# [ncl-talk] Vertical motion with zonal wind

Jenny Taylor jenny63taylor91 at gmail.com
Mon Feb 26 04:33:30 MST 2018

```Hello,

I am sending you the script based on which it is made. Kindly find the
script attached below. I have one question on this matter. In the dataset (
atmos.nc) what are those variables named as 'hyam' and 'hybm'?
It is showing as 'hybrid A coefficient at layer midpoints' and 'hybrid B
coefficient at layer midpoints'.

Kindly also inform me what I am doing wrong as per your observation over NH.

Thanks,
Jenny

On Mon, Feb 26, 2018 at 12:16 PM, Barry Lynn <barry.h.lynn at gmail.com> wrote:

> Hi:
>
> What did you plot?  Is that omega or vertical velocity?  I am wondering
> why the northern hemisphere winds are not convergent with the positive
> vertical motion values like they are in the southern hemisphere.
>
> Barry
>
> On Mon, Feb 26, 2018 at 8:32 AM, Jenny Taylor <jenny63taylor91 at gmail.com>
> wrote:
>
>> 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
>>>>>>
>>>>>> _______________________________________________
>>>>>> ncl-talk mailing list
>>>>>> ncl-talk at ucar.edu
>>>>>> List instructions, subscriber options, unsubscribe:
>>>>>> http://mailman.ucar.edu/mailman/listinfo/ncl-talk
>>>>>>
>>>>>>
>>>>>
>>>>
>>>> _______________________________________________
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>>>>
>>>>
>>>
>>>
>>> --
>>> Associate Scientist,  Climate and Global Dynamics Laboratory, NCAR
>>> www.cgd.ucar.edu/staff/asphilli/   303-497-1726 <(303)%20497-1726>
>>>
>>> <http://www.cgd.ucar.edu/staff/asphilli>
>>>
>>
>>
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>>
>>
>
>
> --
> Barry H. Lynn, Ph.D
> Senior Lecturer,
> The Institute of the Earth Science,
> The Hebrew University of Jerusalem,
> Givat Ram, Jerusalem 91904, Israel
> Tel: 972 547 231 170
> Fax: (972)-25662581
>
> C.E.O, Weather It Is, LTD
> Weather and Climate Focus
> http://weather-it-is.com
> Jerusalem, Israel
> Local: 02 930 9525
> Cell: 054 7 231 170
> Int-IS: x972 2 930 9525
> US 914 432 3108
>
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