July 2021

With the launch of ESA's Sentinel-5P satellite in 2017, it is now possible to monitor global atmospheric pollution on a daily basis, such as tropospheric concentrations of nitrogen dioxide, carbon monoxide, ozone, methane, sulphur dioxide, and formaldehyde. Taking advantage of this data, it is possible to produce temporal trends of pollution in cities and industrial areas, which can be used to understand movements of polluted air and possible risks for the population.

As part of the Copernicus programme the European Space Agency has been developing Sentinels, a family of satellites designed for Earth observation which focus on different types of data:

With more recent Sentinel satellites focusing on atmospheric monitoring to support efforts in improving our environment, we share how Sentinel-5P (the precursor mission dedicated to monitoring the atmosphere) data can be used for pollution monitoring.

Sentinel-5P Data

Nitrogen dioxide (NO2) is a common pollutant from the consumption of fossil fuels, and so it is typically found in large concentrations over industrial areas and cities, particularly those with dense car traffic. NO2 is related to respiratory issues such as asthma, and can create ozone, which can make respiratory conditions worse. Of special interest is NO2 concentrations in cities and areas of lower socio-economic status, where high density traffic and low quality heating (gas stoves) can produce large concentrations of NO2.

In this case study, we show the temporal changes of NO2 over the UK from January 2020 to January 2021 from data observed by the Sentinel-5P satellite. The relevance of this data is seen in the following two images. The first one corresponds to NO2 the same day the COVID-19 lockdown legally came into force for the UK, and the second image shows NO2 three days later, at approximately the same time of the day. The absence of NO2 clusters three days after lockdown shows the dramatic and immediate impact of stopping most industrial and social activities.

The image below shows a NO2 temporal series over the UK over a period of one year, where it can be seen that the Uk's largest cities - London, Liverpool, and Manchester - form the main clusters of NO2. The geographical spread of pollution, particularly on some days in the sequence, highlights the wide impact that local pollution can rapidly produce, and the relevance of this type of imaging for pollution monitoring.

D-CAT's unique set of capabilities allows us to ingest, process and add value to Sentinel data. Taking advantage of our cloud-based Fusion Platform®, we have processed Sentinel-5P NO2 products over the UK over extended periods of time. Extraction of this data is non-trivial, and requires specialist conversion into a useable format, which in this case includes gas concentration, pixel quality, units, time of acquisition and conversion factors, amongst other data.


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