PBLH devt4: Investigate sensitivity of PBLH to vertical resolution

[Ian Culverwell]

The ROPP9.0 beta reviewer recommended

Make the vertical sampling of RO profiles to be 100 m or even 
smaller, e.g., 10-50 m to minimize the interpolation errors in the 
gradient method. This could be especially important for bending 
angle profile.

Generally, the vertical resolution of observed or model fields is not under the user's control, of course. But if the reviewer means that the fields should be interpolated to a higher resolution before calculating the vertical gradients, then it is not clear at first sight that this would be helpful. (Linear interpolation from a coarse grid to a fine grid would generate piecewise constant gradients with discontinuities at the data points. The current ROPP method is based on linear interpolation of the gradients between their (2nd order accurate) values halfway between the data points. It is not clear that this is worse. However, the issue needs logging and investigating - eventually.

[Ian Culverwell]

This should probably be mooted for ROPP10.0, along with the other PBLH devt tickets.