[ncl-talk] Vertical motion with zonal wind

Jenny Taylor jenny63taylor91 at gmail.com
Thu Mar 1 00:43:24 MST 2018


Thanks a lot for sharing all these information.

Then it will be better to use GRIB format file.

Jenny

On Feb 28, 2018 21:29, "Dennis Shea" <shea at ucar.edu> wrote:

> LNSP = in->lnsp
>
> ps  = *exp*(LNSP)        ; exponent
>
> ps at long_name = "Surface Pressure"
> ps at units  = "Pa"
> copy_VarCoords(LNSP,  ps)
> delete(LNSP)
>
> printVarSummary(ps)
> printMinMax(ps, 0)
>
> ===
> As to netCDF files that explicitly have the hybrid coefficients within it,
> I am not aware .
>
> When NCL unpacks GRIB formatted files
>
>     in = f->addfile("ERAI.model.grb", "r")
>
> it *creates* 'value added' information such as the hybrid coefficients.
>
> ===
>
> NCAR's Research Data Archive
>
> https://rda.ucar.edu/
>
> Is a good source for the type of information you request.
>
> Regards
>
>
>
>
>
> On Tue, Feb 27, 2018 at 10:28 PM, Jenny Taylor <jenny63taylor91 at gmail.com>
> wrote:
>
>> Thank you, Dennis Shea. One more thing I want to know in this matter.
>>
>> The surface pressure data in the file is available in logarithomic
>> pressure form.
>>
>> In that case, can we convert this log. pressure by the following way?
>>
>> P=in->lnsp
>> PS=10^(P/2.303) ; in Pa
>>
>> The 'model level' data from ERA-interim are available for 60 levels where
>> surface pressure they are providing in ln of surface pressure form. Inside
>> this data there is no parameter like hyam,hybm that are essential for this
>> case.
>>
>> These parameters are provided in a seperate file as I mention in my
>> earliar mail.
>>
>> So, I want to know that is there any other source for data except
>> ERA-interim where all necessary parameters along with the variables will
>> come in one file according to selection of levels.
>>
>> Kindly inform me.
>>
>> Thanking you for your support.
>>
>> Jenny
>>
>> On Feb 28, 2018 08:28, "Dennis Shea" <shea at ucar.edu> wrote:
>>
>>> *** The most important rule in data processing is "look at your data".
>>> ***
>>> ------
>>>
>>> The reason that ncl-talk recommends using
>>>
>>> printVarSummary(...)
>>>
>>> and
>>>
>>> printMinMax(..., ...)
>>> ------
>>>
>>> is so that *users* can examine a variable's
>>>
>>> (a) data type
>>> (b) dimension sizes and dimension names
>>> (c) units
>>> etc
>>>
>>> You have
>>>
>>>
>>>    T = in->t                                    ; select variable to ave
>>>    W = in->w
>>>    W=-W
>>>    V = in->v
>>>    U = in->u
>>>    Q = in->q
>>>
>>>   printVarSummary(T)
>>>   printVarSummary(W)
>>>   printVarSummary(V)
>>>   printVarSummary(U)
>>>   printVarSummary(hyam)
>>>   printVarSummary(hybm)
>>>  printVarSummary(PS)
>>>
>>>
>>> then you immediately do the vertical interpolation
>>>
>>> ;---Define other arguments required by vinth2p
>>>    interp = 2
>>>    pnew   = (/1000,975,950,900,850,800,750,700,600,500,400,300,250,200,1
>>> 50,100,50/)
>>>    pnew at units = "mb"
>>>
>>> ;---Interpolate to pressure levels on pressure levels
>>>   t = vinth2p(T,hyam,hybm,pnew,PS,interp,P0mb,1,False)
>>>
>>> =========
>>> The initial
>>>
>>> printVarSummary(T)
>>>
>>> Variable: T
>>> *Type: short*
>>> Total Size: 2724120 bytes
>>>             1362060 values
>>> Number of Dimensions: 4
>>> Dimensions and sizes:   [time | 1] x [level | 60] x [latitude | 161] x
>>> [longitude | 141]
>>> Coordinates:
>>>             time: [969705..969705]
>>>             level: [   1..  60]
>>>             latitude: [40.. 0]
>>>             longitude: [65..100]
>>> Number Of Attributes: 7
>>>   standard_name :       air_temperature
>>>   long_name :   Temperature
>>>   units :       K
>>> *  add_offset :  249.3816473297584*
>>>
>>>
>>> *  scale_factor :        0.002009905912815991*
>>> Before use, you ***must***
>>>
>>>
>>> * UNPACK the variable---*
>>> Please read the documentation of the following:
>>>
>>> https://www.ncl.ucar.edu/Document/Functions/Contributed/short2flt.shtml
>>>
>>>
>>> *  T = short2flt(in->t)                                    ; select
>>> variable: unpack;  later ave*
>>>
>>> *  printVarSummary(T)*
>>>
>>>
>>> *  printMinMax(T,0)*
>>> Please look at the output.
>>>
>>> ---
>>> So, unpack each variable that is type short on the file. Thendo the
>>> vertical interpolation, etc
>>>
>>>
>>> Good Luck
>>>
>>>
>>>
>>>
>>>
>>> On Tue, Feb 27, 2018 at 5:25 AM, Jenny Taylor <jenny63taylor91 at gmail.com
>>> > wrote:
>>>
>>>> My thanks to Dennis Shea and Adam Philips for valuable advice.
>>>> I am trying to plot ERA-Interim model data at different vertical
>>>> pressure levels. I have downloaded the 'hyam' and 'hybm' for model levels
>>>> (attached below) as specified in the ERA-Interim link;
>>>>
>>>> https://rda.ucar.edu/datasets/ds627.0/docs/Eta_coordinate/index.html
>>>>
>>>> Downloaded the daily data (time step=4) for all 60 levels in
>>>> the separate file (4 GB approx). Then I merged these two files in CDO and
>>>> time mean the merged data.
>>>>
>>>> Summary of the final processed data is given below;
>>>>
>>>> Variable: PS1
>>>> Type: short
>>>> Total Size: 2724120 bytes
>>>>             1362060 values
>>>> Number of Dimensions: 4
>>>> Dimensions and sizes:   [time | 1] x [level | 60] x [latitude | 161] x
>>>> [longitude | 141]
>>>> Coordinates:
>>>>             time: [969705..969705]
>>>>             level: [   1..  60]
>>>>             latitude: [40.. 0]
>>>>             longitude: [65..100]
>>>> Number Of Attributes: 6
>>>>   long_name :   Logarithm of surface pressure
>>>>   units :       ~
>>>>   add_offset :  11.19559352539406
>>>>   scale_factor :        1.015380172027476e-05
>>>>   _FillValue :  -32767
>>>>   missing_value :       -32767
>>>>
>>>> Variable: T
>>>> Type: short
>>>> Total Size: 2724120 bytes
>>>>             1362060 values
>>>> Number of Dimensions: 4
>>>> Dimensions and sizes:   [time | 1] x [level | 60] x [latitude | 161] x
>>>> [longitude | 141]
>>>> Coordinates:
>>>>             time: [969705..969705]
>>>>             level: [   1..  60]
>>>>             latitude: [40.. 0]
>>>>             longitude: [65..100]
>>>> Number Of Attributes: 7
>>>>   standard_name :       air_temperature
>>>>   long_name :   Temperature
>>>>   units :       K
>>>>   add_offset :  249.3816473297584
>>>>   scale_factor :        0.002009905912815991
>>>>   _FillValue :  -32767
>>>>   missing_value :       -32767
>>>>
>>>> Variable: W
>>>> Type: short
>>>> Total Size: 2724120 bytes
>>>>             1362060 values
>>>> Number of Dimensions: 4
>>>> Dimensions and sizes:   [time | 1] x [level | 60] x [latitude | 161] x
>>>> [longitude | 141]
>>>> Coordinates:
>>>>             time: [969705..969705]
>>>>             level: [   1..  60]
>>>>             latitude: [40.. 0]
>>>>             longitude: [65..100]
>>>> Number Of Attributes: 7
>>>>   standard_name :       lagrangian_tendency_of_air_pressure
>>>>   long_name :   Vertical velocity
>>>>   units :       Pa s**-1
>>>>   add_offset :  -1.799464318323461
>>>>   scale_factor :        0.0001232090956517211
>>>>   _FillValue :  -32767
>>>>   missing_value :       -32767
>>>>
>>>> Variable: V
>>>> Type: short
>>>> Total Size: 2724120 bytes
>>>>             1362060 values
>>>> Number of Dimensions: 4
>>>> Dimensions and sizes:   [time | 1] x [level | 60] x [latitude | 161] x
>>>> [longitude | 141]
>>>> Coordinates:
>>>>             time: [969705..969705]
>>>>             level: [   1..  60]
>>>>             latitude: [40.. 0]
>>>>             longitude: [65..100]
>>>> Number Of Attributes: 7
>>>>   standard_name :       northward_wind
>>>>   long_name :   V component of wind
>>>>   units :       m s**-1
>>>>   add_offset :  -0.1744413644931722
>>>>   scale_factor :        0.001333290509781928
>>>>   _FillValue :  -32767
>>>>   missing_value :       -32767
>>>>
>>>> Variable: U
>>>> Type: short
>>>> Total Size: 2724120 bytes
>>>>             1362060 values
>>>> Number of Dimensions: 4
>>>> Dimensions and sizes:   [time | 1] x [level | 60] x [latitude | 161] x
>>>> [longitude | 141]
>>>> Coordinates:
>>>>             time: [969705..969705]
>>>>             level: [   1..  60]
>>>>             latitude: [40.. 0]
>>>>             longitude: [65..100]
>>>> Number Of Attributes: 7
>>>>   standard_name :       eastward_wind
>>>>   long_name :   U component of wind
>>>>   units :       m s**-1
>>>>   add_offset :  -14.17403101359716
>>>>   scale_factor :        0.002084243991189315
>>>>   _FillValue :  -32767
>>>>   missing_value :       -32767
>>>>
>>>> Variable: hyam
>>>> Type: float
>>>> Total Size: 240 bytes
>>>>             60 values
>>>> Number of Dimensions: 1
>>>> Dimensions and sizes:   [lvl | 60]
>>>> Coordinates:
>>>>             lvl: [1..60]
>>>> Number Of Attributes: 2
>>>>   long_name :   a model ave
>>>>   units :       Pa
>>>>
>>>> Variable: hybm
>>>> Type: float
>>>> Total Size: 240 bytes
>>>>             60 values
>>>> Number of Dimensions: 1
>>>> Dimensions and sizes:   [lvl | 60]
>>>> Coordinates:
>>>>             lvl: [1..60]
>>>> Number Of Attributes: 2
>>>>   long_name :   b model ave
>>>>   units :       Pa Pa**-1
>>>>
>>>> Variable: PS
>>>> Type: float
>>>> Total Size: 90804 bytes
>>>>             22701 values
>>>> Number of Dimensions: 3
>>>> Dimensions and sizes:   [1] x [161] x [141]
>>>> Coordinates:
>>>> Number Of Attributes: 1
>>>>   _FillValue :  -32767
>>>>
>>>> Variable: t
>>>> Type: float
>>>> Total Size: 1543668 bytes
>>>>             385917 values
>>>> Number of Dimensions: 4
>>>> Dimensions and sizes:   [time | 1] x [lev_p | 17] x [latitude | 161] x
>>>> [longitude | 141]
>>>> Coordinates:
>>>>             time: [969705..969705]
>>>>             lev_p: [1000..50]
>>>>             latitude: [40.. 0]
>>>>             longitude: [65..100]
>>>> Number Of Attributes: 1
>>>>   _FillValue :  -32767
>>>>
>>>> Variable: u
>>>> Type: float
>>>> Total Size: 1543668 bytes
>>>>             385917 values
>>>> Number of Dimensions: 4
>>>> Dimensions and sizes:   [time | 1] x [lev_p | 17] x [latitude | 161] x
>>>> [longitude | 141]
>>>> Coordinates:
>>>>             time: [969705..969705]
>>>>             lev_p: [1000..50]
>>>>             latitude: [40.. 0]
>>>>             longitude: [65..100]
>>>> Number Of Attributes: 1
>>>>   _FillValue :  -32767
>>>>
>>>> Variable: v
>>>> Type: float
>>>> Total Size: 1543668 bytes
>>>>             385917 values
>>>> Number of Dimensions: 4
>>>> Dimensions and sizes:   [time | 1] x [lev_p | 17] x [latitude | 161] x
>>>> [longitude | 141]
>>>> Coordinates:
>>>>             time: [969705..969705]
>>>>             lev_p: [1000..50]
>>>>             latitude: [40.. 0]
>>>>             longitude: [65..100]
>>>> Number Of Attributes: 1
>>>>   _FillValue :  -32767
>>>>
>>>> Variable: w
>>>> Type: float
>>>> Total Size: 1543668 bytes
>>>>             385917 values
>>>> Number of Dimensions: 4
>>>> Dimensions and sizes:   [time | 1] x [lev_p | 17] x [latitude | 161] x
>>>> [longitude | 141]
>>>> Coordinates:
>>>>             time: [969705..969705]
>>>>             lev_p: [1000..50]
>>>>             latitude: [40.. 0]
>>>>             longitude: [65..100]
>>>> Number Of Attributes: 1
>>>>   _FillValue :  -32767
>>>>
>>>> My output figure is attached below. Vertical motion is not shaped in
>>>> proper form. The sample data used in this plot are for August 2010. Kindly
>>>> inform me what I am doing wrong in this case.
>>>>
>>>> Thanking you,
>>>> Jenny
>>>>
>>>>
>>>> On Tue, Feb 27, 2018 at 3:46 AM, Dennis Shea <shea at ucar.edu> wrote:
>>>>
>>>>> Hybrid levels are a form of terrain following vertical coordinate
>>>>> formulation.
>>>>> Unlike isobaric levels where the vertical levels are the same at every
>>>>> grid point,
>>>>> hybrid levels differ at each grid point *(j,i) *because they are a
>>>>> function of surface pressure
>>>>> which varies with time and location. The climate atmospheric model
>>>>> uses the following
>>>>> formulation:
>>>>>
>>>>>    * p([t,] k,j,i) = a(k)*p0 + b(k)*ps([t,] k,j,i)        *; t=>time,
>>>>> k=>level, j=>latitude; i=longitude
>>>>>
>>>>> Each calculated pressure level is called the '*m*id-level' (hya*m*
>>>>> and hyb*m*).  Each
>>>>> '*m*id-level' has an upper and lower boundary called the* i*nterface
>>>>> levels (hya*i*, hyb*i*).
>>>>>
>>>>> http://www.ncl.ucar.edu/Document/Functions/Built-in/pres_hyb
>>>>> rid_ccm.shtml
>>>>>
>>>>> There are other hybrid level formulations so be aware of what is being
>>>>> used.
>>>>>
>>>>> A detailed description with some pictures is here:
>>>>>
>>>>> https://rda.ucar.edu/datasets/ds627.0/docs/Eta_coordinate/index.html
>>>>>
>>>>> ====
>>>>> You should talk with an advisor about these topics. ncl-talk is really
>>>>> for language issues.
>>>>>
>>>>> Good luck
>>>>>
>>>>> On Mon, Feb 26, 2018 at 2:23 PM, Adam Phillips <asphilli at ucar.edu>
>>>>> wrote:
>>>>>
>>>>>> 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
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> _______________________________________________
>>>>>>>>>>> ncl-talk mailing list
>>>>>>>>>>> ncl-talk at ucar.edu
>>>>>>>>>>> List instructions, subscriber options, unsubscribe:
>>>>>>>>>>> http://mailman.ucar.edu/mailman/listinfo/ncl-talk
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> --
>>>>>>>>>> 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>
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> _______________________________________________
>>>>>>>>> ncl-talk mailing list
>>>>>>>>> ncl-talk at ucar.edu
>>>>>>>>> List instructions, subscriber options, unsubscribe:
>>>>>>>>> http://mailman.ucar.edu/mailman/listinfo/ncl-talk
>>>>>>>>>
>>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> --
>>>>>>>> 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 <(303)%20497-1726>
>>>>>>
>>>>>> <http://www.cgd.ucar.edu/staff/asphilli>
>>>>>>
>>>>>> _______________________________________________
>>>>>> 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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