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:
- Sentinel-1. Radar imaging for land and ocean services. These 2 satellites can provide images during night and day and independent of weather conditions.
- Sentinel-2. Two optical multispectral imaging with high resolution (10m) designed to provide land services such as vegetation monitoring, soil cover, and inland water bodies monitoring.
- Sentinel-3. Optical multispectral imaging for ocean and land. These 2 satellites have a lower resolution than Sentinel-2, but larger coverage and frequency. They provides products such as total suspended matter concentration on the ocean, photosynthetically active radiation on the ocean, terrestrial chlorophyll index, sea and land surface temperature, land altimetry, snow density and depth, and ocean depth.
- Sentinel-4 (scheduled for 2023), Sentinel-5p, and Sentinel-5 (scheduled for 2021). These are designed for atmospheric composition monitoring. Sentinel-5p provides high-temporal imagery of atmospheric gases such as nitrogen dioxide, carbon monoxide, ozone, methane, formaldehyde, and aerosols.
- Sentinel-6. Provides high precision altimetry sea level measurements.
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.
Benefits
By using this service clients:
- Have access to daily atmospheric pollutant data over any area worldwide.
- Have access to air quality monitoring tools at nationwide scales, allowing decision-making and with evidence to assist in the development of policies to curb pollution.
- Can monitor the temporal evolution of pollution events such as volcanic eruptions, and leaks in large gas pipes.
- Can study historical trends of pollution from urban and industrial areas.
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