Re: [ferret_users] remove annual mean

[Martin Schmidt <martin.schmidt@xxxxxxxxxxxxxxxxx>]

Dear Ektaraful,

this could be done this way. Best, do it step by step, you may verify 
the results. It is done with four lines:

1.) Define a time axis covering the time span of your data with time 
marks in July each year. Here a possible example:

define axis/t=1-jan-2000:31-dec-2004:1/edges/unit=years/cal=julian tax_year
list t[gt=tax_year]

You may chose another calendar. It should be the same like in your data set.

2.) Put your data on this axis using the @ave transformation

let your_data_yearly = your_data[t=tax_year@ave]

It depends on the shape of your data (1d, 2d, 3d) how to verify the 
result.  Best you plot time series.

3.) Put the yearly data back onto the monthly time axis using the @NRST 
transformation. This generates a variable
that is constant throughout each year. Its value is the yearly average.

let your_data_yearly_monthly = your_data_yearly[t=tax_year@NRST]

It depends on the shape of your data (1d, 2d, 3d) how to verify the 
result.  Best you plot time series.

4.) Subtract the yearly average

let your_data_monthly_anomaly = your_data - your_data_yearly_monthly

For the meaning of the transformation, definition of axes etc. please 
visit the ferret manual.

Good luck,
Martin
On 08/17/2016 12:04 PM, ektaraful . wrote:
> Dear ALL,
>
> I want to remove annual mean from olr monthly mean  data? How can I do 
> that?
>
> Thanks and regards