What Makes TROPOMI Special?

News - 11 October 2017

TROPOMI and Sentinel-5P are part of a larger family of satellite missions. So why is Friday’s launch so exciting?

1. The First Atmospheric Mission
Sentinel-5P is the first Copernicus mission dedicated to observing the atmosphere. Previous missions Sentinels-1 to 3 are specified for the land and ocean surface. With TROPOMI on board, Sentinel-5P will monitor gases and particles in our atmosphere that affect climate change and air quality.

2. More and Better Measurements
Following OMI, the push broom spectrometer of TROPOMI has an increased number of spectral bands, allowing it to measure in the longer wavelengths, and therefore, can directly have access to more atmospheric gases. While OMI measures between 270 to 500 nm (UV and visible), TROPOMI will also measure in the near infrared (675–775 nm) and shortwave infrared (2305–2385 nm). With this extended range, TROPOMI can observe the greenhouse gas methane (CH4) as well as carbon monoxide (CO) in addition to ozone (O3), nitrogen dioxide (NO2), sulphur dioxide (SO2), formaldehyde (HCHO) etc. already measured by OMI. TROPOMI will also have better signal to noise ratio than OMI (better measurement quality) as well as improved ability to detect clouds and fine particles (aerosols) and their altitude. 

Spectral ranges for TROPOMI and the heritage instruments OMI, SCIAMACHY and GOME (Veefkind et al., 2012).

3. Seeing on City Scales

TROPOMI will have a pixel size of roughly 7 km x 3 km. This is considerably
smaller than its predecessor, OMI, which has a pixel size of around 24 km x 13 km, and certainly much smaller than GOME2 (80 km x 40 km) and SCIAMACHY (200 km x 30 km). The smaller pixel size means we can begin to resolve air quality on the scale of cities. At such fine resolution, we will be able to get a better idea of regional air quality variability, as well as the different sources of pollutants in our atmosphere. This also means a significant higher number of measurements to be delivered to scientists: while OMI acquires approximately 1 million spectra per day, TROPOMI will deliver around 20 times more! With TROPOMI, we then open a new era of challenges regarding big data and the processing capability.

The TROPOMI instrument has a pixel size of around 7 km x 3 km, allowing us to see on city scales, and much finer resolutions than its predecessors.

The smaller pixel doesn’t mean less coverage of the Earth, though. With a swath width of 2700 km, it provides global coverage every day.

Further Reading:

  1. TROPOMI Fact Sheet
  2. Veefkind et al. (2012)
    Veefkind, J. P., Aben, E. A. A., McMullan, K., Forster, H., de Vries, J., Otter, G., … Visser, H.: TROPOMI on the ESA Sentinel-5 Precursor: A GMES mission for global observations of the atmospheric composition for climate, air quality and ozone layer applications. Remote Sensing of Environment, 120(SI), 70-83. DOI: 10.1016/j.rse.2011.09.027, 2012.