Sentinel-4

Sentinel-4 covers the need for continuous monitoring of atmospheric composition. The mission will focus on air quality, with the main data products being ozone (O₃), nitrogen dioxide (NO₂), sulphur dioxide (SO₂), formaldehyde (HCHO) and aerosol optical depth.

The instruments used for the Sentinel-4 mission will be carried on Meteosat Third Generation satellites. The Sentinel-4 mission is made up of the Ultraviolet Visible Near-infrared (UVN) spectrometer and data from the Infrared Sounder (IRS), both on the MTG-Sounder (MTG-S) satellite.

The InfraRed Sounder will operate in synergy with the UVN spectrometer, to provide a unique, integrated capability to observe ozone, carbon monoxide, sulphur dioxide and other trace gases, in support of air quality, pollution and climate monitoring.

UVN characteristics

The UVN is a spectrometer measuring in the ultraviolet (UV: 305–400nm), the visible (VIS: 400–500nm) and the near infrared (NIR: 750–775nm), with a spatial sampling distance of around 8km.

Its observations are restricted to European area coverage, from 30 to 65º N in latitude and 30º W to 45º E in longitude, depending on seasonality (Figure 1). The observation repeat cycle period will be approximately one hour.

Properties of the UVN Spectrometer:

• An operational field of view of 3.85° north-south, and 11.2° east-west.
• Pushbroom scanning in E/W direction at hourly frequency.
• Imaging Spectrometer:
  • Telescope + UV-VIS & NIR spectrographs.
  • Full refractive optics except the scan mirror (23 elements/19 lenses).
• Two silicon CCDs detectors cooled to ≈ 215K.
• High-performance onboard calibration sources (solar diffusers, white light source, LEDs).
• Mass = 150kg
• Power = 180W
• Data rate = 25Mbit/s

UVN Spectral Information

• Band: UV-VIS1
  Spectral range (nm): 305–400
  Spectral resolution (nm): 0.5
• Band: UV-VIS2
  Spectral range (nm): 400–500
  Spectral resolution (nm): 0.5
• Band: NIR
  Spectral range (nm): 750–775
  Spectral resolution (nm): 0.12

Further details on the Sentinel-4 mission can be found on the ESA Sentinel-4 mission page.