Computation and Study of Atmospheric Temperature from IASI

Marie Bouillon (1) , Sarah Safieddine (1) , Cathy Clerbaux (1, 2) , Maya George (1) , Lieven Clarisse (2) , Simon Whitburn (2)

1 TROPO - LATMOS
2 Spectroscopie de l'atmosphère, Service de Chimie Quantique et Photophysique

Atmospheric remote sounding sounding from satellites is an essential component of the observational strategy deployed to monitor climate change. The Infrared Atmospheric Sounding Interferometer (IASI) is a nadir looking thermal infrared spectrometer flying on board the satellites Metop-A, Metop-B and Metop-C, launched in 2006, 2012 and 2018 respectively. Each IASI observation measures Earth’s infrared radiance over 8461 channels between 645 and 2760 cm-1. Every location on Earth is observed twice a day by IASI, in the morning and in the evening, which gives us good spatial and temporal coverage. Atmospheric temperatures at different altitudes can be retrieved from the radiances measured in the carbon dioxide absorption bands at 15 μm (645 to 800 cm-1) and 4.3 μm (2250 to 2400 cm-1) by selecting channels that are most sensitive to the temperature profile. The European Organization for the Exploitation of Meteorological Satellites (EUMETSAT) already calculates atmospheric temperatures from IASI and other instruments on board of the Metop satellites. Several updates of their retrieval algorithm have had a significant effect on the atmospheric temperatures, and the whole time series has not been reprocessed back in time and therefore no homogeneous record of atmospheric temperatures exists. In this talk, we perform our own selection of IASI channels relevant for temperature retrievals. By carefully selecting radiances, a method is then applied to the full IASI time series and trend analysis is performed. The IASI temperatures are compared to temperatures from ERA5 reanalysis to determine their quality at different atltitudes and latitudes. This project brings continuous and independent information on atmospheric temperature which will allow us to study seasonal and spatial variability of temperature. It will also be possible to analyze the influence of natural events such as El Niño - Southern Oscillation (ENSO) on atmospheric temperature, and deduce climate change signature.

Domaines: Physique Atmosphérique et Océanique [physics.ao-ph]; Climatologie

Marie Bouillon, Sarah Safieddine, Cathy Clerbaux, Maya George, Lieven Clarisse, et al.. Computation and Study of Atmospheric Temperature from IASI. Living Planet Symposium 2019, May 2019, Milan, Italy. ⟨insu-02265319⟩