Sum area integration over latitudes

Hi,

I am trying to interpolate vector pr to 0.05 lat grid, a problem arise when I interpolate it to fit from 30 degrees South to 30 degrees North (phi), some values of the interpolation are NAN (Because of negative phi values)!!!! then I am trying to sum the following:

p=sum over 30 degrees south to 30 degree North of (p(i) cos(i)) where i is the latitudes

% close all
clear all

pr=ncread('data.nc','pr');

lat=1:32;

phi=(-30:0.05:30);
prl = interp1(lat,pr,phi,'linear');
%plot(lat,pr,'o')
%hold on
plot(phi,prl,':.');

n=1201;
ptot=0;
for i=n;
    p=prl(i)*cos(phi);
    ptot=ptot+p;
end

Answer 1

[KSSV]

USe:

prl = interp1(lat,pr,phi,'linear',1);

It does extrapolation also. If still is not working. Attach your .nc file here.

[Nadine]

Doesn't work, here's the pr file, you don't need the entire nc file

[KSSV]

Try spline instead of interp1

prl = spline(lat,pr,phi);

Remember always extrapolation is not suggested..you are extrapolating values to a large range.

[Nadine]

it works, but with:

pri=interp1(lat,pr,lati,'spline');

thnx