CF Standard Names ================= This document summarizes selected CF standard names used in the AC1 dataset for describing seawater properties and meridional transports. ------------------------------------------------------------------ Coordinates ----------- latitude ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ **Canonical Units:** degree_north **Description:** Latitude is positive northward. In rotated grids, use `grid_latitude` instead. ------------------------------------------------------------------ longitude ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ **Canonical Units:** degree_east **Description:** Longitude is positive eastward. In rotated grids, use `grid_longitude` instead. ------------------------------------------------------------------ Temperature ----------- sea_water_conservative_temperature ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ **Canonical Units:** K **Description:** Conservative Temperature is defined as part of the Thermodynamic Equation of Seawater 2010 (TEOS-10), adopted in 2010 by the International Oceanographic Commission (IOC). It is specific potential enthalpy (see `sea_water_specific_potential_enthalpy`) divided by a fixed value of the specific heat capacity of sea water: .. math:: C_T = h^0 / c_{p0}, \quad ext{where } c_{p0} = 3991.86795711963 ext{ J kg⁻¹ K⁻¹} Conservative Temperature is a significantly more accurate measure of seawater heat content than potential temperature (θ), improving precision by a factor of ~100. It is proportional to the heat content per unit mass of seawater. **References:** - TEOS-10: https://www.teos-10.org - McDougall, 2003: doi:10.1175/1520-0485(2003)033<0945:PEACOV>2.0.CO;2 **Metadata Guidance:** Strongly recommended to include a `units_metadata` attribute: `"on-scale"` or `"difference"`. ------------------------------------------------------------------ sea_water_temperature ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ **Canonical Units:** K **Description:** Sea water temperature refers to the *in situ* temperature of seawater. Use a vertical coordinate to specify measurement depth. **Historical Context:** - IPTS-48 (1948–1967) - IPTS-68 (1968–1989) - ITS-90 (1990 onward) **Conversion Equations:** .. math:: t_{68} = t_{48} - 4.4 imes 10^{-6} \cdot t_{48} \cdot (100 - t_{48}) \ t_{90} = 0.99976 \cdot t_{68} **Metadata Guidance:** Use `units_metadata`: `"on-scale"` or `"difference"`. ------------------------------------------------------------------ Salinity ----------- sea_water_absolute_salinity ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ **Canonical Units:** g kg⁻¹ **Description:** Absolute Salinity \( S_A \), from TEOS-10, is the mass fraction of dissolved material in seawater. It accounts for regional composition variations and yields accurate density calculations. **Metadata Guidance:** Include a `comment` attribute specifying the TEOS-10 software version and anomaly climatology. **References:** - TEOS-10: https://www.teos-10.org - Millero et al., 2008: doi:10.1016/j.dsr.2007.10.001 ------------------------------------------------------------------ sea_water_practical_salinity ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ **Canonical Units:** 1 (dimensionless) **Description:** Practical Salinity \( S_P \) is computed from conductivity and is reported on the Practical Salinity Scale of 1978 (PSS-78). Use only for post-1978 data derived from conductivity. **References:** - TEOS-10: https://www.teos-10.org - Lewis, 1980: doi:10.1109/JOE.1980.1145448 ------------------------------------------------------------------ sea_water_salinity ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ **Canonical Units:** 1e-3 (dimensionless; parts per thousand) **Description:** Generic term for salt content in seawater. Use only when the salinity does not conform to a defined standard. Deprecated for post-1978 observations in favor of `sea_water_practical_salinity`. **Conversion Notes:** .. math:: S_P = (S_K - 0.03) \times \left( \frac{1.80655}{1.805} \right) .. math:: S_P = S_C ------------------------------------------------------------------ Pressure -------- sea_water_pressure ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ **Canonical Units:** dbar **Description:** Sea water pressure includes the pressure from the overlying seawater, sea ice, atmosphere, and other media. Use `sea_water_pressure_due_to_sea_water` to isolate seawater-only pressure. ------------------------------------------------------------------ sea_water_pressure_at_sea_floor ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ **Canonical Units:** dbar **Description:** Pressure at the ocean bottom, including contributions from all overlying media. ------------------------------------------------------------------ reference_pressure ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ **Canonical Units:** Pa **Description:** A constant scalar value representing reference pressure (e.g., for calculating potential density). ------------------------------------------------------------------ Density ------- sea_water_sigma_theta ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ **Canonical Units:** kg m⁻³ **Description:** Sigma-theta of sea water is the potential density (i.e. the density when moved adiabatically to a reference pressure) minus 1000 kg m⁻³. To specify the reference pressure, include a scalar coordinate variable with standard name `reference_pressure`. Not to be confused with `ocean_sigma_coordinate`. ------------------------------------------------------------------ ocean_sigma_z_coordinate ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ **Canonical Units:** 1 (dimensionless) **Description:** A parametric vertical coordinate. See Appendix D of the CF convention for details. ------------------------------------------------------------------ ocean_sigma_coordinate ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ **Canonical Units:** 1 (dimensionless) **Description:** A parametric vertical coordinate used in ocean models. Not to be confused with `sea_water_sigma_theta`. ------------------------------------------------------------------ sea_water_potential_density ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ **Canonical Units:** kg m⁻³ **Description:** The density a parcel of sea water would have if moved adiabatically to a reference pressure (typically sea level). Use `reference_pressure` as a scalar coordinate. Subtracting 1000 kg m⁻³ yields `sea_water_sigma_theta`. ------------------------------------------------------------------ sea_water_neutral_density ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ **Canonical Units:** kg m⁻³ **Description:** Neutral density is a variable that approximates the local slope of the neutral tangent plane. Differences between neutral density and potential density anomaly can be substantial away from the equator. See Jackett & McDougall (1997) for details. Velocity -------- baroclinic_northward_sea_water_velocity ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ **Canonical Units:** m s⁻¹ **Description:** Northward component of baroclinic sea water velocity. ------------------------------------------------------------------ barotropic_northward_sea_water_velocity ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ **Canonical Units:** m s⁻¹ **Description:** Northward component of barotropic sea water velocity. Transport -------- northward_ocean_freshwater_transport ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ **Canonical Units:** kg s⁻¹ **Description:** Northward component of total ocean freshwater transport, including both seawater and sea ice. ------------------------------------------------------------------ northward_ocean_freshwater_transport_due_to_gyre ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ **Canonical Units:** kg s⁻¹ **Description:** Part of northward freshwater transport due to ocean gyre circulation, calculated from deviations from zonal means. Excludes parameterized eddy velocity. ------------------------------------------------------------------ northward_ocean_freshwater_transport_due_to_overturning ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ **Canonical Units:** kg s⁻¹ **Description:** Part of northward freshwater transport due to overturning circulation, based on zonal means. Excludes parameterized eddy velocity. ------------------------------------------------------------------ northward_ocean_heat_transport ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ **Canonical Units:** W **Description:** Northward component of total ocean heat transport, including seawater and sea ice. ------------------------------------------------------------------ northward_ocean_heat_transport_due_to_gyre ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ **Canonical Units:** W **Description:** Part of northward heat transport due to ocean gyre circulation, using deviations from zonal means. Excludes parameterized eddy velocity. ------------------------------------------------------------------ northward_ocean_heat_transport_due_to_overturning ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ **Canonical Units:** W **Description:** Part of northward heat transport due to overturning circulation, based on zonal means. Excludes parameterized eddy velocity. ------------------------------------------------------------------ ocean_volume_transport_across_line ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ **Canonical Units:** m³ s⁻¹ **Description:** Transport across a specified line (e.g., latitude), defined as the line integral of normal volume transport across that section. ------------------------------------------------------------------ streamfunction ---------------- ocean_meridional_overturning_mass_streamfunction ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ **Canonical Units:** kg s⁻¹ **Description:** Overturning streamfunction including all resolved and parameterized processes that impact mass or volume transport. ------------------------------------------------------------------ ocean_meridional_overturning_streamfunction ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ **Canonical Units:** m³ s⁻¹ **Description:** Overturning streamfunction excluding the parameterized eddy velocity. ------------------------------------------------------------------