Testing dual-tracer CO+CO2 vs the single tracer systems

I've coded in my CO and CO2 inversions into a more general multi-tracer system. To test the multi-tracer system, at each step we will compare their inputs and outputs to the individual single-tracer systems.

• Are the CO and CO₂ emissions equal? Yes
• Are the CO and CO₂ point observations equal? Yes, except for station_id, which is expected to be different
• Are the RemoTeC and IASI observations equal? Yes
• Are the save_ files in the end equal? Yes
• Are the 3-hourly 3D mixing ratio fields equal? Yes
• Are the point and satellite output/track files equal? Yes
• Are the point and satellite departure files equal? Yes (CO₂ departures are different by ~10^-14, perhaps insignificant)
• Are the adjoint emissions equal? Yes (Again, different by 1 part in 10¹⁴, perhaps insignificant)
• Does the gradient test with two tracers converge? Yes
• Does 4DVAR give the same result as individual CO and CO₂ inversions? See next post