(with thanks to Michail Diamantakis)
For global mass conservation of air the following settings should be added in namelists:
&NAMDYN LMASCOR=true, LMASDRY=true,
(the above fixes the dry air mass only and leaves the fluctuation in the total mass due to moist parametrizations - annual water cycle)
The above turn on the spectral mass fixer.
&NAMCT0 NFRMASSCON=1,
(the above specifies that the mass fixer will be applied every step)
&NAMGFL YS_NL%LMASSFIX=true, YR_NL%LMASSFIX=true, YI_NL%LMASSFIX=true, YL_NL%LMASSFIX=true, YQ_NL%LMASSFIX=true, LTRCMFIX=true,
the above activates and controls the tracer mass fixer. It applies it on spec humidity, cloud water, cloud ice, cloud rain, cloud snow: YQ_NL, YL_NL, YI_NL, YR_NL, YS_NL IFS variables respectively.
An additional small code modification is needed in
ifs/control/tracmf.F90
Uncomment lines 112, 113, 114, 115,
112 !LTRCMFP=.TRUE. ! proportional 113 !LTRCMFA_LAP=.FALSE. ! additive based on hor. Laplace 114 !LTRCMFA_VER=.FALSE. ! additive based on vert. Lapace 115 !LTRCMFA_DIF=.FALSE. ! additiva based on abs gradient
Lot more work has been done on mass fixers at later versions.