Re: computing daily precip from hourly data

Well, if they data

00, 03, 06, 09, 12, 15, 18, 21,
00, 03, 06, 09, .....

then

     ntJump = 8
     ntStrt = 3 ; start at 06
     ntLast = ntStrt+ntJump-1

Good luck

Sho Kawazoe wrote:
> Hi,
>
> I have a script that was discussed in a earlier talk thread (and is
> also attached to this thread). I am looking for a way to adjust the
> starting time with this script. Originally, this script reads in the
> entire file, and converts hourly to daily from the first time step in
> that file. I am looking at a time frame from 6UTC - 6UTC, so this script
> will need a offset.
>
> Comparing the raw input data with unit conversion (simply multiplied
> each 3 hr data by 10800, and summed up 8 time steps to get mm/day) with
> the script using the entire file gives the same values However, trying
> to change the ntStrt value, or doing a simple kitchen sink method to the
> input data (ie start the file one time step further) to accommodate the
> offset gives incorrect results.
>
> Checking values was done with a simple kitchen sink method,
> ncks -d time,0,40 -d xc,1,1 -d yc,1,1 .... to check values at a
> certain location, for simple comparison purposes.
>
> Any help is appreciated. I apologize if my question is a bit vague.
>
> ;*******************************************************************
> ; Load NCL library files.
> ;*******************************************************************
>
> load "/usr/local/ncl/lib/ncarg/nclscripts/csm/gsn_code.ncl"
> load "/usr/local/ncl/lib/ncarg/nclscripts/csm/gsn_csm.ncl"
> load "/usr/local/ncl/lib/ncarg/nclscripts/csm/contributed.ncl"
> load "/usr/local/ncl/lib/ncarg/nclscripts/csm/shea_util.ncl"
>
> begin
>
> ;********************************************************
> ; Read original NetCDF file. Input necessary
> ; files
> ;*********************************************************
>
> ;**********************************************************
> ; MAKE SURE you adjust the time the file reads (currently
> ; set at 3UTC - 3UTC) to time you want to analyze.
> ;**********************************************************
>
> fname = ("region_output.nc <http://region_output.nc/>") ; input
> precip data
> fin = addfile (fname,"r")
> prc = fin->pr ; (time,yc, xc) 3 hrly
> lat = fin->lats_region
> lon = fin->lons_region
> Lambert_Conformal = fin->Lambert_Conformal
> time = fin->time
>
> dimx3 = dimsizes(prc)
> NTIM = dimx3(0) ; TOTAL number of time steps
> print("NTIM="+NTIM)
>
>
> ;************************************************************
> ; Create daily averages.
> ;************************************************************
>
> ntJump = 8
>
> x = prc(::ntJump,:,:) ; trick: create array with meta
> printVarSummary(x) ; values will be overwritten with averages
> printMinMax(x,True)
>
> ntStrt = 0
> ntLast = ntJump-1
> do nt=0,NTIM-1,8
> x(nt/8,:,:) = (dim_avg_n_Wrap(prc(ntStrt:ntLast,:,:), 0))
> ntStrt = ntStrt + ntJump
> ntLast = ntLast + ntJump
> end do
> printVarSummary(x)
> printMinMax(x,True)
>
> x@info_tag = "daily average"
>
> ;**************************************************************
> ; Convert units kg/(m2-s) to mm/day
> ; multiply by (10^3mm m-1 x 86400 s day-1) and
> ; divide by density_H2O (1000 kg m-3):
> ; [kg/m2-s][1000 mm/m][86400 s/day][(1/1000) m3/kg] ==> mm/day
> ;**************************************************************
>
> x = x*86400.
> x@units = "mm/day"
> printVarSummary(x)
> printMinMax(x,True)
>
> ;******************************************************************
> ; Create a new nc output file
> ; Also output variables directly into created netcdf file
> ;******************************************************************
>
> system("/bin/rm -f daily_output.nc <http://daily_output.nc/>")
> ; remove any pre-existing file
> fout = addfile("daily_output.nc <http://daily_output.nc/>","c")
> filedimdef(fout,"time",-1,True) ; Makes time an
> UNLIMITED dimension (as suggested by NCL)
>
> fout->pr = x
> fout->lat = lat
> fout->lon = lon
> fout->Lambert_Conformal = Lambert_Conformal
>
> end
>
> --
> Sho Kawazoe
>
>
> ------------------------------------------------------------------------
>
> _______________________________________________
> ncl-talk mailing list
> List instructions, subscriber options, unsubscribe:
> http://mailman.ucar.edu/mailman/listinfo/ncl-talk
_______________________________________________
ncl-talk mailing list
List instructions, subscriber options, unsubscribe:
http://mailman.ucar.edu/mailman/listinfo/ncl-talk
Received on Mon Mar 29 20:07:29 2010