Model L1 and L2 bending angles by means of model ionosphere

[Ian Culverwell]

Assume (single) Chapman Layer ionosphere, then model L1 and L2 directly. Ideally retrieve too.

[Ian Culverwell]

Postpone to 7.0

[Ian Culverwell]

Working OK in ROPP71_prototype branch. Implies widespread changes to ropp_fm and ropp_1dvar, and some minor changes to the structures in ropp_io. All these changes are protected by direct_ion flags, so that the default behaviour is unaffected.

L1 and L2 bending angles are modelled in ROPP by extending the state vector to hold 3 ionospheric parameters, eg for ECMWF state vectors:

state = {temp, shum, pstar, Ne_max, H_peak, H_width}.

The observation vector is doubled in length:

bangle = {bangle_L1, bangle_L2}.

All this is handled internally; the user can input the usual files, and obtain the usual files, except that the bangle_L1 and bangle_L2 slots in the output files will be filled with the results of the new forward model.

For more details see the ROPP FM/1DVAR User Guide.

[Ian Culverwell]

Passes ROPP test folder OK (there are new standard "compile" tests of this feature for the FM and 1DVAR modules), so closing the ticket.