# [ncl-talk] Vertical motion with zonal wind

Jenny Taylor jenny63taylor91 at gmail.com
Sun Feb 25 23:32:49 MST 2018

```Thank you very much, Adam Phillips. I follow your instruction, please look
at my attached output figure. Kindly inform me it is in proper shape or
not. I think this time it makes some sense.

Thanks again,
Jenny

On Sat, Feb 24, 2018 at 2:14 AM, Adam Phillips <asphilli at ucar.edu> wrote:

> Hi Jenny,
> You are reading in OMEGA. Note that OMEGA has opposite signs and different
> units from the conventional W variable.
>
> For upward motion:  W is positive and OMEGA is negative
> for downward motion: W is negative and OMEGA is positive
>
> A basic, simple relationship
>    omega = -rho*grav*w              ; Pa/s
> Hence:
>    w          = -omega/(rho*grav)    ; (say) m/s
>
> Note the sign ....
> -----
> I believe all you have to do is flip the sign of your W variable:
>    W = in->OMEGA
>    W = -W
> assuming you want upward arrows for upward motion.
>
> Also note that NCL has a omega_to_w function:
> https://www.ncl.ucar.edu/Document/Functions/Contributed/omega_to_w.shtml
>
> Hope that all makes sense! If not or if you have further questions please
> respond to the ncl-talk email list.
>
>
> On Fri, Feb 23, 2018 at 1:24 AM, Jenny Taylor <jenny63taylor91 at gmail.com>
> wrote:
>
>> Mary,
>>
>> I was trying with the following attached script. But vertical motion near
>> the equator, as well as the 30S and 30N, shows rising motion in the output
>> which is not correct in real term. Please kindly look into my script and
>> figure and inform me what I am missing or doing any wrong in this.
>>
>> Data structure is below;
>>
>> Variable: t
>> Type: float
>> Total Size: 655360 bytes
>>             163840 values
>> Number of Dimensions: 4
>> Dimensions and sizes:   [time | 1] x [lev_p | 20] x [lat | 64] x [lon |
>> 128]
>> Coordinates:
>>             time: [ 791.. 791]
>>             lev_p: [950..50]
>>             lat: [-87.8638..87.8638]
>>             lon: [ 0..357.1875]
>> Number Of Attributes: 1
>>   _FillValue :  9.96921e+36
>>
>> Variable: u
>> Type: float
>> Total Size: 655360 bytes
>>             163840 values
>> Number of Dimensions: 4
>> Dimensions and sizes:   [time | 1] x [lev_p | 20] x [lat | 64] x [lon |
>> 128]
>> Coordinates:
>>             time: [ 791.. 791]
>>             lev_p: [950..50]
>>             lat: [-87.8638..87.8638]
>>             lon: [ 0..357.1875]
>> Number Of Attributes: 1
>>   _FillValue :  9.96921e+36
>>
>> Variable: v
>> Type: float
>> Total Size: 655360 bytes
>>             163840 values
>> Number of Dimensions: 4
>> Dimensions and sizes:   [time | 1] x [lev_p | 20] x [lat | 64] x [lon |
>> 128]
>> Coordinates:
>>             time: [ 791.. 791]
>>             lev_p: [950..50]
>>             lat: [-87.8638..87.8638]
>>             lon: [ 0..357.1875]
>> Number Of Attributes: 1
>>   _FillValue :  9.96921e+36
>>
>> Variable: w
>> Type: float
>> Total Size: 655360 bytes
>>             163840 values
>> Number of Dimensions: 4
>> Dimensions and sizes:   [time | 1] x [lev_p | 20] x [lat | 64] x [lon |
>> 128]
>> Coordinates:
>>             time: [ 791.. 791]
>>             lev_p: [950..50]
>>             lat: [-87.8638..87.8638]
>>             lon: [ 0..357.1875]
>> Number Of Attributes: 1
>>   _FillValue :  9.96921e+36
>>
>>
>> Thanking you,
>> Jenny
>>
>>
>> On Thu, Feb 22, 2018 at 1:17 AM, Mary Haley <haley at ucar.edu> wrote:
>>
>>> Jenny,
>>>
>>> In order to do plot overlays of different variables, you need to use the
>>> "overlay" procedure in NCL.
>>>
>>> ----------------------------------------------------------------
>>>
>>> The overlay procedure works one of two ways:
>>>
>>> [1] It overlays data from one plot (called the "overlay" plot) into the
>>> data space of another plot (called the "base" plot).
>>>
>>> The two plots must have intersecting data spaces for this to work. By
>>> "data space", I mean the range of the X and Y axes of the two plots must
>>> intersect. Otherwise, you will not see the overlay plot at all.
>>>
>>> For an example, see overlay_8.ncl at:
>>>
>>> http://www.ncl.ucar.edu/Applications/overlay.shtml#ex8
>>>
>>> [2] It simply "lines up" the two plots in the same rectangular region
>>> and draws them. It's not as common to do overlays this way, because it
>>> requires that you do all the work of making sure the two plots are in the
>>> same data space.
>>>
>>> For an example, see overlay_9.ncl at:
>>>
>>> http://www.ncl.ucar.edu/Applications/overlay.shtml#ex9
>>>
>>> ----------------------------------------------------------------
>>>
>>> It doesn't matter whether you are doing contour plots, vector plots, or
>>> XY plots: you can overlay any of these on another one using the "overlay"
>>> procedure.
>>>
>>> The "overlay" examples page has several other scripts showing how to use
>>> the overlay procedure. In particular, you might want to look at
>>> overlay_1.ncl, overlay_6.ncl, and/or wrf_gsn_5.ncl:
>>>
>>> http://www.ncl.ucar.edu/Applications/overlay.shtml
>>>
>>> If you continue to have problems, please post back to ncl-talk and
>>> include your script and a "printVarSummary" of the data you are trying to
>>> plot.
>>>
>>> Thanks,
>>>
>>> --Mary
>>>
>>>
>>> On Fri, Feb 16, 2018 at 9:59 AM, Jenny Taylor <jenny63taylor91 at gmail.com
>>> > wrote:
>>>
>>>> Dear NCL Users,
>>>>
>>>> I am trying to plot vector wind field at different pressure level for
>>>> latitute range 40N-40S. I am following the below mention script;
>>>> https://www.ncl.ucar.edu/Applications/Scripts/h_lat_7.ncl
>>>>
>>>> I am trying to overlay vertical motion (rising/sinking) in vector
>>>> arrows and zonal wind in color scheme.
>>>>
>>>> Can anyone suggest me, in that case which funtion I need to use in it?
>>>> Any help will be appriciated.
>>>>
>>>> Thanks,
>>>> Jenny
>>>>
>>>> _______________________________________________
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>>>>
>>>>
>>>
>>
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>
>
> --
> Associate Scientist,  Climate and Global Dynamics Laboratory, NCAR
> www.cgd.ucar.edu/staff/asphilli/   303-497-1726
>
> <http://www.cgd.ucar.edu/staff/asphilli>
>
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