How to resolve grid resolution for Longitude-Time (Hovmuller) diagram on GMT?

Q&A
5 
INCREMENT=-I0.025/43200
ROI=$(gmt gmtinfo NGoG_U10_1.txt -I0.25/86400)
gmt surface NGoG_U10_1.txt $ROI $INCREMENT -GNGoG_U10_1_M_surface.nc
gmt grdimage NGoG_U10_1_M_surface.nc -B -png quick -Cvik

quick
quick1970×1985 448 KB