we'll also predict tidal transports. 
% 
% Some notes: 
% 
% # We'll solve transports on a 0.2 degree grid, but we'll only plot
% vectors on a 3 degree grid. This requires anti-aliasing. 
% # Technically, we should solve tides on the native 1/30 degree grid, then
% lowpass filter to 6 degrees or a little more, then interpolate to a 3
% degree grid. That would produce anti-aliased transports that meet the
% Nyquist criteria. Instead, we'll do this sort of hybrid approach, where
% we'll solve transports on a 