Abstract
Abstract. For the first time, carbon monoxide (CO) and formaldehyde (HCHO) satellite retrievals are used together with methane (CH4) and methyl choloroform (CH3CCl3 or MCF) surface measurements in an advanced inversion system. The CO and HCHO are respectively from the MOPITT and OMI instruments. The multi-species and multi-satellite dataset inversion is done for the 2005–2010 period. The robustness of our results is evaluated by comparing our posterior-modeled concentrations with several sets of independent measurements of atmospheric mixing ratios. The inversion leads to significant changes from the prior to the posterior, in terms of magnitude and seasonality of the CO and CH4 surface fluxes and of the HCHO production by non-methane volatile organic compounds (NMVOC). The latter is significantly decreased, indicating an overestimation of the biogenic NMVOC emissions, such as isoprene, in the GEIA inventory. CO and CH4 surface emissions are increased by the inversion, from 1037 to 1394 TgCO and from 489 to 529 TgCH4 on average for the 2005–2010 period. CH4 emissions present significant interannual variability and a joint CO-CH4 fluxes analysis reveals that tropical biomass burning probably played a role in the recent increase of atmospheric methane.
Highlights
Formaldehyde (HCHO), found throughout the troposphere, is a short-lived tropospheric gas acting as an outdoor and indoor air pollutant, with a typical lifetime of a few hours in daytime (Sander et al, 2006)
Even though uncertainties remain large for the HCHO satellite retrievals, past studies have demonstrated the usefulness of HCHO column data from the Global Ozone Monitoring Experiment (GOME) (Abbot et al, 2003; Palmer et al, 2006, 2007; Fu et al, 2007; Barkley et al, 2008), from the SCanning Imaging Absorption spectroMeter for Atmospheric CartograpHY (SCIAMACHY) (Stavrakou et al, 2009) and from the Ozone Monitoring Instrument (OMI) (Millet et al, 2008; Marais et al, 2012) to constrain nonmethane volatile organic compounds (NMVOC) emissions, the latter having the highest spatial resolution of these 3 instruments
Given the large discrepancies associated with the biogenic NMVOC estimates, errors assigned to the scaling factors of the 3-D-chemical production of HCHO are set to 400 %
Summary
Formaldehyde (HCHO), found throughout the troposphere, is a short-lived tropospheric gas acting as an outdoor and indoor air pollutant, with a typical lifetime of a few hours in daytime (Sander et al, 2006). Very large uncertainties remain for the relative contributions of these different sources and sinks to the HCHO budget, for the atmospheric production by NMVOC. Pison et al (2009) implemented the Simplified Atmospheric Chemistry System (SACS) in a variational inversion system and demonstrated the feasibility of a multi-species inversion, inferring simultaneously CH4, OH, H2, and CO sources and sinks These first studies did not use any HCHO observations. Even though uncertainties remain large for the HCHO satellite retrievals, past studies have demonstrated the usefulness of HCHO column data (determined in near-UV wavelengths 310–365 nm) from the Global Ozone Monitoring Experiment (GOME) (Abbot et al, 2003; Palmer et al, 2006, 2007; Fu et al, 2007; Barkley et al, 2008), from the SCanning Imaging Absorption spectroMeter for Atmospheric CartograpHY (SCIAMACHY) (Stavrakou et al, 2009) and from the Ozone Monitoring Instrument (OMI) (Millet et al, 2008; Marais et al, 2012) to constrain NMVOC emissions, the latter having the highest spatial resolution of these 3 instruments. The inverted HCHO and CO sources are evaluated by comparison of the optimized and prior concentrations with independent (i.e. not used in the inversion) measurements from aircraft campaigns (INTEX-B, AMMA) and at the surface (NOAA/ESRL, AGAGE, CSIRO, EMPA, SAWS, NIWA and JMA/MRI)
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