MATLAB: Load time from netcdf file and retain the ‘Hour’ value

Question

Hello,

I have a time variable (attached) that I created from using

netcdf_time = ncread('sample.netcdf','time');

When I use ncdisp on the netcdf file, time is described as the following:

   time     
             Size:       102272x1
             Dimensions: time
             Datatype:   int32
             Attributes:
                         units     = 'hours since 1900-01-01 00:00:0.0'
                         long_name = 'time'
                         calendar  = 'gregorian'

My question is, what do I do with the netcdf_time variable to get the time into matlab datenum format while retaining the 'hour'. I have used this based on online phishing

time = double(netcdf_time/24 + datenum('1900-01-01 00:00:00'));

But, datestr(time(1:7,1),'dd-mm-yyyy HH:MM:SS') returns

01-01-1980 00:00:00
01-01-1980 00:00:00
01-01-1980 00:00:00
02-01-1980 00:00:00
02-01-1980 00:00:00
02-01-1980 00:00:00
02-01-1980 00:00:00

When it should return

01-01-1980 03:00:00
01-01-1980 06:00:00
01-01-1980 09:00:00
01-01-1980 12:00:00
01-01-1980 15:00:00
01-01-1980 18:00:00
01-01-1980 21:00:00

Any ideas?

Answer 1

Instead of

 time = double(netcdf_time/24 + datenum('1900-01-01 00:00:00'));

(netcdf/24 is still happening in int32, hence you are loosing precision)

Try

 time = double(netcdf_time)/24 + datenum('1900-01-01 00:00:00');