CSDMS Standard Names — Quantity Templates

The "templates" listed here 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 "CSDMS_Standard_Name_Quantities.txt".

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

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  (or axial_tilt_angle ??)
friction_angle, incidence_angle, pitch_angle, polarization_angle,
roll_angle, rotation_angle, scattering_angle, slope_angle,
tilt_angle (earth's axis), torsion_angle, yaw_angle, zenith_angle

Some of these examples are in CF Standard Names.

A few terms sound strange in this form, like "repose_angle", instead of "angle_of_repose". But this doesn't pose any real problem.

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 in turns; also channel banks.

Anomaly

quantity_suffix = "anomaly"

Examples

air_pressure_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. See Increment.

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 = "neutron_number" quantity = "proton_number" (number of protons) (instead of "atomic number") quantity = "characteristic_oscillation_frequency"

Examples

cesium_atom_characteristic_oscillation_frequency

There is controversy over the term "atomic_weight" and the term "relative_atomic_mass" seems preferably and more precise.

See the object name pattern for Atoms, Compounds, Ions and Molecules below for more details and examples.

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_orbital_eccentricity     (or just earth_orbit_eccentricity ??)
earth_rotation_rate
earth_rotational_period
earth_sidereal_day
mars_mean_diameter

These are often needed for proper georeferencing or modeling solar radiation via celestial mechanics.

Notice that the word "_ellipsoid" was inserted in the first three examples above. This illustrates another rule: If the quantity is not necessarily well-defined for the object itself (i.e. earth) but pertains more to another object being used to model that one, both object names are used, as in "earth_ellipsoid". This rule also appears in the case of channel cross sections that are modeled as trapezoids. In that case, every channel cross section has a well-defined perimeter, but only trapezoid-shaped cross-sections have a well-defined bottom width and bank angle.

Attributes of Products of a Company

quantity = attribute

See the Quantity pattern for "Product of a Given Company".

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".

Coefficient

base_quantity = "coefficient"

Examples

diffusion_coefficient
kinetic_friction_coefficient
static_friction_coefficient

Coefficients often occur in empirical laws.

See Constants, Exponents, Indexes, Numbers, Parameters

Component of a Vector

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).

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"

There are four main types of concentration and they all have different units, namely:

mass_concentration     [kg m-3]
molar_concentration    [mol m-3]
number_concentration   [m-3]
volume_concentration   [1] = [m3 / m3]

We will probably want to include the appropriate prefix from this list.

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"

Examples

electrical_conductivity  [siemens m-1] or [ohm-1 m-1]
hydraulic_conductivity   [m s-1]
thermal_conductivity     [W m-1 K-1]

Units cannot be determined from the "base quantity" name.

Hydraulic conductivity can depend on coordinate direction unless the soil is assumed to be isotropic. When applicable, specify the assumption "_assuming_isotropic_medium" in the metadata.

Constants in Math

base_quantity = "math_constant" ?? ##########

Examples

pi_math_constant

This includes numbers like "pi", "phi" and "e".

These numbers are not a quantity associated with an object like our others and should perhaps be excluded. However, one model may want to check the number of significant digits of pi that are used in another model, for example.

Constants in Physics

base_quantity = "constant"

Examples

avogadro_constant           [unit mol-1]   (see Note below)
dielectric_constant         [1]            (can be complex; = static_relative_permittivity)
gravitational_constant      [m s-2]
latent_heat_fusion_constant [J kg-1]       (similar for vaporization)
light_speed_constant        [m s-1]
planck_constant             [J s]
solar_constant              [W m-2]        (solar_irradiation_constant may be better)
spring_constant             [kg s-2]       (in Hooke's Law)
von_karman_constant         [1]

The modern name for "Avogadro's number" is the "avogadro_constant". (See wikipedia). 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 refractive 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. Perhaps something like: "visible_light_in_air_speed" (a bit confusing, but follows the "_in_" pattern) or "visible_light_speed_in_air". In the latter, "in_air" is treated as an assumption/condition which instead could be included with metadata.

Content

base_quantity = "_content" quantity = "_energy_content" quantity = "_mass_content" quantity = "_water_content"

Examples

soil_saturated_water_content
snow_cold_content  ? (must be overcome before melting starts to occur)
snow_thermal_energy_content

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
volumetric_water_content

Here are some additional types of "soil_water_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

There are CF Standard Names with:

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 (between 2 quantities)

base_quantity = "correlation"

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".

Density

base_quantity = "density"

Examples

air_density
air_stp_density   (stp = standard temperature and pressure)
sea_water_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".

Depth

base_quantity = "_depth"

Examples

channel_water_mean_depth  ??
sea_water_depth  (or sea_floor_depth ?? #######)
secchi_depth
water_table_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 = 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.

Dimensionless numbers

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

Examples

courant_number
froude_number
mach_number
reynolds_number
richardson_number

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.

What about "atomic_number"? Is "proton_number" a better choice?

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.

Discharges or Volumetric Flow Rates

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. Should we then introduce "_to_" as a special keyword for distances? The keyword "_to_" could similarly be be used for ratios. See "Ratios".

Duration

base_quantity = "duration"

Examples

rainfall_duration
sunshine_duration

Typically preceded by a process name modifier. See [[CSN_Process_Names | CSDMS Process Names ] for a list of process names.

Avoid the pattern "duration_of".

Elevation

base_quantity = "_elevation"

Examples

bedrock_surface_elevation
land_surface_elevation
sea_surface_elevation
water_table_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 Altitude, Depth, Height, Thickness.

Exponent

base_quantity = "_exponent"

Examples

transport_law_slope_exponent  ????

Exponents often occur in empirical laws.

See Coefficients, Constants, Indexes, Numbers, Parameters

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"

In CF Standard Names, units are [Pa].

Fraction

quantity = "area_fraction" quantity = "volume_fraction"

Examples

burned_area_fraction
cloud_area_fraction
forested_area_fraction   ??
land_area_fraction
sea_area_fraction
vegetation_area_fraction
void_volume_fraction   (see porosity)

Used in 18 CF Standard Names and dimensionless. The last four examples above are CF Standard Names.

There are 11 CF Standard Names that use "volume_fraction", also dimensionless. These 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

However, hydrologists typically use the shorter term "soil_water_content" instead of "volume_fraction_of_condensed_water_in_soil".

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
gm_hummer_fuel_consumption_rate
gm_hummer_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.

See: http://en.wikipedia.org/wiki/Fuel_efficiency#Fuel_efficiency_of_vehicles

       http://en.wikipedia.org/wiki/Efficient_energy_use

Humidity

base_quantity = "humidity"

Examples

absolute_humidity
relative_humidity
specific_humidity
volumetric_humidity (synonym for "absolute" ?)

The more general term for relative humidity (when not talking about water vapor in air) is "relative_saturation".

Increment

quantity_suffix = "increment"

Examples

air_pressure_increment
bedrock_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. See Anomaly.

See the Time Step template.

Index

base_quantity = "index"

Examples

diversity_index
normalized_difference_vegetation_index
palmer_drought_severity_index
price_index
refractive_index
soil_moisture_index
wetness_index  (with prefix: soil, topographic, catchment, etc.)

See Coefficients, Constants, Exponents, Numbers, Parameters

Limit

base_quantity = "limit"

Examples

chandrasekhar_limit    (object_white_dwarf_star)
high_frequency_limit   (in human hearing;  object = human_hearing ??)
tolman_oppenheimer_volkoff_limit  (object = neutron_star)

The two limits above named after people should probably not be used by themselves, but should have the extra suffix "_mass". There is also a related "Schwarzchild radius"; see Radius.

It is not clear that "_limit" would ever be used by itself. See Point.

"cutoff" or "threshold" may sometimes be used similarly.

See Radius.

Magnitude (of vectors, etc.)

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).

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 a good quantity name and is not allowed; 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 Fuel Efficiency.

Parameter

base_quantity = "_parameter"

Examples

coriolis_parameter
manning_roughness_parameter

Parameters often occur in empirical laws.

See Coefficients, Constants, Exponents, Indexes, Numbers

Partial Pressures

quantity = [substance1] + "_in_" + [substance2] + "_partial_pressure"

Examples

carbon_dioxide_in_air_partial_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".

Point

base_quantity = "_point"

Examples

boiling_point
breaking_point  ??
dew_point
freezing_point
melting_point
wilting_point    (used in infiltration theory)

The "point" at which something happens; a threshold.

Each of the examples above puts a "process name" prefix, from the list of process names in CSDMS Process Names in front of "_point".

Note that most of these is generally used as a modifier to the base quantity "temperature". It is not clear that "point" would ever be used by itself. See Limit.

"limit" and "threshold" are used similarly. See Limit.

Porosity

base_quantity = "_porosity"

Examples

soil_porosity

Could also be called "void_volume_fraction".

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 ??)
water_vapor_in_air_equilibrium_partial_pressure  (i.e. vapor_pressure)
water_vapor_in_air_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: http://en.wikipedia.org/wiki/Vapor_pressure

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 in the name also.

Pressure may require specifying a single object (e.g. air) or two different objects. See Partial 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.

Radius

base_quantity = "_radius"

Examples

earth_ellipsoid_equatorial_radius
earth_ellipsoid_polar_radius
schwarzchild_radius  (black_holes)
turning_radius

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").

See Process Attributes.

Ratios

quantity = "ratio"

Examples

brain_to_body_mass_ratio
charge_to_mass_ratio
channel_cross_section_width_to_depth_ratio
rocket_payload_mass_ratio
rocket_propellant_mass_ratio

Ratios sometimes make reference to 2 objects as in the example. We could introduce "_to_" as a keyword for this purpose.

These will generally be dimensionless. In fact, most dimensionless numbers are ratios of forces, etc.

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.

See Animals object pattern.

Solubility

base_quantity = "solubility"

Examples

carbon_dioxide_in_water_solubility

These are special in that *two* objects (substances) are involved. We reserve the word "_in_" for these cases. See Partial Pressure.

Stress Component

base_quantity = "_stress_component" quantity = "_normal_stress_component" quantity = "_shear_stress_component" ("shear" -> "shearing" ??)

Stresses are more complex than vectors and are represented mathematically as tensors.

There are two kinds of stress called "normal" and "shear" stress. While a normal stress is associated with a single vector, two vectors are required to describe a shear stress.

There are 19 CF Standard Names that contain "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 boiling_point_temperature dew_point_temperature freezing_point_temperature melting_point_temperature snow_temperature soil_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.

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 Quantities

quantity = "unit_width_" + base_quantity

Examples

surface_water_unit_width_discharge   (begin with "surface" ??)

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.

CSN Quantity Templates

CSDMS Standard Names — Quantity Templates

Altitude

Angle

Anomaly

Attributes of Atoms

Attributes of Planets

Attributes of Products of a Company

Capacity

Coefficient

Component of a Vector

Concentration

Conductivity

Constants in Math

Constants in Physics

Content

Correlation (between 2 quantities)

Density

Depth

Diffusivity

Dimensionless numbers

Discharges or Volumetric Flow Rates

Distance

Duration

Elevation

Exponent

Flux of Heat or Energy

Flux of Mass

Flux of Momentum

Fraction

Fuel Efficiency

Humidity

Increment

Index

Limit

Magnitude (of vectors, etc.)

Mass

Miles per Gallon

Parameter

Partial Pressures

Point

Porosity

Pressure

Process Attributes

Radius

Rates of Processes

Ratios

Solubility

Stress Component

Temperature

Time

Time Step

Unit-width Quantities