area mean with 2d latitude and longitude coordinates

[Andrew Schurer]

Hi,

I am trying to calculate an area mean for a tri-polar coordinate system which has 2D auxiliary coordinates for latitude and longitude. 

sea_surface_temperature / (degC)    (time: 3012; -- : 22; -- : 15)

     Dimension coordinates:

          time                           x          -        -

     Auxiliary coordinates:

          latitude                       -          x        x

          longitude                      -          x        x

I'm aware that one way to do this would be to regrid it to a regular lat-lon grid and then calculate the area mean using cube.collapsed on the new coordinate system.

I was just wondering though if this was the best method or whether there was any way in iris to do this on the native gird?

Many thanks,

Andrew