Tide gage observation and Zref

Dear all

I try to use croco tools and I do not understand one point! My domain is the Adriatic Sea. Should I change Compare with tide gauge observations parts and Zref. or no need?

% Compare with tide gauge observations
%
lon0 = 18.37; % Example:
lat0 = -33.91; % Cape Town location
Z0 = 1; % Mean depth of tide gauge

And

% Level of reference for geostrophy calculation
%
zref = -1000;