[ncl-talk] Month_to_annual with no time dimension attributes nor coordinates

Dennis Shea shea at ucar.edu
Tue Jan 23 06:12:28 MST 2018 

The dimension name change was done to avoid confusion

  x(time,lat,lon)  ... time coordinates has 'monthly' values


  xAnnual(time,lat,lon)     ; here 'time' is a yearly value
or
  xAnnual(year,lat,lon)     ; 'year' was used to emphasize the difference.

The user can assign 'year' coordinates

  yrStrt = ....
  yrLast = ....

  xAnnual&year = ispan(yrStrt,yrLast,1)  ; assign appropriate values

  printVarSummary(xAnnual)






On Mon, Jan 22, 2018 at 2:00 PM, Rick Brownrigg via ncl-talk <
ncl-talk at ucar.edu> wrote:

> Hi,
>
> It appears that month_to_annua() has changed the temporal dimension to
> "year".  I don't know enough about what you are doing, but is it
> appropriate to simply change "time" to "year" in the dimension reordering
> in the call to equiv_sample_size()?
>
> Hope that helps...
> Rick
>
> On Mon, Jan 22, 2018 at 1:49 PM, Sri Nandini via ncl-talk <
> ncl-talk at ucar.edu> wrote:
>
>> Hello
>>
>> I am trying to make estimates the number of independent values of a
>> series of correlated observations using equiv_sample_size based on annual
>> values of my temperature which is below in part of script. However, i keep
>> getting the error:(time) is not a dimension name in variable (t44), could
>> not determine dimension number
>>
>> My simple script is below:
>>
>>
>>
>>
>> ; ==============================================================
>> ; Open the file: Read only the user specified period
>> ; ==============================================================
>> f= addfile("T2M_Cam5.nc", "r") ;Model Control
>> TIME   = f->time
>> ;YYYY   = cd_calendar(TIME,-1)/100                 ; entire file
>> ;iYYYY  = ind(YYYY.ge.yrStrt .and. YYYY.le.yrLast)
>> T41    = f->TREFHT(:,:,:)
>> printVarSummary(T41)                                ; (time, lat,lon)
>> T4    = lonFlip(T41)
>> ;printVarSummary(T4)                                ; (time, lat,lon)
>> T4 at _FillValue = -9.96921e+36
>> t44 = month_to_annual(T4, 0)                   ;; average over the 0th dim
>> printVarSummary(t44)                                ; (lat,lon)
>> aveX = dim_avg_n_Wrap(t44, 0)                   ;; average over the 0th
>> dim
>> printVarSummary(aveX)                                ; (lat,lon)
>> varX = dim_variance_n_Wrap(t44,0) ; compute variance
>> printVarSummary(varX)                                ; (lat,lon)
>> ;===========================================================
>> =====================
>> ;equiv_sample_size: Estimates the number of independent values of a
>> series of correlated observations. Specify a critical significance level to
>> test the lag-one auto-correlation coefficient
>> ;===========================================================
>> ======================
>>   sigr = 0.05                        ; critical sig lvl for r
>>
>>  xEqv = new(dimsizes(aveX),typeof(aveX),aveX at _FillValue)
>> printVarSummary(xEqv)                               ; (lat,lon)
>>   xEqv = equiv_sample_size (t44(lat|:,lon|:,time|:), sigr,0)
>>  copy_VarMeta(aveX,xEqv)
>> printVarSummary(xEqv)                               ; (lat,lon)
>>
>> ;=================================================================
>> The output of running that is here:
>>
>> Variable: T41
>> Type: float
>> Total Size: 403439616 bytes
>>             100859904 values
>> Number of Dimensions: 3
>> Dimensions and sizes:    [time | 1824] x [lat | 192] x [lon | 288]
>> Coordinates:
>>             time: [  31..55480]
>>             lat: [ -90..  90]
>>             lon: [   0..358.75]
>> Number Of Attributes: 3
>>   units :    K
>>   long_name :    Reference height temperature
>>   cell_methods :    time: mean
>>
>> Variable: t44
>> Type: float
>> Total Size: 33619968 bytes
>>             8404992 values
>> Number of Dimensions: 3
>> Dimensions and sizes:    [year | 152] x [lat | 192] x [lon | 288]
>> Coordinates:
>>             lat: [ -90..  90]
>>             lon: [-180..178.75]
>> Number Of Attributes: 6
>>   _FillValue :    -9.96921e+36
>>   units :    K
>>   long_name :    Reference height temperature
>>   cell_methods :    time: mean
>>   lonFlip :    longitude coordinate variable has been reordered via
>> lonFlip
>>   NCL :    month_to_annual
>>
>> Variable: aveX
>> Type: float
>> Total Size: 221184 bytes
>>             55296 values
>> Number of Dimensions: 2
>> Dimensions and sizes:    [lat | 192] x [lon | 288]
>> Coordinates:
>>             lat: [ -90..  90]
>>             lon: [-180..178.75]
>> Number Of Attributes: 7
>>   _FillValue :    -9.96921e+36
>>   units :    K
>>   long_name :    Reference height temperature
>>   cell_methods :    time: mean
>>   lonFlip :    longitude coordinate variable has been reordered via
>> lonFlip
>>   NCL :    month_to_annual
>>   average_op_ncl :    dim_avg_n over dimension(s): year
>>
>> Variable: varX
>> Type: float
>> Total Size: 221184 bytes
>>             55296 values
>> Number of Dimensions: 2
>> Dimensions and sizes:    [lat | 192] x [lon | 288]
>> Coordinates:
>>             lat: [ -90..  90]
>>             lon: [-180..178.75]
>> Number Of Attributes: 7
>>   _FillValue :    -9.96921e+36
>>   units :    K
>>   long_name :    Reference height temperature
>>   cell_methods :    time: mean
>>   lonFlip :    longitude coordinate variable has been reordered via
>> lonFlip
>>   NCL :    month_to_annual
>>   variance_op_ncl :    dim_variance_n over dimension(s): year
>>
>> Variable: xEqv
>> Type: float
>> Total Size: 221184 bytes
>>             55296 values
>> Number of Dimensions: 2
>> Dimensions and sizes:    [192] x [288]
>> Coordinates:
>> Number Of Attributes: 1
>>   _FillValue :    -9.96921e+36
>> fatal:(time) is not a dimension name in variable (t44), could not
>> determine dimension number
>> fatal:["Execute.c":8575]:Execute: Error occurred at or near line 35 in
>> file testing_T2M.ncl
>>
>>
>> Variable: xEqv
>> Type: float
>> Total Size: 221184 bytes
>>             55296 values
>> Number of Dimensions: 2
>> Dimensions and sizes:    [lat | 192] x [lon | 288]
>> Coordinates:
>>             lat: [ -90..  90]
>>             lon: [-180..178.75]
>> Number Of Attributes: 7
>>   average_op_ncl :    dim_avg_n over dimension(s): year
>>   NCL :    month_to_annual
>>   lonFlip :    longitude coordinate variable has been reordered via
>> lonFlip
>>   cell_methods :    time: mean
>>   long_name :    Reference height temperature
>>   units :    K
>>   _FillValue :    -9.96921e+36
>>
>> ;=========================================================
>> Because, upon using month_to_annual i dont get time dimension nor
>> attributes i cannot perform further analysis as it says i havnt defined
>> time dimension. I have tried to use several methods by defining new
>> varible, as well as VarMeta, VarCoords etc, but it doesnt change the
>> outcome.
>>
>> Can someone please advice on how to workaround this issue?
>> The bottom line being i need to use equiv_sample_size on my annual values
>> and i cannot due to time dimension not being defined.
>> Much appreciated
>>
>>
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>
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