Authors: Alain Hauchecorne1, Laurent Blanot2, Robin Wing1, Philippe Keckhut1, Sergey Khaykin1, Jean-Loup Bertaux1, Mustapha Meftah1, Chantal Claud3, and Viktoria Sofieva4
1) LATMOS/IPSL, UVSQ Université Paris-Saclay, Sorbonne Université, CNRS, Guyancourt, France
2) ACRI-ST, Sophia Antipolis, France
3) LMD, Ecole Polytechnique, CNRS/INSU, Palaiseau, France
4) FMI, Helsinki, Finland
The middle atmosphere (MA) is a region very sensitive to global anthropogenic climate change but also to natural external forcings (solar variability, volcanic eruptions). The mesospheric temperature is poorly observed. There are currently only two space instruments observing temperature in the mesosphere, MLS-AURA and SABER-TIMED both of them being in operation for more than 14 years without guaranty for their future life. There is currently no confirmed project for the continuation.
The scattering of sunlight by the Earth atmosphere above the top of the stratospheric layer, about 30-35 km altitude, is only due to Rayleigh scattering by atmospheric molecules. Its intensity is then directly proportional to the atmospheric density. It is then possible to retrieve a temperature profile in absolute value using the hydrostatic equation and the perfect gas law, assuming that the temperature is known from a climatological model at the top of the density profile. This technique is applied to Rayleigh lidar observations since 40 years (Hauchecorne and Chanin, 1980).
GOMOS stellar occultation spectrometer on board ENVISAT satellite observed the daytime Rayleigh scattering profiles at limb. GOMOS data have been used to retrieve temperature profiles from 35 to 85 km, providing dataset of more than 310 thousands profiles from 2002 to 2012 (Hauchecorne et al., AMT, 2019).
We propose to adapt this technique to the a constellation of nanosatellites in the MARTIC (Middle Atmosphere Rayleigh Temperature Instrument Constellation ) mission. This mission will aim to fill this lack of MA temperature observations. If the proposed measurement technique is simple, determining the vertical profile of solar light scattered by the atmospheric limb, the expected results are of considerable strategic interest for a large number of meteorological, climatological, aeronautical and space applications.