CSN Quantity Templates: Difference between revisions

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* While "atomic number" is a standard term, the synonym "proton_number" is winning favor because it is more specific and because "neutron_number" is also used.
* While "atomic number" is a standard term, the synonym "proton_number" is winning favor because it is more specific and because "neutron_number" is also used.


* See the [[CSN_Object_Templates | CSDMS Object Template]] for Atoms, Compounds, Ions and Molecules below for more details and examples.
* See the [[CSN_Object_Templates | '''CSDMS Object Template''']] for Atoms, Compounds, Ions and Molecules below for more details and examples.


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Revision as of 16:02, 22 August 2012

  CSDMS Standard Names — Quantity Templates

  • A CSDMS Standard Name must have an "object" part and a "quantity" part, with adjectives and modifiers (as prefixes) being used to help avoid ambiguity and identify a specific object and associated quantity. This document contains "quantity templates". For "object templates", see: CSDMS Object Templates.

  • The "templates" listed below are not exhaustive, but they do address many commonly needed cases where the pattern may not be obvious. Additional templates can be created from any of the "base quantities" listed in the text file "CSDMS_Standard_Name_Quantities.txt".

  • Each template includes examples and explanatory notes, and many of them make reference to the CF Standard Names, sometimes using the abbreviation "CF".

  • Quantity seems the best word choice here, see Wikipedia: Quantity and Wikipedia: Physical quantities. The word "attribute" is more general and may also be a good choice, but many attributes cannot be measured or quantified with a numerical value that has units. Here we define a quantity as an attribute of an object that has units. A partial list of base quantities is given in the text file: "CSDMS_Standard_Name_Quantities.txt".

  • Quantity Suffix Pattern. A "quantity suffix" is a quantity name like "anomaly", "component", "fraction", "increment", "limit", "magnitude", "scale" or "threshold" (and in some cases "ratio") that produces a new quantity name from an existing quantity name. Note that an "increment" can be associated with any quantity to create a new quantity. Models often update state variables with each time step by an incremental amount and this amount may be the quantity of interest. Note that an increment can be positive or negative.

  • Process_name + Quantity Pattern. Many quantity names contain a process name modifier from the standardized list of CSDMS Process Names. Process names are nouns, not adjectives, so we would use "refraction_index" instead of "refractive_index". (Or "diffusion_coefficient" vs. "diffusive_coefficient", etc.) The templates for Process Attributes and Rates of Processes below provide many more examples.

  • Object-in-Object Quantity Pattern. Some quantities require 2 objects/substances to be specified where one is contained within the other. Examples include: "partial_pressure", "relative_saturation" (see Humidity), "solubility" and "volume_fraction". In such cases we use the reserved word "_in_" and the pattern: object = (object + "_in_" + object), as in:
carbon_dioxide_in_air_partial_pressure
carbon_dioxide_in_air_relative_saturation
carbon_dioxide_in_water_solubility
clay_in_soil_volume_fraction
helium_plume_in_air_richardson_number
sand_in_soil_volume_fraction
silt_in_soil_volume_fraction
visible_light_in_air_speed      ### (possibly; See the Constants in Physics template.)
It appears that bubble_point_temperature, dew_point_temperature and frost_point_temperature also require one substance within another, as in: water_vapor_in_air_dew_point_temperature. See the Temperature template.

  • Saturated Quantity Rule. When using the object-in-object pattern, there are several quantities that refer to a system that is saturated or "at saturation". In these cases we insert the word "saturated" in front of the quantity name to define a new quantity. Examples include:
soil_saturated_hydraulic_conductivity
soil_saturated_water_content    (same as "water_in_soil_saturated_volume_fraction")
water_vapor_in_air_saturated_partial_pressure
While it is true that the soil is saturated in the first two examples, we use this rule instead of inserting "saturated" as an adjective in front of soil and instead of appending a suffix like "at_saturation", which doesn't fit our (object + quantity) pattern. This rule is natural in the sense that each of the "saturated quantities" listed above would be represented by a separate variable in a model, often denoted with a subscript such as "s".
  • Object-on-Object Quantity Pattern. Some quantities require 2 objects/substances to be specified where one is "on" or in contact with the other. Examples often involve friction. In such cases we use the reserved word "_on_" and the pattern: object = (object + "_on_" + object), as in:
rubber_on_concrete_kinetic_friction_coefficient
rubber_on_pavement_static_friction_coefficient
 
Note: Maybe "_and_"or "_to_" would be better than "_on_" here.  We should also list the two object names in alphabetical order to avoid two names for the same thing.
  • Object-to-Object Quantity Pattern. When the quantity refers to a relationship between two objects, we use the reserved word "_to_" and the pattern: (object + "_to_" + object + quantity). The reserved word "_to_" can also be used for ratios. See the Ratio template. Examples include:
brain_to_body_mass_ratio
charge_to_mass_ratio
earth_to_mars_travel_time
earth_to_sun_mean_distance
 
carbon_to_hydrogen_bond_length
hydrogen_to_oxygen_bond_energy (See: Table of bond energies.)
In the last two examples, we put the two object names in alphabetical order to avoid two standard names for the same thing.
We may also be able to use this pattern in constructions like: subsurface_to_surface_water_seepage_rate, where "subsurface_to_surface" is acting as an adjective.
  • There are several terms that may provide a "short name" or synonym for another quantity, such as:
aspect      = surface_gradient_direction
discharge = volumetric_flow_rate
slope       = surface_gradient_magnitude
speed      = velocity_magnitude   (or even "motion_rate")
  • It may be beneficial to allow various standard abbreviations in quantity names. Possible examples are: stp = standard temperature and pressure and toa = top of atmosphere (used in CF).

  • We may need a provision to indicate whether a vector quantity associated with a model grid cell is "incoming" or "outgoing". These adjectives are used in many CF Standard Names, but not with respect to a model cell. We may be able to use a "quantity_suffix" for these cases. While we could use modifiers like "from_cell", "into_cell" and "in_cell", it seems that we should avoid standard names that refer to a model cell in this way.


Altitude

  base_quantity = "altitude"

  Examples 

airplane_altitude
skydiver_altitude
  • The word "altitude" is reserved for objects that are above and not in contact with the land surface. (e.g. aircraft, air parcel, balloon) See the Elevation template. By contrast, "altitude" is used as a synonym for "elevation" in the CF Standard Names.
  • What about the standard term "equilibrium_line_altitude" (ELA) ?


Angle

  base_quantity = "angle"

  Examples 

azimuth_angle, bank_angle, bond_angle, declination_angle,
earth_axis_tilt_angle,  friction_angle, incidence_angle,
pitch_angle, polarization_angle, repose_angle, roll_angle,
rotation_angle, scattering_angle, shock_angle, slope_angle,
torsion_angle, yaw_angle, zenith_angle
  • There are two major conventions used for measuring angles. For bearings, the angle is measured clockwise from north, and this typically includes wind data. (We also need to clarify whether the wind is blowing "to" or "from" that direction.) Most other angles are measured the way you learned in high school, counterclockwise from the x-axis (or from the east). It is therefore important to specify the convention that is used in the Model Metadata File with an <assumption> tag using one of the standardized assumption names from the CSDMS Assumption Names page. A smart framework would be able to convert between these two conventions, when necessary, after examining these <assumption> tags.
  • Note that "earth_axis_tilt_angle" uses the object name "earth_axis" to refer to a "part" of the Earth and "tilt_angle" follows the (process_name + quantity) pattern. (tilt vs. tilting) However, "earth_axial_tilt_angle" uses the modifier "axial" to convey the same concept. We need a rule to decide between such cases. The first version seems preferable.
  • A few terms sound strange in this form, like "repose_angle", instead of "angle_of_repose". But this doesn't pose any real problem.
  • Many of these follow the Process Attribute template (process_name + attribute).
  • Maybe we should always use "aspect_angle" vs. "aspect" for clarity since we distinguish between "slope" and "slope_angle" ?
  • bank_angle is related to banking (e.g. aircraft) in turns but may also be used in the context of channel banks. The object part of the name allows the same quantity name to be used in different contexts.


Anomaly

  quantity_suffix = "anomaly"

  Examples 

air_pressure_anomaly
air_temperature_anomaly
sea_surface_temperature_anomaly
  • Means the difference from climatology in CF Standard Names.
  • This is a quantity suffix that creates a new quantity from an existing base quantity like elevation or pressure. Others are Component, Increment and Magnitude.
  • Used in 4 CF Standard Names, namely:
air_pressure_anomaly
air_temperature_anomaly
geopotential_height_anomaly
surface_temperature_anomaly


Attributes of Atoms

  quantity = attribute
  quantity = "atomic_mass"
  quantity = "relative_atomic_mass" (dimensionless ratio to carbon-12)
  quantity = "mass_number" (number of protons + neutrons)
  quantity = "neutron_number" (number of neutrons)
  quantity = "proton_number" (number of protons)
  quantity = "characteristic_oscillation_frequency"

  Examples 

carbon_isotope_neutron_number  (use "isotope" like this ??)
cesium_atom_proton_number
cesium_atom_characteristic_oscillation_frequency
cesium_atom_relative_atomic_mass
  • There is controversy over the term "atomic_weight" and the term "relative_atomic_mass" seems preferably and more precise.
  • While "atomic number" is a standard term, the synonym "proton_number" is winning favor because it is more specific and because "neutron_number" is also used.


Attributes of Planets

  quantity = attribute

  Examples 

earth_axis_tilt_angle               (or axial_tilt_angle ??)
earth_ellipsoid_equatorial_radius
earth_ellipsoid_flattening_ratio
earth_ellipsoid_polar_radius
earth_mass
earth_orbit_eccentricity        (preferable to earth_orbital_eccentricity ??)
earth_rotation_rate
earth_rotational_period
earth_sidereal_day
earth_solar_irradiation_constant    ( or insolation_constant ?)
earth_standard_gravity_constant    (see the Constant template)
mars_mean_diameter
  • Some of these are needed for proper georeferencing or modeling solar radiation via celestial mechanics.
  • Notice that the word "ellipsoid" was inserted in three examples above. This is an example of the Object_name + Model_name pattern that is explained at the top of the document: CSDMS Object Templates.


Attributes of Processes

  • See the template for Process Attributes.


Attributes of Products of a Company

  quantity = attribute


Attributes of Radiation

  quantity = attribute
  quantity = "absorbance"
  quantity = "albedo"
  quantity = "amplitude"
  quantity = "emission_angle"
  quantity = "emissivity"
  quantity = "flux"
  quantity = "frequency"
  quantity = "incidence_angle"
  quantity = "intensity"
  quantity = "period"
  quantity = "reflectivity"
  quantity = "refraction_index"
  quantity = "transmittance"

  • Albedo is also called "diffuse reflectivity" or "reflectance coefficient".

Amplitude,Electromagnetic radiation, Frequency,Intensity in physics,Reflectivity, Transmittance, Visible radiation and Wavelength.


Attributes of Topography

  quantity = attribute
  quantity = "aspect_angle" (aspect is not used by itself)
  quantity = "elevation"
  quantity = "laplacian_curvature"
  quantity = "mean_curvature"
  quantity = "plan_curvature"
  quantity = "profile_curvature"
  quantity = "slope" [unitless = rise/run = L/L]
  quantity = "slope_angle" [radians or degrees]
  quantity = "streamline_curvature"
  quantity = "tangential_curvature"

  Examples 

bedrock_surface_elevation
derivative_wrt_time_of_land_surface_elevation
derivative_wrt_x_of_land_surface_elevation
glacier_surface_slope
ground_water_table_surface_aspect_angle
land_surface_profile_curvature
sea_water_surface_mean_curvature
  • Note that many of these quantities are defined in terms of first or second derivatives, which requires a certain degree of smoothness (differentiable or twice differentiable). Real topography is generally not this smooth, especially at small scales, but these quantities are nevertheless useful and can be computed from DEMs. In the CSDMS Standard Names, the Object_name + Model_name Pattern indicates that the word "surface" should be inserted in front of the quantity name when the quantity is only defined for some kind of idealized "model" surface. See the Surface template.


Capacity

  base_quantity = "capacity"

  Examples 

air_thermal_capacity
pure_iron_thermal_capacity   (should we add "pure" here? ######)
snow_thermal_capacity
soil_thermal_capacity
  • "thermal_capacity" seems preferable to and more precise than "heat_capacity".
  • There are 4 CF Standard Names that contain "capacity", namely "soil_thermal_capacity" and 3 others that contain the phrase "at_field_capacity" and refer to soil moisture. In our system, quantities like "water_content" associated with "field_capacity" would be given as: "field_capacity_water_content" or perhaps "at_field_capacity_water_content".


Charge

  base_quantity = "charge" [C = Coulombs, SI unit]

  Examples 

electron_electric_charge
  • The total electric charge is a fundamental conserved quantity of an isolated system.
  • Electric charge is quantized, that is, it comes in multiples of the the charge of an electron, called the elementary charge, denoted as "e". The charge of a quark is 1/3 of this value. Electric charge also carries a sign; protons and electrons have charges of e and -e.


Coefficient

  base_quantity = "coefficient"

  Examples 

iron_thermal_expansion_coefficient
channel_bed_manning_roughness_coefficient
rubber_on_road_kinetic_friction_coefficient
rubber_on_road_static_friction_coefficient
salt_in_water_diffusion_coefficient   ####
  • Note that some of these use the Object-in-object Quantity Pattern.
  • "expansion_coefficient" follows the Process_name + Quantity Pattern.
  • Other examples are: "drag_coefficient" and "skin_friction_coefficient".
  • Coefficients often occur in empirical laws.
  • "Manning's roughness coefficient" is sometimes called just "Manning's coefficient" or "Manning's roughness parameter" or something similar.
  • See Constant, Exponent, Factor, Index, Number and Parameter.


Component

  quantity_suffix = "component"
  quantity = [ direction adjective ] + [ vector quantity ] + "_component"

  Examples 

x_axis_velocity_component,
eastward_velocity_component
  • We could also use the pattern:
      quantity = [ vector quantity ] + [ direction ] + "_component"
    but the above pattern seems preferable.
  • This is a quantity suffix that creates a new quantity from an existing base quantity (like a vector or tensor). See Anomaly, Increment and Magnitude.
  • Note that "x_axis_" is used instead of just "x_". It might be interesting (and seems consistent) to introduce a word like "xward".


Concentration

  base_quantity = "concentration"
  quantity = "mass_concentration" [kg m-3]
  quantity = "molar_concentration" [mol m-3]
  quantity = "number_concentration" [m-3]
  quantity = "volume_concentration" [1] = [m3 / m3]

  • There are four main types of concentration, shown above, and they all have different units.
  • There are many related concepts such as:
    molality, mole_fraction, mole_ratio, mass_fraction and mass_ratio.
  • What about "osmotic_concentration" ?


Conductivity

  base_quantity = "conductivity"
  quantity = "electrical_conductivity" [siemens m-1] or [ohm-1 m-1]
  quantity = "hydraulic_conductivity" [m s-1]
  quantity = "ionic_conductivity"
  quantity = "thermal_conductivity" [W m-1 K-1]

  Examples 

sea_water_electrical_conductivity
snow_thermal_conductivity
soil_saturated_hydraulic_conductivity
  • Units cannot be determined from the "base quantity" name as shown above.
  • Hydraulic conductivity can depend on coordinate direction unless the soil is assumed to be isotropic. When applicable, include an <assumption> tag in the Model Metadata File with the standard assumption name: "isotropic_medium". See CSDMS Assumption Names for more information.


Constants in Math

  base_quantity = "constant"
  quantity = "math_" + constant_name + "_constant"

  Examples 

math_catalan_constant
math_chaitin_constant
math_conway_constant
math_e_constant                (or math_euler_e_constant ??)
math_euler_gamma_constant
math_feigenbaum_alpha_constant
math_feigenbaum_delta_constant
math_golden_ratio_constant
math_googol_constant
math_khinchin_constant
math_pythagoras_constant   (= square root of 2)
math_sierpinski_constant
math_twin_prime_constant
math_pi_constant
  • These numbers are not a quantity associated with an object like our others so we have used "math" as a placeholder object. Note that one model may want to check the number of significant digits of a math constant (like pi) that are used in another model, for example.
  • See the Dimensionless Number template.


Constants in Physics

  base_quantity = "constant"

  Examples 

avogadro_constant           [unit mol-1]   (see Note below)
boltzmann_constant         (See ideal_gas_constant)
cosmological_constant       [m-2]   (about 10^{-52};  object = universe)
coulomb_constant            [N m2 C-2]     (C = Coulomb SI unit)
dielectric_constant         [1]            (can be complex; = static_relative_permittivity)
fine_structure_constant     [1]            (about 1/137.035999074)
ideal_gas_constant          [J mol-1 K-1]   (R = 8.3144621)
latent_heat_fusion_constant [J kg-1]       (similar for vaporization)
light_speed_constant        [m s-1]
planck_constant             [J s]
rydberg_constant            [m-1]
solar_constant              [W m-2]        (solar_irradiation_constant may be better)
spring_constant             [kg s-2]       (in Hooke's Law)
standard_gravity_constant   [m s-2]  ("little g", see Attributes of Planets template)
stefan_boltzmann_constant   [W m-2 K-4]
universal_gravitation_constant   [m3 kg-1 s-2]  ("big G", from Newton's law)
von_karman_constant         [1]
  • The modern name for "Avogadro's number" is the "avogadro_constant". (See Avogadro constant.) It has units and is equal to: 6.02214129(27)x10^{23} [mol-1] or [unit mol-1]
  • The speed of light depends on the medium it is traveling through. In a vacuum, v = c = 299,792,458 [m s-1]. In other materials, v = (c / n), where n > 1 is the refraction index. For visible light in air, n is about 1.0003. So an unambiguous standard name should indicate the medium and the wavelength range in the object name. Since the medium that the light is traveling through matters, we use the Object-in-object Quantity Pattern to create standard names such as: "visible_light_in_air_speed".
  • The speed of light in a vacuum is a constant that is independent of wavelength. Perhaps we should give it the standard name "light_in_vacuum_speed_constant" which follows the Object-in-object Quantity Pattern.
  • If there is no naturally-associated object, we could use a placeholder object name like "physics".
  • The "universal gravitational constant' appears in Newton's Law of Gravitation and is denoted as G (big G). It has units of [m3 kg-1 s-2]. The "Earth gravitational constant" is more correctly called the "Earth standard gravity constant". It is the average free-fall acceleration of Earth's gravitational field near the surface of the Earth and is denoted as g (little g). Even though it varies with position on Earth, it is defined to be precisely 9.80665 [m s-2] (an average value). See: Standard gravity and Gravity of Earth.


Content

  base_quantity = "content"
  quantity = "energy_content"
  quantity = "mass_content"
  quantity = "water_content"

  Examples 

coal_thermal_energy_content
dry_wood_thermal_energy_content
gas_thermal_energy_content
 
soil_field_capacity_water_content
soil_hygroscopic_water_content
soil_initial_water_content
soil_normalized_water_content  (also called "effective saturation")
soil_residual_water_content
soil_saturated_water_content
soil_wilting_point_water_content
 
snow_cold_content  ? (must be overcome before melting starts to occur)
snow_thermal_energy_content


  • The word "content" refers to the "amount contained within". It is therefore naturally associated with two objects and the Object-in-object Quantity Pattern. While "soil_water_content" is a fairly standard term in hydrology, it would be perfectly valid and perhaps more clear to use the term "water_in_soil_volume_fraction".
  • The quantity "thermal_energy_content" can be applied to substances like air and snow but is often used in the context of fuels like coal, gas and wood.
  • In CF Standard Names, "content" indicates a quantity per unit area. However, in infiltration theory, "soil_water_content" is a "volume_fraction". CF has "soil_moisture_content", "soil_moisture_content_at_field_capacity" and "soil_carbon_content". See Wikipedia: Water Content.
  • Do we want to distinguish between: gravimetric_water_content and volumetric_water_content ?
  • Many CF Convention Standard Names contain the base quantity "content". The following list shows the number, in parentheses, or each use pattern:
carbon_content [kg m-2]   (14)
energy_content [J m-2]  (25)  e.g. "thermal_energy_content_of_surface_snow"
enthalpy_content [**********] (4)
heat_content [J m-2]  (2)
ice_content [kg m-2]  (2)
mass_content [kg m-2]   (235)
moisture_content [kg m-2] or [m]  (6)
number_content [m-2]  (7)
ozone_content [Pa] or [m]  (2)
soot_content [kg m-2]  (1)
sulfate_content [kg m-2]  (1)
vapor_content [kg m-2] (14)   (most are "tendencies")
water_content [kg m-2]  (16)
We may therefore have a conflict with "water_content" unless it is resolved by the object part.


Correlation

  base_quantity = "correlation"

  Examples 

(None yet)
  • Note that correlations require two quantities to be specified, which is similar to certain other quantities such as Partial Pressure and Solubility.
  • Although the Guidelines for Constructing CF Standard Names includes a provision for correlations as the transformation pattern: "correlation_of_X_and_Y_over_Z", there are currently no examples of CF Standard Names that contain "correlation". The same is true for "covariance" and "convergence". There are only three names with "divergence".


Count

  base_quantity = "count"
  quantity = "blood_cell_count"

  Examples 

channel_bed_wolman_pebble_count
human_platelet_count
human_red_blood_cell_count
human_white_blood_cell_count
  • This quantity name is sometimes used when the attribute being quantified can only take integer values, as in the examples above.
  • In the case of blood cell counts, the units are usually a number per volume (e.g. number per microliter). See: Blood cell count.
  • The "Wolman pebble count" due to M. Gordon "Reds" Wolman is sometimes used in river hydraulics and sediment transport.
  • The "diatom count" of a sample may be another example; are the units may then "abundance"? (e.g. "sediment_core_diatom_relative_abundance" ?)
  • The number of occurrences of a given event may also be called a "count".


Curvature

  • See the Attributes of Topography template which lists several types of curvature. However, curvature can also be defined for curves, such as coastline curves and space curves (or trajectories).


Density

  base_quantity = "density"

  Examples 

air_density
air_stp_density   (stp = standard temperature and pressure)
friedmann_universe_critical_density
sea_water_density
watershed_drainage_density
  • Maybe expand this to "mass_density" to avoid any ambiguity. Units for "mass_density" would always be [kg m-3]. Consider cases like: "drainage_density" [L-1]
  • The adjective "bulk" is often inserted before density.
  • Physicists sometimes use the term "flux_density".
  • Hydrologists use the term "drainage_density", which is defined as the total length of channels in a watershed divided by the watershed area. Similarly, "source_density" refers to the total number of sources (i.e. channel heads) in a watershed divided by the watershed area.
  • Other valid quantities include "current_density", "electron_density" (in plasma physics), "thermal_energy_density" and "magnetic_energy_density".


Depth

  base_quantity = "depth"

  Examples 

channel_water_mean_depth  ??
ground_water_table_depth
sea_water_depth  (or sea_floor_depth ?? #######)
sea_water_secchi_depth
  • Measured as a positive downward distance below a reference surface.
  • CF Standard Names often use "thickness" instead of "depth".
  • See Elevation, Height, Thickness.


Diffusivity

  base_quantity = "diffusivity"
  quantity = "magnetic_diffusivity" [m2 s-1]
  quantity = "mass_diffusivity" [m2 s-1]
  quantity = "momentum_diffusivity" [m2 s-1] (nickname for kinematic_viscosity)
  quantity = "thermal_diffusivity" [m2 s-1]

  • It appears that the units are always [m2 s-1].
  • "thermal_diffusivity" seems preferable to "heat_diffusivity"
  • Common adjectives are: biharmonic, laplacian, epineutral, etc.
  • The term "eddy diffusivity" is sometimes used as a synonym for the "eddy diffusion coefficient", usually denoted as "K". See: Eddy diffusion.


Dimensionless Numbers

  quantity = [ famous person's name ] + "_number"

  Examples 

airplane_mach_number
channel_water_reynolds_number
channel_water_froude_number
heat_equation_courant_number   #### (insert "model" ??)
helium_plume_in_air_richardson_number  ### (vs. helium_in_air_plume_)
  • Some names, like "Reynolds", end in "s", but don't add a possessive "s" at the end.
  • Dimensionless numbers are widely used in physics and typically obtained as the ratio of two quantities that have the same units. For example, Reynolds number gives the ratio of inertial and viscous forces in a flow problem, and flows transition from laminar to turbulent as the Reynolds number increases.
  • The modern name for "Avogadro's number" is the "Avogadro constant" and it is not dimensionless.
  • There are quantities called "wave_number" (from wave theory) and "winding_number" (from math) that are not dimensionless numbers.
  • See the Attributes of Atoms and Number templates for terms like "proton_number".
  • In number theory (a branch of mathematics) there are many special numbers (or types of numbers) named after a famous person, such as: Bell, Catalan, Euler, Fibonacci, Kaprekar, Lucas, and Smith. Some, like Euler's number, are math constants like pi.
  • Outside of science/math, we also have "social_security_number" and "tracking_number", "taxpayer_ID_number", etc.


Discharge or Volumetric Flow Rate

  quantity = "discharge" (OR "volumetric_flow_rate" ?) (see Wikipedia)

  Examples 

channel_sediment_discharge
channel_water_discharge [m3 s-1]
channel_sediment_discharge
watershed_outlet_discharge [m3 s-]
  • Units are [m3 s-1] and typical notation is "Q".
  • It appears that a "volumetric_flux" should have units of [m3 m-2 s-1] = [m s-1], as in Darcy's Law. Discharge is then the integral of a volumetric flux over the cross-sectional area of a channel or pipe. See the notes for the Flux templates below.
  • Avoid "streamflow" and "outflow" as synonyms for "discharge" or else define them to be aliases.
  • Hydrologists also use "unit_width_discharge" or "discharge_per_unit_width", usually denoted by lower-case "q", with units of [m2 s-1].


Distance

  base_quantity = "distance"

  Examples 

earth_to_sun_mean_distance
  • This quantity seems to require specifying two objects, just as solubility, partial_pressure and volume_fraction do. In the latter cases the special keyword "_in_" was introduced. Here the reserved word "_to_" and the pattern: (object + "_to_" + object + distance) is used in a similar way. The keyword "_to_" can also be used for ratios. See "Ratios".


Duration

  base_quantity = "duration"

  Examples 

sunshine_duration
water_precipitation_duration   (vs. "rainfall_duration")
  • See the Precipitation section.


Elevation

  base_quantity = "elevation"

  Examples 

bedrock_surface_elevation
ground_water_table_surface_elevation
land_surface_elevation
sea_surface_elevation
  • The word "altitude" is reserved for objects that are above and not in contact with the land surface. (e.g. aircraft, air parcel, balloon)
  • See the quantity templates for Altitude, Depth, Height, Thickness.
  • See the object template for Surface. Elevation is one of many attributes that can be associated with a surface.


Energy

  base_quantity = "energy"
  quantity = "electric_energy"
  quantity = "internal_energy"
  quantity = "kinetic_energy"
  quantity = "potential_energy"
  quantity = "specific_energy"
  quantity = "thermal_energy"

  Examples 

ball_potential_energy
turbulence_kinetic_energy
  • The SI unit for energy is Joules.
  • Specific energy is energy per unit volume or mass.
  • Some possible forms of energy are thermal, chemical, radiant, nuclear, magnetic, elastic sound, mechanical, luminous and mass.


Exponent

  base_quantity = "exponent"

  Examples 

sediment_transport_law_slope_exponent  ?? ##########
  • Exponents often occur in empirical laws.
  • See Coefficient, Constant, Factor, Index, Number and Parameter.


Factor

  base_quantity = "factor"

  Examples 

crest_factor
particle_cunningham_correction_factor
pipe_water_darcy_weisbach_friction_factor  (same as moody_friction_factor)
pipe_water_fanning_friction_factor
  • Use "manning_roughness_coefficient" instead of "manning_friction_factor".
  • See Coefficients, Constant, Exponent, Index, Number, Parameter


Flux of Heat or Energy

  base_quantity = "flux"

  • "Flux" can be viewed as "surface bombardment rate". See the Wikipedia article on "Flux".
  • In CF Standard Names, "flux" implies per unit area. They say that "flux_density" is used in physics instead. However, "discharge" is a hydrologic flux with units [m3 s-1].
  • In CF Standard Names, "flux" may be preceded by the words:
    mass, momentum,
    energy, heat, longwave, shortwave, radiative,
    water, vapor, evaporation,
    palm, photon, mole, salt
    Units are [W m-2] for the "energy fluxes" such "heat", "longwave", "shortwave" and "radiative".
  • Most energy fluxes in atmospheric models have units of [W m-2].


Flux of Mass

  quantity = "mass_flux"

  • In CF Standard Names, units are [kg m-2 s-1].
  • See Concentrations, Discharges.


Flux of Momentum

  quantity = "momentum_flux"

  • "momentum_diffusivity" [m2 s-1] is a nickname for kinematic_viscosity
  • In CF Standard Names, units are [Pa].


Fraction

  quantity_suffix = "fraction"
  quantity = "area_fraction"
  quantity = "mass_fraction"
  quantity = "mole_fraction"
  quantity = "time_fraction"
  quantity = "volume_fraction"

  Examples 

burned_area_fraction
cloud_area_fraction
forested_area_fraction   ??
land_area_fraction
rocket_payload_mass_fraction
rocket_propellant_mass_fraction  (See: Propellant mass fraction.)
sea_area_fraction
vegetation_area_fraction
void_volume_fraction   (see porosity)
 
clay_in_soil_volume_fraction   (using object_in_object pattern)
sand_in_soil_volume_fraction
silt_in_soil_volume_fraction
 
frozen_water_in_soil_volume_fraction   (modified from CF name below)
oxygen_in_sea_water_volume_fraction  (modified from CF name below)
  • It appears that "fraction" should be viewed as a quantity suffix that can be applied to any base quantity (e.g. area, mass, mole, time, volume) to create a new quantity. In most (if not all) cases it is dimensionless.
  • In the CF Standard Names, "fraction" is used in 306 names to form the following 5 quantities where the number of occurrences is indicated in parentheses:
area_fraction (19)
mass_fraction (179)
mole_fraction (95)
time_fraction (2)
volume_fraction (11)
The ones for "volume_fraction" fall into 5 groups:
ocean_volume_fraction
volume_fraction_of_oxygen_in_sea_water
volume_fraction_of_[clay, silt or sand]_in_soil
volume_fraction_of_condensed_water_in_soil + [assumptions]
volume_fraction_of_frozen_water_in_soil
Hydrologists typically use the shorter term "soil_water_content" instead of "volume_fraction_of_condensed_water_in_soil". However, using "water_in_soil_volume_fraction" instead would be consistent with the Object-in-object Quantity Pattern.


Friction

  • Friction is not a quantity and is really a force as opposed to a process. It is not included in this list of CSDMS Process Names because it doesn't fit the general verb-to-noun process name pattern explained on that page. The word "traction" has similar issues.
  • The adjective "frictional" is used in terms like "frictional_momentum_loss_rate". But the net loss of momentum (per unit time and per unit area) due to friction in a fluid is equivalent to the shear stress. Note that both have units [M L T-2]. See the template for Stress.
  • Some quantities associated with friction are:
kinetic_friction_coefficient  (See the Coefficient template.)
manning_roughness_coefficient
mean_roughness_length   ("z0" for law of the wall)
shear_stress   (See the Stress template.)
static_friction_coefficient
  • A Google search indicates that "friction_rate" is sometimes used in connection with air ducts.


Frequency

  base_quantity = "frequency" [1/second]
  quantity = "angular_frequency" [radians/second]

  Examples 

cesium_atom_characteristic_oscillation_frequency
sea_water_brunt_vaisala_frequency   (also called "buoyancy_frequency")
sea_water_surface_wave_frequency
  • Units of frequency are usually hertz = [1/second].
  • For periodic waves, the frequency is equal to the phase velocity divided by the wavelength. See the Period and Wavelength templates.


Fuel Efficiency

  quantity = "fuel_consumption_rate" ["gallons per mile" or "liters per km"]
  quantity = "fuel_economy" ["miles per gallon" or "km per liter"]
  quantity = "fuel_specific_energy_content" [Joules / kg]

  Examples 

automobile_fuel_consumption_rate
automobile_fuel_economy
gm_hummer_fuel_consumption_rate
toyota_corolla_fuel_economy
  • In everyday language, the term "miles_per_gallon" is often used as if it were a quantity name but it is really a units name. "mileage" has various meanings and is not a well-defined quantity name.
  • Is there a good "process - rate" quantity name for "fuel_economy" ? We could potentially replace "economy" with "per_gallon_miles".
  • energy_efficiency and energy_intensity are related quantities.
  • Efficiency of electric vehicles is often given as "cents_per_mile" which allows comparison to gas-powered vehicles.


Humidity and Relative Saturation

  base_quantity = "humidity"
  quantity = "absolute_humidity" (is "volumetric_humidity" a synonym ?)
  quantity = "relative_humidity"
  quantity = "relative_saturation"
  quantity = "specific_humidity"

  Examples 

air_relative_humidity   (= water_vapor_in_air_relative_saturation)
carbon_dioxide_in_air_relative_saturation   #### CHECK
  • Relative humidity is dimensionless ratio of partial pressures. It is defined as the ratio of the partial pressure of water vapor in the air-water mixture (often called the "vapor pressure") to the saturated vapor (partial) pressure of the water at a prescribed temperature.
  • The relative humidity is often known (measured) and empirical equations for computing saturated vapor pressure as a function of temperature have been given by both Brutsaert and Satterlund. From these, vapor pressure can be computed from the definition.
  • Relative humidity of air depends on both temperature and pressure.
  • The more general term for relative humidity (when not talking about water vapor in air) is relative_saturation. It is the ratio of the partial pressure to the saturated partial pressure of one (condensable phase) gas in another (non-condensable phase) gas mixture.


Increment

  quantity_suffix = "increment"

  Examples 

air_pressure_increment
bedrock_surface_elevation_increment
land_surface_elevation_increment
  • This can be used for the change in a quantity that occurs over some time period, such as a model time step. It can be either negative or positive.
  • This is a quantity suffix that creates a new quantity from an existing base quantity like elevation or pressure. Others are Anomaly, Component, Limit and Magnitude.
  • See the Time Step template.


Index

  base_quantity = "index"

  Examples 

diversity_index
normalized_difference_vegetation_index
palmer_drought_severity_index
price_index
refraction_index
soil_moisture_index
wetness_index  (with prefix: soil, topographic, catchment, etc.)
  • We use "refraction_index" instead of "refractive_index" in accordance with the Process_name + Quantity Pattern.
  • See Coefficient, Constant, Exponent, Factor, Number and Parameter.


Limit

  quantity_suffix = "limit"

  Examples 

human_hearing_high_frequency_limit    (Note:  hearing is a process name)
neutron_star_tolman_oppenheimer_volkoff_mass_limit
photon_in_human_eye_detection_number_limit    (process_name + quantity)
white_dwarf_star_chandrasekhar_mass_limit
  • This is a quantity suffix, similar to Anomaly, Component, Increment and Magnitude. A "limit" is not a quantity by itself and can apply to virtually any quantity.
  • Note that the two limits above named after people include the quantity name "mass" after "limit". There is also a related "Schwarzchild radius"; see the quantity template for Radius. It is not clear that "_limit" would ever be used by itself. See Point.
  • "cutoff" or "threshold" may sometimes be used similarly.


Magnitude

  quantity_suffix = "magnitude"
  quantity = [ vector quantity ] + "_magnitude"

  Examples 

vector_magnitude
normal_stress_magnitude   (or normal_stress_component_magnitude ??)
shear_stress_magnitude
stress_tensor_magnitude ??  #########
  • Magnitude is a general term in mathematics, used to indicate a scalar-valued "size" of something like a vector or complex number.
  • Exception: Use "speed" instead of "velocity_magnitude".
  • This is a quantity suffix that creates a new quantity from an existing base quantity (like a vector or tensor). Others are Anomaly, Component and Increment.
  • In CF Standard Names, "magnitude_of_" is a transformation (prefix) that is used in about 5 names.


Mass

  base_quantity = "mass"

  Examples 

atomic_mass  (also relative_atomic_mass = atomic_weight)
chandrasekhar_limit_mass   (object = white_dwarf_star)
relativistic_mass
rest_mass (also invariant mass, intrinsic_mass, proper mass)
tolman_oppenheimer_volkoff_limit_mass  (object = neutron_star)


Miles per Gallon

  • This is not allowed because it is not a good quantity name; it is really a units name. The associated concepts are "fuel_consumption" and "fuel_economy". The word "mileage" is sometimes used but is also a poor term.
  • See the Fuel Efficiency template.


Number

  base_quantity = "number"
  quantity = "neutron_number"
  quantity = "protron_number"
  quantity = "quantum_number"
  quantity = "wave_number"
  quantity = "winding_number"

  Examples 

carbon_isotope_neutron_number
iron_atom_neutron_number
iron_atom_proton_number
sea_water_surface_wave_number
  • This quantity name is often used when the attribute being quantified can only take integer values, as in the examples above and detectors that count particles. The word "count" is used similarly. However, dimensionless numbers also end with the word "number" as discussed in the Dimensionless Number template and they are typically not integers. Also the wave number need not be an integer.
  • Atomic number is a synonym for "proton_number" but the latter is used for clarity and consistency in the CSDMS standard names. The "mass_number" is defined as the sum of the "proton_number" and "neutron_number".
  • Several other "numbers" are defined in particle physics, such as the "electronic_number", "muonic_number" and "tauonic_number".
  • The winding number is used in mathematics as an attribute of closed, planar curves.
  • See the Count template.


Parameter

  base_quantity = "parameter"

  Examples 

earth_coriolis_parameter
  • Parameters often occur in empirical laws.
  • The CSDMS standard names use "manning_roughness_coefficient" vs. "parameter".
  • See templates for Coefficient, Constant, Exponent, Factor, Index and Number.


Partial Pressure

  quantity = [substance 1] + "_in_" + [substance 2] + "_partial_pressure"

  Examples 

carbon_dioxide_in_air_partial_pressure

water_vapor_in_air_equilibrium_partial_pressure (i.e. vapor_pressure) 

water_vapor_in_air_partial_pressure      ##### (check)
  • These are special in that two objects (substances) are involved. We reserve the word "_in_" for these cases. See Solubility.
  • CF Standard Names currently has only 6 names with "partial_pressure". They all have units of [Pa] and are:
surface_carbon_dioxide_partial_pressure_difference_between_air_and_sea_water
surface_carbon_dioxide_partial_pressure_difference_between_sea_water_and_air
surface_molecular_oxygen_partial_pressure_difference_between_sea_water_and_air
surface_partial_pressure_of_carbon_dioxide_in_air
surface_partial_pressure_of_carbon_dioxide_in_sea_water
water_vapor_partial_pressure_in_air   (alias: water_vapor_pressure)
  • Here are some possible alternative constructions for the CF Standard Name:
    surface_partial_pressure_of_carbon_dioxide_in_air
    that maintain our pattern of: [object] + [quantity]:
carbon_dioxide_in_air + _partial_pressure   (preferred ??)
carbon_dioxide_ + partial_pressure_ + in_air
atmospheric_carbon_dioxide_ + partial_pressure (at_surface?)
    (Here atmospheric implies "in air".)
in_air_carbon_dioxide_ + partial_pressure
air_contained_carbon_dioxide_ + partial_pressure
boa_carbon_dioxide + _partial_pressure
     (Here we introduce "boa = bottom_of_atmosphere" to match "toa" already used in the CF Standard Names.
  • An alternate pattern that doesn't seem general enough is:
    quantity = "atmospheric_" + [substance] + "_partial_pressure"
  • The word "equilibrium" may be inserted just before "partial_pressure".
  • See the quantity template for Pressure.


Point

  Examples 

boiling_point
breaking_point  ??
bubble_point
critical_point   (See: Critical point.)
curie_point  (See: Curie point.)
dew_point
flash_point
freezing_point
frost_point
melting_point
wilting_point    (used in infiltration theory)
  • This is not viewed as a quantity within the CSDMS Standard Names. It is generally inserted just before a base quantity name and refers to a threshold that occurs for that quantity. See the template for Temperature for many examples.
  • Each of the examples above puts a "process name" prefix, from the list of process names in CSDMS Process Names in front of "_point".


Porosity

  base_quantity = "porosity"

  Examples 

soil_porosity
  • Could also be called "void_volume_fraction".


Precipitation

  quantity = "precipitation_" + base_quantity

  Examples 

ice_precipitation_rate
methane_precipitation_rate
snow_precipitation_rate
water_precipitation_duration
water_precipitation_rate
  • Precipitation is not a quantity, but rather a process as defined at the top of the CSDMS Process Names page. However, there are several quantities associated with precipitation, as seen in the examples above.
  • Rainfall is an unusual example of a process name in that the relevant object (rain) and the associated process (falling) have been fused to create the process name. (Others include "icefall", "snowfall" and "throughfall".) Adding the object part in front would mean repeating the word rain. We can avoid this issue by using "precipitation" instead of "rainfall" and then specifying the object that is precipitating as "ice", "snow", "water", or perhaps "methane" for Titan.
  • When necessary, the <assumption> tag "liquid_water_equivalent" can be specified in a Model Metadata File in connection with a quantity like "snow_precipitation_rate". That assumption would be taken for granted with a quantity like "snow_melt_rate".
  • See the templates for Process Attributes and Rates of Processes for more information.


Pressure

  base_quantity = "pressure"

  Examples 

channel_bed_water_hydrostatic_pressure
channel_bed_water_pressure  
channel_water_pressure       (anywhere in the channel)
earth_atmosphere_pressure
    (also: earth_atmosphere_at_land_surface_pressure ??)
  • The quantity "pressure_head" is used in hydraulics and in ground water modeling but it has units of length. It is often negative, and negative pressure is sometimes called suction.
  • Note that additional assumptions like "equilibrium" and "hydrostatic" could be left out of the name and instead provided using the <assumption> tag in the metadata file, but they are currently allowed as modifiers in the quantity name also.
  • Pressure requires specifying a single object (e.g. air) but "partial pressure" requires two different objects to be specified using the "object-in-object" pattern. See the quantity template for Partial Pressure.
  • In meteorology, the term "vapor pressure" is used to mean the partial pressure of water vapor in the atmosphere, even if it is not in equilibrium, and the adjective equilibrium is inserted otherwise. Our "object-in-object" pattern therefore prescribes using: "water_vapor_in_air_partial_pressure" instead of just "air_vapor_pressure". See Wikipedia: Vapor Pressure.
  • In cosmology, there is also a concept of "negative pressure".


Process Attributes

  quantity = [ process name ] + [ base_quantity ]

  Examples 

digestion_period, gestation_period, hibernation_period,
incubation_period, sleeping_period
-------------------------------------------------------------------
infiltration_rate, lapse_rate, melt_rate, precipitation_rate,
rainfall_rate  (use precipitation instead?)
    (Note:  "melt" -> "melting" ?)
-------------------------------------------------------------------
conception_date
delivery_date        (vs. "expected_delivery_date" or "due_date")
launch_date
ovulation_date
starting_date        (or "start_date" ??)
----------------------
rainfall_duration
sunshine_duration
----------------------
failure_frequency
oscillation_frequency
vibration_frequency
wave_frequency        (vs. "waving")
----------------------
recovery_time
starting_time
stopping_time
----------------------
flow_speed
running_speed
wind_speed    (Note: "wind" = "air_flow".)
----------------------
birth_weight
dissociation_energy
penetration_depth
striking_distance
turning_radius
  • Process names are almost always generated by converting a verb to a noun with a standard ending like "tion". See CSDMS Process Names for more details and a long list of examples.
  • The base quantity "_rate" makes sense for most processes, but a given process if often naturally associated with other base quantities.
  • In the example of "birth_weight", "birth" is a process that is happening to the baby, while "delivery" or "giving birth" is the process happening to the mother. (i.e. "infant_birth_weight" and perhaps "pregnant_female_delivery_date")
  • For a discussion of cases where the base quantity is "rate", see "Rates of Processes" below.


Radiation

  quantity = "radiation_" + quantity

  Examples 

air_net_downward_shortwave_radiation_flux
incandescent_light_bulb_radiation_intensity   ? ##### CHECK
universe_cosmic_background_radiation_frequency
  • Note that "radiation" is a process and not a quantity by itself. Quantity names can be constructed using the Process_name + Quantity Pattern. See the Process Attributes template.
  • Adjectives like longwave, shortwave, visible, infrared, thermal_infrared, ultraviolet and so on are typically inserted just before the word radiation.
  • In a vacuum (e.g. space), the refraction index for all wavelengths of light is 1, so the speed of light is independent of wavelength. In other media, such as air and water, the refraction index (and therefore the speed) varies with wavelength. See the Index template.
  • Radiation fluxes typically have units of [W m-2]. See the Flux template.


Radius

  base_quantity = "radius"

  Examples 

automobile_turning_radius
black_hole_schwarzchild_radius
earth_ellipsoid_equatorial_radius
earth_ellipsoid_polar_radius
railway_curve_minimum_radius    (see link below)
  • What about Radius of Curvature? See the object template for Surface.


Rates of Processes

  quantity = [ process name ] + "_rate"

  Examples 

air_temperature_lapse_rate
alcohol_consumption_rate
fuel_consumption_rate
rainfall_rate  ###### (avoid ? see notes.)
snow_precipitation_rate
surface_evaporation_rate
surface_infiltration_rate
surface_snow_melt_rate        ("melt" -> "melting" ??)
water_precipitation_rate
  • For a "melt_rate", we may want to insert a modifier that indicates "liquid_water_equivalent", as in "lwe_melt_rate". (Or assume it is implied?) I think CF Standard Names use an assumption suffix for this like "assuming_liquid_water_equivalent".
    ############## CHECK
  • The term "rainfall_rate" is commonly used and is better than "rain_rate" since rain is an object and not a process. The same applies to the terms snowfall and icefall. However, "rainfall" is a contraction of object (rain) and process (falling) names. A more general approach that adheres to our object-quantity pattern (with quantity as a process rate) is to use terms like:
ice_precipitation_rate
liquid_methane_precipitation_rate   (on Titan)
snow_precipitation_rate
water_precipitation_rate   (liquid_water ??)
  • Note that "rainfall_rate" is used instead of "rain_rate", since rain is an object and not a process. The same for snowfall. But what is the appropriate object here? It could be "rain", but "rain" has been pulled into the process name (vs. "rain_falling_rate").


Ratio

  base_quantity = "ratio"
  quantity_suffix = "ratio" (in some cases)

  Examples 

air_to_fuel_mass_ratio     (or "mixture_ratio")
brain_to_body_mass_ratio
charge_to_mass_ratio
channel_cross_section_width_to_depth_ratio
fuel_to_oxidizer_equivalence_ratio   ###
rocket_to_payload_mass_ratio
rocket_to_propellant_mass_ratio
  • Ratios often make reference to two objects and then the Object-to-object Quantity Pattern is used.
  • Ratios are often dimensionless. In fact, most dimensionless numbers are ratios of forces, etc.
  • "ratio" serves as a quantity suffix in quantities like "mass_ratio", but is also allowed as a base quantity.
  • Perhaps we could replace the standard name:
    - channel_bed_relative_roughness_ratio to
    - channel_bed_roughness_length_to_water_depth_ratio
  • "aspect_ratio" generally means the ratio of the lengths of the long and short sides of a rectangle; 1 for a square and > 1 otherwise.


Scale

  quantity_suffix = "scale"
  quantity = "length_scale"
  quantity = "time_scale"
  quantity = "velocity_scale"

  Examples 

*_batchelor_scale
*_kolmogorov_length_scale 
*_kolmogorov_time_scale
*_kolmogorov_velocity_scale
*_mesoscopic_length_scale
*_obukhov_length_scale
*_planck_length_scale
*_planck_time_scale
*_taylor_length_scale
  • This is another quantity suffix, used to create new quantity names from existing quantity names. It often is used to indicate the value of a quantity that is as small as it can be for the given system and therefore able to serve as a natural unit of measure.


Solubility

  base_quantity = "solubility"

  Examples 

carbon_dioxide_in_water_solubility
diethyl_ether_in_water_solubility
ethanol_in_water_solubility
  • This quantity always involves two substances and therefore requires using the Object-in-object Quantity Pattern. See the templates for Partial Pressure and Fraction (volume fraction) which are similar in this regard.
  • Miscibility is the property of liquids to mix in all proportions to form a homogeneous solution and is a closely related concept. It is not a quantity, however.


Strain

  base_quantity = "strain"

  • Strain is a deflection, with units of length


Stress

  base_quantity = "stress"
  quantity = "deviatoric_stress"
  quantity = "normal_stress"
  quantity = "shearing_stress" (vs. "shear_stress"; see below)

  Examples 

channel_bed_shearing_stress
sea_floor_surface_normal_stress
sea_floor_surface_x_z_shearing_stress_component
sea_water_downward_eastward_shearing_stress_component
sea_water_downward_northward_shearing_stress_component
  • For models that use a geographic coordinate system, we would use "eastward", "northward" and "upward" to describe component directions. For models that use a Cartesian (or equal-area) coordinate system, we would use "x", "y" and "z". But perhaps we should use "xward" or "x_axis" instead ?
  • Conventions like "right_hand_rule" and "positive_downward" could be indicated in a Model Metadata File with <assumption> tags.
  • Note that a quantity suffix like "component" or "magnitude" may be inserted after the word "stress" when it removes ambiguity. Absence of the suffix implies magnitude.
  • Stresses are more complex than vectors and are represented mathematically as tensors.
  • There are two "kinds" of stress called "normal" and "shearing" stress. While a normal stress is associated with a single vector, two vectors are required to describe a shearing stress.
  • Note that "shearing_stress" follows the Process_name + Quantity Pattern, where the process name is "shearing". However, the "ing" ending is often dropped, as is often the case with process names; see the top of the CSDMS Process Names page. Many fluid dynamics textbooks use "shearing", e.g. Batchelor (1988), and "tangential stress" is a synonym.
  • In oceanography there is a concept of radiation stress and for electromagnetic radiation there is radiation pressure.
  • There are 19 CF Convention Standard Names that contain the word "stress". Most contain only one "component adjective" like "eastward", but some have two, such as
surface_downward_eastward_stress
surface_downward_northward_stress
surface_downward_x_stress
surface_downward_y_stress


Temperature

  base_quantity = "temperature"

  Examples 

iron_melting_point_temperature
snow_temperature
soil_temperature
water_boiling_point_temperature
water_freezing_point_temperature
water_vapor_in_air_bubble_point_temperature
water_vapor_in_air_dew_point_temperature
water_vapor_in_air_frost_point_temperature
  • Use "dew_point_temperature" vs. "temperature_at_dew_point". Similarly for "boiling_point", "melting_point", "freezing_point", etc.
  • Can include how measured with assumptions in metadata.


Threshold

  quantity_suffix = "threshold"

  • This is a quantity suffix that could be used with any base quantity and is not a quantity by itself.
  • It is more common for words like "critical" or "point" to be inserted as an adjective in front of a base quantity name to indicate a threshold value. See the template for Temperature.


Time

  quantity_suffix = "time"

  Examples 

channel_reach_peak_outgoing_water_discharge_time
  • Can be used as a "quantity suffix" associated with an event like reaching a peak value.


Time Step

  base_quantity = "_time_step_size" (OR "time_increment" ##########)

  Examples 

model_time_increment
  • We could also use: base_quantity = "_time_step_size" (vs. just "time_step") but we are using "increment" as part of a more general pattern.


Unit-width Quantity

  quantity = "unit_width_" + base_quantity

  Examples 

land_surface_water_unit_width_discharge
  • CF Standard Names use "_across_unit_distance" and "_across_line" to handle this concept.
  • What about "power_per_unit_length_of_wave_crest" ?
  • "unit_stream_power" is somewhat similar.
  • There are several other "per" concepts, such as:
per_capita
per_unit_area
per_unit_length
per_unit_mass
per_unit_time
per_unit_width
 
These could all be used as adjective or modifier prefixes for a base quantity.


Velocity

  quantity = "_speed"
  quantity = "_velocity_component"

  Examples 

sea_water_eastward_velocity_component
sea_water_speed
  • Velocity is a vector quantity with a magnitude and a direction. Most models store the components of a velocity field as separate variables, in which case the quantity suffix component can be used as shown in the example above. (See the template for Component.) However, it is also possible that one model would request a complete vector field (i.e. all components) from another model as a single "quantity". In this case we would need to allow "velocity" itself (a vector) as a base quantity name.
  • The shorter quantity name "speed" is used in CSDMS standard names instead of "velocity_magnitude" but they mean the same thing.


Voltage

  base_quantity = "voltage" [Volts = Joules per Coulomb]

  Examples 

battery_voltage
electric_appliance_voltage
electric_fence_voltage


Yield

  base_quantity = "yield"
  quantity = "specific_yield" (in groundwater modeling)

  Examples 

watershed_sediment_yield
  • In geology, "sediment_yield" refers to the total mass of particulate matter (suspended or bedload) that reaches the outlet of a watershed over a fixed time interval. It has units of [mass / (area * time)] or [M L-2 T-1]. See: sediment yield.
  • What about "yield_strength" (plastic deformation) ?
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