Technique to delete spin-up frames from WRF I'm a user of WRF V3.5 aiming at  meteorological simulation.
Sometimes, I'll run the model for a long period.     

My attempt

I split the long period(e.g 1 year) into serval short ones.    

For example:    

 ## WPS namelist.wps      
 start_date = '2014-01-01_06:00:00'
 end_date   = '2014-01-31_23:00:00'  

 ## WRF run period setting in .csh file.    
 set year = "2014"
 foreach strtime (010106010512 010500011012 011000011512 011500012012 012000012512 012500013012 013000020100)

 set smon = `echo ${strtime}|cut -c1-2`
 set sday = `echo ${strtime}|cut -c3-4`
 set shr  = `echo ${strtime}|cut -c5-6`
 set emon = `echo ${strtime}|cut -c7-8`
 set eday = `echo ${strtime}|cut -c9-10`
 set ehr  = `echo ${strtime}|cut -c11-12`  

 &amp;time_control
 run_days                            = 0,
 run_hours                           = 132,
 run_minutes                         = 0,
 run_seconds                         = 0,
 start_year                          = ${year},${year},
 start_month                         = ${smon},${smon},
 start_day                           = ${sday},${sday},
 start_hour                          = ${shr},${shr},
 start_minute                        = 00,00,
 start_second                        = 00,00,
 end_year                            = ${year},${year},
 end_month                           = ${emon},${emon},
 end_day                             = ${eday},${eday},
 end_hour                            = ${ehr},${ehr},
 end_minute                          = 00,00,
 end_second                          = 00,00,
 interval_seconds                    = 21600


In these short period, I set the first 12-h as the spinning period(except the start one.)        

This is the schematics of the temporal  modeling setup which I clipped from the Internet.   

http://i12.tietuku.cn/afd906ddd823ddd6.png   

Result

It generate 8 .nc file which each contain 132 frames of data.
For now, I use the The netCDF Operators(NCO) to deal with the output files.     


Using ncks to delete the first 12-h frames for each file separately.
Using ncrcatto concat all 8 .nc files together to get one file represent the whole simulation period.   


Problem

I was using this method for a while. But when the amount of files are huge, it really a dump approach.      

Are there someone offering your approaches to dealing with spin-up data deletion?      

My target


The model can generate only one file which contain all the simulation period.   
The spin-up time can be covered by last file's frames automatically. 


Update: Wish you share your approaches!
Here is my  present approach.    


All wrfout-files are located in the same path.
Using pynco in python loop to split the spin-up dataframe

import glob
nco = Nco()
for fn in glob.iglob('*.nc'):
    filename, extname = os.path.splitext(fn)
    output_fn = filename[11:22] + str(int(filename[22:24]) + 12) + extname
    nco.ncks(input=fn, output=output_fn, dimension='Time,13,')  



The input shows like: 2014-04-04_12.nc(120 frame inside)
The output shows like:wrfout_2014-04-04_00:00:00.nc(133 frame inside)