Aerosols

	Atmospheric aerosols are minor constituents of the atmosphere by mass, but a critical component in terms of impacts on the climate and especially climate changes. Aerosols influence the global radiation balance by directly scattering solar radiation and indirectly through influencing cloud reflectivity, cloud cover and cloud lifetime.
	Domain:	Atmosphere
	Subdomain:	Atmospheric Composition
	Scientific Area:	Physical Properties
	ECV Steward:
	Products:	Aerosol Light Extinction Vertical Profile (Troposphere), Aerosol Light Extinction Vertical Profile (Stratosphere), Multi-wavelength Aerosol Optical Depth, Aerosol Single Scattering Albedo, Chemical Composition of Aerosol Particles, Number of Cloud Condensation Nuclei, Aerosol Number Size Distribution

ECV Products and Requirements

These products and requirements reflect the Implementation Plan 2022 (GCOS-244).

The requirements are found in the complete 2022 ECVs Requirements document as well: ECV Aerosols.

Products			Aerosol Light Extinction Vertical Profile (Troposphere)	Aerosol Light Extinction Vertical Profile (Stratosphere)		Multi-wavelength Aerosol Optical Depth		Aerosol Single Scattering Albedo
	(*)	Unit	Values	Values	Unit	Values	Unit	Values
Horizontal Resolution	G	km	50	200	km	20	km	50
	B		100	500 (lat.) x 6000 (long.)		100		200
	T		500			500		500
Vertical Resolution	G	km	0.2	1		-	km	1
	B		1	1 (2)		-		5
	T		2	2		-
Temporal Resolution	G	d	1	5	d	0.01	d	0.01
	B		30	5		1		1
	T		90	30		30		30
Timeliness	G	y	0,003		d	1	d	1
	B		0.08			7		7
	T		1	1		30		30
Required Measurement Uncertainty (2-sigma)	G	%	20	20	% or AOD	4% or 0.02	dimensionless	0.1
	B		40	40		10% or 0.030		0.2
	T		60			20% or 0.06		0.4
Stability	G	%/decade	10	20	%/ decade or AOD/ decade	2% or 0.01	%/decade	0.1
	B		20	40		4% or 0.02		0.4
	T		30			10% or 0.04		1

Products			Chemical Composition of Aerosol Particles	Number of Cloud Condensation Nuclei	Aerosol Number Size Distribution
	(*)	Unit	Values	Values	Values
Horizontal Resolution	G	km	50	50	50
	B		100	100	100
	T		500	500	500
Vertical Resolution	G	km	1	1	1
	B		5	5	5
	T
Temporal Resolution	G	d	1	0.5	0.04
	B		30	1	1
	T		90	30	30
Timeliness	G	d	0.1	0.04	0.25
	B		1	1	30
	T		365	365	365
Required Measurement Uncertainty (2-sigma)	G	%	20	20	40% in number and 20% on size
	B		40	40	60% in number in 40% in size
	T		60	60	40% in number for fine- mode (0.05-0.5um) and 100% in number for coarse- mode (0.5-15um)
Stability	G	%/decade	2	-	2
	B		2	-	4
	T		4	-	10

(*) Goal (G): an ideal requirement above which further improvements are not necessary. Breakthrough (B): an intermediate level between threshold and goal which, if achieved, would result in a significant improvement for the targeted application. The breakthrough value may also indicate the level at which specified uses within climate monitoring become possible. It may be appropriate to have different breakthrough values for different uses. Threshold (T): the minimum requirement to be met to ensure that data are useful

Data Sources

This list provides sources for openly accessible data sets with worldwide coverage for which metadata is available. It is curated by the respective GCOS ECV Steward(s). The list does not claim to be complete. Anyone with a suitable dataset who wishes it to be added to this list should contact the GCOS Secretariat.