Nitrogen Dioxide is one of the atmospheric gas species retrieved from the data acquired by Sentinel-5P multispectral imaging spectrometer: TROPOMI. Sentinel-5P is the umpteenth spacecraft belonging the the Sentinels constellations and conceived in the framework of the Copernicus Programme. The main goal of this mission is to perform atmospheric measurements with high spatio-temporal resolution, to be used for air quality, ozone & UV radiation, and climate monitoring & forecasting [2].

Nitrogen Dioxide is present in both the troposphere and the stratosphere as a result of anthropogenic activities (like fossil fuel combustion and biomass burning) and natural processes (such as microbiological processes in soils, wildfires and lightning) [1], thus is really useful to identify polluted regions around the World. In this respect Earth Starts Beating started to exploit Sentine-5P nitrogen dioxide data, with the aim to generate L3 monthly world map elaborating all the data acquired in a single month. The final goal is to show the NO2 tropospheric distribution around the world and its evolution during the years.

The image above has been generated considering all the data acquired in July 2018 where the NO2 is expressed in umol/m^2. High values are observed in the regions wrapping the main cities and urban areas, even if that month the highest peaks seem to be located in Africa: the central part of the continent is indeed systematically impacted by a lot of wildfires [4] in July (each year), whereas the area near Johannesburg and Pretoria (SA) is one of the most polluted region in the world, also because of the coal mines and coal-fired power stations in Mpumalanga [5&6].

By the way the NO2 distribution change as the months went by, as we can see thanks the L3 map below processed taking in input all the acquisition of March 2019, where the highest peaks are observed in China. Nitrogen oxides are one the main pollutants from the ship’s emissions too [7]: the trails all over the seas and oceans are really clear having a look on the map below, thus highlighting the major shipping routes (e.g Mediterranean Sea, Indian Ocean).

All the used data have been filtered considering the indications about the data quality described into the Nitrogen Dioxide Product Readme File [3]. Global L3 Map are systematically published and updated via the Earth Starts Beating viewer (based on Worldwind technology), where is possible to scroll along time series of data:

http://51.38.225.223/earthstartsbeating/

All the images contains Copernicus modified data. Input products, processors and services allowing the publishing of the images via internet are installed, operated and maintained in the ONDA DIAS cloud infrastructure.

Contains modified Copernicus Sentinel data 2019.

References:

[1] http://www.tropomi.eu/data-products/nitrogen-dioxide

[2] https://sentinels.copernicus.eu/web/sentinel/missions/sentinel-5p

[3] https://sentinel.esa.int/documents/247904/3541451/Sentinel-5P-Nitrogen-Dioxide-Level-2-Product-Readme-File

[4] https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2005JG000142

[5] https://www.businesslive.co.za/bd/national/2018-10-29-the-worlds-worst-nitrogen-dioxide-air-pollution-is-in-sa/

[6] https://mg.co.za/article/2018-10-30-mpumalanga-tops-world-nitrogen-dioxide-air-pollution-charts

[7] https://www.transportenvironment.org/what-we-do/shipping/air-pollution-ships