How is contamination identified by satellites?

Pollution is a problem which we have been working to combat during the last decades. This can occur at atmospheric, light, water and thermal levels, among others, and directly affects human beings, as well as the ecosystems and animals that inhabit them. 

In order to monitor pollution levels, a series of devices have been placed in strategic locations at different heights through towers and above sea level by means of buoys. These devices usually have a sensor that measures a specific parameter and provides data on pollution levels based on these detection parameters.

However, they are not the only devices available to measure pollution levels. There are currently more than 150 Earth observation satellites in orbit, carrying sensors that measure different sections of the visible, infrared and microwave regions of the electromagnetic spectrum. Many of these satellites carry passive sensors that measure both reflected solar radiation and thermal energy emitted from the Earth’s surface or atmosphere. Others also employ active sensors, which emit energy and record the reflected or backscattered response, from which information about the Earth can be inferred.

Sensors inside satellites provide a repeatable view that allows monitoring and analysis of the effect of human activities on the environment.  This vision allows us to constantly evaluate the environment and global changes in terms of atmospheric quality, atmospheric ozone depletion, deforestation levels, global warming, contamination of water bodies, among others; and on the other hand, open-pit mining and possible hydrocarbon spills or natural gas leaks at extraction sites.

The data and images taken by satellites are processed by means of scripts, in other words, codes or algorithms that can be executed on the received data and that can be implemented by means of an interpreter, directly in some digital platforms for the identification, measurement and characterization of objects. Different bands of the electromagnetic spectrum or indices can be mixed through them, in order to visualize a specific object. In water observation bodies, variables such as water turbidity, chlorophyll levels in the water body, contamination by plastics, hydrocarbons, among others, can be identified.

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