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

[Sri Nandini]

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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