how can I take mean of fourth dimension of daily data?

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I have hourly data and I want to convert it into monthly mean.
I have daily data for 20 years (.nc files) and the structure of the daily data is 180 X 360 X 4 X 8, where 8 is hourly data. I want to take mean of 8hours that will represent observation of the day and then finally want to convert it into monthly.
Any kind of help would be appreciated.
Thanks
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Aarti Soni
Aarti Soni il 3 Ott 2022
Spostato: Cris LaPierre il 3 Ott 2022
Yes the SM variable contains NaN. I tried to save with values but the file size was exceeding the size (>5Mb), so I replaced all the values with NaN.
Cris LaPierre
Cris LaPierre il 3 Ott 2022
Modificato: Cris LaPierre il 3 Ott 2022
SM is an array of data type single. Singles are 32 bit numbers. So saving 75x100x4x8 = 240,000 singles at 4 bytes per number should yield a mat file size of approximately 960 KB, well under the 5 MB upload limit. Including Times and lev only adds 0.1 KB.

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Cris LaPierre
Cris LaPierre il 3 Ott 2022
Modificato: Cris LaPierre il 3 Ott 2022
I see your times are recorded as decimal days:
Times =
0
0.1250
0.2500
0.3750
0.5000
0.6250
0.7500
0.8750
Note that you have measurements taken at 4 levels each time (your 3rd dimension)
lev =
1
2
3
4
Therefore, the most logical way to me to compute a daily average is to compute the mean of the 8 SM values at each lon/lat pair and each level. This means the result will by lon x lat x lev (e.g. 50x50x4)
This cam be accomplished by useing the mean function and specifiying which dimension to take the mean in. Here, that is the 4th dimension, or time.
dayAvg = mean(SM,4);
Your file only contains information for a single day, so you would need to take the average of each file and then combine the results to compute a monthly average. Again, you will have a daily average for each leavel (4 values per lon/lat pair).

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