[ncl-talk] Vertical motion with zonal wind
Adam Phillips
asphilli at ucar.edu
Mon Feb 26 14:23:11 MST 2018
Hi Jenny,
With regards to whether the plot looks correct: It looks like you took
NCL's vector_5 example script, and modified it slightly. That script uses
the atmos.nc NetCDF file, which according to the global history attribute
is an old NCAR-CSM file. The data may be October averages. You're selecting
20E as the longitude to plot, but are basing your weights on 160E. All that
being said, it is honestly up to you to investigate the file you are
reading in, and to interpret the results. I am not an expert at looking at
this kind of diagnostic.
With regards to your question about hyam and hybm, that information is
given within the NetCDF file, which you can see by doing a ncdump atmos.nc.
More information on hyam/hybm can be found by entering either term within
the NCL website search engine.
If you have any further questions please respond to the ncl-talk email list.
Adam
On Mon, Feb 26, 2018 at 4:33 AM, Jenny Taylor <jenny63taylor91 at gmail.com>
wrote:
> 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:
>>
>>> 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/omeg
>>>> a_to_w.shtml
>>>>
>>>> Hope that all makes sense! If not or if you have further questions
>>>> please respond to the ncl-talk email list.
>>>> Adam
>>>>
>>>>
>>>> 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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>>>>>
>>>>>
>>>>
>>>>
>>>> --
>>>> Adam Phillips
>>>> 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 <(914)%20432-3108>
>>
>
>
--
Adam Phillips
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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