• Citer

First Space Detection of Anthropogenic Point Sources of Ethylene (C2H4)

par Franco, Bruno ;Clarisse, Lieven ;Van Damme, Martin ;Hadji-Lazaro, Juliette;Clerbaux, Cathy ;Coheur, Pierre
Référence IASI 2021 Conference (06-10 December 2021: Evian, France)
Publication Non publié, 2021-12-09

Communication à un colloque

• Détails
• Contenu

Résumé :

Ethylene (ethene, C2H4) is one of the most abundant unsaturated hydrocarbons in the Earth’s atmosphere. Emitted by fires, it also emanates from various biogenic and anthropogenic sources. These include incomplete fuel combustion (e.g., motor vehicle exhaust) and leakage from industrial processes. Produced industrially by cracking petroleum hydrocarbons, e.g., naphtha (petroleum crude) and ethane (natural gas), ethylene is the raw material for polyethylene plastics and other products, and the most abundant industrially produced organic compound. Along with propylene (propene, C3H6), the global industrial production of these olefins is estimated at >200 Tg/yr and is projected to increase further. With a short atmospheric lifetime and a high ozone production rates per oxidized carbon, ethylene is an important contributor to tropospheric ozone and formaldehyde, and can thus affect air quality in the vicinity of its emission sources.The spatially dense measurements from the Infrared Atmospheric Sounding Interferometer (IASI/Metop) offer a good opportunity to monitor ethylene. However, its column abundance is challenging to retrieve owing to its weak absorption in the thermal infrared. Moreover, its main absorption feature (the Q-branch of the ν7 vibrational band near 949 cm-1) is partly overlapped by a strong CO2 line. Here, we detect and quantify the signal strength of ethylene in the IASI spectra, using a sensitive hyperspectral range index (HRI) that exploits all the channels in which ethylene absorbs. This HRI is then converted via a neural network to gas vertical abundance.We apply to the entire IASI/Metop-A and -B time series of ethylene HRI, a wind-adjusted super-resolution technique. Developed to track down ammonia point sources, it allows increasing the spatial resolution of averaged satellite data beyond the native resolution and is more effective in locating the target emitter sources than regular oversampling techniques. We demonstrate that this technique allows for the first time detection of point sources of ethylene from space. We identify and categorize more than 150 of these point sources, which are found to be mainly associated with megacities, petrochemical hubs that include ethylene production and transformation plants, iron and steel plants, and coal-related industries. Finally, total columns of ethylene are retrieved over these hotspots and a first order estimate is provided on their annual emissions.