Suggested fixes for atmospheric N and P deposition diagnostics

[MichaelBarryBMT]

Hi Matt and Casper

This pull request is around atmospheric N and P deposition diags. I have come across it because I am trying to do mass balance calcs for the WQM manual. I think there are two things worth looking at:

1) In both the N and P atm deposition sheet diags, the update to the _DIAG_VARS(data%id_atm_dep) array adds the new atmospheric fluxes at each timestep (which is fine), but also adds itself. I think this means that the atmospheric sheet diags report cumulative atmospheric deposition, (which is what I am seeing) which is not consistent with the other sheet diags such as sed fluxes. My suggested fix is to just have the _DIAG_VARS(data%id_atm_dep) bet set to the FLUX_VAR_T's and nothing else (for both N and P). I don't think this affects the actual fluxes (the N is added), but the diags are not consistent with the fluxes so it is confusing to reconcile both.

2) The P atmospheric deposition _DIAG_VARS only adds wet deposition fluxes to the sheet if adsorption is simulated. This means that a user not simulating adsorption gets zeros for the atmospheric flux of P in the diagnostic, even if they specify rainfall and TP concentrations. I think the actual flux is fine (the P gets added) but the diagnostic doesn't reflect this flux (and my mass balances are broken!) and it is again confusing.

Thanks!!

MB

[matthipsey]

Im happy with these - thanks for the updates!

[MichaelBarryBMT]

Ta Matt - this is great!