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Summary

Action	Implementation of iceberg and ice shelf Fe source in PISCES
PI(S)	Renaud Person
Digest	see person et al. (2019), doi: 10.5194/bg-16-3583-2019
Dependencies	coupling with feshwater fluxes from ice shelf and iceberg
Branch	source:/NEMO/branches/2020/dev_r{REV}_{ACTION_NAME}
Previewer(s)	O.Aumont, C. Éthe
Reviewer(s)	O.Aumont, C. Éthe
Ticket	#2443

Description

Based on the development done with NEMO 3.6 of the representation of the missing external source of Fe from iceberg and ice shelf in the PISCES model

Implementation

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No macro or processor named 'box' found

External sources of biogeochemical tracers from iceberg and ice shelf. For instance, for dissoved Fe, a sediment content associated to a solubility fraction of sediment Fe is added to the freshwater fluxes of iceberg and ice shelf. For ice shelf, the parameterization of Mathiot et al. (2017) is used for the distribution of Fe throughout the water column. For iceberg, a homogeneous distribution until 120 m of depth is applied.

File dependency: feshwater fluxes from ice shelf and iceberg from observations and model climatology:

• runoff-icb_DaiTrenberth_Depoorter_eORCA1_JD.nc
• runoff-icb_DaiTrenberth_Depoorter_eORCA025_JD.nc

This file dependency didn’t exist for ORCA2 grid. I have build one but roughly interpolated. Another issue with the ORCA2 configuration is that the grid is not extended in the Antarctic. There is no representation of ice shelf cavities which are needed to model the distribution of freshwater flux under ice shelves with the parameterization of Mathiot et al. (2017) used in the present development.

Consequently, this external of source Fe will be disabled in the ORCA2 configuration.

• Activation in TOP: namelist_top

Creation of the trc_ais routine controllable in the TOP module and allowing to adjust the concentration of Fe and other biogeochemical tracers in icebergs and ice shelves through a loop over all the biogeochemical tracers. This AIS tracers source can be activated with a boolean in the namelist_top:

ln_trcais = .false. ! Antarctic Ice Sheet nutrient supply

!----------------------------------------------------------------------- &namtrc_ais ! Representation of Antarctic Ice Sheet tracers supply !-----------------------------------------------------------------------

rn_trafac(14) = 4.476e-07 ! ( 0.5e-3 / 55.85 * 0.05 )

!

nn_ais_tr = 1 ! tracer concentration in iceberg and ice shelf

! = 0 (null concentrations) ! = 1 prescribed concentrations

rn_icbdep = 120. ! Mean underwater depth of iceberg (m)

Warning: the isf source has to be activated in the namelist_cfg: parameter

ln_isf = .true.

then chose one of the two options for isf melt:

ln_isfcav_mlt = .false. or ln_isfpar_mlt = .true.

and activate runoff from icebergs

ln_rnf_icb = .true. ! freshwater flux from icebergs

Documentation updates

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Preview

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Tests

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Review

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No macro or processor named 'box' found

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