[gradsusr] help in monthly average precipitation script for aphrodite data

[Muhammad Rahiz]

Dear Waheed,

A quick query and a suggestion which follows. If you're trying to get 
the monthly average for May (t=121,t=151) for each year which you've done 
by 'p53=ave(precip,t=121,t=151)', why do you need to issue 'sum7=sum6+p58' 
which suggests a cumulative total?

You could condense the script by creating a loop (not tested);

*** Start of script ***
m = 1
while(m <= 10)		# 10 = 1951-1960
  ifile = 'files.txt' 	# files.txt contains a list of your netcdf files
  rec = read(ifile)

  IO = sublin(rec,1)
  if(IO = 1)
    say ifile' > File open error'
  endif
  if (IO = 0)
    a = subwrd(rec,2)
  endif

'sdfopen 'a''
say ''
say ' Filename: 'a''
say ' File no: 'm''

'set lat 23.025 37.475'
'set lon 60.025 79.975'
'define var=ave(precip,t=121,t=151)' # change values if leap year

'set sdfwrite yr.'m'.nc
'sdfwrite 'var'

'close 1'
m = m + 1
endwhile
'quit'
*** End of script ***

What this does is to produce the May average for each year and write the 
output to a separate file for each year. The sdfwrite command does not 
allow to write >1 variable to a file. But this can be overcome by 
concantenating the files using other utilities like NetCDF operators, CDO.

Since you're dealing with leap years, you could specify the files 
containing leap years in files.txt and change the 't' values and repeat 
the step for non-leap years.


-- 
Muhammad Rahiz
Researcher & DPhil Candidate (Climate Systems & Policy)
School of Geography & the Environment
University of Oxford

On Thu, 10 Mar 2011, Waheed wrote:

> Dear all
>  
> Grads version: 2.0.a8
> OS : RHL 5 (32bit).
>  
> i am trying to find the monthly average precipitation from yearly nc files  of daily data.
> i want to get ouput in nc format but monthly average for each month.
> dkiktev had sent me a script and i made modifications in it. now i m running it for 10
> years from 1951-1960 for the month of May . But i am having trouble with it.
>  
> the script is as follows :
> * monthly average for the month on May from 1951-1960
>  
> 'sdfopen 1951.nc'
> 'set lat 23.025 37.475'
> 'set lon 60.025 79.975'
> 'define p51=ave(precip,t=121,t=151)'
> 'close 1'
> 'sdfopen 1952.nc'
> 'set lat 23.025 37.475'
> 'set lon 60.025 79.975'
> 'define p52=ave(precip,t=122,t=152)'
> 'define sum1=p51+p52'
> 'close 1'
> 'undefine p51'
> 'undefine p52'
> 'sdfopen 1953.nc'
> 'set lat 23.025 37.475'
> 'set lon 60.025 79.975'
> 'define p53=ave(precip,t=121,t=151)'
> 'define sum2=sum1+p53'
> 'undefine sum1'
> 'undefine p53'
> 'close 1'
> 'sdfopen 1954.nc'
> 'set lat 23.025 37.475'
> 'set lon 60.025 79.975'
> 'define p54=ave(precip,t=121,t=151)'
> 'define sum3=sum2+p54'
> 'undefine sum2'
> 'undefine p54'
> 'close 1'
> 'sdfopen 1955.nc'
> 'set lat 23.025 37.475'
> 'set lon 60.025 79.975'
> 'define p55=ave(precip,t=121,t=151)'
> 'define sum4=sum3+p55'
> 'undefine sum3'
> 'undefine p55'
> 'close 1'
> 'sdfopen 1956.nc'
> 'set lat 23.025 37.475'
> 'set lon 60.025 79.975'
> 'define p56=ave(precip,t=122,t=152)'
> 'define sum5=sum4+p56'
> 'undefine sum4'
> 'undefine p56'
> 'close 1'
> 'sdfopen 1957.nc'
> 'set lat 23.025 37.475'
> 'set lon 60.025 79.975'
> 'define p57=ave(precip,t=121,t=151)'
> 'define sum6=sum5+p57'
> 'undefine sum5'
> 'undefine p57'
> 'close 1'
> 'sdfopen 1958.nc'
> 'set lat 23.025 37.475'
> 'set lon 60.025 79.975'
> 'define p58=ave(precip,t=121,t=151)'
> 'define sum7=sum6+p58'
> 'undefine sum6'
> 'undefine p58'
> 'close 1'
> 'sdfopen 1959.nc'
> 'set lat 23.025 37.475'
> 'set lon 60.025 79.975'
> 'define p59=ave(precip,t=121,t=151)'
> 'define sum8=sum7+p59'
> 'undefine sum7'
> 'undefine p59'
> 'close 1'
> 'sdfopen 1960.nc'
> 'set lat 23.025 37.475'
> 'set lon 60.025 79.975'
> 'define p60=ave(precip,t=122,t=152)'
> 'define sum9=sum8+p60'
> 'undefine sum8'
> 'undefine p60'
> 'close 1'
> 'define pave=sum9/10'
> 'set sdfwrite waheed.nc'
> 'sdfwrite pave'
> 'quit'
>  
> It gives an error " define error : no files open yet"
>  
> any suggestions for this script or if there is something better please tell .
>  
> Thanx in advance
>  
>  
> Best regards
> --
> Waheed Iqbal
>  (Meteorologist)
> Pakistan Meteorological Department
> R & D Islamabad,Pakistan
> +923334547814
>  
>  
> 
>