Other Names

Aerosol Absorbing Index, Aerosol Absorbing Indicator, AI, AAI

Definition

It is an index that detects the presence of uv-absorbing aerosols such as dust and soot.

TOMS Aerosol index (AI) is based on a spectral contrast method in a UV region where the ozone absorption is very small. It is the difference between the observations and model calculations of absorbing and non absorbing spectral radiance ratios. For TOMS, AI is defined as

AI = 100   [ log₁₀ (I₃₆₀/I₃₃₁)_measured - log₁₀ (I₃₆₀/I₃₃₁)_calculated]

Positive values of Aerosol Index generally represent absorbing aerosols (dust and smoke) while small or negative values represent nonabsorbing aerosols and clouds. The Index can be interpreted in terms of optical depth if the index of refraction, particle size distribution, and the height of the aerosol layer are known from other measurements.

GOME (ERS-2) defines similar index called Absorbing Aerosols Indicator (AAI). Following TOMS AI definition GOME AAI also uses two wavelength intervals around 340 nm and 380 nm.

However, POLDER on ADEOS-1 & 2 define Aerosol Index (for small size particles) as the product of the retrieved aerosol optical thickness and Angstrom exponent.

Applications

(1) Atmospheric correction of remotely sensed surface features	(5) Air Quality
(2) Monitoring of sources and sinks of aerosols	(6) Health and Environment
(3) Monitoring of volcanic eruptions and forest fire	(7) Earth Radiation Budget
(4) Radiative Transfer Model	(8) Climate Change

GES DISC Datasets

Quick Search for 'Aerosol Index' with Mirador
Click on the corresponding 'WHOM access' links in the table below to access products containing specific parameter.

Parameter	Units	Platform /Instrument	Data
			Begin Date	End Date	WHOM Access	Doc
Aerosol Index over land and ocean at ground pixel resolution	None	Aura/OMI	2004-08-15	Current	OMTO3.003	Y
		Earth Probe/TOMS	1996-07-25	2005-12-31	TOMSEPL2	Y
		Nimbus-7/TOMS	1978-11-01	1993-05-06	TOMSN7L2	Y
Aerosol Index over land and ocean at ground pixel resolution global gridded (0.25 deg lat/lon grid)	None	Aura/OMI	2004-08-15	Current	OMTO3G.003	Y
Daily means of Aerosol Index over land and ocean, global gridded (~1 x 1.25 deg grids)	None	Earth Probe/TOMS	1996-07-25	2005-12-31	TOMSEPL3	Y
		Nimbus-7/TOMS	1978-11-01	1993-05-06	TOMSN7L3	Y
		Aura/OMI	2004-08-15	Current	OMTO3D.003	Y
					OMTO3e.003	Y

Other sources for data

1. POLDER (ADEOS) 2. GOME (ERS-2) 3. SCIAMACHY(Envisat)