>>>>>> filtered)
>>>>>>>>>>> ????? measure of vertical position. (As are sway and surge
>>>>>>>>>>> in relation
>>>>>>>>>>> ????? to their corresponding horizontal coordinates.) As was
>>>>>>>>>>> pointed
>>>>>>>>>>> ????? out, heave is used in certain communities, so it's
>>>>>>>>>>> reasonable to
>>>>>>>>>>> ????? provide a standard name, but it seems rather imprecise
>>>>>>>>>>> as it has
>>>>>>>>>>> ????? been described so far.
>>>>>>>>>>>
>>>>>>>>>>> ????? If I have understood the explanations correctly, a
>>>>>>>>>>> time series of
>>>>>>>>>>> ????? platform height relative to a fixed datum that has
>>>>>>>>>>> sufficient
>>>>>>>>>>> ????? precision and frequency would fully represent the
>>>>>>>>>>> heave along with
>>>>>>>>>>> ????? the more slowly varying effects of tide, waves, etc.
>>>>>>>>>>> So is heave,
>>>>>>>>>>> ????? as usually used, the first-order instantaneous
>>>>>>>>>>> difference between
>>>>>>>>>>> ????? the height of an actual platform and the height of a
>>>>>>>>>>> massless
>>>>>>>>>>> ????? ideal platform that would maintain a fixed offset
>>>>>>>>>>> relative to the
>>>>>>>>>>> ????? sea surface? And, just out of curiosity, how would a
>>>>>>>>>>> time series
>>>>>>>>>>> ????? of instantaneous measures of height relative to a
>>>>>>>>>>> fixed datum be
>>>>>>>>>>> ????? separated in practice into heave and "non-heave" height?
>>>>>>>>>>>
>>>>>>>>>>> ????? Getting back on track, it seems to me that the
>>>>>>>>>>> definition ought to
>>>>>>>>>>> ????? somehow assist the reader in understanding how heave
>>>>>>>>>>> relates to
>>>>>>>>>>> ????? other measures of height.
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> ????? On Sat, May 26, 2018 at 3:11 AM, Lowry, Roy K. wrote:
>>>>>>>>>>>
>>>>>>>>>>> ????????? Dear Jim and John,
>>>>>>>>>>>
>>>>>>>>>>> ????????? Heave is indeed a height relative to a datum, that
>>>>>>>>>>> datum being
>>>>>>>>>>> ????????? the calm sea surface, which is a local short
>>>>>>>>>>> interval mean sea
>>>>>>>>>>> ????????? level that isn't linked into any global reference
>>>>>>>>>>> system.
>>>>>>>>>>> ????????? Indeed the 'datum' moves relative to the rest of
>>>>>>>>>>> the world -
>>>>>>>>>>> ????????? but not the platform - as tide rises and falls so
>>>>>>>>>>> many would
>>>>>>>>>>> ????????? prefer to call it an 'instrument zero' rather than
>>>>>>>>>>> a 'datum'.
>>>>>>>>>>>
>>>>>>>>>>> ????????? Heave is therefore a very different measurement to
>>>>>>>>>>> any sea
>>>>>>>>>>> ????????? level parameter and is the raw measurement
>>>>>>>>>>> recorded at high
>>>>>>>>>>> ????????? (Hz to kHz) frequency as a time series by floating
>>>>>>>>>>> wave
>>>>>>>>>>> ????????? instruments such as waveriders and shipborne wave
>>>>>>>>>>> recorders.
>>>>>>>>>>> ????????? It therefore cannot be sensibly described by the
>>>>>>>>>>> same or
>>>>>>>>>>> ????????? similar Standard Name as a measurement of height
>>>>>>>>>>> above a
>>>>>>>>>>> ????????? globally referenced datum like long-term mean sea
>>>>>>>>>>> level or
>>>>>>>>>>> ????????? geoid. Whilst the Standard Name could be
>>>>>>>>>>> 'platform_height_above_calm_sea_surface' or
>>>>>>>>>>> 'platform_height_above_stationary_position' I would argue that
>>>>>>>>>>> ????????? 'heave' is a term from the same domain vocabulary
>>>>>>>>>>> as 'pitch',
>>>>>>>>>>> ????????? 'roll' and 'yaw' and therefore should be used.
>>>>>>>>>>>
>>>>>>>>>>> ????????? John is right to point out that the heave
>>>>>>>>>>> measurement is
>>>>>>>>>>> ????????? affected by the nature of the platform with a
>>>>>>>>>>> 250,000 tonne
>>>>>>>>>>> ????????? supertanker moving up and down much less than a
>>>>>>>>>>> rowing boat in
>>>>>>>>>>> ????????? a given wave climate, especially a wind sea. That
>>>>>>>>>>> was what was
>>>>>>>>>>> ????????? behind the SBWR corrections based on platform
>>>>>>>>>>> dimensions set
>>>>>>>>>>> ????????? up by Laurie Draper and Tom Tucker back in the 1980s.
>>>>>>>>>>>
>>>>>>>>>>> ????????? Cheers, Roy.
>>>>>>>>>>>
>>>>>>>>>>> ----------------------------------------------------------------------
>>>>>>>>>>>
>>>>>>>>>>> --
>>>>>>>>>>>
>>>>>>>>>>> ????????? From: John Helly<hellyj at ucsd.edu>
>>>>>>>>>>> <mailto:hellyj at ucsd.edu>
>>>>>>>>>>> ????????? Sent: 26 May 2018 04:48
>>>>>>>>>>>
>>>>>>>>>>> ????????? 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
>>>>>>>>>>> <https://urldefense.proofpoint.com/v2/url?u=https-3A__en.wikipedia.org_wiki_Ship-5Fmotions&d=DwMDaQ&c=qKdtBuuu6dQK9MsRUVJ2DPXW6oayO8fu4TfEHS8sGNk&r=Vm7o2ZGxPkkqRuPs8nVMVQ&m=fsDk1eg5rM-so0h_XCTK_Pl1w5MGnQK88vuvHcbhUUI&s=gxXkUfvVSqtWNEzxwyAeuKgEMzADzXWv2OOZtOBRAao&e=>
>>>>>>>>>>>
>>>>>>>>>>> ????????????? Ship motions - Wikipedia
>>>>>>>>>>> <https://en.wikipedia.org/wiki/Ship_motions>
>>>>>>>>>>> <https://urldefense.proofpoint.com/v2/url?u=https-3A__en.wikipedia.org_wiki_Ship-5Fmotions&d=DwMDaQ&c=qKdtBuuu6dQK9MsRUVJ2DPXW6oayO8fu4TfEHS8sGNk&r=Vm7o2ZGxPkkqRuPs8nVMVQ&m=fsDk1eg5rM-so0h_XCTK_Pl1w5MGnQK88vuvHcbhUUI&s=gxXkUfvVSqtWNEzxwyAeuKgEMzADzXWv2OOZtOBRAao&e=><https://en.wikipedia.org/
>>>>>>>>>>> wiki/Ship_motions>
>>>>>>>>>>> <https://urldefense.proofpoint.com/v2/url?u=https-3A__en.wikipedia.org_wiki_Ship-5Fmotions&d=DwMDaQ&c=qKdtBuuu6dQK9MsRUVJ2DPXW6oayO8fu4TfEHS8sGNk&r=Vm7o2ZGxPkkqRuPs8nVMVQ&m=fsDk1eg5rM-so0h_XCTK_Pl1w5MGnQK88vuvHcbhUUI&s=gxXkUfvVSqtWNEzxwyAeuKgEMzADzXWv2OOZtOBRAao&e=>
>>>>>>>>>>>
>>>>>>>>>>> ????????????? en.wikipedia.org
>>>>>>>>>>> <https://urldefense.proofpoint.com/v2/url?u=http-3A__en.wikipedia.org_&d=DwMFaQ&c=qKdtBuuu6dQK9MsRUVJ2DPXW6oayO8fu4TfEHS8sGNk&r=Vm7o2ZGxPkkqRuPs8nVMVQ&m=J2x5E3dUpn954rPN8-v-TFQOZiyobvfd2MaoRgJ8_Zg&s=vxsAvAgVXgUOS72MntIS3EeYgiYMynA6M4SbIbilSDk&e=>
>>>>>>>>>>> <http://en.wikipedia.org>
>>>>>>>>>>> <https://urldefense.proofpoint.com/v2/url?u=http-3A__en.wikipedia.org&d=DwMDaQ&c=qKdtBuuu6dQK9MsRUVJ2DPXW6oayO8fu4TfEHS8sGNk&r=Vm7o2ZGxPkkqRuPs8nVMVQ&m=fsDk1eg5rM-so0h_XCTK_Pl1w5MGnQK88vuvHcbhUUI&s=tpfIR7_HY7_jSNmPjinu0I6CgCY2PCb65KOJTYnwrFg&e=><http://en.wikipedia.org>
>>>>>>>>>>> <https://urldefense.proofpoint.com/v2/url?u=http-3A__en.wikipedia.org&d=DwMDaQ&c=qKdtBuuu6dQK9MsRUVJ2DPXW6oayO8fu4TfEHS8sGNk&r=Vm7o2ZGxPkkqRuPs8nVMVQ&m=fsDk1eg5rM-so0h_XCTK_Pl1w5MGnQK88vuvHcbhUUI&s=tpfIR7_HY7_jSNmPjinu0I6CgCY2PCb65KOJTYnwrFg&e=>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> ????????????? Ship motions are defined by the six degrees of
>>>>>>>>>>> freedom
>>>>>>>>>>> ????????????? that a ship, boat or any other craft can
>>>>>>>>>>> experience.
>>>>>>>>>>>
>>>>>>>>>>> ????????????? 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
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> ????????????????? On Fri, May 25, 2018 at 7:28 AM, Lowry,
>>>>>>>>>>> Roy K.
>>>>>>>>>>> ????????????????? <rkl at bodc.ac.uk
>>>>>>>>>>> <mailto:rkl at bodc.ac.uk><mailto: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.
>>>>>>>>>>>
>>>>>>>>>>> ----------------------------------------------------------------------
>>>>>>>>>>>
>>>>>>>>>>> --
>>>>>>>>>>>
>>>>>>>>>>> ????????????????????? From:? Nan
>>>>>>>>>>> Galbraith<ngalbraith at whoi.edu> <mailto:ngalbraith at whoi.edu>
>>>>>>>>>>> ????????????????????? Sent: 25 May 2018 14:46
>>>>>>>>>>>
>>>>>>>>>>> ????????????????????? 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.
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>> --
>>>>>>>>>> *******************************************************
>>>>>>>>>> * Nan Galbraith??????? Information Systems Specialist *
>>>>>>>>>> * Upper Ocean Processes Group??????????? Mail Stop 29 *
>>>>>>>>>> * Woods Hole Oceanographic Institution??????????????? *
>>>>>>>>>> * Woods Hole, MA 02543???????????????? (508) 289-2444 *
>>>>>>>>>> *******************************************************
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> _______________________________________________
>>>>>>>>>> CF-metadata mailing list
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>>>>>>>>>> http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
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>>>>>>>>>>
>>>>>>>>>> _______________________________________________
>>>>>>>>>> CF-metadata mailing list
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>>>>>>>>>> _______________________________________________
>>>>>>>>>> CF-metadata mailing list
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>>>>>>>>>
>>>>>>>>> --
>>>>>>>>> CICS-NC
>>>>>>>>> <https://urldefense.proofpoint.com/v2/url?u=http-3A__www.cicsnc.org_&d=DwMDaQ&c=qKdtBuuu6dQK9MsRUVJ2DPXW6oayO8fu4TfEHS8sGNk&r=Vm7o2ZGxPkkqRuPs8nVMVQ&m=fsDk1eg5rM-so0h_XCTK_Pl1w5MGnQK88vuvHcbhUUI&s=8lHJz6dH2XHkNWXpzlPzw9Vx2dTDwQ5Ow4uXUIZBPZU&e=>Visit
>>>>>>>>> us on
>>>>>>>>> Facebook
>>>>>>>>> <https://urldefense.proofpoint.com/v2/url?u=http-3A__www.facebook.com_cicsnc&d=DwMDaQ&c=qKdtBuuu6dQK9MsRUVJ2DPXW6oayO8fu4TfEHS8sGNk&r=Vm7o2ZGxPkkqRuPs8nVMVQ&m=fsDk1eg5rM-so0h_XCTK_Pl1w5MGnQK88vuvHcbhUUI&s=oNLIHSVmCaO1TkAm6PFzxmtZ9Wz1oyQ9pzpsG7e3obE&e=>
>>>>>>>>> ????*Jim Biard*
>>>>>>>>> *Research Scholar*
>>>>>>>>> Cooperative Institute for Climate and Satellites
>>>>>>>>> NC<https://urldefense.proofpoint.com/v2/url?u=http-3A__cicsnc.org_&d=DwMDaQ&c=qKdtBuuu6dQK9MsRUVJ2DPXW6oayO8fu4TfEHS8sGNk&r=Vm7o2ZGxPkkqRuPs8nVMVQ&m=fsDk1eg5rM-so0h_XCTK_Pl1w5MGnQK88vuvHcbhUUI&s=J44MNoS3a3tRZadexG7eUT9VHnim-C1Q38Gg053klgA&e=>
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>>>>>>>>> NOAA National Centers for Environmental
>>>>>>>>> Information<https://urldefense.proofpoint.com/v2/url?u=http-3A__ncdc.noaa.gov_&d=DwMDaQ&c=qKdtBuuu6dQK9MsRUVJ2DPXW6oayO8fu4TfEHS8sGNk&r=Vm7o2ZGxPkkqRuPs8nVMVQ&m=fsDk1eg5rM-so0h_XCTK_Pl1w5MGnQK88vuvHcbhUUI&s=F-xQ7THSSP276ClTb8arUk9hFLSJ8wJhSEKZwbfQNVM&e=>
>>>>>>>>> /formerly NOAA?s National Climatic Data Center/
>>>>>>>>> 151 Patton Ave, Asheville, NC 28801
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>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> _______________________________________________
>>>>>>>>> CF-metadata mailing list
>>>>>>>>> CF-metadata at cgd.ucar.edu <mailto:CF-metadata at cgd.ucar.edu>
>>>>>>>>> http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
>>>>>>>>> <https://urldefense.proofpoint.com/v2/url?u=http-3A__mailman.cgd.ucar.edu_mailman_listinfo_cf-2Dmetadata&d=DwMFaQ&c=qKdtBuuu6dQK9MsRUVJ2DPXW6oayO8fu4TfEHS8sGNk&r=Vm7o2ZGxPkkqRuPs8nVMVQ&m=J2x5E3dUpn954rPN8-v-TFQOZiyobvfd2MaoRgJ8_Zg&s=7WZod_Yl4Ny2ikX4Vb__7Og8ciU0cQVZe4z5EPcKMe0&e=>
>>>>>>>>
>>>>>>>> --
>>>>>>>> Kenneth E. Kehoe
>>>>>>>> ?? Research Associate - University of Oklahoma
>>>>>>>> ?? Cooperative Institute for Mesoscale Meteorological Studies
>>>>>>>> ?? ARM Climate Research Facility - Data Quality Office
>>>>>>>> e-mail:kkehoe at ou.edu <mailto:kkehoe at ou.edu> | Office:
>>>>>>>> 303-497-4754 | Cell: 405-826-0299
>>>>>>>>
>>>>>>>>
>>>>>> --
>>>>>> Kenneth E. Kehoe
>>>>
>>>
>>
>> --
>> Kenneth E. Kehoe
>> Research Associate - University of Oklahoma
>> Cooperative Institute for Mesoscale Meteorological Studies
>> ARM Climate Research Facility - Data Quality Office
>> e-mail:kkehoe at ou.edu | Office: 303-497-4754 | Cell: 405-826-0299
>>
>>
>>
>> _______________________________________________
>> CF-metadata mailing list
>> CF-metadata at cgd.ucar.edu
>> http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
>
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-- 
Kenneth E. Kehoe
   Research Associate - University of Oklahoma
   Cooperative Institute for Mesoscale Meteorological Studies
   ARM Climate Research Facility - Data Quality Office
   e-mail: kkehoe at ou.edu | Office: 303-497-4754 | Cell: 405-826-0299
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Received on Fri Aug 03 2018 - 12:56:16 BST