Re: contouring station data

James,

Glad to hear it worked. Just to make sure I didn't cause more
conflicting information for you: if you are still setting:

   res_at_sfXArray = lat
   res_at_sfYArray = lon

then make sure that you are *not* doing this part:

    cn_at_lat2d = ...
    cn_at_lon2d = ...

--Mary

On Wed, 22 Oct 2008, James Correia wrote:

> Mary-
> Thanks. I set res_at_tfDoNDCOverlay = False
> and it worked perfectly. The other issues you mentioned were needed since
> the station (point) data are 1d arrays. I just needed to tell NCL to allow
> me to project the data onto the grid.
> jimmyc
>
> On Wed, Oct 22, 2008 at 12:46 PM, Mary Haley <haley_at_ucar.edu> wrote:
>
>> James,
>>
>> You have some conflicting information in your script that might be
>> causing a problem.
>>
>> First you have:
>>
>> res_at_tfDoNDCOverlay = True
>>
>> which tells NCL that the data has already been projected onto a particular
>> map projection, so no calculations will be done to
>> transform your data to the given map projection. This setting
>> only works if you know the *exact* projection your data
>> was measured on. And, given that you are calling WRF_mapres_c,
>> this is supposed to set up your map resources to set up
>> the correct map projection.
>>
>> But, then you have:
>>
>> res_at_mpRightCornerLonF = lona(y2,x2)
>> res_at_mpRightCornerLatF = lata(y2,x2)
>> res_at_mpLeftCornerLonF = lona(y1,x1)
>> res_at_mpLeftCornerLatF = lata(y1,x1)
>>
>> This is effectively changing the map projection to something different
>> than what your data were actually measured, on, so now your data will
>> probably not look correct.
>>
>> Finally, you have:
>>
>> res_at_sfXArray = lon
>> res_at_sfYArray = lat
>>
>> I'm not sure where the "lon" and "lat" variables came from,
>> but these should probably be "lata" and "lona", if anything.
>> You don't want to set sfXArray/sfYArray if you've set tfDoNDCOverlay to
>> True.
>>
>> To fix all of this, please try the following steps:
>>
>> Remove or comment out the line:
>>
>> res_at_tfDoNDCOverlay = True
>>
>> (The default of this resource is False).
>>
>> Change the following "if" statement:
>>
>> if (.not.res_at_tfDoNDCOverlay) then
>> lat2d = f->XLAT(0,:,:) ; need for map limits
>> lon2d = f->XLONG(0,:,:)
>> end if
>>
>> to:
>>
>> if (.not.res_at_tfDoNDCOverlay) then
>> cp_at_lat2d = f->XLAT(0,:,:) ; need for map limits
>> cp_at_lon2d = f->XLONG(0,:,:)
>> end if
>>
>> The gsn_csm_xxx_map scripts recognize the special "lat2d"
>> and "lon2d" attributes and will use these to determine where
>> on the map your data is projected. Hence, you no longer need to
>> worry about getting the map projection exactly right.
>>
>> Finally, remove or comment out the lines:
>>
>> ; res_at_sfXArray = lon
>> ; res_at_sfYArray = lat
>>
>> These two lines will be handled for you internally by virtue of
>> setting the special lat2d/lon2d attributes.
>>
>> Hope this all makes sense.
>>
>> --Mary
>>
>>
>>
>> On Wed, 22 Oct 2008, James Correia wrote:
>>
>> All-
>>> I am having trouble getting my station data to conform to the projection I
>>> am using. I can use the gsn_add_text function to overlay numbers, but when
>>> I
>>> contour the data, the data are shifted relative to the map (looks more
>>> like
>>> "triangularmesh" assumes the grid is a rectangle, than actually
>>> transforming
>>> the lat-lon locations to match the LambertConformal projection).
>>>
>>> Perhaps an alternative is to use rgrid2rcm?
>>>
>>> jimmyc
>>>
>>> below is the relevant code.
>>> wks = gsn_open_wks("ps" ,"freq") ; ps,pdf,x11,ncgm,eps
>>> gsn_define_colormap(wks ,"BlAqGrYeOrReVi200"); choose colormap
>>>
>>> res = True ; plot mods desired
>>> res_at_gsnMaximize = True ; uncomment to maximize
>>> size
>>> res_at_gsnSpreadColors = True ; use full range of
>>> colormap
>>> res_at_cnFillOn = True ; color plot desired
>>> res_at_cnLinesOn = False ; turn off contour lines
>>> res_at_cnLineLabelsOn = False ; turn off contour labels
>>> res_at_lbLabelAutoStride = True ; let NCL figure lb stride
>>> res_at_cnLevelSelectionMode = "ExplicitLevels" ; explicit [unequal] cn
>>> levels
>>>
>>> res_at_cnLevels = (/10,20,30,40,50,60,70,80,90/)
>>> ;************************************************
>>> ; Use WRF_contributed procedure to set map resources
>>> ;************************************************
>>> WRF_map_c(f,res,0) ; set map resources
>>> ;************************************************
>>> ; set True for native mapping (faster plotting)
>>> ; set to False othewise
>>> ;************************************************
>>> res_at_tfDoNDCOverlay = True
>>>
>>> ;************************************************
>>> ; associate the 2-dimensional coordinates to variables for plotting
>>> ; only if res_at_tfDoNDCOverlay=False
>>> ;************************************************
>>> if (.not.res_at_tfDoNDCOverlay) then
>>> lat2d = f->XLAT(0,:,:) ; need for map limits
>>>
>>> lon2d = f->XLONG(0,:,:)
>>> end if
>>>
>>>
>>> ;************************************************
>>> ; allocate array for 3 plots
>>> ;************************************************
>>> plot = new (1,"graphic")
>>> ;************************************************
>>>
>>>
>>> lata = f->XLAT(0,:,:)
>>> lona = f->XLONG(0,:,:)
>>> ;x2 = 105
>>> ;y2 = 80
>>> ;x1 = 43
>>> ;y1 = 18
>>> x2 = 100
>>> y2 = 85
>>> x1 = 38
>>> y1 = 22
>>> ;x2 = 143
>>> ;y2 = 118
>>> ;x1 = 10
>>> ;y1 = 10
>>>
>>> res_at_mpRightCornerLonF = lona(y2,x2)
>>> res_at_mpRightCornerLatF = lata(y2,x2)
>>> res_at_mpLeftCornerLonF = lona(y1,x1)
>>> res_at_mpLeftCornerLatF = lata(y1,x1)
>>>
>>> ;************************************************
>>> ; Tell NCL not to draw or advance frame for individual plots
>>> ;************************************************
>>> ; res_at_gsnDraw = False ; (a) do not draw
>>> ; res_at_gsnFrame = False ; (b) do not advance
>>> 'frame'
>>> res_at_trGridType = "TriangularMesh" ; The default if
>>> you
>>> ; have 1D data
>>> res_at_sfXArray = lon
>>> res_at_sfYArray = lat
>>> print(res)
>>>
>>> res_at_gsnLeftString ="CAPE 500 J kg-1"
>>> ;plot(0) = gsn_csm_map(wks,res)
>>> print(cp)
>>> plot = gsn_csm_contour_map(wks,cp,res)
>>>
>>> --
>>> James Correia Jr.
>>> Post Doc
>>> Climate Physics Group, PNNL
>>>
>>>
>
>
> --
> James Correia Jr.
> Post Doc
> Climate Physics Group, PNNL
>
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Received on Wed Oct 22 2008 - 14:30:54 MDT