WMO OSCAR | Application Area: 2.5 Atmospheric Climate Monitoring

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Application: 2.5 Atmospheric Climate Monitoring

Details

Name	2.5 Atmospheric Climate Monitoring
Description	This AA covers the set of atmospheric observations defined by Global Climate Observing System (GCOS) as essential to detect, model and assess climate change and its impact; support adaptation to climate change; monitor the effectiveness of policies for mitigating climate change; and develop climate information services.
Organization	Global Climate Observing System
Focal Point	Caterina Tassone
Earth System Application Category	2. Atmospheric Applications

Variables measured in this Application Area

Subdomain	Variables
Basic atmospheric	Air pressure (near surface) Air specific humidity (near surface) Air temperature (near surface) Atmospheric temperature Specific humidity Integrated Water Vapour (IWV) Wind (horizontal) Wind (vertical) Wind speed (near surface) Wind vector (near surface) Relative Humidity (near surface) Dew Point Temperature Relative humidity Wind direction (near surface) Water Vapour Mixing Ratio Air Thickness
Clouds and precipitations	Accumulated precipitation Cloud cover Cloud drop effective radius Cloud liquid water (CLW) Cloud optical depth Cloud top height Cloud top temperature Precipitation intensity at surface (liquid or solid) Total lightning stroke density Cloud top pressure Number of Cloud Condensation Nuclei
Aerosols and radiation	Aerosol Extinction Coefficient Aerosol Optical Depth Downward short-wave irradiance at Earth surface Downward short-wave irradiance at TOA Downward long-wave irradiance at Earth surface Earth surface albedo Fraction of Absorbed PAR (FAPAR) Upward short-wave irradiance at TOA Upward long-wave irradiance at TOA Upward long-wave irradiance at Earth surface Aerosol single-scattering albedo Aerosol Layer Height Solar spectral irradiance Radiation profile Aerosol Light Extinction Vertical Profile Multi-wavelength Aerosol Optical Depth Aerosol Number Size Distribution Chemical Composition of Aerosol Particles
Ocean	Coastal sea level (tide) Dissolved inorganic carbon (DIC) Ocean chlorophyll concentration Ocean dynamic topography Ocean salinity Ocean subsurface dissolved oxygen concentration Ocean subsurface tracers Ocean surface currents (vector) Ocean temperature Ocean velocity pCO2 Sea surface salinity Sea surface temperature Significant wave height Water-leaving spectral radiance Wind stress Sea surface heat flux
Land surface	Biomass Fire fractional cover Fire radiative power Glacier cover Lake area Lake Surface Temperature Land cover Land surface temperature Leaf Area Index (LAI) River discharge Snow cover Snow water equivalent Soil moisture (in the roots region) Soil moisture at surface Snow depth
Solid Earth and magnetic field	Schumann Resonances
Atmospheric chemistry	HCHO Total Column CH4 mole fraction CO CO2 mole fraction N2O mole fraction NO2 O3 O3 Total Column SO2 Total Column CO2 column average dry air mixing ratio CH4 column average dry air mixing ratio CO2 Tropospheric Column CH4 Tropospheric column NO2 Tropospheric column CO Tropospheric column HCHO Tropospheric column SO2 Tropospheric Column NO2 Stratospheric Column O3 mole fraction O3 Tropospheric Column O3 Stratospheric Column CO mole fraction SO2 Stratospheric Column NO2 Mole fraction
Sea Ice	Sea-ice cover Sea-ice thickness Sea-ice motion

Requirements defined for 2.5 Atmospheric Climate Monitoring (123)

This tables shows all related requirements. For more operations/filtering, please consult the full list of Requirements
Note: In reading the values, goal is marked blue, breakthrough green, threshold orange
Application-dependent Technical Priority (ATP) Magenta and Relative priority of the attributes Red

Id	Variable	Layer	App Area	ATP	Uncertainty	Stability / decade	Hor Res	Ver Res	Obs Cyc	Timeliness	Coverage	Conf Level	Val Date	Source	General Comment	Observation Comment	Performance Comment
768	Wind speed (near surface)	Near Surface	2.5 Atmospheric Climate Monitoring	0.5	0.1 m/s 0.5 m/s 1 m/s 0.5	0.1 m/s 0.25 m/s 0.5 m/s 0.5	10 km 100 km 500 km 0.5		60 min 60 min 3 h 0.5	6 h 24 h 30 d 0.5	Global	firm	2023-04-28	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Requirements for uncertainty are specified at 2-sigma.	Goal for temporal resolution is sub-hourly
773	Precipitation intensity at surface (liquid or solid)	Near Surface	2.5 Atmospheric Climate Monitoring		0.5 mm/h	0.02 mm/h	25 km		30 d		Global	reasonable	2019-09-25	GCOS-200: The Global Observing System for Climate: Implementation Needs (Published 2016)	Requirements in the GCOS-200 IP, Annex A, are only specified at the goal level. Requirements for observing cycle are monthly (resolving diurnal cycles and with statistics of three-hour values)
774	Air temperature (near surface)	Near Surface	2.5 Atmospheric Climate Monitoring	0.5	0.1 K 0.5 K 1 K 0.5	0.01 K 0.05 K 0.1 K 0.5	10 km 100 km 500 km 0.5		60 min 60 min 3 h 0.5	6 h 24 h 30 d 0.5	Global	firm	2023-04-28	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Requirements for uncertainty are specified at 2-sigma.	Temporal resolution goal is sub-hourly. Required for derivation of extreme indices.
775	Air pressure (near surface)	Near Surface	2.5 Atmospheric Climate Monitoring	0.5	0.5 hPa 1 hPa 1 hPa 0.5	0.02 hPa 0.1 hPa 0.2 hPa 0.5	10 km 100 km 500 km 0.5		60 min 6 h 12 h 0.5	6 h 24 h 30 d 0.5	Global	firm	2023-04-27	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Requirements for uncertainty are specified at 2-sigma.
776	Relative Humidity (near surface)	Near Surface	2.5 Atmospheric Climate Monitoring	0.5	0.5 % 2.5 % 5 % 0.5	0.05 % 0.25 % 0.5 % 0.5	10 km 100 km 500 km 0.5		60 min 60 min 3 h 0.5	6 h 24 h 30 d 0.5	Global	firm	2023-04-28	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Requirements for uncertainty are specified at 2-sigma.	Goal for temporal resolution is sub-hourly
777	Dew Point Temperature	Near Surface	2.5 Atmospheric Climate Monitoring	0.5	0.1 K 0.5 K 1 K 0.5	0.01 K 0.05 K 0.1 K 0.5	10 km 100 km 500 km 0.5		60 min 60 min 3 h 0.5	6 h 24 h 30 d 0.5	Global	firm	2023-04-28	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Requirements for uncertainty are specified at 2-sigma.	Goal for temporal resolution is sub-hourly
778	Atmospheric temperature	PBL	2.5 Atmospheric Climate Monitoring	0.5	0.1 K 0.5 K 1 K 0.5	0.01 K 0.05 K 0.1 K 0.5	15 km 100 km 500 km 0.5	0.001 km 0.01 km 0.1 km 0.5	60 min 6 h 12 h 0.5	60 min 3 h 24 h 0.5	Global	firm	2023-04-28	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Requirements for uncertainty are specified at 2-sigma.	Goal for temporal resolution: Sub-hourly. A typical 4D-Var timeslot length, a subdivision into which observations are grouped for processing (ECMWF 2018)
779	Atmospheric temperature	UTLS	2.5 Atmospheric Climate Monitoring	0.5	0.1 K 0.5 K 1 K 0.5	0.01 K 0.02 K 0.05 K 0.5	15 km 100 km 500 km 0.5	0.025 km 0.1 km 0.25 km 0.5	60 min 12 h 24 h 0.5	60 min 3 h 6 h 0.5	Global	firm	2023-04-27	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Requirements for uncertainty are specified at 2-sigma.
780	Atmospheric temperature	MUS M	2.5 Atmospheric Climate Monitoring	0.5	0.1 K 0.5 K 1 K 0.5	0.05 K 0.1 K 0.2 K 0.5	50 km 100 km 1500 km 0.5	0.5 km 1 km 3 km 0.5	60 min 12 h 24 h 0.5	60 min 3 h 6 h 0.5	Global	firm	2023-05-05	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Requirements for uncertainty are specified at 2-sigma.
781	Wind (horizontal)	PBL	2.5 Atmospheric Climate Monitoring	0.5	0.5 m.s^-1 3 m.s^-1 5 m.s^-1 0.5	0.1 m.s^-1 0.3 m.s^-1 0.5 m.s^-1 0.5	15 km 100 km 500 km 0.5	0.01 km 0.1 km 0.5 km 0.5	30 min 60 min 12 h 0.5	6 h 18 h 2 d 0.5	Global	firm	2023-04-28	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Requirements for uncertainty are specified at 2-sigma.	Goal for vertical resolution is 1m for the lowermost part of the boundary layer (up to 100 m above the ground) Breakthrough for vertical resolution is 10m for the lowermost part of the boundary layer (up to 100 m above the ground) Goal for temporal is 1 min for the lowermost part of the boundary layer (up to 100 m above the ground)
784	Upward long-wave irradiance at TOA	TOA	2.5 Atmospheric Climate Monitoring	0.5	0.2 W/m² 0.5 W/m² 1 W/m² 0.5	0.05 W/m² 0.1 W/m² 0.2 W/m² 0.5	10 km 50 km 100 km 0.5		60 min 24 h 30 d 0.5	60 min 24 h 30 d 0.5	Global	firm	2023-05-03	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Requirements for uncertainty are specified at 2-sigma.
785	Upward short-wave irradiance at TOA	TOA	2.5 Atmospheric Climate Monitoring	0.5	0.2 W/m² 0.5 W/m² 1 W/m² 0.5	0.06 W/m² 0.15 W/m² 0.3 W/m² 0.5	10 km 50 km 100 km 0.5		60 min 24 h 30 d 0.5	60 min 24 h 30 d 0.5	Global	firm	2023-05-03	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Requirements for uncertainty are specified at 2-sigma.
786	Downward short-wave irradiance at TOA	TOA	2.5 Atmospheric Climate Monitoring	0.5	0.04 W.m^-2 0.08 W.m^-2 0.12 W.m^-2 0.5	0.01 W.m^-2 0.02 W.m^-2 0.04 W.m^-2 0.5	10 km 50 km 100 km 0.5		60 min 6 h 24 h 0.5	60 min 24 h 30 d 0.5	Global	firm	2023-04-27	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Requirements for uncertainty are specified at 2-sigma.
787	Downward long-wave irradiance at Earth surface	Near Surface	2.5 Atmospheric Climate Monitoring	0.5	1 W.m^-2 5 W.m^-2 10 W.m^-2 0.5	0.2 W.m^-2 0.5 W.m^-2 10 W.m^-2 0.5	10 km 50 km 100 km 0.5		60 min 24 h 30 d 0.5	30 d	Global	firm	2023-04-27	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Requirements for uncertainty are specified at 2-sigma.
788	Downward short-wave irradiance at Earth surface	Near Surface	2.5 Atmospheric Climate Monitoring	0.5	1 W.m^-2 5 W.m^-2 10 W.m^-2 0.5	0.2 W.m^-2 0.5 W.m^-2 1 W.m^-2 0.5	10 km 50 km 100 km 0.5		60 min 24 h 30 d 0.5	30 d	Global	firm	2023-04-27	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Requirements for uncertainty are specified at 2-sigma.
789	Relative humidity	PBL	2.5 Atmospheric Climate Monitoring	0.5	0.1 % 0.5 % 1 % 0.5	0.1 % 0.5 % 1 % 0.5	15 km 100 km 500 km 0.5	0.001 km 0.01 km 0.1 km 0.5	30 min 6 h 12 h 0.5	60 min 5 d 30 d 0.5	Global	firm	2023-05-09	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Requirements for uncertainty are specified at 2-sigma. Units for uncertainty and stability are %RH	GOAL for temporal resolution is sub-hourly
790	Relative humidity	UTLS	2.5 Atmospheric Climate Monitoring	0.5	0.5 % 1 % 2 % 0.5	0.5 % 0.5 % 2 % 0.5	15 km 100 km 500 km 0.5	0.01 km 0.1 km 0.25 km 0.5	3 h 6 h 24 h 0.5	60 min 5 d 30 d 0.5	Global	firm	2023-05-09	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Requirements for uncertainty are specified at 2-sigma. Units for uncertainty and stability are %RH	Goal for stability is < 0.5%RH
791	Cloud cover		2.5 Atmospheric Climate Monitoring	0.5	3 % 6 % 12 % 0.5	0.3 % 0.6 % 1.2 % 0.5	25 km 100 km 500 km 0.5		60 min 24 h 30 d 0.5	60 min 3 h 12 h 0.5	Global	firm	2023-04-28	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Requirements for uncertainty are specified at 2-sigma.
792	Cloud top temperature	Cloud-top	2.5 Atmospheric Climate Monitoring	0.5	2 K 4 K 8 K 0.5	0.2 K 0.4 K 0.8 K 0.5	25 km 100 km 500 km 0.5		60 min 24 h 30 d 0.5	60 min 3 h 12 h 0.5	Global	firm	2023-04-27	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Requirements for uncertainty are specified at 2-sigma.
793	Cloud optical depth	TC	2.5 Atmospheric Climate Monitoring	0.5	20 dimless 40 dimless 80 dimless 0.5	2 dimless 4 dimless 8 dimless 0.5	25 km 100 km 500 km 0.5		60 min 24 h 30 d 0.5	60 min 3 h 12 h 0.5	Global	firm	2023-04-27	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Requirements for uncertainty are specified at 2-sigma.
794	Cloud liquid water (CLW)	FT PBL	2.5 Atmospheric Climate Monitoring		25 %	5 %	50 km		3 h		Global	reasonable	2019-09-25	GCOS-200: The Global Observing System for Climate: Implementation Needs (Published 2016)	Requirements in the GCOS-200 IP, Annex A, are only specified at the goal level. In GCOS IP cloud water path includes liquid and ice
795	Cloud drop effective radius		2.5 Atmospheric Climate Monitoring	0.5	1 μm 2 μm 4 μm 0.5	0.1 μm 0.2 μm 0.4 μm 0.5	25 km 100 km 500 km 0.5		60 min 24 h 30 d 0.5	60 min 3 h 12 h 0.5	Global	firm	2025-04-11	GCOS-245: The 2022 ECVs Requirements (GCOS-245)		Requirements for uncertainty and stability are for cloud drop effective radius as water. For ice apply factor 2
796	CO2 mole fraction		2.5 Atmospheric Climate Monitoring	0.5	0.1 ppm 0.2 ppm 0.5 ppm 0.5	0.1 ppm 0.1 ppm 0.3 ppm 0.5	100 km 500 km 2000 km 0.5	100 m 1000 m 3000 m 0.5	60 min 24 h 7 d 0.5	24 h 30 d 180 d 0.5	Global	firm	2023-05-03	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Requirement for uncertainty is at 2-sigma
797	CH4 mole fraction		2.5 Atmospheric Climate Monitoring	0.5	1 ppb 2 ppb 5 ppb 0.5	1 ppb 1 ppb 3 ppb 0.5	100 km 500 km 2000 km 0.5	100 m 1000 m 3000 m 0.5	60 min 24 h 7 d 0.5	24 h 30 d 180 d 0.5	Global	firm	2025-04-11	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Requirements for uncertainty are at 2-sigma
800	CO2 Tropospheric Column	TrC	2.5 Atmospheric Climate Monitoring				5 km 10 km		4 h		Global	reasonable	2019-09-26	GCOS-200: The Global Observing System for Climate: Implementation Needs (Published 2016)	Requirements for uncertainty and stability in the GCOS IP are expressed in ppm
801	CH4 Tropospheric column	TrC	2.5 Atmospheric Climate Monitoring				5 km 10 km		4 h		Global	reasonable	2019-09-26	GCOS-200: The Global Observing System for Climate: Implementation Needs (Published 2016)	Requirements for uncertainty and stability in the GCOS IP are expressed in ppb
802	O3 Total Column	TC	2.5 Atmospheric Climate Monitoring	0.5	1 % 2 % 3 % 0.5	1 % 2 % 3 % 0.5	20 km 100 km 500 km 0.5		60 min 24 h 30 d 0.5	60 min 24 h 30 d 0.5	Global	firm	2023-05-03	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Requirement for uncertainty at 2-sigma
803	NO2 Tropospheric column	TrC	2.5 Atmospheric Climate Monitoring	0.5			10 km 30 km 100 km 0.5		60 min 24 h 30 d 0.5	24 h 7 d 30 d 0.5	Global	firm	2023-05-03	GCOS-200: The Global Observing System for Climate: Implementation Needs (Published 2016)	Requirement for uncertainty at 2-sigma. For uncertainty and stability requirements see notes	requirements for uncertainty: G:max(20%,1E15) B: max(40%,2E15) T: max(100%,5E15) Stability: G:max(4%,1E15) B:max(8%,1E15) T: max(20%,1E15)
804	SO2 Tropospheric Column	TrC	2.5 Atmospheric Climate Monitoring	0.5			10 km 30 km 100 km 0.5		60 min 24 h 30 d 0.5	24 h 7 d 30 d 0.5	Global	firm	2023-05-03	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Requirement for uncertainty are for 2-sigma. For values of uncertainty and stability see notes	Uncertainty - G:max (30%,6E15) B;max(60%,12E15) T: max(100%,20E15) Stability: G: max(6%,1.2E15 T:max(12%,2.4E15) Bmax(20%, 4E15)
805	HCHO Tropospheric column	TrC	2.5 Atmospheric Climate Monitoring	0.5			10 km 30 km 100 km 0.5		60 min 24 h 30 d 0.5	24 h 7 d 30 d 0.5	Global	firm	2023-05-03	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Requirement for uncertainty are at 2-sigma. For values see comments	Uncertainty: Goal: max (20%,8E15) B: max(40%,16E15) T: max(100%,40E15) Stabilitiy: G: max (4%,8E15) B:max(8%,8E15) T:max(20%,8E15) molecules cm-2
806	CO Tropospheric column	TrC	2.5 Atmospheric Climate Monitoring	0.5	1 ppb 5 ppb 10 ppb 0.5	0.9 ppb 1 ppb 2 ppb 0.5	10 km 30 km 100 km 0.5		60 min 24 h 30 d 0.5	24 h 7 d 30 d 0.5	Global	reasonable	2025-04-11	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Uncertainty in 2-sigma
807	Aerosol Optical Depth	FT PBL	2.5 Atmospheric Climate Monitoring		0.03 Dimensionless	0.02 Dimensionless	5 km 10 km		4 h		Global	reasonable	2019-09-26	GCOS-200: The Global Observing System for Climate: Implementation Needs (Published 2016)	Requirement for uncertainty in the GCOS IP is expressed as max (0.03; 10%)
808	Aerosol single-scattering albedo		2.5 Atmospheric Climate Monitoring	0.5	0.1 % 0.2 % 0.4 % 0.5	0.1 dimensionless 0.4 dimensionless 1 dimensionless 0.5	50 km 200 km 500 km 0.5	1 km 5 km	14 min 24 h 30 d 0.5	24 h 7 d 30 d 0.5	Global	firm	2023-05-03	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Requirements for uncertainty are at 2-sigma
809	Aerosol Layer Height	n/a (2D)	2.5 Atmospheric Climate Monitoring		1 km	0.5	5 km 10 km		4 h		Global	reasonable	2019-09-26	GCOS-200: The Global Observing System for Climate: Implementation Needs (Published 2016)
810	Aerosol Extinction Coefficient	FT PBL	2.5 Atmospheric Climate Monitoring		0.1 m^-1	0.2 m^-1	200 km 500 km	1 km 2 km	7 d		Global	reasonable	2019-09-26	GCOS-200: The Global Observing System for Climate: Implementation Needs (Published 2016)	Requirement for vertical resolution in the GCOS IP is 1km near tropopause and 2 km in mod-stratosphere
812	O3	FT PBL	2.5 Atmospheric Climate Monitoring				20 km 50 km	5 km	4 h		Global	reasonable	2019-09-27	GCOS-200: The Global Observing System for Climate: Implementation Needs (Published 2016)	Requirements for uncertainty and stability in the GCOS IP are expressed in different units than in the OSCAR/Requirements
813	O3	UTLS	2.5 Atmospheric Climate Monitoring				100 km 200 km	1 km 2 km	4 h		Global	reasonable	2019-09-27	GCOS-200: The Global Observing System for Climate: Implementation Needs (Published 2016)	Requirements for uncertainty and stability in the GCOS IP are expressed in different units than in OSCAR/requirements
814	O3	MUS M	2.5 Atmospheric Climate Monitoring				100 km 200 km	3 km	24 h		Global	reasonable	2019-09-27	GCOS-200: The Global Observing System for Climate: Implementation Needs (Published 2016)	Requirements for uncertainty and stability in the GCOS IP are expressed in different units than in the OSCAR/Requirements
815	CO	UTLS FT PBL	2.5 Atmospheric Climate Monitoring	0.5	1 ppb 5 ppb 10 ppb 0.5	1 ppb 1 ppb 3 ppb 0.5	10 km 30 km 100 km 0.5	1 km 3 km 5 km 0.5	60 min 24 h 30 d 0.5	24 h 7 d 30 d 0.5	Global	firm	2023-05-03	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Requirements for uncertainty are at 2-sigma	Goal for stability less than 1ppb
817	Integrated Water Vapour (IWV)	TC	2.5 Atmospheric Climate Monitoring	0.5	0.1 kg.m^-2 0.5 kg.m^-2 1 kg.m^-2 0.5	0.1 kg.m^-2 0.2 kg.m^-2 0.5 kg.m^-2 0.5	25 km 250 km 1000 km 0.5		12 min 60 min 24 h 0.5	24 h 5 d 30 d 0.5	Global	firm	2023-04-27	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Requirements for uncertainty are specified at 2-sigma.
818	River discharge	Land surface	2.5 Atmospheric Climate Monitoring	0.5					24 h		Global	reasonable	2025-08-08	GCOS-200: The Global Observing System for Climate: Implementation Needs (Published 2016)	Requirements in the GCOS-200 IP, Annex A, are only specified at the goal level. Requirements for uncertainty and stability in the GCOS IP are specified in different units than in OSCAR/requirement		8 Aug 2025: PoC of AA 4.2 requested to archive these requirements under 2.5, because this GCOSTOPC variable will be moved under AA .4.2. The change was supported by PoC and the owner of AA 2.5.
819	Lake area	Land surface	2.5 Atmospheric Climate Monitoring	0.5			20 m		24 h		Global	reasonable	2025-08-08	GCOS-200: The Global Observing System for Climate: Implementation Needs (Published 2016)	Requirements in the GCOS-200 IP, Annex A, are only specified at the goal level. Requirements for uncertainty and stability in the GCOS IP are specified in different units than in OSCAR/requirement		8 Aug 2025: PoC of AA 4.2 requested to archive these requirements under 2.5, because this GCOSTOPC variable will be moved under AA .4.2. The change was supported by PoC and the owner of AA 2.5.
821	Lake Surface Temperature	Land surface	2.5 Atmospheric Climate Monitoring		1 K	0.1 K	0.3 km		7 d		Global	reasonable	2019-09-30	GCOS-200: The Global Observing System for Climate: Implementation Needs (Published 2016)	Requirements in the GCOS-200 IP, Annex A, are only specified at the goal level.
822	Soil moisture (in the roots region)	Root	2.5 Atmospheric Climate Monitoring	0.5	0.04 m³ /m³	0.01 m³ /m³	1 km 25 km		24 h		Global	reasonable	2025-08-08	GCOS-200: The Global Observing System for Climate: Implementation Needs (Published 2016)	Requirements in the GCOS-200 IP, Annex A, are only specified at the goal level. Requirements for stability in the GCOS IP are specified per year.		8 Aug 2025: PoC of AA 4.2 requested to archive these requirements under 2.5, because this GCOSTOPC variable will be moved under AA .4.2. The change was supported by PoC and the owner of AA 2.5.
823	Soil moisture at surface	Land surface	2.5 Atmospheric Climate Monitoring	0.5	0.04 m³ /m³		1 km 25 km		24 h		Global	reasonable	2025-08-08	GCOS-200: The Global Observing System for Climate: Implementation Needs (Published 2016)	Requirements in the GCOS-200 IP, Annex A, are only specified at the goal level. Requirements for stability in the GCOS IP are specified in different units than in OSCAR/requirement.		8 Aug 2025: PoC of AA 4.2 requested to archive these requirements under 2.5, because this GCOSTOPC variable will be moved under AA .4.2. The change was supported by PoC and the owner of AA 2.5.
824	Snow cover	Land surface	2.5 Atmospheric Climate Monitoring	0.5	5 %	4 %	0.1 km 1 km		24 h		Global	reasonable	2025-08-08	GCOS-200: The Global Observing System for Climate: Implementation Needs (Published 2016)	Requirements in the GCOS-200 IP, Annex A, are only specified at the goal level.		8 Aug 2025: PoC of AA 4.2 requested to archive these requirements under 2.5, because this GCOSTOPC variable will be moved under AA .4.2. The change was supported by PoC and the owner of AA 2.5.
825	Snow water equivalent	Land surface	2.5 Atmospheric Climate Monitoring	0.5	10 mm	10 mm	1 km		24 h		Global	reasonable	2025-08-08	GCOS-200: The Global Observing System for Climate: Implementation Needs (Published 2016)	Requirements in the GCOS-200 IP, Annex A, are only specified at the goal level.		8 Aug 2025: PoC of AA 4.2 requested to archive these requirements under 2.5, because this GCOSTOPC variable will be moved under AA .4.2. The change was supported by PoC and the owner of AA 2.5.
826	Glacier cover	Land surface	2.5 Atmospheric Climate Monitoring		5 %		15 m 30 m		1 y		Global	reasonable	2019-09-30	GCOS-200: The Global Observing System for Climate: Implementation Needs (Published 2016)	Requirements in the GCOS-200 IP, Annex A, are only specified at the goal level.
827	Fraction of Absorbed PAR (FAPAR)	Land surface	2.5 Atmospheric Climate Monitoring		10 %	3 %	0.05 km 0.2 km 0.5 km		24 h		Global	reasonable	2019-09-30	GCOS-200: The Global Observing System for Climate: Implementation Needs (Published 2016)	Requirements in the GCOS-200 IP, Annex A, are only specified at the goal level.
828	Leaf Area Index (LAI)	Land surface	2.5 Atmospheric Climate Monitoring		15 %	10 %	0.05 km 0.25 km		24 h		Global	reasonable	2019-09-30	GCOS-200: The Global Observing System for Climate: Implementation Needs (Published 2016)	Requirements in the GCOS-200 IP, Annex A, are only specified at the goal level.
829	Earth surface albedo	Near Surface	2.5 Atmospheric Climate Monitoring		5 %	1 %	0.05 km 0.2 km 0.5 km		24 h		Global	reasonable	2019-09-30	GCOS-200: The Global Observing System for Climate: Implementation Needs (Published 2016)	Requirements in the GCOS-200 IP, Annex A, are only specified at the goal level.
830	Land surface temperature	Land surface	2.5 Atmospheric Climate Monitoring		1 K	0.1 K	1 km		3 h		Global	reasonable	2019-09-30	GCOS-200: The Global Observing System for Climate: Implementation Needs (Published 2016)	Requirements in the GCOS-200 IP, Annex A, are only specified at the goal level.
831	Biomass	Land surface	2.5 Atmospheric Climate Monitoring		10 t/ha 50 t/ha		0.5 km 1 km		1 y		Global	reasonable	2019-09-30	GCOS-200: The Global Observing System for Climate: Implementation Needs (Published 2016)	Requirements in the GCOS-200 IP, Annex A, are only specified at the goal level. Requirements for stability in the GCOS IP are specified in different units than in OSCAR/requirement
832	Land cover	Land surface	2.5 Atmospheric Climate Monitoring				10 m 250 m 1000 m		1 y 5 y 10 y		Global	reasonable	2019-09-30	GCOS-200: The Global Observing System for Climate: Implementation Needs (Published 2016)	Requirements in the GCOS-200 IP, Annex A, are only specified at the goal level. Requirements for uncertainty and stability in the GCOS IP are specified in different units than in OSCAR/requirement
833	Fire fractional cover	Land surface	2.5 Atmospheric Climate Monitoring		5 % 10 %		0.25 km 1 km 3 km		60 min 6 h		Global	reasonable	2019-09-30	GCOS-200: The Global Observing System for Climate: Implementation Needs (Published 2016)	Requirements in the GCOS-200 IP, Annex A, are only specified at the goal level.
834	Fire radiative power	Land surface	2.5 Atmospheric Climate Monitoring		0.0005 kW*m^-2		0.25 km 1 km 3 km		60 min 6 h		Global	reasonable	2019-09-30	GCOS-200: The Global Observing System for Climate: Implementation Needs (Published 2016)	Requirements in the GCOS-200 IP, Annex A, are only specified at the goal level.
835	Sea surface temperature	Sea surface	2.5 Atmospheric Climate Monitoring	0.5	0.1 K	0.03 K	1 km 100 km		60 min 7 d		Global	reasonable	2019-10-15	GCOS-200: The Global Observing System for Climate: Implementation Needs (Published 2016)	Requirements in the GCOS-200 IP, Annex A, are only specified at the goal level.
836	Ocean temperature	Upper oc	2.5 Atmospheric Climate Monitoring	0.5	0.01 K		1 km 10 km		60 min 30 d		Global	reasonable	2019-10-15	GCOS-200: The Global Observing System for Climate: Implementation Needs (Published 2016)	Requirements in the GCOS-200 IP, Annex A, are only specified at the goal level.
837	Sea surface salinity	Sea surface	2.5 Atmospheric Climate Monitoring		0.01 psu	0.001 psu	1 km 100 km		60 min 30 d		Global	reasonable	2019-10-15	GCOS-200: The Global Observing System for Climate: Implementation Needs (Published 2016)	Requirements in the GCOS-200 IP, Annex A, are only specified at the goal level.
838	Ocean salinity	Upper oc	2.5 Atmospheric Climate Monitoring		0.01 psu		1 km 10 km		60 min 30 d		Global	reasonable	2019-10-15	GCOS-200: The Global Observing System for Climate: Implementation Needs (Published 2016)	Requirements in the GCOS-200 IP, Annex A, are only specified at the goal level.
839	Ocean surface currents (vector)	Sea surface	2.5 Atmospheric Climate Monitoring		5 cm/s		30 km		60 min 7 d		Global	reasonable	2019-10-15	GCOS-200: The Global Observing System for Climate: Implementation Needs (Published 2016)	Requirements in the GCOS-200 IP, Annex A, are only specified at the goal level.
840	Ocean velocity	Upper oc	2.5 Atmospheric Climate Monitoring		2 cm/s		1 km 10 km		60 min 7 d		Global	reasonable	2019-10-15	GCOS-200: The Global Observing System for Climate: Implementation Needs (Published 2016)	Requirements in the GCOS-200 IP, Annex A, are only specified at the goal level.
841	Ocean dynamic topography	Sea surface	2.5 Atmospheric Climate Monitoring	0.5	0.2 cm 0.4 cm	0.03 cm	10 km 100 km		7 d 30 d		Global	reasonable	2019-10-15	GCOS-200: The Global Observing System for Climate: Implementation Needs (Published 2016)	Requirements in the GCOS-200 IP, Annex A, are only specified at the goal level.
842	Coastal sea level (tide)	Bulk	2.5 Atmospheric Climate Monitoring	0.5	1 cm	0.1 cm	10 km		60 min 7 d		Global	reasonable	2019-10-15	GCOS-200: The Global Observing System for Climate: Implementation Needs (Published 2016)	Requirements in the GCOS-200 IP, Annex A, are only specified at the goal level.
843	Significant wave height	Sea surface	2.5 Atmospheric Climate Monitoring		0.1 m	0.05 m	25 km		3 h		Global	reasonable	2019-10-15	GCOS-200: The Global Observing System for Climate: Implementation Needs (Published 2016)	Requirements in the GCOS-200 IP, Annex A, are only specified at the goal level.
844	Wind stress	Sea surface	2.5 Atmospheric Climate Monitoring		0.01 Pa 4 Pa		10 km 100 km		60 min 30 d		Global	reasonable	2019-10-15	GCOS-200: The Global Observing System for Climate: Implementation Needs (Published 2016)	Requirements in the GCOS-200 IP, Annex A, are only specified at the goal level.
845	Sea surface heat flux	Sea surface	2.5 Atmospheric Climate Monitoring		10 W/m² 15 W/m²	1 W/m² 2 W/m²	1 km 25 km		60 min 30 d		Global	reasonable	2019-10-15	GCOS-200: The Global Observing System for Climate: Implementation Needs (Published 2016)	Requirements in the GCOS-200 IP, Annex A, are only specified at the goal level.
846	Sea-ice cover	Sea surface	2.5 Atmospheric Climate Monitoring		5 %	5 %	1 km 15 km		7 d		Global	reasonable	2019-10-15	GCOS-200: The Global Observing System for Climate: Implementation Needs (Published 2016)	Requirements in the GCOS-200 IP, Annex A, are only specified at the goal level.
847	Sea-ice thickness	Sea surface	2.5 Atmospheric Climate Monitoring		10 cm		25 km		30 d		Global	reasonable	2019-10-15	GCOS-200: The Global Observing System for Climate: Implementation Needs (Published 2016)	Requirements in the GCOS-200 IP, Annex A, are only specified at the goal level.
848	Sea-ice motion	Sea surface	2.5 Atmospheric Climate Monitoring		1 km*d^-1		5 km		7 d		Global	reasonable	2019-10-15	GCOS-200: The Global Observing System for Climate: Implementation Needs (Published 2016)	Requirements in the GCOS-200 IP, Annex A, are only specified at the goal level.
849	Ocean subsurface dissolved oxygen concentration	Bulk	2.5 Atmospheric Climate Monitoring		0.5 μmol kg^⁻1 2 μmol kg^⁻1		3 km 20 km		7 d 10 y		Global	reasonable	2019-10-15	GCOS-200: The Global Observing System for Climate: Implementation Needs (Published 2016)	Requirements in the GCOS-200 IP, Annex A, are only specified at the goal level.
850	pCO2	Sea surface	2.5 Atmospheric Climate Monitoring		2 microatm		500 km 1000 km		7 d 10 y		Global	reasonable	2019-10-15	GCOS-200: The Global Observing System for Climate: Implementation Needs (Published 2016)	Requirements in the GCOS IP are goal values.
851	Dissolved inorganic carbon (DIC)	Bulk	2.5 Atmospheric Climate Monitoring		2.0E-6 μmol kg^⁻1		1000 km 2000 km		10 y		Global	reasonable	2019-10-15	GCOS-200: The Global Observing System for Climate: Implementation Needs (Published 2016)	Requirements in the GCOS-200 IP, Annex A, are only specified at the goal level.
852	Ocean subsurface tracers	Bulk	2.5 Atmospheric Climate Monitoring		0.005 % 0.5 %		1000 2000		1 y 10 y		Global	reasonable	2019-10-15	GCOS-200: The Global Observing System for Climate: Implementation Needs (Published 2016)	Requirements in the GCOS-200 IP, Annex A, are only specified at the goal level.
853	Water-leaving spectral radiance	Sea surface	2.5 Atmospheric Climate Monitoring		5 %		4		24 h		Global	reasonable	2019-10-15	GCOS-200: The Global Observing System for Climate: Implementation Needs (Published 2016)	Requirements in the GCOS-200 IP, Annex A, are only specified at the goal level.
854	Ocean chlorophyll concentration	Bulk	2.5 Atmospheric Climate Monitoring				4 km		7 d		Global	reasonable	2019-10-15	GCOS-200: The Global Observing System for Climate: Implementation Needs (Published 2016)	Requirements in the GCOS-200 IP, Annex A, are only specified at the goal level. Uncertainty in GCOS IP is expressed in a different unit
858	Cloud top pressure	Cloud-top	2.5 Atmospheric Climate Monitoring		15 hPa 50 hPa	3 hPa 15 hPa	50 km		3 h		Global	reasonable	2020-03-05	AOPC	GCOS-200: The Global Observing System for Climate: Implementation Needs (Published 2016)
859	Total lightning stroke density	TrC	2.5 Atmospheric Climate Monitoring	0.5	1 Dimensionless 15 Dimensionless	1 % 10 %	10 km		60 min 24 h 30 d 0.5	10 d 30 d 1 y 0.5	Global	tentative	2025-04-11	GCOS-245: The 2022 ECVs Requirements (GCOS-245)
860	Snow depth	Land surface	2.5 Atmospheric Climate Monitoring		0.1 cm	0.1 cm	1 km		24 h		Global	reasonable	2020-03-05	TOPC	GCOS-200: The Global Observing System for Climate: Implementation Needs (Published 2016)
865	N2O mole fraction	MUS UTLS FT PBL M	2.5 Atmospheric Climate Monitoring	0.5	0.05 ppb 0.1 ppb 0.3 ppb 0.5	0.05 ppb 0.05 ppb 0.2 ppb 0.5	100 km 500 km 2000 km 0.5	0.1 km 1 km 3 km 0.5	60 min 24 h 7 d 0.5	24 h 30 d 180 d 0.5	Global	firm	2023-05-03	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Uncertainty specified at 2-sigma
878	CO2 column average dry air mixing ratio		2.5 Atmospheric Climate Monitoring	0.5	0.6 ppm 1 ppm 1.6 ppm 0.5	0.1 ppm/decade 0.2 ppm/decade 0.3 ppm/decade 0.5	1 km 5 km 10 km 0.5		24 h 12 d 72 d 0.5	24 h 7 d 14 d 0.5	Global	firm	2025-04-11	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	uncertainty units are expressed in ppm according to GCOS-245
887	CH4 column average dry air mixing ratio		2.5 Atmospheric Climate Monitoring	0.5	7 ppb 10 ppb 20 ppb 0.5	1 ppb 2 ppb 4 ppb 0.5	0.3 km 1 km 10 km 0.5		60 min 12 h 3 d 0.5	24 h 7 d 14 d 0.5	Global	firm	2025-04-11	GCOS-245: The 2022 ECVs Requirements (GCOS-245)
896	NO2		2.5 Atmospheric Climate Monitoring								Global	firm		AOPC
900	HCHO Total Column		2.5 Atmospheric Climate Monitoring								Global	firm		AOPC
906	SO2 Total Column		2.5 Atmospheric Climate Monitoring								Global	firm		GAW Expert Team on Atmospheric Composition Network Design and Evolution
983	Wind direction (near surface)	Near Surface	2.5 Atmospheric Climate Monitoring	0.5	1 degrees 5 degrees 10 degrees 0.5	1 degrees 2 degrees 5 degrees 0.5	10 km 100 km 500 km 0.5		60 min 60 min 3 h 0.5	6 h 24 h 30 d 0.5	Global	firm	2023-04-28	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Requirements for uncertainty are specified at 2-sigma.	Goal for temporal resolution is sub-hourly
984	Wind vector (near surface)	Near Surface	2.5 Atmospheric Climate Monitoring	0.5	0.1 m/s 0.5 m/s 1 m/s 0.5	0.1 m/s 0.25 m/s 0.5 m/s 0.5	10 km 100 km 500 km 0.5		60 min 60 min 3 h 0.5	6 h 24 h 30 d 0.5	Global	firm	2023-04-28	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Requirements for uncertainty are specified at 2-sigma.	Goal for temporal resolution is sub-hourly
985	Air specific humidity (near surface)	Near Surface	2.5 Atmospheric Climate Monitoring	0.5	0.1 g kg^-1 0.5 g kg^-1 1 g kg^-1 0.5	0.01 g kg^-1 0.05 g kg^-1 0.1 g kg^-1 0.5	10 km 100 km 500 km 0.5		60 min 60 min 3 h 0.5	6 h 24 h 30 d 0.5	Global	firm	2025-04-11	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Requirements for uncertainty are specified at 2-sigma.	Goal for temporal resolution sub-hourly
986	Upward long-wave irradiance at Earth surface	Near Surface	2.5 Atmospheric Climate Monitoring	0.5	1 W/m² 5 W/m² 10 W/m² 0.5	0.2 W/m² 0.5 W/m² 1 W/m² 0.5	10 km 50 km 100 km 0.5		60 min 24 h 30 d 0.5	30 d	Global	reasonable	2023-04-26	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Requirements for uncertainty are specified at 2-sigma.
988	Wind (horizontal)	FT	2.5 Atmospheric Climate Monitoring	0.5	1 m.s^-1 3 m.s^-1 5 m.s^-1 0.5	0.1 m.s^-1 0.3 m.s^-1 0.5 m.s^-1 0.5	15 km 100 km 1000 km 0.5	0.01 km 0.1 km 1.5 km 0.5	60 min 6 h 12 h 0.5	6 h 18 h 2 d 0.5	Global	firm	2023-04-27	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Requirements for uncertainty are specified at 2-sigma.
989	Wind (horizontal)	UTLS	2.5 Atmospheric Climate Monitoring	0.5	1 m.s^-1 3 m.s^-1 5 m.s^-1 0.5	0.1 m.s^-1 0.3 m.s^-1 0.5 m.s^-1 0.5	15 km 100 km 500 km 0.5	0.025 km 0.1 km 0.5 km 0.5	60 min 6 h 12 h 0.5	6 h 18 h 2 d 0.5	Global	firm	2023-04-27	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Requirements for uncertainty are specified at 2-sigma.
992	Wind (vertical)	PBL	2.5 Atmospheric Climate Monitoring	0.5	0.5 cm.s^-1 1 cm.s^-1 1.5 cm.s^-1 0.5	0.05 cm.s^-1 0.1 cm.s^-1 0.15 cm.s^-1 0.5	15 km 200 km 500 km 0.5	0.01 km 0.1 km 0.5 km 0.5	30 min 60 min 12 h 0.5	6 h 18 h 2 d 0.5	Global	firm	2023-04-28	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Requirements for uncertainty are specified at 2-sigma.	Goal for vertical resolution is 1m for the lowermost part of the boundary layer (up to 100 m above the ground) Goal for temporal resolution is 1 min for the lowermost part of the boundary layer (up to 100 m above the ground)
993	Wind (vertical)	FT	2.5 Atmospheric Climate Monitoring	0.5	0.5 cm.s^-1 1.5 cm.s^-1 2.5 cm.s^-1 0.5	0.05 cm.s^-1 0.15 cm.s^-1 0.25 cm.s^-1 0.5	15 km 200 km 1000 km 0.5	0.01 km 0.1 km 1.5 km 0.5	60 min 6 h 12 h 0.5	6 h 18 h 2 d 0.5	Global	firm	2023-04-27	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Requirements for uncertainty are specified at 2-sigma.
994	Wind (vertical)	UTLS	2.5 Atmospheric Climate Monitoring	0.5	0.5 cm.s^-1 1.5 cm.s^-1 2.5 cm.s^-1 0.5	0.05 cm.s^-1 0.15 cm.s^-1 0.25 cm.s^-1 0.5	15 km 200 km 500 km 0.5	0.025 km 0.1 km 0.5 km 0.5	60 min 6 h 12 h 0.5	6 h 18 h 2 d 0.5	Global	firm	2023-04-27	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Requirements for uncertainty are specified at 2-sigma.
995	Wind (vertical)	MUS	2.5 Atmospheric Climate Monitoring	0.5	1 cm.s^-1 3 cm.s^-1 5 cm.s^-1 0.5	0.05 cm.s^-1 0.15 cm.s^-1 0.25 cm.s^-1 0.5	50 km 200 km 3000 km 0.5	0.5 km 2 km 3 km 0.5	60 min 6 h 24 h 0.5	6 h 18 h 2 d 0.5	Global	firm	2023-04-27	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Requirements for uncertainty are specified at 2-sigma.
996	Wind (vertical)	M	2.5 Atmospheric Climate Monitoring	0.5	2 cm.s^-1 6 cm.s^-1 10 cm.s^-1 0.5	0.1 cm.s^-1 0.2 cm.s^-1 0.3 cm.s^-1 0.5	50 km 200 km 3000 km 0.5	1 km 2 km 3 km 0.5	60 min 6 h 24 h 0.5	6 h 18 h 2 d 0.5	Global	firm	2023-04-27	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Requirements for uncertainty are specified at 2-sigma.
997	Relative humidity	FT	2.5 Atmospheric Climate Monitoring	0.5	0.1 % 0.5 % 1 % 0.5	0.1 % 0.5 % 1 % 0.5	15 km 100 km 1000 km 0.5	0.01 km 0.1 km 1 km 0.5	30 min 6 h 12 h 0.5	60 min 5 d 30 d 0.5	Global	firm	2023-05-09	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Requirements for uncertainty are specified at 2-sigma. Units for uncertainty and stability are %RH	Goal for temporal resolution is Sub-hourly
1000	Radiation profile		2.5 Atmospheric Climate Monitoring	0.5	0.1 W/m2 0.2 W/m2 0.4 W/m2 0.5	0.025 W/m2 0.05 W/m2 0.1 W/m2 0.5	10 km 50 km 100 km 0.5	1 km 2 km 4 km 0.5	60 min 24 h 30 d 0.5	60 min 24 h 30 d 0.5	Global	firm	2023-04-28	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Requirements for uncertainty are specified at 2-sigma.	Values given for uncertainty and stability are for shortwave radiation. A factor of two is considered for longwave radiation
1001	Solar spectral irradiance		2.5 Atmospheric Climate Monitoring	0.5							Global	firm	2023-05-03	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Refer to GCOS Publication (GOS-245) for spectral resolution
1002	Cloud top height		2.5 Atmospheric Climate Monitoring	0.5	0.3 km 0.6 km 1.2 km 0.5	0.03 km 0.06 km 0.12 km 0.5	25 km 100 km 500 km 0.5		60 min 24 h 30 d 0.5	60 min 3 h 12 h 0.5	Global	firm	2023-04-27	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Requirements for uncertainty are specified at 2-sigma.
1003	Accumulated precipitation	Near Surface	2.5 Atmospheric Climate Monitoring	0.5	1 mm 2 mm 5 mm 0.5	0.02 mm 0.05 mm 0.1 mm 0.5	50 km 125 km 250 km 0.5		24 h 30 d 1 y 0.5	24 h 7 d 30 d 0.5	Global	firm	2023-05-02	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Requirements for uncertainty are specified at 2-sigma.	Temporal Resolution: For goal: daily aggregation over period which defines the upper limit of temporal sampling For breakthrough: monthly aggregation over period which defines the upper limit of temporal sampling For threshold: aggregation over period which defines the upper limit of temporal sampling
1010	O3 mole fraction	FT	2.5 Atmospheric Climate Monitoring	0.5	2 % 5 % 10 % 0.5	1 % 2 % 3 % 0.5	1 km 20 km 100 km 0.5	1000 m 3000 m 5000 m 0.5	60 min 6 h 30 d 0.5	60 min 24 h 30 d 0.5	Global	firm	2023-05-03	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Requirements for uncertainty are at 2-sigma	Goal for uncertainty less than 1%
1012	O3 mole fraction	UTLS	2.5 Atmospheric Climate Monitoring	0.5	2 % 5 % 10 % 0.5	1 % 2 % 3 % 0.5	10 km 50 km 200 km 0.5	500 m 1000 m 3000 m 0.5	6 h 24 h 30 d 0.5	6 h 24 h 30 d 0.5	Global	firm	2023-05-03	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Requirements for uncertainty at 2-sigma
1013	O3 mole fraction	MUS	2.5 Atmospheric Climate Monitoring	0.5	5 % 10 % 15 % 0.5	1 % 2 % 3 % 0.5	20 km 100 km 500 km 0.5	1000 m 3000 m 10000 m 0.5	6 h 24 h 30 d 0.5	4 h 24 h 30 d 0.5	Global	firm	2023-05-03	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Requirements for uncertainty at 2-sigma
1014	O3 Tropospheric Column	TrC	2.5 Atmospheric Climate Monitoring	0.5	5 % 10 % 15 % 0.5	1 %/decade 2 %/decade 3 %/decade 0.5	5 km 20 km 100 km 0.5		60 min 6 h 30 d 0.5	60 min 24 h 30 d 0.5	Global	firm	2023-05-03	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Requirements for uncertainty are at 2-sigma
1015	O3 Stratospheric Column		2.5 Atmospheric Climate Monitoring	0.5	1 % 3 % 5 % 0.5	1 %/dacade 2 %/dacade 3 %/dacade 0.5	20 km 100 km 500 km 0.5		60 min 24 h 30 d 0.5	6 h 24 h 30 d 0.5	Global	firm	2023-05-03	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Requirements for uncertainty at 2-sigma
1016	Atmospheric temperature	FT	2.5 Atmospheric Climate Monitoring	0.5	0.1 K 0.5 K 1 K 0.5	0.01 K 0.02 K 0.05 K 0.5	15 km 100 km 1000 km 0.5	0.01 km 0.1 km 1 km 0.5	60 min 12 h 24 h 0.5	60 min 3 h 6 h 0.5	Global	firm	2023-05-05	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Requirements for uncertainty are at 2-sigma
1017	Wind (horizontal)	MUS M	2.5 Atmospheric Climate Monitoring	0.5	1 m.s^-1 5 m.s^-1 10 m.s^-1 0.5	0.1 m.s^-1 0.5 m.s^-1 1 m.s^-1 0.5	50 km 100 km 3000 km 0.5	1 km 2 km 3 km 0.5	60 min 6 h 24 h 0.5	6 h 18 h 2 d 0.5	Global	firm	2023-05-05	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Requirements for uncertainty are specified at 2-sigma
1079	Air Thickness	TC	2.5 Atmospheric Climate Monitoring	0.5							Global	reasonable	2024-08-22	J van der Meulen	required for Actinometric data
1130	Specific humidity	PBL	2.5 Atmospheric Climate Monitoring	0.5	0.1 g kg^-1 0.5 g kg^-1 1 g kg^-1 0.5	0.01 g kg^-1 0.05 g kg^-1 0.1 g kg^-1 0.5	15 km 100 km 500 km 0.5	0.001 km 0.01 km 0.1 km 0.5	50 min 60 min 3 h 0.5	60 min 5 d 30 d 0.5	Global	firm	2025-04-11	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Uncertainty at 2 sigma
1132	Specific humidity	FT	2.5 Atmospheric Climate Monitoring	0.5	0.1 g kg^-1 0.5 g kg^-1 1 g kg^-1 0.5	0.01 g kg^-1 0.05 g kg^-1 0.1 g kg^-1 0.5	15 km 100 km 1000 km 0.5	0.01 km 0.1 km 1 km 0.5	57 min 60 min 3 h 0.5	60 min 5 d 30 d 0.5	Global	firm	2025-04-11	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	uncertainty at 2 sigma
1133	Water Vapour Mixing Ratio	UTLS	2.5 Atmospheric Climate Monitoring	0.5	0.1 ppmv 0.25 ppmv 0.5 ppmv 0.5	0.09 ppmv 0.1 ppmv 0.25 ppmv 0.5	15 km 100 km 500 km 0.5	10 m 10 m 250 m 0.5	3 h 6 h 24 h 0.5	60 min 5 d 30 d 0.5	Global	firm	2025-04-11	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	uncertainty at 2-sigma
1134	Water Vapour Mixing Ratio	MUS	2.5 Atmospheric Climate Monitoring	0.5	0.1 ppmv 0.25 ppmv 0.5 ppmv 0.5	0.19 ppmv 0.2 ppmv 0.5 ppmv 0.5	50 km 500 km 1500 km 0.5	500 m 1000 m 3000 m 0.5	3 h 6 h 3 d 0.5	60 min 7 d 30 d 0.5	Global	firm	2025-04-11	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	uncertainty at 2-sigma
1135	Schumann Resonances		2.5 Atmospheric Climate Monitoring	0.5	1 fT² Hz^-1 5 fT² Hz^-1	1 pT² Hz^-1 5 pT² Hz^-1			60 min 24 h 30 d 0.5	24 h 30 d	Global	firm	2025-04-11	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	One value represents the globe, so no horizontal or vertical resolution required
1136	CO mole fraction		2.5 Atmospheric Climate Monitoring	0.5	1 ppb 5 ppb 10 ppb 0.5	0.9 ppb 1 ppb 3 ppb 0.5	10 km 30 km 100 km 0.5	1 m 3 m 5 m 0.5	60 min 24 h 30 d 0.5	24 h 7 d 30 d 0.5	Global	firm	2025-04-11	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	uncertainty at 2-sigma
1137	SO2 Stratospheric Column		2.5 Atmospheric Climate Monitoring	0.5			10 km 30 km 100 km 0.5		60 min 24 h 30 d 0.5	24 h 7 d 30 d 0.5	Global	firm	2025-04-11	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Uncertainty and stability are in notes	Uncertainty: Goal max(30%,6E15) Breakthrough: max(60%,12E15) Threshold: max(100%,20E15) Stability: Goal max(10%,3E15) Breakthrough: max(20%,4E15) Threshold: max(30%,7E15)
1138	NO2 Mole fraction		2.5 Atmospheric Climate Monitoring	0.5	20 % 40 % 60 % 0.5	4 % 8 % 12 % 0.5	20 km 100 km 500 km 0.5	1 km 3 km 5 km 0.5	6 d 24 h 30 d 0.5	24 h 7 d 30 d 0.5	Global	firm	2025-04-11	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	uncertainty in 2-sigma
1139	Aerosol Light Extinction Vertical Profile		2.5 Atmospheric Climate Monitoring	0.5	20 % 40 % 60 % 0.5	10 % 20 % 30 % 0.5	50 km 100 km 500 km 0.5	0.2 km 1 km 2 km 0.5	24 h 30 d 90 d 0.5	26 h 29 d 1 y 0.5	Global	firm	2025-04-15	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	Values specified here are for troposphere Values in stratosphere specified in GCOS-245 Uncertainty at 2-sigma
1140	Multi-wavelength Aerosol Optical Depth		2.5 Atmospheric Climate Monitoring	0.5	4 % 10 % 20 % 0.5	2 % 4 % 10 % 0.5	20 km 100 km 500 km 0.5		14 min 24 h 30 d 0.5	24 h 7 d 30 d 0.5	Global	firm	2025-04-15	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	uncertainty at 2-sigma. For uncertainty in AOD see GCOS-245
1141	Chemical Composition of Aerosol Particles		2.5 Atmospheric Climate Monitoring	0.5	20 μg m^-3 40 μg m^-3 60 μg m^-3 0.5	2 % 2 % 4 % 0.5	50 km 100 km 500 km 0.5	1 km 5 km	24 h 30 d 90 d 0.5	2 h 24 h 1 y 0.5	Global	firm	2025-04-15	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	uncertainty at 2-sigma
1142	Number of Cloud Condensation Nuclei		2.5 Atmospheric Climate Monitoring	0.5	20 % 40 % 60 % 0.5		50 km 100 km 500 km 0.5	1 km 5 km	12 h 24 h 30 d 0.5	58 min 24 h 1 y 0.5	Global	firm	2025-04-15	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	uncertainty at 2-sigma stability: difficult to evaluate as no trend in CNN are currently available
1143	Aerosol Number Size Distribution		2.5 Atmospheric Climate Monitoring	0.5		2 4 10 0.5	50 km 100 km 500 km 0.5	1 km 5 km	58 min 24 h 30 d 0.5	6 h 30 d 1 y 0.5	Global	firm	2025-04-15	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	uncertainty at 2 sigma Uncertainty: 40% in number and 20% in size 60% in number and 40% in size 40% in number for fine-mode and 100% in number for coarse
1144	Aerosol single-scattering albedo		2.5 Atmospheric Climate Monitoring	0.5	0.1 % 0.2 % 0.4 % 0.5	0.1 dimensionless 0.4 dimensionless 1 dimensionless 0.5	50 km 200 km 500 km 0.5	1 km 5 km	14 min 24 h 30 d 0.5	24 h 7 d 30 d 0.5	Global	firm	2025-04-15	GCOS-245: The 2022 ECVs Requirements (GCOS-245)	uncertainty at 2-sigma