I want to interpolate onto different grid, how can I do this?

I want to interpolate a 365 x 3127 x 254 grid onto an 365 x 84 x 180 grid. What is the best way to do this?

I think I should use interp2 (see code below) but I get the error 'Subscript indices must either be real positive integers or logicals.'. I have checked this answer but I can't seem to fix it so I ask if there is an easier way to do this?

clear
clc

load '/work/uo0122/u253082/REF.mat'

weight = cos(REF_lat);

lon = ones(180,84);
lat = ones(84,180);
lat = lat';

for yr = 1993%:2010;
    yr
    load(['/work/uo0122/u253082/Mat_Time/ssh_',num2str(yr),'.mat']);   
    ssh = ssh_int;

      mask = zeros(size(ssh_int)); 
      mask(find(ssh_int > -9E33)) = 1;
      mask = repmat(mask,1,365);

      ssh = ssh.*mask

      for day = 1:size(ssh,1);
          ssh(i,:,:) = interp2(REF_lon,REF_lat,squeeze(ssh(i,:,:)),lon,lat,'linear');
      end

        end

I tried getting rid of NaN's in SSH with no fix and also converting every variable to logical format with no fix. REF_lat & REF_lon = 3127 x 254 reference long and lat. SSH is a 365 x 3127 x 254 matrix and contains NaN's.

Many thanks for your attention! Michael

[Michael]

I can't seem to see your answers supersyrena baklad and zcrom...