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Earth Topics (Applications)
  • Atmosphere
  • Air Quality (Ozone); Atmospheric chemistry (Trace Gases)

    Date of Launch:
    13 August 2003
    Mission Status:
    Operating nominally
    Orbit Height:
    650 km
    Orbit type:
    Circular high-inclination
    Swath Width:
    FOV 1.25 mrad
    SciSat-1/Ace FTS and MAESTRO
    (4938) recent views

    SCISAT-1/Ace data aim at monitoring and analysing the chemical processes that control the distribution of ozone in the upper troposphere and stratosphere. It provides acquisitions from the 2 instruments MAESTRO and FTS.

    • MAESTRO: Measurement of Aerosol Extinction in the Stratosphere and Troposphere Retrieved by Occultation.
      Dual-channel optical spectrometer in the spectral region of 285-1030 nm. The objective is to measure ozone, nitrogen dioxide and aerosol/cloud extinction (solar occultation measurements of atmospheric attenuation during satellite sunrise and sunset with the primary objective of assessing the stratospheric ozone budget).
      Solar occultation spectra are being used for retrieving vertical profiles of temperature and pressure, aerosols, and trace gases (O3, NO2, H2O, OClO, and BrO) involved in middle atmosphere ozone distribution. The use of two overlapping spectrometers (280 - 550 nm, 500 - 1030 nm) improves the stray-light performance. The spectral resolution is about 1-2 nm.

    • FTS: Fourier Transform Spectrometer
      The objective is to measure the vertical distribution of atmospheric trace gases, in particular of the regional polar O3 budget, as well as pressure and temperature (derived from CO2 lines). The instrument is an adapted version of the classical sweeping Michelson interferometer, using an optimized optical layout.
      The Level 2 V2.2 includes the retrieval of 28 main isotopes, and 4 subsidiary isotopologues from the FTS spectra.
      The ACE-FTS measurements are recorded every 2 s. This corresponds to a measurement spacing of 2-6 km which decreases at lower altitudes due to refraction. The typical altitude spacing changes with the orbital beta angle. For historical reasons, the retrieved results are interpolated onto a 1 km "grid" using a piecewise quadratic method. For ACE-FTS version 1.0, the results were reported only on the interpolated grid (every 1 km from 0.5 to 149.5 km). For versions 2.2, both the "retrieval" grid and the "1 km" grid profiles are available.
    Data Set Specifications
    Spatial coverage: 90 N, 90 S, 180 W, 180 E
    Temporal coverage: 2003-08-13 - current day
    NASA - Horizontal Resolution Range: 1 km - < 10 km or approximately .01 degree - < .09 degree
    Processing level
    Level 2
    How to access this data

    Data are available through the SciSAt-1/Ace database.

    Terms & Conditions applicable
    Utilisation of this data is subject to the Terms and Conditions for ESA's Third Party Missions scheme


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    ESA has been involved in many Earth Observation campaigns over the past 25 years, from ground-based surveys, to ships at sea, aircraft and balloons in the atmosphere and the orbiting satellites in space.

    To learn more about these campaigns and available datasets from them, please see the Campaigns page.