|Paper title||CarbonCGI: a road map to observation of faint GHG source’s emissions with high resolution observing system|
|Form of presentation||Poster|
The paper presents the results of the CarbonCGI study proposed by ESA and carried out by Thales Alenia Space and partners for the observation of faint GHG source’s emissions with a high resolution Compact Gas Imager (CGI).
Atmospheric remote sensing from CGI allows observation of atmosphere features ranging from largest scales of meteorology and smaller spatial scales down to the finest scales allowing direct observations of biogenic and anthropogenic inter-actions with atmosphere. For this, multi-mission deployment is foreseen from geostationary to low orbit satellites as well as on airborne platform and on ground for mobile applications. CGI has the potential to acquire high resolution images of gas in the spectral regions of solar emission from UV to SWIR, and also to take images of atmospheric temperature and humidity profiles in TIR spectral bands.
This paper is focused on the detection and characterisation of Carbon dioxide and Methane gas concentrations, from low orbit satellite, for climate applications. CarbonCGI development includes simulation and experimental validation of level 0 (instrument design and acquisition chain), level 1 (data correction), level 2 (Radiative Transfer Model), and level 4 (Transport Model). CarbonCGI is developed in an integrated team of scientists and engineers. Knowledge in the field of physics of atmosphere from laboratories and scientific engineering institutes aim at designing the most efficient atmosphere remote sensor. Thus, the described CGI principle optimises the retrieval of atmospheric states from the spectra variability with acquisition of specific Partially Scanned Interferograms (PSI), resulting from a double optimisation of both spectral bands and Optical Path Difference range. The optical concept works at low aperture number, and provides very long dwell time, to reach unprecedented radiometric resolution with very low sounding precision and accuracy, in a very high spatial resolution image.
The paper presents the results obtained by applying the Performance Simulation Platform developed in the framework of the scientific chair TRACE https://trace.lsce.ipsl.fr to the CarbonCGI imaging and sounding performance. The obtained results highlight the capacity to carry out early mission trade-off from acquisition chain parameters.
The sounding performance obtained by coupling level 0-1 and level 2 models are described. After the presentation of level 0-2 models, this paper presents the sounding performance which have been achieved during the optimisation of the acquisition chain design. CGI instrument design delivers an inherent solution to correct for the presence of atmospheric aerosol up aerosol optical depths of 1. An optimised aerosol’s bias measurement concept and associated models and performance are presented.
Level 0-1 activity are then summarised with the presentation of the payload’s design, optical thermal and mechanical design, with an introduction to the CarbonCGI stray light model and the CarbonCGI Line of Sight Stabilisation system inferred from the ISABELA LS3 design, developed in the frame of the ISABELA TRP for ESA.
The paper concludes with a proposal of an incremental implementation plan of weak source measurement missions based on high resolution CarbonCGI imagers. The first step is a CarbonCGI instrument to complement CO2M mission with observation at higher spatial resolution and smaller swath, the second step is a self-standing high resolution observing system.