Calculating seasonal mean of precipitation from 25 years daily data

Hello,

I have precipitation data for 25 years in excel. My data is arranged like this: year(column 1), month(column 2), day(column 3), precipitation(column 4). how can i calculate seasonal mean from this data please?

Answer 1

[Ameer Hamza]

See retime(): https://www.mathworks.com/help/matlab/ref/timetable.retime.html

[tshering lhamo]

Thank you! i have used retime to calculate the monthly and yearly means but im lost when it comes to seasonal mean. Im still a beginner in MATLAB. Can you please help me how to go about with seasonal calculation.

This is the code i used for the monthly and yearly means:

Time=datetime(stationdat(:,1),stationdat(:,2),stationdat(:,3));
precip=stationdat(:,4);
TT=timetable(Time,precip);
TT_mth=retime(TT,'monthly','mean');
TT_yr=retime(TT,'yearly','mean');

[Ameer Hamza]

How do you define seasons? Can you tell the range of months each season last?

[tshering lhamo]

december, january, feb would be winter months. march,april,may-spring; june,july,august- summer : sept,oct,nov-autumn

[tshering lhamo]

the data starts from 1st jan 1996- 29th febuary, 2020

[Ameer Hamza]

You can also pass the new time vector to the retime. In the new time vector, specify the months at which you want values. Following start from January, then add March and then add intervals of 3 months.

t = datetime(2000, 1, 1):calmonths(1):datetime(2001, 12, 1);
t_new = [datetime(2000, 1, 1) datetime(2000, 3, 1):calmonths(3):datetime(2001, 12, 1)]; % start from March

T = timetable(t.', (1:24).');
T_new = retime(T, t_new);

[tshering lhamo]

this would give me values of each season of every year is it correct? is it possible to get the seasonal values of all 25 years together? such that the end result has only 4 mean values(one for each season)

[Ameer Hamza]

Can you attach a sample dataset in a .mat file. It will be easier to suggest a solution.

[tshering lhamo]

this is my dataset and thank you!

[Ameer Hamza]

I am not able to load this file. This seems to be some issue in creation of this file.

[tshering lhamo]

i have reattached the data file, this should work

[Ameer Hamza]

If you want just for values for mean across all the years, then the following will work

seasons = {[12 1 2], [3 4 5], [6 7 8], [9 10 11]};

mean_values = zeros(size(seasons));
for i = 1:numel(seasons)
    idx = ismember(month1, seasons{i});
    mean_values(i) = mean(prcp(idx));
end

[tshering lhamo]

thank you very much!

[Ameer Hamza]

I am glad to be of help!

[Jesper Sam]

Thanks please all this discussion and code are very helpful. I have monthly data 1981 to 2016, i want seasonal values

Can you please help me to how to write a code in such a way that i get mean of seasons like this; first col is mean avalue for 3 month and the second col of mean values of next three months

Thanks