How can I write missing value ncwriteatt

I created a netcdf file with attributes correctly, but I tried to add also missing value (1.0000e+20) as number to variabel attribute part, I encountering with error. Does anyone know where my mistake is so that I can correct it. I tried below command.

missing_value = 1.0000e+20;
missing = string(missing_value);
ncwriteatt(outputfile,'salinity','missing_value','missing')

Error using netcdflib

The NetCDF library encountered an error during execution of 'putAttText'

function - 'Not a valid data type or missing_value type mismatch (NC_EBADTYPE)'.

Thanks!

[Walter Roberson]

ncwriteatt(outputfile,'salinity','missing_value',missing)

would be more likely.

... But I suspect that you want

ncwriteatt(outputfile,'salinity','missing_value',single(missing_value))

[Farshid Daryabor]

Thanks!

What about 'NaN' value as missing_value, it should be;

ncwriteatt(outputfile,'salinity','missing_value',single(NaN))

Answer 1

[Walter Roberson]

You cannot set the _FillValue of a variable after the variable is created.

https://www.mathworks.com/help/matlab/ref/nccreate.html#d126e1053932

FillValue — Replacement value for missing values

scalar | "disable"

Replacement value for missing values, specified as a scalar or "disable". The default value is supplied by the netCDF library. To disable replacement values, specify a value of "disable". You cannot disable FillValue when writing string data to files with format netcdf4.

Note

The nccreate function assigns the value of FillValue to the _FillValue attribute of the new netCDF variable varname. You cannot change the value of this attribute after you have created the variable.

This argument is available only for files with format netcdf4 or netcdf4_classic.