# [ncl-talk] Computing max of monthly NO2 data each year

Doumbia thiernodoumbia at yahoo.fr
Tue Sep 29 10:02:13 MDT 2015

```Hi Jack,
I really appreciate your teaching skills.

I recognize that there’s weird things in my script but I apologize for that, I am new in NCL.

Unfortunately, your suggestions don’t give the good results i.e. the maximum of monthly NO2 data for each year. I compared these results with those obtained from excel.

You are right, the "EU(120:395,0)” is for 1990 to 2012 (23 years).

Thierno

>
> ...
> “The results I’ve obtained aren’t what I expected.”
> ...
> Well, even Aristotle would struggle to figure out what you expected if you didn't tell him…
>
> Your script still got visible mistakes though. For example the loop is quite extravagant:
> …
>  k = ispan(0,11,1)
>  do n=0,7
>   do i = 0,275,12
>    do j=0,11
>      EUmax(n,:) = max(EU_plot(n,i+k(j))) <== “j” will always be the same type as, and equal to “k(j)”?
>    end do
>   end do
>  end do
> …
> and since the left side of your equation has a free dimension, the variable will always be overwritten up to the end of the loop.
>
> You can clean the loop and do something like,
>  do n=0,7
>     yr=0
>     k =0
>     do i = 11,275,12
>        EUmax(n,k) = max(EU_plot(n,yr:i))
>        k=k+1
>        yr=i
>     end do
>  end do
>
> I was also wondering whether from your file “EU(120:395,0)” will give you information from 2000 to 2012(12 years)? Probably that is the unexpected result you mentioned. Who knows?
>
> I hope that helps.
>
> Jack
>
>> On 29 Sep 2015, at 15:02, Doumbia <thiernodoumbia at yahoo.fr> wrote:
>>
>> Dear ncl users,
>>
>> I am trying to compute the monthly maximum NO2 in a yearly basis.
>>
>> My input file contains 7 columns representing different variables and 396 lines (monthly mean NO2 data from 1980 to 2012). I am only interested by the 2000-2012 period .
>>
>> The results I’ve obtained aren’t what I expected.
>> <max_of_monthly_data.ncl><Europe_bis_ncl.txt>
>> I will appreciate any help to resolve this.
>>
>> Please find attached my script as well as my input file.
>>