# Re: how to average months and then make the time series

```Hi Yogesh,
To get the series of three-month averages you need to define a new
time axis whose coordinages are every third point of the existing time
axis.  Then regrid your variable to that axis using the @AVE regridding
transformation.

! This is a list of the time points you want to use
yes? let timepoints = t[GT=CO2,t=2:48:3]

! Define a new time axis having the same time origin and coordinates
! at the list of timepoints

yes? define symbol time_origin = "`CO2,RETURN=T0`"
yes? define axis/T/T0=(\$time_origin)  time_3 = timepoints
yes? show axis time_3

yes? let C02_ave = CO2[GT=time_3@AVE]

Yogesh K. Tiwari wrote:

```
Dear Ferret Users,

I have netcdf data looks like :

--------------------------------------
currently SET data sets:
1> ./concat_tovs_data.cdf (default)

name title I J K L

CO2 CO2 concentration 1:360 1:180 ... 1:49
---------------------------------------

The data is on monthly interval.

Now if I run the following script :

*********************
*********************
use concat_tovs_data.cdf

set window/size=0.9
set window/aspect=1.7
ppl AXLSZE , 0

plot/nolab/vlim=300:360:5 CO2[x=@ave,y=25:20@ave,l=1:49]
plot/nolab/vlim=300:360:5/ov CO2[x=@ave,y=20:15@ave,l=1:49]-5
plot/nolab/vlim=300:360:5/ov CO2[x=@ave,y=15:10@ave,l=1:49]-10
plot/nolab/vlim=300:360:5/ov CO2[x=@ave,y=10:5@ave,l=1:49]-15
plot/nolab/vlim=300:360:5/ov CO2[x=@ave,y=5:0@ave,l=1:49]-20
plot/nolab/vlim=300:360:5/ov CO2[x=@ave,y=0:-5@ave,l=1:49]-25

************************
*********************

ferret plots the nice time series month by month ordered by 5 degree latitude interval.

Now what I want to do next :-

First I want to average each three month and then I want to plot three monthly averaged time series. Average something like following :

l=1:3@ave
l=4:6@ave
l=7:9@ave
........
.....
..
l=47:49@ave

Therefore how to average first three month and then next three month and
then next .............. and then plot the above time series.

Kindly help!!!!!!!!!!!!!

```