[ncl-talk] how to plot divergent winds, divergence and velocity potential in one single plot?
Dennis Shea
shea at ucar.edu
Sat Feb 24 08:57:54 MST 2018
[0]
The error message is that you do not have any "coordinate variables"
associated with the variables being plotted.
[1]
If you are "new to NCL", please look at:
https://test.www.ncl.ucar.edu/Document/Manuals/
User Guide
[2]
When you send questions to ncl-talk, it is always useful to include the
output from:
https://www.ncl.ucar.edu/Document/Functions/Built-in/printVarSummary.shtml
and
https://www.ncl.ucar.edu/Document/Functions/Contributed/printMinMax.shtml
printVarSummary(u)
printMinMax(u,0)
print("===")
printVarSummary(up)
printMinMax(u,0)
print("===")
[3]
NCL's spherical harmonic functions, as noted in the documentation, require
that the data be ordered South-to-North. Operational centers (ECMWF, NCEP,
JRA, ...) order the data North-to-South. It is your responsibility to
perform this operation.
Good Luck
On Sat, Feb 24, 2018 at 2:33 AM, Vyankatesh Manoj Mundhada <
vyankatesh at iiserb.ac.in> wrote:
> Hello,
>
> I am new to NCL and I am trying to plot annual mean climatology for
> divergent winds (vectors), divergence (contours (shading)) and velocity
> potential (contours (lines)) in a single plot using velocities u and v
> only. I am using two input .nc files f1 and f2, where f1 contains u and v
> and f2 contains velocity potential.
> I am trying to plot divergent velocities over velocity potential using the
> following script:
>
> begin
> ;*************************************************
> ; open file and read in data: data are on a gaussian grid
> ;*************************************************
> f1 = addfile ("ERAI_200uvd_1979-2010_new.nc", "r")
> u = f1->u
> v = f1->v
> f2 = addfile ("ERAI_200sfvp_1979-2010_new.nc", "r")
> vp = f2->velopot
> ;*************************************************
> ; calculate divergence on a gaussian grid
> ;*************************************************
> div = uv2dvG_Wrap(u,v) ; u,v ==>
> divergence
> div at long_name = "Divergence"
> div at units = "s-1"
> ;*************************************************
> ; calculate velocity potential
> ;*************************************************
> ;chi = ilapsG_Wrap ( div , 0)
> chi = new ( dimsizes(vp), double, vp at _FillValue )
> chi = (/vp/1e4/) ;
> arbitrary scale
> copy_VarCoords(vp, chi )
> ;chi at long_name = "velocity potential"
> ;chi at units = "m^2/s"
> ;*************************************************
> ; calculate divergent wind component
> ; --
> ; note: the calculation uses a procedure, so memory
> ; must be preallocated.
> ;*************************************************
> ud = new ( dimsizes(u), double, u at _FillValue )
> vd = new ( dimsizes(v), double, v at _FillValue )
>
> dv2uvg(div,ud,vd) ; div ==> divergent wind components
>
> copy_VarCoords(u, ud )
> copy_VarCoords(v, vd )
> ud at long_name = "Zonal Divergent Wind"
> ud at units = u at units
> vd at long_name = "Meridional Divergent Wind"
> vd at units = v at units
>
> ;udAve = avg(ud(:,:,:,:))
> ;vdAve = avg(vd(:,:,:,:))
> ;scale =(/vdAve/udAve/)
> ;ud = (/scale*ud/)
>
> ud = (/ud/1e3/)
> vd = (/vd/1e3/)
> div = (/div*1e3/)
>
> ;UD = month_to_annual(ud, 1)
> ;VD = month_to_annual(vd, 1)
> ;DIV = month_to_annual(div, 1)
> ;CHI = month_to_annual(chi, 1)
>
> UDavg = dim_avg_n_Wrap(ud, (/0,1/))
> VDavg = dim_avg_n_Wrap(vd, (/0,1/))
> DIVavg = dim_avg_n_Wrap(div, (/0,1/))
> CHIavg = dim_avg_n_Wrap(chi, (/0,1/))
> CHIavg = abs(CHIavg)
>
> ;*************************************************
> ; plot results
> ;*************************************************
> wks = gsn_open_wks("png","vp_dv_d") ; send graphics to PNG
> file
> ;cmap = read_colormap_file("GMT_polar")
> ;cmap = read_colormap_file("GMT_seis")
> cmap = read_colormap_file("cmp_b2r")
> nc = dimsizes(cmap(:,0))
>
> res = True
> res at gsnDraw = False
> res at gsnFrame = False
> cnres1 = res
> cnres2 = res
> vcres = res
>
> cnres1 at cnFillOn = True ; color on
> cnres1 at cnLinesOn = False ; turn off contour lines
> cnres1 at cnFillPalette = cmap(:nc-4,:)
> cnres1 at tiMainString = "Divergent Winds, Divergence and Velocity
> Potential"
> cnres1 at cnLevelSelectionMode = "ManualLevels" ; manually set the
> contour levels with the following 3 resources
> cnres1 at cnMinLevelValF = -5.
> ; set the minimum contour level
> cnres1 at cnMaxLevelValF = 5.
> ; set the maximum contour level
> cnres1 at cnLevelSpacingF = 0.5
> ; set the interval between contours
> cnres1 at lbOrientation = "vertical"
> cnres1 at lbBoxSeparatorLinesOn = False
> cnres1 at lbTitleString = div at long_name
> cnres1 at lbTitlePosition = "Left"
> cnres1 at lbAutoManage = False
> cnres1 at lbTitleFontHeightF = 0.012
> ;cnres1 at lbLabelStrings = (/"-5.0","-2.5","0","2.5","5.0"/)
> cnres1 at mpMinLonF = 0
> cnres1 at mpMaxLonF = 360
> cnres1 at mpCenterLonF = 180 ; This is necessary to get the
> correct map
> cnres1 at mpMinLatF = -80
> cnres1 at mpMaxLatF = 80
>
> vcres at vcRefMagnitudeF = 10. ; make vectors larger
> vcres at vcRefLengthF = 0.05 ; ref vector length
> vcres at vcGlyphStyle = "CurlyVector" ; turn on curly vectors
> vcres at vcMinDistanceF = 0.012 ; thin the vectors
> vcres at vcRefAnnoOrthogonalPosF = 0 ; Move ref anno into plot
> vcres at vcRefAnnoBackgroundColor = "Background"
> vcres at vcRefAnnoString2On = False
> ;vcres at vcRefAnnoSide = "Left"
>
> ;cnres2 at gsnCenterString = "Chi scaled by 1e8"
> cnres2 at cnFillOn = False
> cnres2 at cnLinesOn = True
> ;cnres2 at mpMinLonF = 0
> ;cnres2 at mpMaxLonF = 360
> ;cnres2 at mpCenterLonF = 180 ; This is necessary to get the
> correct map
> cnres2 at trGridType = "TriangularMesh"
>
> plot1 = gsn_csm_vector(wks,UDavg(:,:),VDavg(:,:),vcres)
> plot2 = gsn_csm_contour_map_overlay(wks,DIVavg(:,:),CHIavg(:,:),
> cnres1,cnres2)
>
> overlay(plot2,plot1)
>
> draw(plot2)
> frame(wks)
>
> end
>
>
> I am getting the following warning messages:
>
> (0) check_for_y_lat_coord: Warning: Data either does not contain a
> valid latitude coordinate array or doesn't contain one at all.
> (0) A valid latitude coordinate array should have a 'units' attribute
> equal to one of the following values:
> (0) 'degrees_north' 'degrees-north' 'degree_north' 'degrees north'
> 'degrees_N' 'Degrees_north' 'degree_N' 'degreeN' 'degreesN' 'deg north'
> (0) check_for_lon_coord: Warning: Data either does not contain a valid
> longitude coordinate array or doesn't contain one at all.
> (0) A valid longitude coordinate array should have a 'units' attribute
> equal to one of the following values:
> (0) 'degrees_east' 'degrees-east' 'degree_east' 'degrees east'
> 'degrees_E' 'Degrees_east' 'degree_E' 'degreeE' 'degreesE' 'deg east'
>
>
> and the plot which is attached to this mail. I think I am getting proper
> divergence but velocity potential lines are not getting plotted at all and
> I feel the direction of winds are also wrong. So please help me to get a
> proper plot without error. I am expecting humble reply from your side.
>
> Thanking you,
>
> Vyankatesh Mundhada
>
> On Wed, Feb 21, 2018 at 5:40 PM, Vyankatesh Manoj Mundhada <
> vyankatesh at iiserb.ac.in> wrote:
>
>> Thank you very much. That was really helpful.
>>
>> Regards,
>> Vyankatesh
>>
>> On Wed, Feb 21, 2018 at 4:03 PM, Guido Cioni <guidocioni at gmail.com>
>> wrote:
>>
>>> Hi,
>>> This error usually pops up when you're doing assignment that delete the
>>> original attributes of the variable, including the reference to the
>>> coordinate variables.
>>>
>>> I'm just speculating but...could it be this line?
>>>
>>> plot1 = gsn_csm_vector_map(wks,0.001*ud(0,0,:,:),0.001*vd(0,0,:,:),v
>>> cres)
>>>
>>> You are doing 0.001*ud(0,0,:,:), so merely assigning a new variable
>>> without copying the attributes.
>>> You should instead do the scaling first
>>>
>>> ud=0.001*ud(:,:,:,:) ; here the attributes are preserved
>>>
>>> and then plot ud(0,0,:,:).
>>> Or just a define a new variable based un ud first.
>>>
>>> Let us know whether that works, that's the first thing that comes to my
>>> mind.
>>>
>>>
>>>
>>> On 21. Feb 2018, at 10:20, Vyankatesh Manoj Mundhada <
>>> vyankatesh at iiserb.ac.in> wrote:
>>>
>>> 0.001*vd(0,0,:,:)
>>>
>>>
>>>
>>> Guido Cioni
>>> http://guidocioni.altervista.org
>>>
>>>
>>
>
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