[ncl-talk] Interpolation error

Sunmin Park mireiyue at gmail.com
Wed Aug 13 11:53:44 MDT 2014


Hi Mary 

I think the interpolation still generates some errors. I sent you the values and the minimum still shows minus.
I plotted original data and interpolated data with same legend scale. It showed quite different plotting. I modified the script as you suggested.
The original data has following min max => (0) Ambient Aerosol Extinction at 550 nm: min=0   max=0.00242234
After interpolation => (0)	min=-0.000818642   max=0.00353843
I think it should not be minus value. How can I fix this?

Attached plots. the first plot is from original data and second is after interpolation. 

Any suggestions will help.

Thank you
Sun- 

hyam = filenc->a(::-1)
hybm = filenc->b(::-1)

;hyam = filenc->a
;hybm = filenc->b
plev0 = (/1000,925,850,700,600,500,400,300,250,200,150,100,70,50,30,20,10/)
psfc = filenc->ps
p0=1000.

;printVarSummary(psfc)
;printVarSummary(hyam)

ec550aer = data(:,::-1,:,:)
printVarSummary(ec550aer)
;ec550aer = data                ; read ec550aer from all files
ec550aerNEW=vinth2p(ec550aer,hyam,hybm,plev0,psfc,1,p0,1,True)
delete(ec550aer)
ec550aer=ec550aerNEW
delete(ec550aerNEW)
printMinMax(ec550aer,0)
return





 

On Aug 8, 2014, at 6:37 AM, Mary Haley <haley at ucar.edu> wrote:

> Hi Sun,
> 
> Thanks for providing the files. I consulted with Dennis offline about your hyam/hybm values, and he stated the following:
> 
> [1] These look like sigma coordinates.
> 
> [2]  p(k) = A(k)*PO + B(k)*PS 
>       k=level, A(k)=>hyam=>pressure coord; B(k)=>sigma coord
> 
>       Apparently, there are no pressure coords [ A(:)=0.0 ]
> 
>      p(k) = B(k)*PS = sigma(k)*PS
> 
> [3] The vinth2p function requires the hybrid coefficients and data to be
>       top-of-atmos to bottom. These coefficients are bottom-to-top.
> 
>      A sample hybm => sigma looks like the following.
>      Note the ordering. The fact that the #s are different is no big deal.
>      Just different sigma levels:
> 
>     hybm = 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0.0196774136275053, 
> 
>     0.062504293397069, 0.112887907773256, 0.172161616384983, 
> 
>     0.241894043982029, 0.323930636048317, 0.420442461967468, 
> 
>     0.524799540638924, 0.624887734651566, 0.713207691907883, 
> 
>     0.783669710159302, 0.831102818250656, 0.864811271429062, 
> 
>     0.896237164735794, 0.92512384057045, 0.951230525970459, 
> 
>     0.974335998296738, 0.992556095123291 ; 
> ----------------------
> 
> The fix is to reorder your hyam and hybm values. You will also need to reorder your data values in the level dimension:
>     hyam = filenc->a(::-1)
>     hybm = filenc->b(::-1)
>     ec550aer = data(:,::-1,:,:)
> 
> Please also review the documentation for vinth2p which talks about the ordering required for all input variables:
> 
> http://www.ncl.ucar.edu/Document/Functions/Built-in/vinth2p.shtml
> --Mary
> 
> 
> 
> 
> 
> On Thu, Aug 7, 2014 at 10:51 AM, Sunmin Park <mireiyue at gmail.com> wrote:
> Hi, Mary
> 
> I uploaded the data files (start with “ec550aer_aero_NorESM1”) and script (CMIP5_ec,ncl). I checked the FillValue which is 1e+20 I tried with and without this part but the results showed same.
> 
> Thank you 
> Sun-
> 
> On Aug 7, 2014, at 8:44 AM, Mary Haley <haley at ucar.edu> wrote:
> 
>> My first thought this looked like a _FillValue issue, but I can't tell simply from the output.
>> 
>> Can you provide the data file for this script? You can use our ftp:
>> 
>> http://www.ncl.ucar.edu/report_bug.shtml#HowToFTP
>> 
>> Thanks,
>> 
>> --Mary
>> 
>> 
>> 
>> On Wed, Aug 6, 2014 at 3:16 PM, Sunmin Park <mireiyue at gmail.com> wrote:
>> Dear NCL users,
>> 
>> I have a problem to do interpolation using NorESM1 model results. I am using extinction coefficient values and when I read the data from the files, the MIN and MAX values are
>> "(0)    Ambient Aerosol Extinction at 550 nm: min=0   max=0.00242234 “
>> But after interpolation the values are
>> "(0)    min=-2.58212e+22   max=0.0127834”
>> 
>> I do not understand why the values are changing and the MIN value shows minus. How can I fix it?
>> 
>> Thank you for any help!!
>> 
>> Sun-
>> 
>> ; ==============================================================
>> ; Open the file:
>> ; ==============================================================
>>   fili    = "ec550aer_aero_NorESM1-M_historicalExt_r1i1p1_200601-201212.nc"
>> ;  fili    = "ec550aer_aero_NorESM1-M_historicalExt_"+version(ii)+"i1p1_200601-201212.nc"
>>   varname = "ec550aer"
>>   varname1 = "a"
>>   varname2 = "b"
>>   varname3 = "ps"
>>   varname4 = "p0"
>>   filenc       = addfile (diri+fili+".nc", "r")      ; entire file
>> ;  printMinMax(varname,0)
>> ;  print(varname1)
>> ;  print(varname2)
>> ;  print(varname3)
>> ;  print(varname4)
>> ;  print (filenc)
>> ;  return
>> 
>>   data   = filenc->$varname$                          ; (time, ver, lat, lon)
>> ;  print (dimsizes(data))
>>   time =filenc->time
>>   lev =filenc->lev
>>   lat =filenc->lat
>>   printMinMax(data,0)
>>   printVarSummary(data)
>> ;return
>>   lon =filenc->lon
>> ;  print(time)
>> ;  print(lev)
>> ;  print(lat)
>> ;  print(lon)
>> ;  data at _FillValue=1e+20
>> ;  newlev =lev*1000
>> ;  print(newlev)
>> 
>> ;return
>> 
>> ;############Converting from hybrid levels to standard pressure levels######################################
>> hyam = filenc->a
>> hybm = filenc->b
>> plev0 = (/1000,925,850,700,600,500,400,300,250,200,150,100,70,50,30,20,10/)
>> psfc = filenc->ps
>> p0=1000.
>> 
>> ;printVarSummary(psfc)
>> ;printVarSummary(hyam)
>> 
>> ec550aer = data;filenc->ec550aer                ; read ec550aer from all files
>> ec550aerNEW=vinth2p(ec550aer,hyam,hybm,plev0,psfc,1,p0,1,True)
>> delete(ec550aer)
>> ec550aer=ec550aerNEW
>> delete(ec550aerNEW)
>> printVarSummary(ec550aer)
>> printMinMax(ec550aer,0)
>> return
>> ;###################################################################################
>> 
>> 
>> RESULTS
>> 
>> (0)     Ambient Aerosol Extinction at 550 nm: min=0   max=0.00242234
>> 
>> Variable: data
>> Type: float
>> Total Size: 120766464 bytes
>>             30191616 values
>> Number of Dimensions: 4
>> Dimensions and sizes:   [time | 84] x [lev | 26] x [lat | 96] x [lon | 144]
>> Coordinates:
>>             time: [15.5..2539.5]
>>             lev: [0.9925560999999998..0.00354463800000001]
>>             lat: [ -90..  90]
>>             lon: [   0..357.5]
>> Number Of Attributes: 12
>>   standard_name :       volume_extinction_coefficient_in_air_due_to_ambient_aerosol
>>   long_name :   Ambient Aerosol Extinction at 550 nm
>>   comment :     """ambient"" means ""wetted"".  "
>>   units :       m-1
>>   original_name :       BAK
>>   original_units :      1/km
>> 
>> 
>> Variable: ec550aer
>> Type: float
>> Total Size: 78962688 bytes
>>             19740672 values
>> Number of Dimensions: 4
>> Dimensions and sizes:   [time | 84] x [lev_p | 17] x [lat | 96] x [lon | 144]
>> Coordinates:
>>             time: [15.5..2539.5]
>>             lev_p: [1000..10]
>>             lat: [ -90..  90]
>>             lon: [   0..357.5]
>> Number Of Attributes: 1
>>   _FillValue :  1e+20
>> (0)     min=-2.58212e+22   max=0.0127834
>> 
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> 
> 

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