Extra WLC diagnostic in ropp_pp

[Ian Culverwell]

User Kjartan Kinch has raised the following request, on behalf of Hans Gleisner:

The variable we would like to include in the list of diagnostic quantities is an array that measures the weight of the observation contribution in the optimized bending angle. This weight is an array of numbers between 0 and 1. A weight of 1 at a given impact parameter indicates that at this height the optimized bending angle is 100% data, in other words the optimized bending angle is identical to the raw bending angle at this height. If the weight is 0 the optimized bending angle is 100% MSIS with no contribution from the data. The array of weights will gradually transition from numbers close to zero at high altitude to numbers close to one at low altitude.



I am attaching 3 Fortran code files (made by Hans) that demonstrate a possible implementation. These are modified versions of ropp_pp_occ_tool.f90, ropp_pp.f90 and ropp_pp_ionospheric_correction.f90. They are based on ROPP 5.0 and you should be able to proceed from these without to much trouble. Changes are marked with !HGL (although there might be a few changes that slipped in without this comment)



The solution implemented here adds the variable WLC to all three routines and the internal variable WLCH inside ropp_pp_ionospheric_correction.f90. Both variables represent the array of weights, just at two different sets of impact heights. The values are calculated in WLCH and then interpolated to form WLC, which is added to the output. 



In this implementation WLC is just added to standard output. It is probably more reasonable to add it to the diag structure and only add it to the output if the diag = .true. flag is set.



The extra argument to ropp_pp_ionospheric_correction.f90 is made OPTIONAL since we weren't sure that we know all the routines that called this. You might want to implement it differently

The programs are attached.

Sounds fair enough to me. I asked Hans Gleisner for comparison files to test.