Iris-flux computation

[pletzer]

Given a target line specified as a set of (lon, lat) points, compute the lateral flux across the line.

In file:
iris_flux.py

Write a class that implements

flux_calc = IrisMintFlux(src_mesh, src_flags, tgt_line)
value = flux_calc.evaluate(field_cube)

Here:
src_mesh: Iris mesh object
src_flags: flags to pass to the constructor, eg (1,1,1) for cubed-sphere
tgt_line: array of points [(x0,y0), (x1, y1), ...] where x0, y0 ... are longitude-latitude pairs
field_cube: field cube

• Decide on the API
• Implement the API
• Test the API

[pletzer]

Question:

What should we do for 3d field? MINT currently only integrates on the horizontal plane, essentially performing a line integral instead of a surface integral. In principle one would need to multiply the contributions from line segments inside each cell by dz, the height in metre of the cell, which can vary from cell to cell.

[pletzer]

Also need a method

def flux_calc.evaluate_from_vector(u_cube, v_cube)