Hi. Understand.
I am still getting an error. The function does not like what I am
using for "r" (or dX, second part of command) although I don't see
what else to use...
dX = radius*cos(radian*lat)*dlon
do nl=0,nlat-1
dvdx(nl,:) = center_finite_diff_n (v(nl,:), dX, False, 0, 0)
end do
Did I have it written correctly the first time?
-Bold
[ 06:23:38 ] > ncl tester.ncl
Copyright (C) 1995-2010 - All Rights Reserved
University Corporation for Atmospheric Research
NCAR Command Language Version 5.2.1
The use of this software is governed by a License Agreement.
See http://www.ncl.ucar.edu/ for more details.
Variable: v
Type: float
Total Size: 27156 bytes
6789 values
Number of Dimensions: 2
Dimensions and sizes: [lat | 73] x [lon | 93]
Coordinates:
lat: [-19.5..34.5]
lon: [-34.5..34.5]
Number Of Attributes: 13
lev : 700
lonFlip : longitude coordinate variable has been reordered via lonFlip
initial_time : 09/02/2006 (00:00)
forecast_time_units : hours
forecast_time : 0
parameter_number : 132
parameter_table_version : 128
gds_grid_type : 0
level_indicator : 109
_FillValue : 1e+20
units : m s**-1
long_name : V velocity
center : European Center for Medium-Range Weather Forecasts (RSMC)
Variable: dX
Type: float
Total Size: 292 bytes
73 values
Number of Dimensions: 1
Dimensions and sizes: [73]
Coordinates:
fatal:center_finite_diff_n: r must either be a scalar, a 1D array the
same length as the dim-th dimemsion of q, or the same size as q
fatal:Execute: Error occurred at or near line 32 in file tester.ncl
Variable: dY
Type: float
Total Size: 4 bytes
1 values
Number of Dimensions: 1
Dimensions and sizes: [1]
Coordinates:
(0)
(0) min=-999 max=-999
[ 06:24:14 ] >
!!!!!!!!!!! CODE
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl"
;;; some contants
pi = 4.0*atan(1.0)
radian = pi/180.0
radius = 6370949.0
FILEIN = "era_uv.nc"
;;;;;;;;
a = addfile(FILEIN,"r")
U=a->U
u=U(0,{700},:,:)
V=a->V
v=V(0,{700},:,:)
printVarSummary(v)
lat = a->lat
lon = a->lon
nlat = dimsizes(lat)
mlon = dimsizes(lon)
dlon = (max(lon)-min(lon))/(mlon-1)
dlat = (max(lat)-min(lat))/(nlat-1)
; Arrays
dvdx = new ( (/nlat,mlon/), typeof(v), v@_FillValue)
dudy = new ( (/nlat,mlon/), typeof(v), v@_FillValue)
; Calculate dv/dx & du/dy with loops
dX = radius*cos(radian*lat)*dlon ; array dX[*] because lat[*]
printVarSummary(dX)
do nl=0,nlat-1
dvdx(nl,:) = center_finite_diff_n (v(nl,:), dX, False, 0, 0)
end do
dY = radius*radian*dlat
printVarSummary(dY)
do ml=0,mlon-1
dudy(:,ml) = center_finite_diff_n (v(:,ml), dY, False, 0, 0)
end do
vor = dvdx - dudy
printMinMax(vor,True)
On Sun, Dec 19, 2010 at 5:40 PM, Dennis Shea <shea@ucar.edu> wrote:
> dX = radius*cos(radian*lat)*dlon ; array dX[*] because lat[*]
>
> do nl=0,nlat-1
> dvdx(nl,:) = center_finite_diff_n (v(nl,:), dX, False, 0, 0)
> end do
>
> dY = radius*radian*dlat
>
> do ml=0,mlon-1
> dudy(:,ml) = center_finite_diff_n (v(:,ml), dY, False, 0, 0)
> end do
>
> Essentially the same as in fortran 90, Matlab,....
>
>
> On 12/19/10 3:28 PM, Bold Khan wrote:
>>
>> Dennis, Thank you! This was an oversight on my part. I made this
>> correction.
>> So the script, the way it's written, works. But I am not sure if its
>> actually right. I don't feel that it is.
>> May I have a little conceptual help?
>>
>> If I want to calculate vorticity: (i.e. rv = (dv/dy) - (du/dx)
>> Do dv/dx and dvdy need to be in the same loop or can they be
>> separate as I have done?
>> And, since I yearn to be an efficient NCLer, and avoid do loops where
>> possible, is there a way not
>> to use loops for this calculation?
>>
>> Again, thank you for your time.
>> Still trying to wrap my brain around this.
>> -Bold
>>
>>
>> 05:12:16 ]> ncl tester.ncl
>> Copyright (C) 1995-2010 - All Rights Reserved
>> University Corporation for Atmospheric Research
>> NCAR Command Language Version 5.2.1
>> The use of this software is governed by a License Agreement.
>> See http://www.ncl.ucar.edu/ for more details.
>> (0)
>> (0) min=-4.3992e-05 max=4.80107e-05
>>
>> CODE
>>
>> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
>> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"
>> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl"
>> ;======================== some contants
>> pi = 4.0*atan(1.0)
>> radian = pi/180.0
>> radius = 6370949.0
>> FILEIN = "era_uv.nc"
>> ;======================== Read in file and variables
>> a = addfile(FILEIN,"r")
>> U=a->U
>> u=U(0,{700},:,:)
>> V=a->V
>> v=V(0,{700},:,:)
>>
>> lat = a->lat
>> lon = a->lon
>> nlat = dimsizes(lat)
>> mlon = dimsizes(lon)
>> dlon = (max(lon)-min(lon))/(mlon-1)
>> dlat = (max(lat)-min(lat))/(nlat-1)
>> ;===================================== Arrays
>> dvdx = new ( (/nlat,mlon/), typeof(v), v@_FillValue)
>> dudy = new ( (/nlat,mlon/), typeof(v), v@_FillValue)
>> ;===================================== loops
>> do nl=0,nlat-1
>> dX = radius*cos(radian*lat(nl))*dlon
>> dvdx(nl,:) = center_finite_diff_n (v(nl,:), dX, False, 0, 0)
>> end do
>> do ml=0,mlon-1
>> dY = radius*radian*dlat
>> dudy(:,ml) = center_finite_diff_n (v(:,ml), dY, False, 0, 0)
>> end do
>> vor = dvdx - dudy
>>
>> printMinMax(vor,True)
>>
>>
>>
>> On Sun, Dec 19, 2010 at 4:44 PM, Dennis Shea<shea@ucar.edu> wrote:
>>>
>>> You did not define the variables correctly.
>>>
>>> You created the following arrays
>>>
>>>> dvdx = new ( (/nlat,mlon/), typeof(v), v@_FillValue)
>>>> dudx = new ( (/nlat,mlon/), typeof(v), v@_FillValue)
>>>
>>> Then you used
>>>
>>>> dvdx(nl,:) = center_finite_diff_n (v(nl,:), dX, False, 0, 0)
>>>
>>> :
>>>>
>>>> dudy(:,ml) = center_finite_diff_n (v(:,ml), dY, False, 0, 1)
>>>
>>> Where did you preallocate space for dudy??
>>> The error messages told you exactly what the problem is:
>>>
>>>> fatal:Undefined identifier: (dudy) is undefined, can't continue
>>>> fatal:Execute: Error occurred at or near line 30 in file tester.ncl
>>>>
>>>> fatal:Variable (dudy) is undefined
>>>> fatal:Execute: Error occurred at or near line 33 in file tester.ncl
>>>>
>>>> fatal:Variable (vor) is undefined
>>>
>>> vor is undefined because the dudy is undefined
>>>
>>> ==
>>>
>>> I think waht you want is:
>>>
>>> dudy = new ( (/nlat,mlon/), typeof(v), v@_FillValue)
>>>
>>>
>>> On 12/19/10 12:55 PM, Bold Khan wrote:
>>>>
>>>> Dear ncl users,
>>>> Could I have some help? I am still learning ncl.
>>>> I am getting confused with using the center_finite_diff_n command to
>>>> calculate relative vorticity (RV) with non-cyclic data.
>>>> I want to calculate (RV) using center_finite_diff_n, instead of just
>>>> resorting to using the uv2vr_cfd command that is available, because I
>>>> want to calculate RV and then shear vorticity separately.
>>>> I am following example 6 at
>>>>
>>>>
>>>> http://www.ncl.ucar.edu/Document/Functions/Built-in/center_finite_diff_n.shtml.
>>>>
>>>> 1) Do dv/dx and dvdy need to be in the same loop or can they be
>>>> separate as I have done?
>>>> 2) Since we want to try and avoid do loops in ncl, is there a way not
>>>> to use loops for this calculation
>>>> Any amount of advice, would be greatly appreciated.
>>>> Sincerely,
>>>> Bold
>>>>
>>>>
>>>> [ 02:42:16 ]> ncl tester.ncl
>>>> Copyright (C) 1995-2010 - All Rights Reserved
>>>> University Corporation for Atmospheric Research
>>>> NCAR Command Language Version 5.2.1
>>>> The use of this software is governed by a License Agreement.
>>>> See http://www.ncl.ucar.edu/ for more details.
>>>> fatal:Undefined identifier: (dudy) is undefined, can't continue
>>>> fatal:Execute: Error occurred at or near line 30 in file tester.ncl
>>>>
>>>> fatal:Variable (dudy) is undefined
>>>> fatal:Execute: Error occurred at or near line 33 in file tester.ncl
>>>>
>>>> fatal:Variable (vor) is undefined
>>>> fatal:Execute: Error occurred at or near line 35 in file tester.ncl
>>>>
>>>> [ 02:48:25 ]>
>>>>
>>>>
>>>>
>>>> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
>>>> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"
>>>> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl"
>>>> ;;; some contants
>>>> pi = 4.0*atan(1.0)
>>>> radian = pi/180.0
>>>> radius = 6370949.0
>>>> FILEIN = "era_uv.nc"
>>>> ;=========================variables
>>>> a = addfile(FILEIN,"r")
>>>> U=a->U
>>>> u=U(0,{700},:,:)
>>>> V=a->V
>>>> v=V(0,{700},:,:)
>>>>
>>>> lat = a->lat
>>>> lon = a->lon
>>>> nlat = dimsizes(lat)
>>>> mlon = dimsizes(lon)
>>>> dlon = (max(lon)-min(lon))/(mlon-1)
>>>> dlat = (max(lat)-min(lat))/(nlat-1)
>>>> ; Arrays
>>>> dvdx = new ( (/nlat,mlon/), typeof(v), v@_FillValue)
>>>> dudx = new ( (/nlat,mlon/), typeof(v), v@_FillValue)
>>>> ; loops
>>>> do nl=0,nlat-1
>>>> dX = radius*cos(radian*lat(nl))*dlon
>>>> dvdx(nl,:) = center_finite_diff_n (v(nl,:), dX, False, 0, 0)
>>>> end do
>>>> do ml=0,mlon-1
>>>> dY = radius*radian*dlat
>>>> dudy(:,ml) = center_finite_diff_n (v(:,ml), dY, False, 0, 1)
>>>> end do
>>>> vor = dvdx - dudy
>>>>
>>>> printMinMax(vor,True)
>>>> _______________________________________________
>>>> ncl-talk mailing list
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>>>
>
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Received on Sun Dec 19 16:35:20 2010
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