In this video Dr Andreas Richter from the University of Bremen explains how satellites are used to collect data on atmospheric pollution and aerosols, and the challenges involved.

As we mentioned in Week 2, smoke can be tracked in the atmosphere along with other particles including dust and pollution. These aerosols in the atmosphere can reduce the amount of sunlight reaching the ground and can affect air quality at ground level. Most aerosols reflect sunlight having a slightly cooling effect on the Earth’s atmosphere, but soot – also known as black carbon – traps heat and contributes to the greenhouse effect. Aerosols also act to encourage cloud formation, as cool water vapour in the atmosphere needs something to condense around. For example, particulate matter from ships’ exhausts stimulates cloud formation revealing shipping tracks .

Clouds reflect sunlight well, making them obvious (and often an unwelcome addition) in satellite imagery. Their net effect on the temperature of the atmosphere varies, depending on their height, thickness and persistence.

Aerosol Optical Depths (the effective capacity of the atmosphere to absorb light passing through it i.e. how opaque the atmosphere is, clear atmosphere has a low AOD; dusty or hazy atmosphere has a high AOD) can be calculated using optical wavelength measurements, although some thermal observations can also be added to refine the measurement. This can help where aerosols are not distinct in visible wavelengths, such as over bright surfaces.

A combination of observations and modelling of aerosol distribution has taught us more about circulation patterns in the atmosphere all over the world. Near-infrared wavelengths are used by a range of different instruments to track aerosols .

Featured Educators:

• Dr Andreas Richter

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Don’t forget you can download the video, transcript and take any quizzes available with the links on the right.