W4XPBKK3 downward_air_velocity A velocity is a vector quantity."Downward" indicates a vector component which is positive when directed downward (negative upward). Downward air velocity is the vertical component of the 3D air velocity vector. The standard name upward_air_velocity may be used for a vector component with the opposite sign convention. M 4UZJL4HX tendency_of_atmosphere_mass_content_of_elemental_carbon_dry_aerosol_particles_due_to_emission_from_land_transport "tendency_of_X" means derivative of X with respect to time. "Content" indicates a quantity per unit area. The "atmosphere content" of a quantity refers to the vertical integral from the surface to the top of the atmosphere. For the content between specified levels in the atmosphere, standard names including "content_of_atmosphere_layer" are used. The mass is the total mass of the particles. The specification of a physical process by the phrase "due_to_" process means that the quantity named is a single term in a sum of terms which together compose the general quantity named by omitting the phrase. "Emission" means emission from a primary source located anywhere within the atmosphere, including at the lower boundary (i.e. the surface of the earth). "Emission" is a process entirely distinct from "re-emission" which is used in some standard names. "Aerosol" means the system of suspended liquid or solid particles in air (except cloud droplets) and their carrier gas, the air itself. Aerosol takes up ambient water (a process known as hygroscopic growth) depending on the relative humidity and the composition of the aerosol. "Dry aerosol particles" means aerosol particles without any water uptake. The "land transport" sector includes fuel combustion activities related to road transportation, railways and other transportation. "Land transport" is the term used in standard names to describe a collection of emission sources. A variable which has this value for the standard_name attribute should be accompanied by a comment attribute which lists the source categories and provides a reference to the categorization scheme, for example, "IPCC (Intergovernmental Panel on Climate Change) source categories 1A3b, 1A3c and 1A3e as defined in the 2006 IPCC guidelines for national greenhouse gas inventories". Chemically, "elemental carbon" is the carbonaceous fraction of particulate matter that is thermally stable in an inert atmosphere to high temperatures near 4000K and can only be gasified by oxidation starting at temperatures above 340 C. It is assumed to be inert and non-volatile under atmospheric conditions and insoluble in any solvent (Ogren and Charlson, 1983). M TKHC48UB tendency_of_atmosphere_mass_content_of_elemental_carbon_dry_aerosol_particles_due_to_emission_from_industrial_processes_and_combustion "tendency_of_X" means derivative of X with respect to time. "Content" indicates a quantity per unit area. The "atmosphere content" of a quantity refers to the vertical integral from the surface to the top of the atmosphere. For the content between specified levels in the atmosphere, standard names including "content_of_atmosphere_layer" are used. The mass is the total mass of the particles. The specification of a physical process by the phrase "due_to_" process means that the quantity named is a single term in a sum of terms which together compose the general quantity named by omitting the phrase. "Emission" means emission from a primary source located anywhere within the atmosphere, including at the lower boundary (i.e. the surface of the earth). "Emission" is a process entirely distinct from "re-emission" which is used in some standard names. "Aerosol" means the system of suspended liquid or solid particles in air (except cloud droplets) and their carrier gas, the air itself. Aerosol takes up ambient water (a process known as hygroscopic growth) depending on the relative humidity and the composition of the aerosol. "Dry aerosol particles" means aerosol particles without any water uptake. The "industrial processes and combustion" sector comprises fuel combustion activities related to manufacturing industries and construction, industrial processes related to mineral products, the chemical industry, metal production, the production of pulp, paper, food and drink, and non-energy industry use of lubricants and waxes. It may also include any not-classified or "other" combustion, which is commonly included in industry-related inventory data. "Industrial processes and combustion" is the term used in standard names to describe a collection of emission sources. A variable which has this value for the standard_name attribute should be accompanied by a comment attribute which lists the source categories and provides a reference to the categorization scheme, for example, "IPCC (Intergovernmental Panel on Climate Change) source categories 1A2, 2A, 2B, 2C, 2D and 2G as defined in the 2006 IPCC guidelines for national greenhouse gas inventories". Chemically, "elemental carbon" is the carbonaceous fraction of particulate matter that is thermally stable in an inert atmosphere to high temperatures near 4000K and can only be gasified by oxidation starting at temperatures above 340 C. It is assumed to be inert and non-volatile under atmospheric conditions and insoluble in any solvent (Ogren and Charlson, 1983). M SZU3PDKK reference_air_pressure_for_atmosphere_vertical_coordinate For models using a dimensionless vertical coordinate, for example, sigma, hybrid sigma-pressure or eta, the values of the vertical coordinate at the model levels are calculated relative to a reference level. "Reference air pressure" is the air pressure at the model reference level. It is a model-dependent constant. I TRTUVQF8 height_above_geopotential_datum_at_top_of_atmosphere_model "Height_above_X" means the vertical distance above the named surface X. The "geopotential datum" is any estimated surface of constant geopotential used as a datum i.e. a reference level; for the geoid as a datum, specific standard names are available. To specify which geoid or geopotential datum is being used as a reference level, a grid_mapping variable should be attached to the data variable as described in Chapter 5.6 of the CF Convention. "Top of atmosphere model" means the upper boundary of the top layer of an atmosphere model. I CFSN0327 surface_air_pressure The surface called "surface" means the lower boundary of the atmosphere. Air pressure is the force per unit area which would be exerted when the moving gas molecules of which the air is composed strike a theoretical surface of any orientation. M HTG3FF2P tendency_of_atmosphere_mass_content_of_elemental_carbon_dry_aerosol_particles_due_to_emission_from_maritime_transport "tendency_of_X" means derivative of X with respect to time. "Content" indicates a quantity per unit area. The "atmosphere content" of a quantity refers to the vertical integral from the surface to the top of the atmosphere. For the content between specified levels in the atmosphere, standard names including "content_of_atmosphere_layer" are used. The mass is the total mass of the particles. The specification of a physical process by the phrase "due_to_" process means that the quantity named is a single term in a sum of terms which together compose the general quantity named by omitting the phrase. "Emission" means emission from a primary source located anywhere within the atmosphere, including at the lower boundary (i.e. the surface of the earth). "Emission" is a process entirely distinct from "re-emission" which is used in some standard names. "Aerosol" means the system of suspended liquid or solid particles in air (except cloud droplets) and their carrier gas, the air itself. Aerosol takes up ambient water (a process known as hygroscopic growth) depending on the relative humidity and the composition of the aerosol. "Dry aerosol particles" means aerosol particles without any water uptake. The "maritime transport" sector includes fuel combustion activities related to maritime transport. "Maritime transport" is the term used in standard names to describe a collection of emission sources. A variable which has this value for the standard_name attribute should be accompanied by a comment attribute which lists the source categories and provides a reference to the categorization scheme, for example, "IPCC (Intergovernmental Panel on Climate Change) source category 1A3d as defined in the 2006 IPCC guidelines for national greenhouse gas Inventories". Chemically, "elemental carbon" is the carbonaceous fraction of particulate matter that is thermally stable in an inert atmosphere to high temperatures near 4000K and can only be gasified by oxidation starting at temperatures above 340 C. It is assumed to be inert and non-volatile under atmospheric conditions and insoluble in any solvent (Ogren and Charlson, 1983). M CFSN0016 air_pressure_anomaly The term "anomaly" means difference from climatology. Air pressure is the force per unit area which would be exerted when the moving gas molecules of which the air is composed strike a theoretical surface of any orientation. M L3JS2L1M height_above_geopotential_datum "Height_above_X" means the vertical distance above the named surface X. The "geopotential datum" is any estimated surface of constant geopotential used as a datum i.e. a reference level; for the geoid as a datum, specific standard names are available. To specify which geoid or geopotential datum is being used as a reference level, a grid_mapping variable should be attached to the data variable as described in Chapter 5.6 of the CF Convention. I YX6OSE3Y tendency_of_atmosphere_mass_content_of_elemental_carbon_dry_aerosol_particles_due_to_emission_from_savanna_and_grassland_fires "tendency_of_X" means derivative of X with respect to time. "Content" indicates a quantity per unit area. The "atmosphere content" of a quantity refers to the vertical integral from the surface to the top of the atmosphere. For the content between specified levels in the atmosphere, standard names including "content_of_atmosphere_layer" are used. The mass is the total mass of the particles. The specification of a physical process by the phrase "due_to_" process means that the quantity named is a single term in a sum of terms which together compose the general quantity named by omitting the phrase. "Emission" means emission from a primary source located anywhere within the atmosphere, including at the lower boundary (i.e. the surface of the earth). "Emission" is a process entirely distinct from "re-emission" which is used in some standard names. "Aerosol" means the system of suspended liquid or solid particles in air (except cloud droplets) and their carrier gas, the air itself. Aerosol takes up ambient water (a process known as hygroscopic growth) depending on the relative humidity and the composition of the aerosol. "Dry aerosol particles" means aerosol particles without any water uptake. The "savanna and grassland fires" sector comprises the burning (natural and human-induced) of living or dead vegetation in non-forested areas. It excludes field burning of agricultural residues. "Savanna and grassland fires" is the term used in standard names to describe a collection of emission sources. A variable which has this value for the standard_name attribute should be accompanied by a comment attribute which lists the source categories and provides a reference to the categorization scheme, for example, "IPCC (Intergovernmental Panel on Climate Change) source category 5 as defined in the 2006 IPCC guidelines for national greenhouse gas inventories". Chemically, "elemental carbon" is the carbonaceous fraction of particulate matter that is thermally stable in an inert atmosphere to high temperatures near 4000K and can only be gasified by oxidation starting at temperatures above 340 C. It is assumed to be inert and non-volatile under atmospheric conditions and insoluble in any solvent (Ogren and Charlson, 1983). M HDLR6IEX surface_height_above_geopotential_datum "Height_above_X" means the vertical distance above the named surface X. The surface called "surface" means the lower boundary of the atmosphere. The "geopotential datum" is any estimated surface of constant geopotential used as a datum i.e. a reference level; for the geoid as a datum, specific standard names are available. To specify which geoid or geopotential datum is being used as a reference level, a grid_mapping variable should be attached to the data variable as described in Chapter 5.6 of the CF Convention. I CFSN0201 tendency_of_air_pressure "tendency_of_X" means derivative of X with respect to time. Air pressure is the force per unit area which would be exerted when the moving gas molecules of which the air is composed strike a theoretical surface of any orientation. M KE3VGDT1 tendency_of_atmosphere_mass_content_of_elemental_carbon_dry_aerosol_particles_due_to_emission_from_residential_and_commercial_combustion "tendency_of_X" means derivative of X with respect to time. "Content" indicates a quantity per unit area. The "atmosphere content" of a quantity refers to the vertical integral from the surface to the top of the atmosphere. For the content between specified levels in the atmosphere, standard names including "content_of_atmosphere_layer" are used. The mass is the total mass of the particles. The specification of a physical process by the phrase "due_to_" process means that the quantity named is a single term in a sum of terms which together compose the general quantity named by omitting the phrase. "Emission" means emission from a primary source located anywhere within the atmosphere, including at the lower boundary (i.e. the surface of the earth). "Emission" is a process entirely distinct from "re-emission" which is used in some standard names. "Aerosol" means the system of suspended liquid or solid particles in air (except cloud droplets) and their carrier gas, the air itself. Aerosol takes up ambient water (a process known as hygroscopic growth) depending on the relative humidity and the composition of the aerosol. "Dry aerosol particles" means aerosol particles without any water uptake. The mass is the total mass of the particles. The "residential and commercial combustion" sector comprises fuel combustion activities related to the commercial/institutional sector, the residential sector and the agriculture/forestry/fishing sector. It may also include any not-classified or "other" combustion, which is commonly included in the inventory data. "Residential and commercial combustion" is the term used in standard names to describe a collection of emission sources. A variable which has this value for the standard_name attribute should be accompanied by a comment attribute which lists the source categories and provides a reference to the categorization scheme, for example, "IPCC (Intergovernmental Panel on Climate Change) source categories 1A4a, 1A4b and 1A4c as defined in the 2006 IPCC guidelines for national greenhouse gas inventories". Chemically, "elemental carbon" is the carbonaceous fraction of particulate matter that is thermally stable in an inert atmosphere to high temperatures near 4000K and can only be gasified by oxidation starting at temperatures above 340 C. It is assumed to be inert and non-volatile under atmospheric conditions and insoluble in any solvent (Ogren and Charlson, 1983). M JJ56NSBF sea_floor_depth_below_reference_ellipsoid "Depth_below_X" means the vertical distance below the named surface X. A reference ellipsoid is a regular mathematical figure that approximates the irregular shape of the geoid. A number of reference ellipsoids are defined for use in the field of geodesy. To specify which reference ellipsoid is being used, a grid_mapping variable should be attached to the data variable as described in Chapter 5.6 of the CF Convention. I BOMY8L2Z tendency_of_atmosphere_mass_content_of_elemental_carbon_dry_aerosol_particles_due_to_emission_from_waste_treatment_and_disposal "tendency_of_X" means derivative of X with respect to time. "Content" indicates a quantity per unit area. The "atmosphere content" of a quantity refers to the vertical integral from the surface to the top of the atmosphere. For the content between specified levels in the atmosphere, standard names including "content_of_atmosphere_layer" are used. The mass is the total mass of the particles. The specification of a physical process by the phrase "due_to_" process means that the quantity named is a single term in a sum of terms which together compose the general quantity named by omitting the phrase. "Emission" means emission from a primary source located anywhere within the atmosphere, including at the lower boundary (i.e. the surface of the earth). "Emission" is a process entirely distinct from "re-emission" which is used in some standard names. "Aerosol" means the system of suspended liquid or solid particles in air (except cloud droplets) and their carrier gas, the air itself. Aerosol takes up ambient water (a process known as hygroscopic growth) depending on the relative humidity and the composition of the aerosol. "Dry aerosol particles" means aerosol particles without any water uptake. The "waste treatment and disposal" sector comprises solid waste disposal on land, wastewater handling, waste incineration and other waste disposal. "Waste treatment and disposal" is the term used in standard names to describe a collection of emission sources. A variable which has this value for the standard_name attribute should be accompanied by a comment attribute which lists the source categories and provides a reference to the categorization scheme, for example, "IPCC (Intergovernmental Panel on Climate Change) source categories 6A, 6B, 6C and 6D as defined in the 2006 IPCC guidelines for national greenhouse gas inventories". Chemically, "elemental carbon" is the carbonaceous fraction of particulate matter that is thermally stable in an inert atmosphere to high temperatures near 4000K and can only be gasified by oxidation starting at temperatures above 340 C. It is assumed to be inert and non-volatile under atmospheric conditions and insoluble in any solvent (Ogren and Charlson, 1983). M 8BFOBHU2 height_above_mean_sea_level "Height_above_X" means the vertical distance above the named surface X. "Mean sea level" means the time mean of sea surface elevation at a given location over an arbitrary period sufficient to eliminate the tidal signals. I ZEP7E2DN sea_surface_height_above_geopotential_datum "Height_above_X" means the vertical distance above the named surface X. "Sea surface height" is a time-varying quantity. The "geopotential datum" is any estimated surface of constant geopotential used as a datum i.e. a reference level; for the geoid as a datum, specific standard names are available. To specify which geoid or geopotential datum is being used as a reference level, a grid_mapping variable should be attached to the data variable as described in Chapter 5.6 of the CF Convention. I TJBER2QW tendency_of_atmosphere_mass_content_of_elemental_carbon_dry_aerosol_particles_due_to_gravitational_settling "Content" indicates a quantity per unit area. The "atmosphere content" of a quantity refers to the vertical integral from the surface to the top of the atmosphere. For the content between specified levels in the atmosphere, standard names including content_of_atmosphere_layer are used. "Aerosol" means the system of suspended liquid or solid particles in air (except cloud droplets) and their carrier gas, the air itself. Aerosol takes up ambient water (a process known as hygroscopic growth) depending on the relative humidity and the composition of the aerosol. "Dry aerosol particles" means aerosol particles without any water uptake. The specification of a physical process by the phrase due_to_process means that the quantity named is a single term in a sum of terms which together compose the general quantity named by omitting the phrase. "tendency_of_X" means derivative of X with respect to time. The sum of turbulent deposition and gravitational settling is dry deposition. Chemically, "elemental carbon" is the carbonaceous fraction of particulate matter that is thermally stable in an inert atmosphere to high temperatures near 4000K and can only be gasified by oxidation starting at temperatures above 340 C. It is assumed to be inert and non-volatile under atmospheric conditions and insoluble in any solvent (Ogren and Charlson, 1983). M TY6BSI8K sea_floor_depth_below_geopotential_datum "Depth_below_X" means the vertical distance below the named surface X. The "geopotential datum" is any estimated surface of constant geopotential used as a datum i.e. a reference level; for the geoid as a datum, specific standard names are available. To specify which geoid or geopotential datum is being used as a reference level, a grid_mapping variable should be attached to the data variable as described in Chapter 5.6 of the CF Convention. I 3ZP5PFW6 tendency_of_atmosphere_mass_content_of_sea_salt_dry_aerosol_particles_due_to_emission "Content" indicates a quantity per unit area. The "atmosphere content" of a quantity refers to the vertical integral from the surface to the top of the atmosphere. For the content between specified levels in the atmosphere, standard names including "content_of_atmosphere_layer" are used. The mass is the total mass of the particles. "Aerosol" means the system of suspended liquid or solid particles in air (except cloud droplets) and their carrier gas, the air itself. Aerosol particles take up ambient water (a process known as hygroscopic growth) depending on the relative humidity and the composition of the particles. "Dry aerosol particles" means aerosol particles without any water uptake. The specification of a physical process by the phrase "due_to_" process means that the quantity named is a single term in a sum of terms which together compose the general quantity named by omitting the phrase. "Emission" means emission from a primary source located anywhere within the atmosphere, including at the lower boundary (i.e. the surface of the earth). "Emission" is a process entirely distinct from "re-emission" which is used in some standard names. "tendency_of_X" means derivative of X with respect to time. M BDBKOEIB air_pressure_at_top_of_atmosphere_model "Top of atmosphere model" means the upper boundary of the top layer of an atmosphere model. Air pressure is the force per unit area which would be exerted when the moving gas molecules of which the air is composed strike a theoretical surface of any orientation. I EJ5JLPG7 phase_of_global_average_sea_level_change Global average sea level change is due to change in volume of the water in the ocean, caused by mass and/or density change, or to change in the volume of the ocean basins, caused by tectonics etc. It is sometimes called "eustatic", which is a term that also has other definitions. It differs from the change in the global average sea surface height relative to the centre of the Earth by the global average vertical movement of the ocean floor. Zero sea level change is an arbitrary level. Phase is the initial angle of a wave modelled by a sinusoidal function. A coordinate variable of harmonic_period should be used to specify the period of the sinusoidal wave. Because global average sea level change quantifies the change in volume of the world ocean, it is not calculated necessarily by considering local changes in mean sea level. M BBAH2118 depth_below_geoid The geoid is a surface of constant geopotential with which mean sea level would coincide if the ocean were at rest. (The volume enclosed between the geoid and the sea floor equals the mean volume of water in the ocean). In an ocean GCM the geoid is the surface of zero depth, or the rigid lid if the model uses that approximation. To specify which geoid or geopotential datum is being used as a reference level, a grid_mapping variable should be attached to the data variable as described in Chapter 5.6 of the CF Convention. "Depth_below_X" means the vertical distance below the named surface X. M CFSN0099 tropopause_air_pressure Air pressure is the force per unit area which would be exerted when the moving gas molecules of which the air is composed strike a theoretical surface of any orientation. M CDDBJ4AL mass_concentration_of_elemental_carbon_dry_aerosol_particles_in_air Mass concentration means mass per unit volume and is used in the construction mass_concentration_of_X_in_Y, where X is a material constituent of Y. A chemical species denoted by X may be described by a single term such as "nitrogen" or a phrase such as "nox_expressed_as_nitrogen". "Aerosol" means the system of suspended liquid or solid particles in air (except cloud droplets) and their carrier gas, the air itself. Aerosol takes up ambient water (a process known as hygroscopic growth) depending on the relative humidity and the composition of the aerosol. "Dry aerosol particles" means aerosol particles without any water uptake. Chemically, "elemental carbon" is the carbonaceous fraction of particulate matter that is thermally stable in an inert atmosphere to high temperatures near 4000K and can only be gasified by oxidation starting at temperatures above 340 C. It is assumed to be inert and non-volatile under atmospheric conditions and insoluble in any solvent (Ogren and Charlson, 1983). M CFSN0017 air_pressure_at_cloud_base The phrase "cloud_base" refers to the base of the lowest cloud. Air pressure is the force per unit area which would be exerted when the moving gas molecules of which the air is composed strike a theoretical surface of any orientation. M CFV10N24 ocean_rigid_lid_pressure_expressed_as_sea_surface_height_above_geoid "Ocean rigid lid pressure" means the pressure at the surface of an ocean model assuming that it is bounded above by a rigid lid. "Sea surface height" is a time-varying quantity. The geoid is a surface of constant geopotential with which mean sea level would coincide if the ocean were at rest. (The volume enclosed between the geoid and the sea floor equals the mean volume of water in the ocean). In an ocean GCM the geoid is the surface of zero depth, or the rigid lid if the model uses that approximation. To specify which geoid or geopotential datum is being used as a reference level, a grid_mapping variable should be attached to the data variable as described in Chapter 5.6 of the CF Convention. M CFSN0321 square_of_lagrangian_tendency_of_air_pressure The phrase "square_of_X" means X*X. "tendency_of_X" means derivative of X with respect to time. The Lagrangian tendency of a quantity is its rate of change following the motion of the fluid, also called the "material derivative" or "convective derivative". The Lagrangian tendency of air pressure, often called "omega", plays the role of the upward component of air velocity when air pressure is being used as the vertical coordinate. If the vertical air velocity is upwards, it is negative when expressed as a tendency of air pressure; downwards is positive. Air pressure is the force per unit area which would be exerted when the moving gas molecules of which the air is composed strike a theoretical surface of any orientation. M CLQ62JNA tendency_of_mass_concentration_of_elemental_carbon_dry_aerosol_particles_in_air_due_to_emission_from_aviation "tendency_of_X" means derivative of X with respect to time. Mass concentration means mass per unit volume and is used in the construction mass_concentration_of_X_in_Y, where X is a material constituent of Y. A chemical species denoted by X may be described by a single term such as "nitrogen" or a phrase such as "nox_expressed_as_nitrogen". The mass is the total mass of the particles. The specification of a physical process by the phrase "due_to_" process means that the quantity named is a single term in a sum of terms which together compose the general quantity named by omitting the phrase. "Emission" means emission from a primary source located anywhere within the atmosphere, including at the lower boundary (i.e. the surface of the earth). "Emission" is a process entirely distinct from "re-emission" which is used in some standard names. "Aerosol" means the system of suspended liquid or solid particles in air (except cloud droplets) and their carrier gas, the air itself. Aerosol takes up ambient water (a process known as hygroscopic growth) depending on the relative humidity and the composition of the aerosol. "Dry aerosol particles" means aerosol particles without any water uptake. The "aviation" sector includes fuel combustion activities related to civil aviation. "Aviation" is the term used in standard names to describe a collection of emission sources. A variable which has this value for the standard_name attribute should be accompanied by a comment attribute which lists the source categories and provides a reference to the categorization scheme, for example, "IPCC (Intergovernmental Panel on Climate Change) source category 1A3a as defined in the 2006 IPCC guidelines for national greenhouse gas inventories". Chemically, "elemental carbon" is the carbonaceous fraction of particulate matter that is thermally stable in an inert atmosphere to high temperatures near 4000K and can only be gasified by oxidation starting at temperatures above 340 C. It is assumed to be inert and non-volatile under atmospheric conditions and insoluble in any solvent (Ogren and Charlson, 1983). M CF12N587 square_of_sea_surface_height_above_geoid The phrase "square_of_X" means X*X. "Height_above_X" means the vertical distance above the named surface X. "Sea surface height" is a time-varying quantity. The geoid is a surface of constant geopotential with which mean sea level would coincide if the ocean were at rest. (The volume enclosed between the geoid and the sea floor equals the mean volume of water in the ocean). In an ocean GCM the geoid is the surface of zero depth, or the rigid lid if the model uses that approximation. To specify which geoid or geopotential datum is being used as a reference level, a grid_mapping variable should be attached to the data variable as described in Chapter 5.6 of the CF Convention. By definition of the geoid, the global average of the time-mean sea surface height (i.e. mean sea level) above the geoid must be zero. M 2YAPTDYX original_air_pressure_of_lifted_parcel Various stability and convective potential indices are calculated by "lifting" a parcel of air: moving it dry adiabatically from a starting height (often the surface) to the Lifting Condensation Level, and then wet adiabatically from there to an ending height (often the top of the data/model/atmosphere). The quantities with standard names original_air_pressure_of_lifted_parcel and final_air_pressure_of_lifted_parcel are the ambient air pressure at the start and end of lifting, respectively. Air pressure is the force per unit area which would be exerted when the moving gas molecules of which the air is composed strike a theoretical surface of any orientation. M CFSN0777 sea_surface_height_above_reference_ellipsoid "Height_above_X" means the vertical distance above the named surface X. "Sea surface height" is a time-varying quantity. A reference ellipsoid is a regular mathematical figure that approximates the irregular shape of the geoid. A number of reference ellipsoids are defined for use in the field of geodesy. The geoid is a surface of constant geopotential with which mean sea level would coincide if the ocean were at rest. To specify which reference ellipsoid is being used, a grid_mapping variable should be attached to the data variable as described in Chapter 5.6 of the CF Convention. The standard name for the height of the sea surface above the geoid is sea_surface_height_above_geoid. The standard name for the height of the sea surface above mean sea level is sea_surface_height_above_mean_sea_level. M CFSN0374 sea_surface_height_above_geoid "Height_above_X" means the vertical distance above the named surface X. "Sea surface height" is a time-varying quantity. The geoid is a surface of constant geopotential with which mean sea level would coincide if the ocean were at rest. (The volume enclosed between the geoid and the sea floor equals the mean volume of water in the ocean). In an ocean GCM the geoid is the surface of zero depth, or the rigid lid if the model uses that approximation. To specify which geoid or geopotential datum is being used as a reference level, a grid_mapping variable should be attached to the data variable as described in Chapter 5.6 of the CF Convention. By definition of the geoid, the global average of the time-mean sea surface height (i.e. mean sea level) above the geoid must be zero. The standard name for the height of the sea surface above mean sea level is sea_surface_height_above_mean_sea_level. The standard name for the height of the sea surface above the reference ellipsoid is sea_surface_height_above_reference_ellipsoid. M Q9ZYSAOC air_pressure_at_mean_sea_level Air pressure at sea level is the quantity often abbreviated as MSLP or PMSL. Air pressure is the force per unit area which would be exerted when the moving gas molecules of which the air is composed strike a theoretical surface of any orientation. "Mean sea level" means the time mean of sea surface elevation at a given location over an arbitrary period sufficient to eliminate the tidal signals. M CFSN0616 lagrangian_tendency_of_air_pressure "tendency_of_X" means derivative of X with respect to time. The Lagrangian tendency of a quantity is its rate of change following the motion of the fluid, also called the "material derivative" or "convective derivative". The Lagrangian tendency of air pressure, often called "omega", plays the role of the upward component of air velocity when air pressure is being used as the vertical coordinate. If the vertical air velocity is upwards, it is negative when expressed as a tendency of air pressure; downwards is positive. Air pressure is the force per unit area which would be exerted when the moving gas molecules of which the air is composed strike a theoretical surface of any orientation. M CFSN0019 air_pressure_at_convective_cloud_base The phrase "cloud_base" refers to the base of the lowest cloud. Convective cloud is that produced by the convection schemes in an atmosphere model. Air pressure is the force per unit area which would be exerted when the moving gas molecules of which the air is composed strike a theoretical surface of any orientation. M I19BNSXH final_air_pressure_of_lifted_parcel Various stability and convective potential indices are calculated by "lifting" a parcel of air: moving it dry adiabatically from a starting height (often the surface) to the Lifting Condensation Level, and then wet adiabatically from there to an ending height (often the top of the data/model/atmosphere). The quantities with standard names original_air_pressure_of_lifted_parcel and final_air_pressure_of_lifted_parcel are the ambient air pressure at the start and end of lifting, respectively. Air pressure is the force per unit area which would be exerted when the moving gas molecules of which the air is composed strike a theoretical surface of any orientation. M CF12N209 histogram_of_backscattering_ratio_over_height_above_reference_ellipsoid Scattering of radiation is its deflection from its incident path without loss of energy. Backwards scattering refers to the sum of scattering into all backward angles i.e. scattering_angle exceeding pi/2 radians. A scattering_angle should not be specified with this quantity. "Backscattering ratio" is the ratio of the quantity with standard name volume_attenuated_backwards_scattering_function_in_air to the quantity with standard name volume_attenuated_backwards_scattering_function_in_air_assuming_no_aerosol_or_cloud. "histogram_of_X[_over_Z]" means histogram (i.e. number of counts for each range of X) of variations (over Z) of X. The data variable should have an axis for X. A reference ellipsoid is a regular mathematical figure that approximates the irregular shape of the geoid. A number of reference ellipsoids are defined for use in the field of geodesy. The geoid is a surface of constant geopotential with which mean sea level would coincide if the ocean were at rest. To specify which reference ellipsoid is being used, a grid_mapping variable should be attached to the data variable as described in Chapter 5.6 of the CF Convention. M CFSN0724 difference_of_air_pressure_from_model_reference In some atmosphere models, the difference of air pressure from model reference is a prognostic variable, instead of the air pressure itself. The model reference air pressure is a model-dependent constant. Air pressure is the force per unit area which would be exerted when the moving gas molecules of which the air is composed strike a theoretical surface of any orientation. M CFSN0420 sea_floor_depth_below_geoid "Depth_below_X" means the vertical distance below the named surface X. The geoid is a surface of constant geopotential with which mean sea level would coincide if the ocean were at rest. (The volume enclosed between the geoid and the sea floor equals the mean volume of water in the ocean). In an ocean GCM the geoid is the surface of zero depth, or the rigid lid if the model uses that approximation. To specify which geoid or geopotential datum is being used as a reference level, a grid_mapping variable should be attached to the data variable as described in Chapter 5.6 of the CF Convention. M CFSN0018 air_pressure_at_cloud_top The phrase "cloud_top" refers to the top of the highest cloud. Air pressure is the force per unit area which would be exerted when the moving gas molecules of which the air is composed strike a theoretical surface of any orientation. M CFSN0020 air_pressure_at_convective_cloud_top The phrase "cloud_top" refers to the top of the highest cloud. Convective cloud is that produced by the convection schemes in an atmosphere model. Air pressure is the force per unit area which would be exerted when the moving gas molecules of which the air is composed strike a theoretical surface of any orientation. M CF12N210 histogram_of_equivalent_reflectivity_factor_over_height_above_reference_ellipsoid "Equivalent reflectivity factor" is the radar reflectivity factor that is calculated from the measured radar return power assuming the target is composed of liquid water droplets whose diameter is less than one tenth of the radar wavelength, i.e., treating the droplets as Rayleigh scatterers. The actual radar reflectivity factor would depend on the size distribution and composition of the particles within the target volume and these are often unknown. "histogram_of_X[_over_Z]" means histogram (i.e. number of counts for each range of X) of variations (over Z) of X. The data variable should have an axis for X. A reference ellipsoid is a regular mathematical figure that approximates the irregular shape of the geoid. A number of reference ellipsoids are defined for use in the field of geodesy. The geoid is a surface of constant geopotential with which mean sea level would coincide if the ocean were at rest. To specify which reference ellipsoid is being used, a grid_mapping variable should be attached to the data variable as described in Chapter 5.6 of the CF Convention. M CFSN0633 global_average_thermosteric_sea_level_change Global average thermosteric sea level change is the part caused by change in density due to change in temperature i.e. thermal expansion. This in turn results in a change in volume of the world ocean. Zero sea level change is an arbitrary level. Because global average sea level change quantifies the change in volume of the world ocean, it is not calculated necessarily by considering local changes in mean sea level. M 49ICY8QO mole_fraction_of_sulfur_hexafluoride_in_air Mole fraction is used in the construction "mole_fraction_of_X_in_Y", where X is a material constituent of Y. A chemical species denoted by X may be described by a single term such as "nitrogen" or a phrase such as "nox_expressed_as_nitrogen". The chemical formula of sulfur hexafluoride is SF6. I 3SGXMKJ9 tendency_of_atmosphere_mass_content_of_elemental_carbon_dry_aerosol_particles_due_to_emission_from_forest_fires "tendency_of_X" means derivative of X with respect to time. "Content" indicates a quantity per unit area. The "atmosphere content" of a quantity refers to the vertical integral from the surface to the top of the atmosphere. For the content between specified levels in the atmosphere, standard names including "content_of_atmosphere_layer" are used. The mass is the total mass of the particles. The specification of a physical process by the phrase "due_to_" process means that the quantity named is a single term in a sum of terms which together compose the general quantity named by omitting the phrase. "Emission" means emission from a primary source located anywhere within the atmosphere, including at the lower boundary (i.e. the surface of the earth). "Emission" is a process entirely distinct from "re-emission" which is used in some standard names. "Aerosol" means the system of suspended liquid or solid particles in air (except cloud droplets) and their carrier gas, the air itself. Aerosol takes up ambient water (a process known as hygroscopic growth) depending on the relative humidity and the composition of the aerosol. "Dry aerosol particles" means aerosol particles without any water uptake. The "forest fires" sector comprises the burning (natural and human-induced) of living or dead vegetation in forests. "Forest fires" is the term used in standard names to describe a collection of emission sources. A variable which has this value for the standard_name attribute should be accompanied by a comment attribute which lists the source categories and provides a reference to the categorization scheme, for example, "IPCC (Intergovernmental Panel on Climate Change) source category 5 as defined in the 2006 IPCC guidelines for national greenhouse gas inventories". Chemically, "elemental carbon" is the carbonaceous fraction of particulate matter that is thermally stable in an inert atmosphere to high temperatures near 4000K and can only be gasified by oxidation starting at temperatures above 340 C. It is assumed to be inert and non-volatile under atmospheric conditions and insoluble in any solvent (Ogren and Charlson, 1983). M 0K0F0Y2P tendency_of_atmosphere_mass_content_of_elemental_carbon_dry_aerosol_particles_due_to_emission "tendency_of_X" means derivative of X with respect to time. "Content" indicates a quantity per unit area. The "atmosphere content" of a quantity refers to the vertical integral from the surface to the top of the atmosphere. For the content between specified levels in the atmosphere, standard names including "content_of_atmosphere_layer" are used. The mass is the total mass of the particles. "Aerosol" means the system of suspended liquid or solid particles in air (except cloud droplets) and their carrier gas, the air itself. Aerosol takes up ambient water (a process known as hygroscopic growth) depending on the relative humidity and the composition of the aerosol. "Dry aerosol particles" means aerosol particles without any water uptake. The specification of a physical process by the phrase "due_to_" process means that the quantity named is a single term in a sum of terms which together compose the general quantity named by omitting the phrase. "Emission" means emission from a primary source located anywhere within the atmosphere, including at the lower boundary (i.e. the surface of the earth). "Emission" is a process entirely distinct from "re-emission" which is used in some standard names. Chemically, "elemental carbon" is the carbonaceous fraction of particulate matter that is thermally stable in an inert atmosphere to high temperatures near 4000K and can only be gasified by oxidation starting at temperatures above 340 C. It is assumed to be inert and non-volatile under atmospheric conditions and insoluble in any solvent (Ogren and Charlson, 1983). M CFV9N3 sea_surface_subskin_temperature The sea surface subskin temperature is the temperature at the base of the conductive laminar sub-layer of the ocean surface, that is, at a depth of approximately 1 - 1.5 millimeters below the air-sea interface. For practical purposes, this quantity can be well approximated to the measurement of surface temperature by a microwave radiometer operating in the 6 - 11 gigahertz frequency range, but the relationship is neither direct nor invariant to changing physical conditions or to the specific geometry of the microwave measurements. Measurements of this quantity are subject to a large potential diurnal cycle due to thermal stratification of the upper ocean layer in low wind speed high solar irradiance conditions. M CFV10N14 height_above_reference_ellipsoid "Height_above_X" means the vertical distance above the named surface X. A reference ellipsoid is a mathematical figure that approximates the geoid. The geoid is a surface of constant geopotential with which mean sea level would coincide if the ocean were at rest. The ellipsoid is an approximation because the geoid is an irregular shape. A number of reference ellipsoids are defined for use in the field of geodesy. To specify which reference ellipsoid is being used, a grid_mapping variable should be attached to the data variable as described in Chapter 5.6 of the CF Convention. M XRCBF7SB tendency_of_global_average_sea_level_change Global average sea level change is due to change in volume of the water in the ocean, caused by mass and/or density change, or to change in the volume of the ocean basins, caused by tectonics etc. It is sometimes called "eustatic", which is a term that also has other definitions. It differs from the change in the global average sea surface height relative to the centre of the Earth by the global average vertical movement of the ocean floor. Zero sea level change is an arbitrary level. "tendency_of_X" means derivative of X with respect to time. Because global average sea level change quantifies the change in volume of the world ocean, it is not calculated necessarily by considering local changes in mean sea level. M YEP61YZ8 tendency_of_atmosphere_mass_content_of_elemental_carbon_dry_aerosol_particles_due_to_dry_deposition "Content" indicates a quantity per unit area. The "atmosphere content" of a quantity refers to the vertical integral from the surface to the top of the atmosphere. For the content between specified levels in the atmosphere, standard names including content_of_atmosphere_layer are used. The mass is the total mass of the particles. "Aerosol" means the system of suspended liquid or solid particles in air (except cloud droplets) and their carrier gas, the air itself. Aerosol particles take up ambient water (a process known as hygroscopic growth) depending on the relative humidity and the composition of the particles. "Dry aerosol particles" means aerosol particles without any water uptake. The specification of a physical process by the phrase due_to_process means that the quantity named is a single term in a sum of terms which together compose the general quantity named by omitting the phrase. "Dry deposition" is the sum of turbulent deposition and gravitational settling. "tendency_of_X" means derivative of X with respect to time. Chemically, "elemental carbon" is the carbonaceous fraction of particulate matter that is thermally stable in an inert atmosphere to high temperatures near 4000K and can only be gasified by oxidation starting at temperatures above 340 C. It is assumed to be inert and non-volatile under atmospheric conditions and insoluble in any solvent (Ogren and Charlson, 1983). M Y8LMUTED mole_fraction_of_carbonyl_sulfide_in_air Mole fraction is used in the construction "mole_fraction_of_X_in_Y", where X is a material constituent of Y. A chemical species denoted by X may be described by a single term such as "nitrogen" or a phrase such as "nox_expressed_as_nitrogen". The chemical formula for carbonyl sulfide is COS. The IUPAC name for carbonyl sulfide is carbon oxide sulfide. I ND7TN6U4 automated_tropical_cyclone_forecasting_system_storm_identifier The Automated Tropical Cyclone Forecasting System (ATCF) storm identifier is an 8 character string which identifies a tropical cyclone. The storm identifier has the form BBCCYYYY, where BB is the ocean basin, specifically: AL - North Atlantic basin, north of the Equator; SL - South Atlantic basin, south of the Equator; EP - North East Pacific basin, eastward of 140 degrees west longitude; CP - North Central Pacific basin, between the dateline and 140 degrees west longitude; WP - North West Pacific basin, westward of the dateline; IO - North Indian Ocean basin, north of the Equator between 40 and 100 degrees east longitude; SH - South Pacific Ocean basin and South Indian Ocean basin. CC is the cyclone number. Numbers 01 through 49 are reserved for tropical and subtropical cyclones. A cyclone number is assigned to each tropical or subtropical cyclone in each basin as it develops. Numbers are assigned in chronological order. Numbers 50 through 79 are reserved for internal use by operational forecast centers. Numbers 80 through 89 are reserved for training, exercises and testing. Numbers 90 through 99 are reserved for tropical disturbances having the potential to become tropical or subtropical cyclones. The 90's are assigned sequentially and reused throughout the calendar year. YYYY is the four-digit year. This is calendar year for the northern hemisphere. For the southern hemisphere, the year begins July 1, with calendar year plus one. Reference: Miller, R.J., Schrader, A.J., Sampson, C.R., & Tsui, T.L. (1990), The Automated Tropical Cyclone Forecasting System (ATCF), American Meteorological Society Computer Techniques, 5, 653 - 660. M CFV9N1 sea_surface_foundation_temperature The sea surface foundation temperature is the water temperature that is not influenced by a thermally stratified layer of diurnal temperature variability (either by daytime warming or nocturnal cooling). The foundation temperature is named to indicate that it is the temperature from which the growth of the diurnal thermocline develops each day, noting that on some occasions with a deep mixed layer there is no clear foundation temperature in the surface layer. In general, sea surface foundation temperature will be similar to a night time minimum or pre-dawn value at depths of between approximately 1 and 5 meters. In the absence of any diurnal signal, the foundation temperature is considered equivalent to the quantity with standard name sea_surface_subskin_temperature. The sea surface foundation temperature defines a level in the upper water column that varies in depth, space, and time depending on the local balance between thermal stratification and turbulent energy and is expected to change slowly over the course of a day. If possible, a data variable with the standard name sea_surface_foundation_temperature should be used with a scalar vertical coordinate variable to specify the depth of the foundation level. Sea surface foundation temperature is measured at the base of the diurnal thermocline or as close to the water surface as possible in the absence of thermal stratification. Only in situ contact thermometry is able to measure the sea surface foundation temperature. Analysis procedures must be used to estimate sea surface foundation temperature value from radiometric satellite measurements of the quantities with standard names sea_surface_skin_temperature and sea_surface_subskin_temperature. Sea surface foundation temperature provides a connection with the historical concept of a "bulk" sea surface temperature considered representative of the oceanic mixed layer temperature that is typically represented by any sea temperature measurement within the upper ocean over a depth range of 1 to approximately 20 meters. The general term, "bulk" sea surface temperature, has the standard name sea_surface_temperature with no associated vertical coordinate axis. Sea surface foundation temperature provides a more precise, well defined quantity than "bulk" sea surface temperature and, consequently, is more representative of the mixed layer temperature. The temperature of sea water at a particular depth (other than the foundation level) should be reported using the standard name sea_water_temperature and, wherever possible, supplying a vertical coordinate axis or scalar coordinate variable. M CFSN0021 air_pressure_at_freezing_level Air pressure is the force per unit area which would be exerted when the moving gas molecules of which the air is composed strike a theoretical surface of any orientation. M Y5UYGUUV thermosteric_change_in_sea_surface_height "Sea surface height" is a time-varying quantity. The thermosteric change in sea surface height is the change in height that a water column having standard temperature zero degrees Celsius would undergo when its temperature is changed to the observed value. The sum of the quantities with standard names thermosteric_change_in_sea_surface_height and halosteric_change_in_sea_surface_height is the total steric change in the water column height, which has the standard name of steric_change_in_sea_surface_height. M NBNM4BKR atmosphere_absorption_optical_thickness_due_to_sea_salt_ambient_aerosol_particles The optical thickness is the integral along the path of radiation of a volume scattering/absorption/attenuation coefficient. The radiative flux is reduced by a factor exp(-optical_thickness) on traversing the path. A coordinate variable of radiation_wavelength or radiation_frequency can be specified to indicate that the optical thickness applies at specific wavelengths or frequencies. "Absorption optical thickness" means that part of the atmosphere optical thickness that is caused by the absorption of incident radiation. "Aerosol" means the system of suspended liquid or solid particles in air (except cloud droplets) and their carrier gas, the air itself. "Ambient_aerosol" means that the aerosol is measured or modelled at the ambient state of pressure, temperature and relative humidity that exists in its immediate environment. "Ambient aerosol particles" are aerosol particles that have taken up ambient water through hygroscopic growth. The extent of hygroscopic growth depends on the relative humidity and the composition of the particles. The specification of a physical process by the phrase due_to_process means that the quantity named is a single term in a sum of terms which together compose the general quantity named by omitting the phrase. M CFSN0632 global_average_sea_level_change Global average sea level change is due to change in volume of the water in the ocean, caused by mass and/or density change, or to change in the volume of the ocean basins, caused by tectonics etc. It is sometimes called "eustatic", which is a term that also has other definitions. It differs from the change in the global average sea surface height relative to the centre of the Earth by the global average vertical movement of the ocean floor. Zero sea level change is an arbitrary level. Because global average sea level change quantifies the change in volume of the world ocean, it is not calculated necessarily by considering local changes in mean sea level. M V6QCY6T5 mass_fraction_of_pm10_elemental_carbon_dry_aerosol_particles_in_air Mass fraction is used in the construction "mass_fraction_of_X_in_Y", where X is a material constituent of Y. It means the ratio of the mass of X to the mass of Y (including X). A chemical species denoted by X may be described by a single term such as "nitrogen" or a phrase such as "nox_expressed_as_nitrogen". "Aerosol" means the system of suspended liquid or solid particles in air (except cloud droplets) and their carrier gas, the air itself. Aerosol particles take up ambient water (a process known as hygroscopic growth) depending on the relative humidity and the composition of the particles. "Dry aerosol particles" means aerosol particles without any water uptake. "Pm10 aerosol" means atmospheric particulate compounds with an aerodynamic diameter of less than or equal to 10 micrometers. Chemically, "elemental carbon" is the carbonaceous fraction of particulate matter that is thermally stable in an inert atmosphere to high temperatures near 4000K and can only be gasified by oxidation starting at temperatures above 340 C. It is assumed to be inert and non-volatile under atmospheric conditions and insoluble in any solvent (Ogren and Charlson, 1983). M EDUTEJ6O mass_fraction_of_elemental_carbon_dry_aerosol_particles_in_air Mass fraction is used in the construction mass_fraction_of_X_in_Y, where X is a material constituent of Y. It means the ratio of the mass of X to the mass of Y (including X). "Aerosol" means the system of suspended liquid or solid particles in air (except cloud droplets) and their carrier gas, the air itself. Aerosol takes up ambient water (a process known as hygroscopic growth) depending on the relative humidity and the composition of the aerosol. "Dry aerosol particles" means aerosol particles without any water uptake. Chemically, "elemental carbon" is the carbonaceous fraction of particulate matter that is thermally stable in an inert atmosphere to high temperatures near 4000K and can only be gasified by oxidation starting at temperatures above 340 C. It is assumed to be inert and non-volatile under atmospheric conditions and insoluble in any solvent (Ogren and Charlson, 1983). M OHV8PBIF tendency_of_atmosphere_mass_content_of_elemental_carbon_dry_aerosol_particles_due_to_emission_from_energy_production_and_distribution "tendency_of_X" means derivative of X with respect to time. "Content" indicates a quantity per unit area. The "atmosphere content" of a quantity refers to the vertical integral from the surface to the top of the atmosphere. For the content between specified levels in the atmosphere, standard names including "content_of_atmosphere_layer" are used. The mass is the total mass of the particles. The specification of a physical process by the phrase "due_to_" process means that the quantity named is a single term in a sum of terms which together compose the general quantity named by omitting the phrase. "Emission" means emission from a primary source located anywhere within the atmosphere, including at the lower boundary (i.e. the surface of the earth). "Emission" is a process entirely distinct from "re-emission" which is used in some standard names. Aerosol" means the system of suspended liquid or solid particles in air (except cloud droplets) and their carrier gas, the air itself. Aerosol takes up ambient water (a process known as hygroscopic growth) depending on the relative humidity and the composition of the aerosol. "Dry aerosol particles" means aerosol particles without any water uptake. The "energy production and distribution" sector comprises fuel combustion activities related to energy industries and fugitive emissions from fuels. It may also include any not-classified or "other" combustion, which is commonly included in energy-related inventory data. "Energy production and distribution" is the term used in standard names to describe a collection of emission sources. A variable which has this value for the standard_name attribute should be accompanied by a comment attribute which lists the source categories and provides a reference to the categorization scheme, for example, "IPCC (Intergovernmental Panel on Climate Change) source categories 1A1 and 1B as defined in the 2006 IPCC guidelines for national greenhouse gas inventories". Chemically, "elemental carbon" is the carbonaceous fraction of particulate matter that is thermally stable in an inert atmosphere to high temperatures near 4000K and can only be gasified by oxidation starting at temperatures above 340 C. It is assumed to be inert and non-volatile under atmospheric conditions and insoluble in any solvent (Ogren and Charlson, 1983). M 37U1ZUXR tendency_of_atmosphere_mass_content_of_elemental_carbon_dry_aerosol_particles_due_to_emission_from_agricultural_waste_burning "tendency_of_X" means derivative of X with respect to time. "Content" indicates a quantity per unit area. The "atmosphere content" of a quantity refers to the vertical integral from the surface to the top of the atmosphere. For the content between specified levels in the atmosphere, standard names including "content_of_atmosphere_layer" are used. The mass is the total mass of the particles. "Aerosol" means the system of suspended liquid or solid particles in air (except cloud droplets) and their carrier gas, the air itself. Aerosol takes up ambient water (a process known as hygroscopic growth) depending on the relative humidity and the composition of the aerosol. "Dry aerosol partilces" means aerosol particles without any water uptake. The specification of a physical process by the phrase "due_to_" process means that the quantity named is a single term in a sum of terms which together compose the general quantity named by omitting the phrase. "Emission" means emission from a primary source located anywhere within the atmosphere, including at the lower boundary (i.e. the surface of the earth). "Emission" is a process entirely distinct from "re-emission" which is used in some standard names. "Agricultural waste burning" is the term used in standard names to describe a collection of emission sources. A variable which has this value for the standard_name attribute should be accompanied by a comment attribute which lists the source categories and provides a reference to the categorization scheme, for example, "IPCC (Intergovernmental Panel on Climate Change) source category 4F as defined in the 2006 IPCC guidelines for national greenhouse gas inventories". Chemically, "elemental carbon" is the carbonaceous fraction of particulate matter that is thermally stable in an inert atmosphere to high temperatures near 4000K and can only be gasified by oxidation starting at temperatures above 340 C. It is assumed to be inert and non-volatile under atmospheric conditions and insoluble in any solvent (Ogren and Charlson, 1983). M UR379UIX sea_water_mass_per_unit_area_expressed_as_thickness "Thickness" means the vertical extent of a layer. The quantity with standard name sea_water_mass_per_unit_area_expressed_as_thickness is the thickness of the water column from sea floor to surface, minus any contribution to column thickness from steric changes. The sea water density used to convert mass to thickness is assumed to be the density of water of standard temperature zero degrees Celsius and practical salinity S=35.0 unless an auxiliary scalar coordinate variable with standard name sea_water_density is used to specify an alternative value. The sum of the quantities with standard names sea_water_mass_per_unit_area_expressed_as_thickness and steric_change_in_sea_surface_height is the total thickness of the sea water column. Sea_water_mass_per_unit_area is the mass per unit area of the sea water contained within each grid cell. The extent of an individual grid cell is defined by the horizontal coordinates and any associated coordinate bounds or by a string valued auxiliary coordinate variable with a standard name of "region". M CFSN0157 tendency_of_surface_air_pressure The surface called "surface" means the lower boundary of the atmosphere. "tendency_of_X" means derivative of X with respect to time. Air pressure is the force per unit area which would be exerted when the moving gas molecules of which the air is composed strike a theoretical surface of any orientation. M ZSDAR2KM amplitude_of_global_average_sea_level_change Global average sea level change is due to change in volume of the water in the ocean, caused by mass and/or density change, or to change in the volume of the ocean basins, caused by tectonics etc. It is sometimes called "eustatic", which is a term that also has other definitions. It differs from the change in the global average sea surface height relative to the centre of the Earth by the global average vertical movement of the ocean floor. Zero sea level change is an arbitrary level. Amplitude is the magnitude of a wave modelled by a sinusoidal function. A coordinate variable of harmonic_period should be used to specify the period of the sinusoidal wave. Because global average sea level change quantifies the change in volume of the world ocean, it is not calculated necessarily by considering local changes in mean sea level. M P3XFHO4W steric_change_in_sea_surface_height "Sea surface height" is a time-varying quantity. The steric change in sea surface height is the change in height that a water column of standard temperature zero degrees Celsius and practical salinity S=35.0 would undergo when its temperature and salinity are changed to the observed values. The sum of the quantities with standard names thermosteric_change_in_sea_surface_height and halosteric_change_in_sea_surface_height is the total steric change in the water column height, which has the standard name of steric_change_in_sea_surface_height. The sum of the quantities with standard names sea_water_mass_per_unit_area_expressed_as_thickness and steric_change_in_sea_surface_height is the total thickness of the sea water column. M V4O6KUO9 atmosphere_mass_content_of_elemental_carbon_dry_aerosol_particles "Content" indicates a quantity per unit area. The "atmosphere content" of a quantity refers to the vertical integral from the surface to the top of the atmosphere. For the content between specified levels in the atmosphere, standard names including content_of_atmosphere_layer are used. The mass is the total mass of the particles. "Aerosol" means the system of suspended liquid or solid particles in air (except cloud droplets) and their carrier gas, the air itself. Aerosol takes up ambient water (a process known as hygroscopic growth) depending on the relative humidity and the composition of the aerosol. "Dry aerosol particles" means aerosol particles without any water uptake. Chemically, "elemental carbon" is the carbonaceous fraction of particulate matter that is thermally stable in an inert atmosphere to high temperatures near 4000K and can only be gasified by oxidation starting at temperatures above 340 C. It is assumed to be inert and non-volatile under atmospheric conditions and insoluble in any solvent (Ogren and Charlson, 1983). M VUKDVF70 mass_fraction_of_pm2p5_elemental_carbon_dry_aerosol_particles_in_air Mass fraction is used in the construction "mass_fraction_of_X_in_Y", where X is a material constituent of Y. It means the ratio of the mass of X to the mass of Y (including X). A chemical species denoted by X may be described by a single term such as "nitrogen" or a phrase such as "nox_expressed_as_nitrogen". "Aerosol" means the system of suspended liquid or solid particles in air (except cloud droplets) and their carrier gas, the air itself. Aerosol particles take up ambient water (a process known as hygroscopic growth) depending on the relative humidity and the composition of the particles. "Dry aerosol particles" means aerosol particles without any water uptake. "Pm2p5 aerosol" means atmospheric particulate compounds with an aerodynamic diameter of less than or equal to 2.5 micrometers. Chemically, "elemental carbon" is the carbonaceous fraction of particulate matter that is thermally stable in an inert atmosphere to high temperatures near 4000K and can only be gasified by oxidation starting at temperatures above 340 C. It is assumed to be inert and non-volatile under atmospheric conditions and insoluble in any solvent (Ogren and Charlson, 1983). M VGGKKZOX land_ice_basal_specific_mass_balance_flux "Land ice" means glaciers, ice-caps and ice-sheets resting on bedrock and also includes ice-shelves. In accordance with common usage in geophysical disciplines, "flux" implies per unit area, called "flux density" in physics. "Specific mass balance" means the net rate at which ice is added per unit area. A negative value means loss of ice. For an area-average, the cell_methods attribute should be used to specify whether the average is over the area of the whole grid cell or the area of land ice only. "Basal specific mass balance" means the net rate at which ice is added per unit area at the land ice base. M RAWK0OMW tendency_of_atmosphere_mass_content_of_elemental_carbon_dry_aerosol_particles_due_to_wet_deposition "tendency_of_X" means derivative of X with respect to time. "Content" indicates a quantity per unit area. The "atmosphere content" of a quantity refers to the vertical integral from the surface to the top of the atmosphere. For the content between specified levels in the atmosphere, standard names including "content_of_atmosphere_layer" are used. The mass is the total mass of the particles. "Aerosol" means the system of suspended liquid or solid particles in air (except cloud droplets) and their carrier gas, the air itself. Aerosol takes up ambient water (a process known as hygroscopic growth) depending on the relative humidity and the composition of the aerosol. "Dry aerosol particles" means aerosol particles without any water uptake. The specification of a physical process by the phrase "due_to_" process means that the quantity named is a single term in a sum of terms which together compose the general quantity named by omitting the phrase. "Wet deposition" means deposition by precipitation. Chemically, "elemental carbon" is the carbonaceous fraction of particulate matter that is thermally stable in an inert atmosphere to high temperatures near 4000K and can only be gasified by oxidation starting at temperatures above 340 C. It is assumed to be inert and non-volatile under atmospheric conditions and insoluble in any solvent (Ogren and Charlson, 1983). M IJWJWK1A tendency_of_atmosphere_mass_content_of_elemental_carbon_dry_aerosol_particles_due_to_turbulent_deposition "Content" indicates a quantity per unit area. The "atmosphere content" of a quantity refers to the vertical integral from the surface to the top of the atmosphere. For the content between specified levels in the atmosphere, standard names including content_of_atmosphere_layer are used. The mass is the total mass of the molecules. "Aerosol" means the system of suspended liquid or solid particles in air (except cloud droplets) and their carrier gas, the air itself. Aerosol takes up ambient water (a process known as hygroscopic growth) depending on the relative humidity and the composition of the aerosol. "Dry aerosol particles" means aerosol particles without any water uptake. The specification of a physical process by the phrase due_to_process means that the quantity named is a single term in a sum of terms which together compose the general quantity named by omitting the phrase. The sum of turbulent deposition and gravitational settling is dry deposition. "tendency_of_X" means derivative of X with respect to time. Chemically, "elemental carbon" is the carbonaceous fraction of particulate matter that is thermally stable in an inert atmosphere to high temperatures near 4000K and can only be gasified by oxidation starting at temperatures above 340 C. It is assumed to be inert and non-volatile under atmospheric conditions and insoluble in any solvent (Ogren and Charlson, 1983). M CF12N205 global_average_steric_sea_level_change Global average steric sea level change is caused by changes in sea water density due to changes in temperature (thermosteric) and salinity (halosteric). This in turn results in a change in volume of the world ocean. Zero sea level change is an arbitrary level. Because global average sea level change quantifies the change in volume of the world ocean, it is not calculated necessarily by considering local changes in mean sea level. M OEYCNJ15 altitude_at_top_of_atmosphere_model Altitude is the (geometric) height above the geoid, which is the reference geopotential surface. The geoid is similar to mean sea level. "Top of atmosphere model" means the upper boundary of the top layer of an atmosphere model. I CFV9N2 sea_surface_skin_temperature The sea surface skin temperature is the temperature measured by an infrared radiometer typically operating at wavelengths in the range 3.7 - 12 micrometers. It represents the temperature within the conductive diffusion-dominated sub-layer at a depth of approximately 10 - 20 micrometers below the air-sea interface. Measurements of this quantity are subject to a large potential diurnal cycle including cool skin layer effects (especially at night under clear skies and low wind speed conditions) and warm layer effects in the daytime. M CFSN0015 air_pressure Air pressure is the force per unit area which would be exerted when the moving gas molecules of which the air is composed strike a theoretical surface of any orientation. M CFV10N12 geoid_height_above_reference_ellipsoid The geoid is a surface of constant geopotential with which mean sea level would coincide if the ocean were at rest. (The volume enclosed between the geoid and the sea floor equals the mean volume of water in the ocean). In an ocean GCM the geoid is the surface of zero depth, or the rigid lid if the model uses that approximation. A reference ellipsoid is a regular mathematical figure that approximates the irregular shape of the geoid. A number of reference ellipsoids are defined for use in the field of geodesy. To specify which reference ellipsoid is being used, a grid_mapping variable should be attached to the data variable as described in Chapter 5.6 of the CF Convention. M JEB22TKP mole_fraction_of_carbonyl_fluoride_in_air Mole fraction is used in the construction "mole_fraction_of_X_in_Y", where X is a material constituent of Y. A chemical species denoted by X may be described by a single term such as "nitrogen" or a phrase such as "nox_expressed_as_nitrogen". The chemical formula of carbonyl fluoride is COF2. The IUPAC name for carbonyl fluoride is carbonyl difluoride. I GYGQPPOA mole_fraction_of_carbon_tetrafluoride_in_air Mole fraction is used in the construction "mole_fraction_of_X_in_Y", where X is a material constituent of Y. A chemical species denoted by X may be described by a single term such as "nitrogen" or a phrase such as "nox_expressed_as_nitrogen". The chemical formula for carbon tetrafluoride is CF4. The IUPAC name for carbon tetrafluoride is tetrafluoromethane. I