[ncl-talk] Extracting dates when multiple conditions are met

[Dennis Shea]

; Details:
; I am extracting the dates from a netcdf file, when multiple conditions
are met. I am using NCL 6.6.2.

; Conditions:
; 1. OLR < 240
; 2. uwnd < 0
; 3. stretch_sph > 0


      latS = 13.0
      latN = 22.0
      lonL = 120.0
      lonR = 122.5

      f          = *addfile*("test_file_olr_wind_deform.nc","r")
      olr_region = *short2flt*(f->olr(:,{latS:latN},{lonL:lonR}))
      u_region   = f->uwnd(:,{latS:latN},{lonL:lonR})
      stretch_region = f->stretch_sph(:,{latS:latN},{lonL:lonR})

      *printVarSummary*(olr_region)
      *printMinMax*(olr_region,0)
      print("=====")

      printVarSummary(u_region)
      printMinMax(  u_region,0)
      print("=====")

      printVarSummary(stretch_region)
      printMinMax(stretch_region,0)
      print("=====")

      olr_threshold     = 240
      uwnd_threshold    = 0
      stretch_threshold = 0

      olr_thres         = *dim_min_n*(olr_region,(/1,2/))          ;min at
each time step
      uwnd_thres    = *dim_min_n*(  u_region,(/1,2/))          ;min at each
time step
      stretch_thres = *dim_max_n*(stretch_region,(/1,2/))   ;max at each
time step

      printVarSummary(olr_thres)           ; [*]
      print("=====")
      printVarSummary(uwnd_thres)
      print("=====")
      printVarSummary(stretch_thres)
      print("=====")

      n_thres  =* ind*((olr_thres .le. olr_threshold)  .and. \
                              (uwnd_thres.le. uwnd_threshold) .and. \
                              (stretch_thres .ge. stretch_threshold))
      print(n_thres)
      print("=====")

      TIME  = u_region*&*time               ; all times
      YMD  = *cd_calendar(*TIME,-2)   ; all yyyy-mm-dd
      ymd   = YMD(n_thres)                 ; dates that satisfy criteria
      print(ymd)

      OLR = u_region(n_thres,:,:)
      printVarSummary(OLR)
; or
      u_region := u_region(n_thres,:,:)
      printVarSummary(u_region)

; etc

On Sun, May 26, 2019 at 11:13 PM Lyndz <olagueralyndonmark429 at gmail.com>
wrote:

> Dear NCL-experts,
>
> *Details:*
> I am extracting the dates from a netcdf file, when multiple conditions are
> met. I am using NCL 6.6.2.
>
> The file that I am working with can be accessed from this link:
> https://www.dropbox.com/s/cycpbdgxdzsdnbh/test_file_olr_wind_deform.nc?dl=0
>
> This file contains 3 variables: OLR (short); uwnd(float);
> stretch_sph(float), with 123 timesteps.
>
> Attached is the script that I am using (date_filter.ncl).
> Also attached is the time series of OLR for verification.
>
> *Conditions:*
> 1. OLR < 240
> 2. uwnd < 0
> 3. stretch_sph > 0
>
> *Problem/What I have so far:*
> I am filtering these variables using these lines:
>
>
>
>
>
> *latS = 13.0      latN = 22.0      lonL = 120.0      lonR = 122.5*
>
> *      olr_region=olr(:,{latS:latN},{lonL:lonR})  *
>
> *      u_region=u(:,{latS:latN},{lonL:lonR})
> stretch_region=stretch(:,{latS:latN},{lonL:lonR})*
>
>
>
>
>
>
>
>
>
>
> *      olr_threshold = 240      olr_thres  = dim_min_n(olr_region,(/1,2/))
>   ;min at each time step      uwnd_threshold = 0      uwnd_thres  =
> dim_min_n(u_region,(/1,2/))   ;min at each time step      stretch_threshold
> = 0      stretch_thres  = dim_max_n(stretch_region,(/1,2/))   ;max at each
> time step       n_thres  = ind((olr_thres .le. olr_threshold) .and.
> (uwnd_thres .le. uwnd_threshold) .and. *
> *      (stretch_thres .ge. stretch_threshold))*
>
> When I print the dates, I am getting a value at *19810419*, but the time
> series shows that the OLR value at this period is above 240; hence, not
> satisfying condition 1. I would like to ask for help on how to implement
> this correctly in NCL.
>
> *Expected output:*
> Netcdf or csv file containing the dates that satisfied the 3 conditions.
>
>
> I'll appreciate any suggestions.
> --
> Lyndz
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