Several satellites and space-based instruments were launched in the 1990s-2000 to observe the ozone layer in the stratosphere. More generally, the objective was to better understand the chemistry of the middle stratosphere (stratosphere, mesosphere) and to validate chemistry-transport models to reproduce and predict the ozone hole.

These instruments are generally spectrometers covering various spectral ranges, from microwave to ultraviolet. They record atmospheric absorption or emission spectra (level 1) from which inverse models can be used to produce columns or vertical profiles of atmospheric constituent concentrations (level 2) with very high accuracy.

The instruments

SAGE II (Stratospheric Aerosol and Gas Experiment)

The SAGE II instrument was developed by NASA to provide the scientific community with a global and long-term description of the distribution of aerosols, ozone, water vapour and NO2. It thus provides a unique and crucial database to improve our understanding of global, seasonal and interannual climate variability and, in particular, stratospheric ozone trends. This instrument was installed on the Earth Radiation Budget Satellite (ERBS) which was launched in October 1984 and ceased operation in August 2005.

POAM (Polar Ozone and Aerosol Measurement)

The POAM instruments were developed by the US Naval Research Laboratory (NRL) to measure the vertical distribution in the atmosphere of ozone, water vapour and nitrogen dioxide (NO2), as well as aerosol extinction and temperature. The first, POAM 2, was installed on the CNES satellite SPOT 3: it was launched in September 1996 and ceased operation in November 1996. The second, POAM 3, was installed on the CNES SPOT 4 satellite: it was launched in March 1998 and ceased operations in May 2006. Both instruments are visible/IR spectrometers making observations through the Earth’s atmosphere using the solar occultation technique. POAM measures solar extinction in nine narrow-band channels, covering the spectral range from about 350 to 1060 nm.

ILAS (Improved Limb Atmospheric Photometer)

The ILAS instrument, developed by the Japan Environment Agency (NIES), was launched on the ADEOS 1 satellite on 17 August 1996. It was a visible/infrared spectrometer, recording atmospheric absorption spectra by solar occultation and its main objective was to monitor stratospheric ozone in the polar regions.

SMR (Sub-millimeter Microwave Radiometer)

The Swedish SMR instrument, developed jointly with France and Finland, was launched on 20 February 2001 on board the Swedish mini-satellite ODIN . This microwave receiver is operational in the millimetre range around 119 GHz and in the submillimetre range between 480 and 580 GHz (although to date only submillimetre measurements have been analysed). Aimed at the edge of the Earth’s atmosphere, it records the emission spectra of important molecules such as ozone and its isotopes, chlorine monoxide, nitrous oxide, nitric acid, water vapour and its isotopes and carbon monoxide.

Products available on AERIS

• SAGE II :Two types of data are available on Ether from 24/10/1984, these data are from the official NASA production: vertical profiles (level 2) and correlative temperature, pressure, density and coordinate data.
• POAM III : Two types of POAM III data are available via Ether from 22/04/1988 to 05/12/2005; those related to official NRL data products (level 2 vertical profiles) and auxiliary data concerning temperature, pressure and potential vorticity. Access to POAMIII data is restricted.
• POAM II : Two types of POAM II data are available on Ether, from 15/10/1993; link to official NRL output: vertical profiles (level 2) and correlative data such as temperature, pressure and potential vorticity.
• ILAS : Two ILAS datasets are available from Ether for the period 18/09/1996 to 29/06/1997: the vertical profile data (level 2) and the auxiliary data. These data are part of the official production of the ILAS project team.
• SMR : Two types of SMR/ODIN data are available from Ether since 21 August 2001:
  • Spectrum (level 1) and vertical profile (level 2) data corresponding to the official data products generated by the ODIN project team (PDC/Chalmers);
  • Vertical profile data (level 2) corresponding to the unofficial data products of the Toulouse Aerology Laboratory, accessible from Ether using the MOLIERE software.