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EM: Carbon Generic Estuary Model (C-GEM), Lousiana Continental Shelf, USA (EM-947)

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EM Identity and Description

EM Identification

EM ID em.detail.idHelp ?	EM-947
EM Short Name em.detail.shortNameHelp ?	C-GEM, Lousiana continental shelf, USA
EM Full Name em.detail.fullNameHelp ?	Carbon Generic Estuary Model (C-GEM), Lousiana Continental Shelf, USA
EM Source or Collection em.detail.emSourceOrCollectionHelp ?	US EPA
EM Source Document ID	441
Document Author em.detail.documentAuthorHelp ?	Jarvis, B.M., Lehrter, J.C., Lowe, L.L., Hagy, J.D., Wan, Y., Murrell, M.C., Ko, D.S., Penta, B., and R.W. Gould
Document Year em.detail.documentYearHelp ?	2020
Document Title em.detail.sourceIdHelp ?	Modeling spatiotemporal patterns of ecosystem metabolism and organic carbon dynamics affecting hypoxia on the Louisiana continental shelf
Document Status em.detail.statusCategoryHelp ?	Peer reviewed and published
Comments on Status em.detail.commentsOnStatusHelp ?	Published journal manuscript

Software and Access

EM Software Access info Exit em.detail.modelAccessInformationHelp ?	Not applicable
Contact Name em.detail.contactNameHelp ?	Brandon Jarvis
Contact Address	1US EPA, Office of Research and Development, 1 Sabine Island Drive, Gulf Breeze, FL 32561, USA Office of Research and Development, U.S. EPA, Gulf Breeze, FL, USA
Contact Email	jarvis.brandon@epa.gov

EM Description

Summary Description em.detail.summaryDescriptionHelp ?	ABSTRACT: "The hypoxic zone on the Louisiana Continental Shelf (LCS) forms each summer due to nutrient‐enhanced primary production and seasonal stratification associated with freshwater discharges from the Mississippi/Atchafalaya River Basin (MARB). Recent field studies have identified highly productive shallow nearshore waters as an important component of shelf‐wide carbon production contributing to hypoxia formation. This study applied a three‐dimensional hydrodynamic‐biogeochemical model named CGEM (Coastal Generalized Ecosystem Model) to quantify the spatial and temporal patterns of hypoxia, carbon production, respiration, and transport between nearshore and middle shelf regions where hypoxia is most prevalent. We first demonstrate that our simulations reproduced spatial and temporal patterns of carbon production, respiration, and bottom‐water oxygen gradients compared to field observations. We used multiyear simulations to quantify transport of articulate organic carbon (POC) from nearshore areas where riverine organic matter and phytoplankton carbon production are greatest. The spatial displacement of carbon production and respiration in our simulations was created by westward and offshore POC flux via phytoplankton carbon flux in the surface layer and POC flux in the bottom layer, supporting heterotrophic respiration on the middle shelf where hypoxia is frequently observed. These results support existing studies suggesting the importance of offshore carbon flux to hypoxia formation, particularly on the west shelf where hypoxic conditions are most variable. "
Specific Policy or Decision Context Cited em.detail.policyDecisionContextHelp ?	None reported
Biophysical Context	Louisiana coastal continental shelf
EM Scenario Drivers em.detail.scenarioDriverHelp ?	Coastal Shelf location

EM Relationship to Other EMs or Applications

Method Only, Application of Method or Model Run em.detail.methodOrAppHelp ?	Method + Application
New or Pre-existing EM? em.detail.newOrExistHelp ?	New or revised model

Related EMs (for example, other versions or derivations of this EM) described in ESML

em.detail.relatedEmHelp

Document ID for related EM em.detail.relatedEmDocumentIdHelp ?	None
EM ID for related EM em.detail.relatedEmEmIdHelp ?	None

EM Modeling Approach

EM Relationship to Time

EM Temporal Extent em.detail.tempExtentHelp ?	2003-2007
EM Time Dependence em.detail.timeDependencyHelp ?	time-dependent
EM Time Reference (Future/Past) em.detail.futurePastHelp ?	past time
EM Time Continuity em.detail.continueDiscreteHelp ?	discrete
EM Temporal Grain Size Value em.detail.tempGrainSizeHelp ?	1
EM Temporal Grain Size Unit em.detail.tempGrainSizeUnitHelp ?	Season

EM Spatial Extent

Bounding Type em.detail.boundingTypeHelp ?	Physiographic or ecological
Spatial Extent Name em.detail.extentNameHelp ?	Lousiana continental shelf
Spatial Extent Area (Magnitude) em.detail.extentAreaHelp ?	100,000-1,000,000 km^2

Spatial Distribution of Computations

EM Spatial Distribution em.detail.distributeLumpHelp ?	spatially distributed (in at least some cases)
Spatial Grain Type em.detail.spGrainTypeHelp ?	area, for pixel or radial feature
Spatial Grain Size em.detail.spGrainSizeHelp ?	regions of shelf

EM Structure and Computation Approach

EM Computational Approach em.detail.emComputationalApproachHelp ?	Numeric
EM Determinism em.detail.deterStochHelp ?	deterministic
Statistical Estimation of EM em.detail.statisticalEstimationHelp ?	Other or unclear (comment)

Model Checking Procedures Used

Model Calibration Reported? em.detail.calibrationHelp ?	Yes
Model Goodness of Fit Reported? em.detail.goodnessFitHelp ?	No
Goodness of Fit (metric\| value \| unit) em.detail.goodnessFitValuesHelp ?	None
Model Operational Validation Reported? em.detail.validationHelp ?	Yes
Model Uncertainty Analysis Reported? em.detail.uncertaintyAnalysisHelp ?	No
Model Sensitivity Analysis Reported? em.detail.sensAnalysisHelp ?	Yes
Model Sensitivity Analysis Include Interactions? em.detail.interactionConsiderHelp ?	Unclear

EM Locations, Environments, Ecology

Location of EM Application

Terrestrial location (Classification hierarchy: Continent > Country > U.S. State [United States only])

em.detail.relationToSpaceTerrestrialHelp

None

Marine location (Classification hierarchy: Realm > Region > Province > Ecoregion)

em.detail.relationToSpaceMarineHelp

None

Centroid Lat/Long (Decimal Degree)

Centroid Latitude em.detail.ddLatHelp ?	30.28
Centroid Longitude em.detail.ddLongHelp ?	-88.39
Centroid Datum em.detail.datumHelp ?	WGS84
Centroid Coordinates Status em.detail.coordinateStatusHelp ?	Estimated

Environments and Scales Modeled

EM Environmental Sub-Class em.detail.emEnvironmentalSubclassHelp ?	Near Coastal Marine and Estuarine
Specific Environment Type em.detail.specificEnvTypeHelp ?	Louisiana continental shelf
EM Ecological Scale em.detail.ecoScaleHelp ?	Ecological scale corresponds to the Environmental Sub-class

Scale and taxa of organisms modeled

Scale of differentiation of organisms modeled

em.detail.nameOfOrgsOrGroupsHelp

EM Organismal Scale

em.detail.orgScaleHelp

Not applicable

Taxonomic level and name of organisms or groups identified

taxonomyHelp

None Available

EnviroAtlas URL

em.detail.enviroAtlasURLHelp

National Hydrography Dataset Plus (NHD PlusV2), Average Annual Precipitation, Total Annual Reduced Nitrogen Deposition, Average Annual Daily Potential Wind Energy, Carbon Storage by Tree Biomass

EM Ecosystem Goods and Services (EGS) potentially modeled, by classification system

CICES v 4.3 - Common International Classification of Ecosystem Services (Section > Division > Group > Class)

em.detail.cicesHelp

[Ecosystem] Regulation & Maintenance
- Maintenance of physical, chemical, biological conditions
  - Water conditions
    - Chemical condition of salt waters

National Ecosystem Services Classification System (NESCS) Plus

(Environmental Subclass > Ecological End-Product (EEP) > EEP Subclass > EEP Modifier)

fegs2Help

Near Coastal Marine/Estuarine (113)
- Water (3)
  - Liquid water
    - Quality Indicator

EM Variable Names (and Units)

View Details (122) | View Variable Relationship Diagram (PDF)(1 pp, 80 KB, About PDF)

Predictor

em.detail.variablesPredictorHelp

Driving Variables (and Units) view details (23 variables)

em.detail.drivingVariableHelp

Ammonicum (mmol m^-3)
Cell nitrogen quota (phytoplankton) (mmol N cell^-1)
Cell phosphorus quota (phytoplankton) (mmol P cell^-1)
Colored dissolved organic matter (ppb)
Dissolved inorganic carbon (mmol m^-3)
Macrozooplankton (M1) or microzooplankton (M2) (ind. M^-3)
Macrozooplankton (Z1) or microzooplankton(Z2) (individuals m^-3)
Naval coastal ocean model (unitless)
Nitrate (mmol m^-3)
Oxygen (mmol m^-3)
Phosphate (mmol m^-3)
Photosynthetically active radiation (PAR) ( μmol quanta m^-2^−1)
Phytoplankton abundance (i=1:3) (cells m^-3)
Phytoplankton dissolved organic matter (mmol m^-3)
Phytoplankton functional type (Not applicable)
Phytoplankton particulate organic matter (mmol m^-3)
River dissolved organic matter (mmol m^-3)
River particulate organic matter (mmol m^-3)
Shelf location (west, AR plume, east, MR plume) (Not applicable)
Silica (mmol m^-3)
Tides (day, time, height) (Not reported)
Water temperature (°C)
Zooplankton fecal pellet particulate organic matter (mmol m^-3)

Constant or Factor Variables (and Units) view details (84 variables)

em.detail.constantFactorVariableHelp

Absorption of water at 490 nm (m^-1)
Assimilation efficiency as a fraction of ingestion (unitless)
Atmospheric CO2 (mmol m^-3)
Basal respiration coefficient (d^-1)
Basal-dependent respiration (d^-1)
Basal-dependent respiration (d^-1)
Biovolume per cell (um^3 cell^-1)
Carbon per cell (mmol C cell^-1)
Carbon per individual (mmol C individual^-1)
Cell volume (um^3 individual^-1)
Chlorophyll a absorption at 490 nm (m^-1(mg Chla m^-3)^-1)
Coarse detritis organic matter decay rate (d^-1)
Coefficient for non-limiting nutrient (unitless)
Decay rate of Organic matter1_A and Organic matter1_Z (yr^-1)
Decay rate of Organic matter1_BC (yr^-1)
Decay rate of Organic matter1_R (yr^-1)
Decay rate of Organic matter2_A and Organic matter2_Z (yr^-1)
Decay rate of Organic matter2_BC (yr^-1)
Decay rate of Organic matter2_R (yr^-1)
Denitrification half-saturation constant (mmol m^-3)
Denitrification inhibition constant (mmol m^-3)
Dissolved organic matter lability (yrs)
Edibility vector (unitless)
Fixed carbon to chlorophyll ratio (unitless)
Grazing half-saturation coefficient (um^3 m^-3)
Grazing half-saturation coefficient (µm^3 m^-3)
Growth dependent respiration coefficient (d^-1)
Growth-dependent respiration (unitless)
Growth-dependent respiration (d^-1)
Half saturation coefficient for N uptake (mmol N m^-3)
Half saturation coefficient for P uptake (mmol P m^-3)
Half saturation coefficient for Si uptake (mmol Si m^-3)
Initial C:P stoichiomentry of Organic matter1_BC (mol/mol)
Initial C:P stoichiometry of Organic matter1_R (mol/mol)
Initial C:P stoichiometry of Organic matter2_BC (mol/mol)
Initial C:P stoichiometry of Organic matter2_R (mol/mol)
Initial N:P stoichiometry of Organic matter1_BC (mol/mol)
Initial N:P stoichiometry of Organic matter1_R (mol/mol)
Initial N:P stoichiometry of Organic matter2_BC (mol/mol)
Initial N:P stoichiometry of Organic matter2_R (mol/mol)
Initial slope of the photosynthesis versus irradiance curve (cm^2s quanta^-1d^-1)
Maximum N cell-quota (mmol N cell^-1)
Maximum N uptake rate (mmol cell^-1 d^-1)
Maximum P cell quota (mmol P cell^-1)
Maximum P uptake rate (mmol cell^-1 d^-1)
Maximum Si uptake rate (mmol cell^-1 d^-1)
Maximum growth rate (um^-3 ind^-1 d^-1)
Maximum growth rate (µm^3 ind^−1 d^−1)
Maximum growth rate at 20°C (d^-1)
Maximum nitrification rate (mmol m^-3 d^-1)
Minimum N cell-quota (mmol N cell^-1)
Minimum P cell-quota (mmol P cell^-1)
Mortality (d^-1)
Mortality constant for quadratic mortality (m^6 ind^-2 d^-1)
Nitrification half-saturation constant (mmol m^-3)
Nitrogen per individual (mmol N individual^-1)
O2 uptake half-saturation constant (mmol m^-3)
Organic matter1_A absorption at 490 nm (m^-1(g OM1_A m^-3)^-1)
Organic matter1_A sinking rate (m d^-1)
Organic matter1_BC absorption at 490 nm (m^-1(g OM1_BC m^-3)^-1)
Organic matter1_BC sinking rate (m d^-1)
Organic matter1_R absorption at 490 nm (m^-1(g OM1_R m^-3)^-1)
Organic matter1_R sinking rate (m d^-1)
Organic matter1_Z absorption at 490 nm (m-1(g OM1_Z m-3)-1)
Organic matter1_Z sinking rate (m d^-1)
Organic matter2_A sinking rate (m d^-1)
Organic matter2_BC sinking rate (m d^-1)
Organic matter2_R sinking rate (m d^-1)
Organic matter2_Z sinking rate (m d^-1)
Particulate organic matter lability (yrs.)
Percent river organic matter1 (%)
Phosphorus per individual (mmol P individual^-1)
Photoinhibition (cm^2s quanta^-1 d^-1)
Sinking rates (m d^-1)
Sloppy feeding coefficient (unitless)
α0 (unitless)
α1 (unitless)
α2 (unitless)
ζ0 (unitless)
ζ1 (unitless)
ζ2 (unitless)
χ1 (unitless)
χ2 (unitless)
χo (unitless)

Intermediate

Intermediate (Computed) Variables (and Units) view details (8 variables)

em.detail.intermediateVariableHelp

Chlorophyll a (bottom) ( mmol m^-3)
Chlorophyll a (surface) (mmol m^-3)
Dissolved inorganic nitrogen (bottom) (mmol m^-3)
Integrated primary production (bottom) (mmol m^-3)
Open ocean boundary transport rates (m d^-1)
Particulate organic matter (bottom) (mmol m^-3)
Phytoplankton C (C m^-3)
Phytoplankton population growth (cells m^3 d^-1)

Response

em.detail.variablesResponseHelp

Observed Response Variables (and Units) view details (5 variables) em.detail.observedResponseHelp ?	Field chlorophyll a (bottom) (mg m^-3) Field dissolved inorganic nitrogen (bottom) (mmol m^-3) Field integrated primary production (bottom) (mmol m^-3) Field oxygen (bottom) (mmol m^-3) Field particulate organic matter (bottom) (mmol m^-3)
Computed Response Variables (and Units) view details (2 variables) em.detail.computedResponseHelp ?	Oxygen concentration (bottom) (mmol m^-3) Oxygen concentration (surface) (mmol m^-3)