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How is aerosol depth calculated?
I(λ) = I0(λ)exp(-m(θ)*τ(λ)) Here, AOD is calculated at wavelengths of 368, 412, 500 and 862 nm as recommended by the World Climate Research Programme (WCRP) in a technical report (WCRP (1986)) in Tsukuba.
What does an optical depth of 1 mean?
Instead of using. physical distance (vertical or horizontal), we rescale to a dimensionless coordinate, where optical depth = 1 means that only e-1 = 0.368 of the energy is passed without being extincted (absorbed or scattered) in passing through one unit of optical depth.
How do you measure optical thickness?
Firstly, optical techniques work basically by locating the physical surfaces of the strip to be measured, so that the measurement is of actual thickness and is not modified by the internal composition of the material.
What is the unit of optical depth?
Optical depth is dimensionless, and in particular is not a length, though it is a monotonically increasing function of optical path length, and approaches zero as the path length approaches zero. The use of the term “optical density” for optical depth is discouraged.
What is aerosol optical thickness?
Aerosol Optical Depth (AOD) is the measure of aerosols (e.g., urban haze, smoke. particles, desert dust, sea salt) distributed within a column of air from the instrument. (Earth’s surface) to the top of the atmosphere.
What is the definition of aerosol optical depth?
The product is a measure of the solid and/or liquid particles suspended in the air including dust, sand, volcanic ash, smoke, and urban/industrial aerosols. The aerosol optical depth (AOD) measures the amount of light lost due to the presence of aerosols on a vertical path through the atmosphere.
How is the AOD of an aerosol measured?
The aerosol optical depth (AOD) measures the amount of light lost due to the presence of aerosols on a vertical path through the atmosphere. More formally the AOD is the extinction (scattering + absorption) vertical optical thickness of aerosols.
Where can I find aerosol optical thickness data?
The NEO site provides processed aerosol optical thickness data from the MODIS sensor in graphical and text formats from January 2005 to present. The data is available as JPEG, PNG, GeoTiff, GoogleEarth, and CSV formats.
What does the thickness of aerosols in the sky mean?
“Aerosol Optical Thickness is the degree to which aerosols prevent the transmission of light” in the atmoshpere. 1 “An aerosol optical thickness of less than 0.1 indicates a crystal clear sky with maximum visibility, whereas a value of 4 indicates the presence of aerosols so dense that people would have difficulty seeing the Sun, even at mid-day!”