On the capability of IASI measurements to inform about CO surface emissions

Abstract

Abstract. Between July and November 2008, simultaneous observations were conducted by several orbiting instruments that monitor carbon monoxide in the atmosphere, among them the Infrared Atmospheric Sounding Instrument (IASI) and Measurements Of Pollution In The Troposphere (MOPITT). In this paper, the concentration retrievals at about 700 hPa from these two instruments are successively used in a variational Bayesian system to infer the global distribution of CO emissions. Our posterior estimate of CO emissions using IASI retrievals gives a total of 793 Tg for the considered period, which is 40% higher than the global budget calculated with the MOPITT data (566 Tg). Over six continental regions (Eurasian Boreal, South Asia, South East Asia, North American Boreal, Northern Africa and South American Temperate) and thanks to a better observation density, the theoretical uncertainty reduction obtained with the IASI retrievals is better or similar than with MOPITT. For the other continental regions, IASI constrains the emissions less than MOPITT because of lesser sensitivity in the lower troposphere. These first results indicate that IASI may play a major role in the quantification of the emissions of CO.