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1. Summary
2. Preview
3. Tests
4. Review

Summary

Action	Validation of the TOP Antarctic Ice Sheet Tracer Module
PI(S)	Person R.
Digest	Validation of AIS iron source in eORCA1
Dependencies	If any
Branch	source:/NEMO/branches/{YEAR}/dev_r{REV}_{ACTION_NAME}
Previewer(s)	O. Aumont, C. Ethé
Reviewer(s)	O. Aumont, C. Ethé
Ticket	#2656

Description

• NEMO trunk rev: 14723
• Configuration : eORCA1

Validation of the TOP trcais.F90 module for representing the external source of biogeochemical tracers from icebergs and ice shelves, currently active for dissolved Fe.

The validation consists of activating the AIS source of Fe in namelist TOP with open and non-open ice shelf cavities in eORCA1 configuration grid and comparing the results with the respective control experiment, i.e., with open or non-open ice shelf cavities (CTL_CAV and CTL_PAR, respectively), in which the external source of Fe is not activated.

Each experiment have a duration of 10 years.

Implementation

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Documentation updates

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Preview

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Tests

Results of the validation experiments:
See attached plots of surface Fe anomalies (relative to CTLs) for resolved (Fig.1.2) and parameterized (Fig.2.2) ice shelf cavities (Fig.1 and Fig.2 are wrong but don't know how to removed them from the wiki page) when activating Fe input from the Antarctic Ice Sheet (nn_ais_tr = 1, prescribed tracer concentration in iceberg and ice shelf).

• The addition of Fe from the AIS in both ice shelf cavity cases results as expected in a net positive effect on surface Fe concentrations relative to CTLs.
  
• Fig.3 shows the surface Fe anomalies when the AIS Fe source is activated between the open and non-open cavity experiments. This illustrates the potential impacts that seawater circulation in ice shelf cavities and Fe inputs associated with this circulation as well as direct inputs from melting ice shelves could have on surface Fe concentrations in the Southern Ocean. However, the seawater properties with open ice shelf cavities have not been initialised correctly for T, S and nutrients. A run should be performed once the initial condition files in the cavities are constructed (see work by K. Hutchinson).

The model outputs are available on jeanzay (idris)

• CTL_PAR run : /gpfsstore/rech/omr/romr014/IGCM_OUT/NEMO/DEVT/clim/eOR1Si3Pv4-CLIM-CORE-CTL
• CTL_CAV run: /gpfsstore/rech/omr/romr014/IGCM_OUT/NEMO/DEVT/clim/eOR1Si3Pv4-CTL-CAV/
• ice shelf cavities parametrized (nn_ais_tr = 1): /gpfsstore/rech/omr/romr014/IGCM_OUT/NEMO/DEVT/clim/eOR1Si3Pv4-AISFe-PAR1
• ice shelf cavities resolved (nn_ais_tr = 1): /gpfsstore/rech/omr/romr014/IGCM_OUT/NEMO/DEVT/clim/eOR1Si3Pv4-AISFe-CAV1

Review

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