[ncl-talk] Running the NCL code becomes slower

[Zhifeng Yang]

Hi

I am trying to read SEVIRI data with a lot of variables and the dimension
of each variable is 3712*3712. I know the data are pretty large. But the
computer should read them smoothly. Since the memory that I specified is
about 50GB. Unfortunately, the code is becoming slower and slower while it
do the time loop. Here is a sample of my code.

;  SET UP THE START TIME AND END TIME
   start_year = 2008
   end_year   = 2008
   start_month= 6
   end_month  = 6
   start_day  = 1
   start_hour = 0
   end_hour   = 23
   start_min  = 0
   end_min    = 45
   min_stride = 15
   start_ind_lat = 1400
   end_ind_lat   = 3000
   start_ind_lon = 1100
   end_ind_lon   = 2600

;  DO YEAR LOOP
   do iyear = start_year, end_year

;  DO MONTH LOOP
      do imonth = start_month, end_month

;  CALCULATE THE NUMBER OF DAYS IN THIS MONTH
         nday_month = days_in_month(iyear, imonth)
;  DO DAY LOOP
         do iday = start_day, 10;nday_month
;  DO HOUR LOOP
            do ihour = start_hour, end_hour
;  DO MINUTE LOOP
               do imin = start_min, end_min, min_stride
;  READ VARIABLES FROM HDF FILE
                     a     = addfile(dir + siyear + "/" + symd1 + "/" +
filename, "r")
                     lat   = (/a->MSG_Latitude(start_ind_lat:end_ind_lat,
start_ind_lon:end_ind_lon)/)
                     lon   = (/a->MSG_Longitude(start_ind_lat:end_ind_lat,
start_ind_lon:end_ind_lon)/)
                     Cloud_Optical_Thickness_16 =
a->Cloud_Optical_Thickness_16(start_ind_lat:end_ind_lat,
start_ind_lon:end_ind_lon)

               end do ;imin
            end do ;ihour
         end do ;iday
      end do ;imonth
   end do ;iyear


Thank you
Zhifeng
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