Does this mean that Julia and gmt simply ignore that 0 is NAN in the .tif datafile? gdalinfo reports NoData Value=0, Python/rioxarray provides an indication: _FillValue: 0.
gdal_translate LC2013.tif LC2013.nc
gmt grdimage LC2013.nc -png quick -R99.4/99.45/38.34/38.35 -B
the result, a NAN color is assigned and used:
gdal_translate -ot Uint16 LC2013.tif LC2013-uint16.tif
gmt grdimage LC2013-uint16.tif -png quick -R99.4/99.45/38.34/38.35 -B
result, presence of NAN (NoData Value=0) seems ignored, zeroes are part of the color scale:
also, the color bar seems to include different data ranges (out of 1-8) when plotting .nc and .tif.