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Sentinel-5P TROPOMI: the first atmospheric Sentinel

Research Topic Chapter
News flash intro
On October 13, 2017, ESA launched Sentinel-5 Precursor (S5P), the first mission dedicated to atmospheric composition in the series of Sentinel missions, as part of the European program for Earth Observation, Copernicus. On board, the instrument TROPOMI measures atmospheric composition data, relaying the information in near-real time. BIRA-IASB has played a key role developing some of the TROPOMI level-2 algorithms, managing the operational validation service, and contributing to the scientific data exploitation.
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Sentinel-5p Ramp-up in the Copernicus World

The Sentinel-5p mission (“p” stands for Precursor) is part of the European Earth Observation programme Copernicus, of which the space component is developed by the European Space Agency (ESA). After the successful lift-off of several Sentinel satellites for the global monitoring of lands, ice and oceans, Sentinel-5p was launched on October 13, 2017, as the precursor of the three Sentinel-5 atmospheric composition satellites that will be launched in the 2021-2035 timeframe, providing all together continuous monitoring nominally until 2042.

Aboard, Sentinel-5p carries the TROPOMI instrument, which measures daily, on the global scale and at the unprecedented horizontal resolution of 7 x 3.5 km2, atmospheric composition data related to:

  • air quality
  • ozone
  • climate change
  • volcanic hazards.

The outstanding performances of TROPOMI enable more detailed than ever detection of pollution emitters at city level, of small-scale atmospheric effects on regional climate change, and of aviation hazards due to volcanic eruptions. Not only its remarkable capabilities but also the operational vocation of the Copernicus programme raise several challenges that have been addressed step by step in the so-called ramp-up phase of the mission.

Data and Algorithms

Developed partly at BIRA-IASB, the data processors and quality assurance systems for TROPOMI rely on several heritage missions like GOME, SCIAMACHY and GOME-2.  

In recent years, those processors and systems have been updated to respond to more and more stringent requirements.  Special care has been given to the operationalization of the heritage systems conceived initially for off-line scientific exploration of data acquired by lower resolution satellites, thus at much lower data rates.  During the ongoing ramp-up of TROPOMI, several data products have reached operational production:

  • O3
  • NO2
  • HCHO
  • SO2
  • CO
  • clouds
  • aerosols

Other data products like CH4 will follow in 2019.

Confidence in Uncertainties

Without proper quality assessment and uncertainty estimates, no data should be used, and especially for any new generation measurement system intended to provide quality verified information to public authorities and policy makers.

Therefore, in collaboration with ESA and worldwide partners, BIRA-IASB has set up a comprehensive validation programme, consisting of an automated validation facility monitoring routinely the performance of operational TROPOMI data products, complemented by a range of in-depth validation studies carried out by independent scientists.

Ground-based measurements from global monitoring networks and data from other satellites serve as independent references. Dedicated model simulations enhanced by inverse modelling offer complementary insights. Altogether, routine operations validation and in-depth studies provide the necessary uncertainty estimates and elaborate recommendations for further Sentinel-5p algorithm and product evolution.

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Figure 1. Artist view of the Sentinel-5p satellite and its payload, the TROPOMI instrument. ©Image credit ESA 2017.
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Figure 2. Typical architecture of an operational satellite data processor. ©Image credit BIRA-IASB 2017.
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