How to use interpolation to transform data of one resolution onto the same grid as data of another resolution?

I have bathymetry data at a 2-minute resolution, for an 8 degree by 10 degree area over the bay of Biscay, and chlorophyll satellite data, for the same area, at a 9km resolution.

I need to use an appropriate interpolation technique to transform the chlorophyll dataset for the area onto the same grid as the bathymetry dataset.

Any pointers? I don't even know where to start I tried to read the grid-based interpolation section on matlab but I just couldn't get my head round it.

Oh and there are 60 minutes in a degree if longitude/latitude and 111km in a degree.

Thank you!!

Answer 1

[Chad Greene]

A clarification: There are about 111 km in a degree of latitude, but that relation is not valid for longitude.

Do you have any projection information for the chlorophyll data set? If yes, project the lat/lon bathymetry grid to some meters northing/easting using the same projection as the chlorophyll data. Then use interp2 to interpolate bathymetry data to the chlorophyll grid. Syntax would look like this:

[BathyX,BathyY] = someCoordinateTransformation(BathyLat,BathyLon); 
BathyZinterp = interp2(BathyX,BathyY,BathyZ,ChlorX,ChlorY);

This or this might help for coordinate transformations, depending on the projection of your chlorophyll data.

Do you have the mapping toolbox, by chance? Type license('test','map_toolbox'). If the answer is 1, you have the mapping toolbox.

[Chad Greene]

Or, if your bathymetry data are in .tif format, geotiffinterp will do all the thinking for you.

[Emma Whettall]

Thank you for your help. I haven't had chance to have a good go at it yet but I'm going to try tomorrow.

Oh and I do have the mapping toolbox.

[Judith Ewald]

I am just working on something similar, and I think your answer was very helpful, but shouldn't it be the other way around, since she wanted to project chlorophyll data onto the same grid as of the bathymetry data? Would your suggestion not lead to the interpolation of the bathymetry data and projection on the chlorophyll grid? Thank you!