Sentinel-5P Mission Overview
In the Copernicus programme, the Sentinel-4, Sentinel-5, and Sentinel-5 Precursor satellite missions are designated to address air quality, the protection of the ozone layer and climate change as important environmental challenges. Sentinel-5P has been the first of these satellites that was launched. Sentinel-5 and Sentinel-5P are polar orbiters and provide global air quality observations until ~2040, while Sentinel-4 will be in a geoynchronous orbit and is expected to provide hourly daytime observations over Europe, Africa, and the Atlantic Ocean on-board the Meteosat Third Generation Sounder (MTG-S) satellites during 2025-2045. Sentinel-5P was launched on 13 October 2017 and has a designed mission lifetime of ~7 years. Sentinel-5P’s payload is the Tropospheric Monitoring Instrument (TROPOMI, Veefkind et al., 2012). Although Sentinel-5P is a precursor to Sentinel-5, TROPOMI will achieve the majority of the Sentinel-5 observational requirements.
Sentinel-5P’s mission objective is to provide accurate and timely observations of key atmospheric species, for services on air quality, climate, and the ozone layer. These daily global Sentinel-5P observations are used to improve air quality forecasts and to monitor the atmospheric constituents’ concentrations over multiple years. Trend monitoring is very important to verify the effectiveness of implemented atmospheric emission control measures. In addition, the mission contributes to services, such as volcanic ash monitoring for aviation safety, service warnings of high UV radiation levels to the general public, and for numerical weather prediction. Scientists use the Sentinel-5P data to improve knowledge of important chemical and dynamical atmospheric processes and to address the following science questions:
- constrain the strength, evolution, and spatiotemporal variability of trace gas and aerosol sources that impact air quality and climate
- climate forcing attribution through better understanding of lifetime and distribution of methane, tropospheric ozone, and aerosol processes
- to better estimate long-term trends in the troposphere related to air quality and climate from the regional to the global scale
- to improve air quality model processes and data assimilation in support of operational services, including air quality forecasting and protocol monitoring
Tropospheric Ozone Monitoring Instrument (TROPOMI)
TROPOMI measures the reflected solar light in the ultraviolet (UV) and visible (270–500 nm), near-infrared (675–775 nm), and shortwave infrared (2305–2385 nm) spectral bands. The spectral resolution is 0.25–1.0 nm (SWIR-UV). With a nadir spatial resolution of 5.5 \(\times\) 3.5 km2 it has the potential to detect air pollution at sub-urban scale. This resolution is considerably finer than its predecessor, the Ozone Monitoring Instrument (OMI), which has a pixel size of around 24 \(\times\) 13 km2, and much smaller than the Global Ozone Monitoring Experiment-2 (GOME-2, 80 \(\times\) 40 km2) and Scanning Imaging Absorption Spectrometer for Atmospheric Cartography (SCIAMACHY, 200 \(\times\) 30 km2).
Daily global coverage is ensured by a 2,600 km swath width, which means that significantly more observations are available to scientists (around 20 times more observations than OMI).
Figure 1 shows the Sentinel-5P flight concept and TROPOMI’s measurement principle, while Figure 2 presents TROPOMI’s spectral bands and the data products. Both figures are taken from Veefkind et al. (2012). The OMI, GOME-2, and SCIAMACHY spectral bands are included for reference.
Figure 1: TROPOMI measurement principle. The dark-gray ground pixel is imaged on the two-dimensional detector as a spectrum. All ground pixels in the 2,600 km wide swath are measured simultaneously. From Veefkind et al. (2012).
Figure 2: TROPOMI spectral ranges and those of the heritage instruments OMI, SCIAMACHY, and GOME. From Veefkind et al. (2012).
More information on the Sentinel-5P Data Products can be found here.