Variables

Temperature

CF Standard Name	AC1 Name	Units	Description
sea_water_conservative_temperature	CT	degree_C	Conservative temperature
sea_water_temperature	TEMP	degree_C	Sea water temperature
sea_water_potential_temperature	POTEMP	degree_C	Sea water potential temperature

Salinity

CF Standard Name	AC1 Name	Units	Description
sea_water_absolute_salinity	SA	g kg-1	Absolute salinity (g/kg)
sea_water_practical_salinity	PSAL	1	Practical salinity

Pressure

CF Standard Name	AC1 Name	Units	Description
sea_water_pressure	PRES	dbar	Pressure
sea_water_pressure_at_sea_floor	OBP	dbar	Pressure at sea floor

Density

CF Standard Name	AC1 Name	Units	Description
sea_water_sigma_theta	SIGMA0	kg m-3	Density anomaly to 1000 kg m-3, surface reference
sea_water_sigma_theta	SIGMA2	kg m-3	Density anomaly to 1000 kg m-3, 2000 dbar reference
sea_water_neutral_density	GAMMA	kg m-3	Neutral density estimate

Velocity

CF Standard Name	AC1 Name	Units	Description
eastward_sea_water_velocity	UCUR	m s-1	Eastward sea water velocity
northward_sea_water_velocity	VCUR	m s-1	Northward sea water velocity
baroclinic_northward_sea_water_velocity	VCUR	m s-1	Baroclinic (layered) meridional velocity
barotropic_northward_sea_water_velocity	VCUR	m s-1	Depth-averaged (barotropic) meridional velocity

Transport

CF Standard Name	AC1 Name	Units	Description
northward_ocean_freshwater_transport	MFT	Sverdrup	Total northward freshwater transport
northward_ocean_freshwater_transport_due_to_gyre	MFT_GYRE	Sverdrup	Gyre component of freshwater transport
northward_ocean_freshwater_transport_due_to_overturning	MFT_OT	Sverdrup	Overturning component of freshwater transport
northward_ocean_heat_transport	MHT	PW	Total northward heat transport
ocean_volume_transport_across_line	TRANS	Sverdrup	Volume transport across a defined line or section
ocean_meridional_overturning_streamfunction	MOC, MOC_SIGMA0, MOC_SIGMA2, MOC_Z	Sverdrup	General overturning streamfunction

Uncertainty Variables

Convention: All uncertainty variables follow the pattern {VARIABLE}_ERR

Uncertainty Variables (Examples)

Variable Name	Long Name	Units	Standard Name	Description
MOC_ERR	Uncertainty in MOC	Sverdrup	ocean_meridional_overturning_transport	Standard error/uncertainty in MOC estimate
MOC_SIGMA0_ERR	Uncertainty in MOC (σ₀)	Sverdrup	ocean_meridional_overturning_streamfunction	Uncertainty in σ₀-referenced MOC
MHT_ERR	Uncertainty in heat transport	PW	northward_ocean_heat_transport	Standard error in heat transport estimate
MFT_ERR	Uncertainty in freshwater transport	Sverdrup	northward_ocean_freshwater_transport	Standard error in freshwater transport estimate
TRANS_EKMAN_ERR	Uncertainty in Ekman transport	Sverdrup	ocean_volume_transport_across_line	Standard error in Ekman transport estimate

Rules for Uncertainty Variables:

• Same units as parent variable

• Same standard_name as parent variable where appropriate

• long_name: “Uncertainty in {parent_long_name}”

• Include method of uncertainty calculation in description

Variable Metadata Requirements

Variable Attributes

Every variable in AC1.0 format should include the following attributes:

standard_name (string):

• Use CF-1.8 standard name vocabulary where available

• For AMOC-specific variables, document extensions clearly

• Use closest CF standard name with clarification in description

long_name (string):

• Human-readable name for the variable

• Use sentence case (capitalize first word only)

• Be descriptive but concise (< 60 characters recommended)

units (string):

• UDUNITS-2 compliant unit specification

• Use AMOCatlas preferred units (see Unit Standards)

• Coordinate variables: use appropriate CF units

description (string, optional but recommended):

• Extended description providing additional context

• Include methodology, reference levels, coordinate systems

• Clarify any deviations from standard definitions

coordinates (string, for data variables):

• Space-separated list of coordinate variables

• Standard format: “TIME DEPTH LATITUDE LONGITUDE”

Optional Attributes

valid_range (numeric array):

• [minimum, maximum] physically meaningful values

• Use for data validation and quality control

_FillValue (numeric):

• Value used for missing data

• Should be outside valid_range

comment (string):

• Additional notes about the variable

• Methodology details, known issues, etc.

source (string):

• Original data source or instrument

• Useful for multi-source composite products

processing_notes (string):

• Details about data processing applied

• Quality control procedures, filtering, etc.

reference_pressure (numeric):

• For density variables, specify reference pressure in dbar

• Important for interpreting potential density coordinates

Vocabulary Standards

CF Standard Name Vocabulary

CF Standard Name Table v84

• URL: https://cfconventions.org/Data/cf-standard-names/current/

• Use for all geophysical variables where applicable

• Document extensions in AMOCatlas vocabulary supplement

Quality Control Flags

Following OceanSITES-1.5 QC flag conventions:

Quality Control Flags

Flag	Meaning	Description
0	No QC performed	No quality control has been performed
1	Good data	Passed documented required QC tests
2	Not evaluated	Used for data when no QC test could be performed
3	Questionable	Questionable data (may require user evaluation)
4	Bad data	Bad data that should not be used
7	Nominal value	Nominal value (e.g., from climatology)
8	Interpolated	Missing values filled by interpolation
9	Missing data	Used as _FillValue for missing data