Interpolation Effects

Every interpolation technique has its advantages and disadvantages.  When the interpolation grid length is significantly more coarse than the NWP model grid, any small-scale variability might misleadingly appear to represent larger scales.  If the interpolation is made to a location close to one of the grid points it will more or less take this value, even if it happens to represent a small-scale extreme.  Only if the interpolation point is in the centre of a set of points on the native grid will such an extreme be smoothed out.  This means that some points on an interpolated grid can have a tendency to show extremes more than others.  However the tendency for some points on the grid to show extremes more than others depends also on the method of interpolation adopted.  One can use a "nearest neighbour" approach to circumvent this issue, but this would be at the expense of losing some information.