How to mask out a certain region below a particular water depth or above a particular elevation with GEBCO_2019.nc dataset.
GEBCO_2019.nc is a global topographic and bathymetric chart with 15 arc-sec resolution which can be obtained from https://www.gebco.net/
Below is an example to mask out the ocean part with water depth below 200 m.
reinit sdfopen GEBCO_08.nc q file > set lon 128 147 set lat 30 46 set mpdset hires set map 1 1 10 set gxout shaded d elevation > define d200 = maskout(maskout(elevation, elevation-(-200)),0-elevation) d d200 cbarn > open surf_xxxx.ctl q file 2 define mask = const(d200,10,-u) d mask > set t 1 set z 1 define maskdata=lterp(mask,u.2(t=1)) d maskdata > d maskout(u.2(t=1),-maskdata) > draw title Wind resource within 200 m depth
