Supporting model output for article "Assessing the potential impact of river chemistry on Arctic coastal production"

The following is a summary of processed model output data from a series of HiLAT model runs.
A description of the model runs and visualization of model output and analysis can be found in the
accompanying manuscript.

Gibson G. A., Elliott, S., Piliouras, A. Clement Kinney, J., Jeffery, N. (2022) Assessing the potential
impact of river nitrate on coastal production in the Arctic. Frontiers in Marine Science: Coastal Ocean
Processes.

This work was supported by the Regional and Global Model Analysis (RGMA) program of the US
Department of Energy’s Office of Science as a contribution to the HiLAT project. Additional support for
this project was provided by the National Science Foundation, under award #173886.
 

River Nutrient Forcing

The experiments involved modifying the nutrient concentrations in the river nutrient forcing files.
The river nutrient files are specified during model setup. For use in the HiLAT model, GNEWS annual
river nutrient inputs were partitioned into twelve monthly forcing values. The nearest ocean grid point
to each of the GNEWS river mouth locations was identified and then, as with the runoff, the nutrient
inputs for each river basin were spatially mapped to surface ocean model grid cells, which are 10 meters
thick, such that the spatial pattern of river nutrient dispersion follows river water inputs to the oceans.

The experiments were:
i) The baseline model simulation: The 12 monthly values for each grid cell were constant in time.
river_nutrients_GNEWS2000_gx1v6.nc
ii) an experiment in which baseline Arctic River Nitrogen (NO 3 and NH 4 ) concentrations were doubled.
river_nutrients_GNEWS2000_gx1v6_x2Arctic.nc
iii) an experiment in which baseline Arctic River Nitrogen (DON and DIN) concentrations were scaled to
the river volume discharge contained in runoff.daitren.iaf.20120419.nc
river_nutrients_GNEWS2000_gx1v6_scaled_climatology.nc
iv) an experiment in which the scaled river nutrient discharge (iii) was shifted earlier by two months.
river_nutrients_GNEWS2000_gx1v6_shifted2m_climatology.nc
v) an experiment in which the scaled river nutrient discharge (iii) was shifted earlier by a month and
doubled in concentration.
river_nutrients_GNEWS2000_gx1v6_shifted_climatology_x2.nc

River nutrient fluxes are in units of nmol/cm2/s
Only concentrations within the domain TLONG>=60 &TLONG <=340 & TLAT >=60 were modified in
concentration/timing.

Variables of interest:
din_riv_flux: dissolved inorganic nitrogen river flux
don_riv_flux: dissolved organic nitrogen river flux

Each of the experiments is described in detail in Gibson et al (2022).

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There are multiple versions of most output file types, corresponding to the river nutrient experiments that
were conducted.

Many variables in the output files are regional averages where model regions are indicated by a number
*note - for aesthetics, the numbering used in the model output files differs slightly from the numbering
used in the accompanying manuscript. The numbers assigned in the analysis files aligns with the numbers
assigned to regions within the region mask provided in the grid file.

Grid File/region masks
gx1v6_polar_mask_coast.5.22.20c.nc This file is an updated version of the standard grid file. It has been
updated to include the addition of a coastal Arctic region variable ‘Arctic_Coast_Mask’ which indicates
which grid cells are in the coastal regions used in the analysis and the Arctic_Region variable which
indicates which grid cells are in the broader regions.

Variables contained in this file are:
Arctic_Coast_Mask: contains values 0-9 indicating which (if any) coastal region a grid cell is in
Arctic_Region Mask: contains values 0-11 indicating which (if any) region a grid cell is in

TLAT: latitude of grid cell
TLONG: longitude of grid cell
TAREA: Area of grid cell
HT: Bathymetry of grid cell

Model outputs that were analyzed in the manuscript are contained in three different kinds of output file.
For each file type a file exists for each river nutrient experiment.

The following series of files contains variables related to the particulate organic carbon flux to the
sediment, demineralization and remineralization rates.
bgc_T62_gx1GIF_nut-riv-BASELINE-coast_region-sed-137-157.nc
bgc_T62_gx1GIF_nut-riv-month-shiftx2-coast_region-sed-137-157.nc
bgc_T62_gx1GIF_nut-riv-2xArcticN-coast_region-sed-137-157.nc
bgc_T62_gx1GIF_nut-riv-mon-clim-coast_region-sed-137-157.nc
bgc_T62_gx1GIF_nut-riv-2mon-shift-coast_region-sed-137-157.nc
bgc_T62_gx1GIF_nut-riv_2XDC-coast_region-sed-137-157.nc
bgc_T62_gx1GIF_nut-riv-BASELINE-seas_region-sed-137-157.nc
bgc_T62_gx1GIF_nut-riv-month-shiftx2-seas_region-sed-137-157.nc
bgc_T62_gx1GIF_nut-riv-2xArcticN-seas_region-sed-137-157.nc
bgc_T62_gx1GIF_nut-riv-mon-clim-seas_region-sed-137-157.nc
bgc_T62_gx1GIF_nut-riv-2mon-shift-seas_region-sed-137-157.nc

Variables contained in these are:
POCTOSED_AVG* : Particulate organic carbon flux to sediment
PONTOSED_AVG* : Particulate organic nitrogen flux to sediment
SEDDENITRIF_AVG* : Sediment denitrification rate
POC_PROD_AVG* : Production of Particulate organic carbon
POC_FLUX_AVG* : Particulate organic carbon flux into layer/cell
DON_REMIN_AVG* : Dissolved Organic Nitrogen remineralization rate
DOC_REMIN_AVG* : Dissolved Organic Carbon remineralization rate
DIAT_N_LIM_AVG* : Diatom nitrogen limitation
DIAT_N_LIM_AVG* : Diatom nitrogen limitation
DIAT_P_LIM_AVG* : Diatom phosphorous limitation
DIAT_FE_LIM_AVG* : Diatom iron limitation
DIAT_LIGHT_LIM_AVG*: Diatom light limitation
SP_N_LIM_AVG* : Small phytoplankton nitrogen limitation
SP_P_LIM_AVG* : Small phytoplankton phosphorous limitation
SP_FE_LIM_AVG* : Small phytoplankton iron limitation
SP_LIGHT_LIM_AVG* : Small phytoplankton light limitation
Where * represents the coastal region number.
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The following series of files contains primary production for the small and large phytoplankton groups
and the zooplankton biomass.

Coastal regional averages – based on regions marked in the Arctic_Coast_Mask variable
bgc_T62_gx1GIF_runoff-2xArcticN-region-prod-ACM-137-157.nc
bgc_T62_gx1GIF_nut-riv-mon-clim-region-prod-ACM-137-157.nc
bgc_T62_gx1GIF_nut-riv-month-shiftx2-region-prod-ACM-137-157.nc
bgc_T62_gx1GIF_riv-BASELINE-region-prod-ACM-137-157.nc
bgc_T62_gx1GIF_nut-riv-2mon-shift-region-prod-ACM-137-157.nc
bgc_T62_gx1GIF_nut-riv-2XDC-region-prod-ACM-137-157.nc

Regional seas averages – based on regions marked in the Arctic_Region variable
bgc_T62_gx1GIF_runoff-2xArcticN-region-prod-seas-137-157.nc
bgc_T62_gx1GIF_nut-riv-mon-clim-region-prod-seas-137-157.nc
bgc_T62_gx1GIF_nut-riv-month-shiftx2-region-prod-seas-137-157.nc
bgc_T62_gx1GIF_riv-BASELINE-region-prod-seas-137-157.nc
bgc_T62_gx1GIF_nut-riv-2mon-shift-region-prod-seas-137-157.nc

Variables contained in these files are:
TAREA_SUM* – total area of the region
PPSP_REGSUM* – sum of primary production by small phytoplankton in a region
PPDIAT_REGSUM*– sum of primary production by diatoms in a region
ZOOC_AVG*– sum of zooplankton biomass in a region

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The following series of files contains ice associated variables and mixed layer nutrients

bgc_T62_gx1GIF_nut_riv-2xArcticN-ice_coastal-137-157.nc
bgc_T62_gx1GIF_nut-riv-mon-clim-ice_coastal -137-157.nc
bgc_T62_gx1GIF_nut-riv-month-shiftx2-ice_coastal -137-157.nc
bgc_T62_gx1GIF_nut-riv-BASELINE-ice_coastal -137-157.nc
bgc_T62_gx1GIF_nut-riv-2mon-shift-ice_coastal -137-157.nc
bgc_T62_gx1GIF_nut-riv-2XDC-ice_coastal -137-157.nc
bgc_T62_gx1GIF_nut-riv-2xArcticN-ice_seas-137-157.nc
bgc_T62_gx1GIF_nut-riv-mon-clim-ice_seas -137-157.nc
bgc_T62_gx1GIF_nut-riv-month-shiftx2-ice_seas -137-157.nc
bgc_T62_gx1GIF_nut-riv-BASELINE-ice_seas -137-157.nc
bgc_T62_gx1GIF_nut-riv-2mon-shift-ice_seas-137-157.nc

HI_REGAVG* : Regional averaged ice depth
HS_REGAVG* : Regional averaged snow depth
ICEAREA_REGSUM* : Regional sum ice area
ICEVOL_REGSUM*: Regional sum volume area
MLAM_REGAVG* : Regional average ammonium concentration in mixed layer
MLNIT_REGAVG* : Regional average nitrate concentration in mixed layer
PP_REGAVG* : Regional average primary production (ice algae)
PP_REGSUM* : Regional total primary production (ice algae)
TAREA_SUM* : Total area of region
TIME : time