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Proceedings Paper • Open Access

The CarbonSat candidate mission for imaging greenhouse gases from space: concepts and system requirements
Author(s): B. Sierk; J. Caron; J.-L. Bézy; A. Löscher; Y. Meijer; P. Jurado

Paper Abstract

CarbonSat is a candidate mission for ESA's Earth Explorer program, currently undergoing industrial feasibility studies. The primary mission objective is the identification and quantification of regional and local sources and sinks of carbon dioxide (CO2) and methane (CH4). The mission also aims at discriminating natural and anthropogenic fluxes. The space-borne instrument will quantify the spatial distribution of CO2 and CH4 by measuring dry air column-averaged mixing ratios with high precision and accuracy (0.5 ppm for CO2 and 5 ppb for CH4). These products are inferred from spectrally resolved measurements of Earth reflectance in three spectral bands in the Near Infrared (747-773 nm) and Short Wave Infrared (1590-1675 nm and 1925-2095 nm), at high and medium spectral resolution (0.1nm, 0.3 nm, and 0.55 nm). Three spatially co-aligned push-broom imaging spectrometers with a swath width <180 km will acquire observations at a spatial resolution of 2 x 3 km2 , reaching global coverage every 12 days above 40 degrees latitude (30 days at the equator). The targeted product accuracy translates into stringent radiometric, spectral and geometric requirements for the instrument. Because of the high sensitivity of the product retrieval to spurious spectral features of the instrument, special emphasis is placed on constraining relative spectral radiometric errors from polarisation sensitivity, diffuser speckles and stray light. A new requirement formulation targets to simultaneously constrain both the amplitude and the correlation of spectral features with the absorption structures of the targeted gases. The requirement performance analysis of the so-called effective spectral radiometric accuracy (ESRA) establishes a traceable link between instrumental artifacts and the impact on the level-2 products (column-averaged mixing ratios). This paper presents the derivation of system requirements from the demanding mission objectives and report preliminary results of the feasibility studies.

Paper Details

Date Published: 17 November 2017
PDF: 9 pages
Proc. SPIE 10563, International Conference on Space Optics — ICSO 2014, 105633I (17 November 2017); doi: 10.1117/12.2304154
Show Author Affiliations
B. Sierk, ESA-ESTEC (Netherlands)
J. Caron, ESA-ESTEC (Netherlands)
J.-L. Bézy, ESA-ESTEC (Netherlands)
A. Löscher, ESA-ESTEC (Netherlands)
Y. Meijer, ESA-ESTEC (Netherlands)
P. Jurado, ESA-ESTEC (Netherlands)

Published in SPIE Proceedings Vol. 10563:
International Conference on Space Optics — ICSO 2014
Zoran Sodnik; Bruno Cugny; Nikos Karafolas, Editor(s)

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