Summertime upper tropospheric nitrous oxide over the Mediterranean as a footprint of Asian emissions

• Published in: Journal of geophysical research. Atmospheres 2017-04, Vol.122 (8), p.4746-4759
• Main Authors: Kangah, Yannick, Ricaud, Philippe, Attié, Jean‐Luc, Saitoh, Naoko, Hauglustaine, Didier A., Wang, Rong, El Amraoui, Laaziz, Zbinden, Régina, Delon, Claire
• Format: Article
• Language: English
• Subjects: Airborne sensing; Anticyclones; Asian monsoon; Asian monsoons; Atmospheric chemistry; Chemical transport; Emissions; Environmental research; Error reduction; Fertilizers; Footprints; Fourier transform spectrometers; Fourier transforms; Gases; Geophysics; GOSAT; Greenhouse effect; Greenhouse gases; Infrared detectors; Infrared spectrometers; LMDz‐OR‐INCA; Mediterranean; Modelling; Monsoons; N2O retrieval; Near infrared radiation; Nitrous oxide; Ocean, Atmosphere; Pixels; Satellite observation; Sciences of the Universe; Spatial discrimination; Spatial resolution; Summer; Transport; Troposphere
• ISSN: 2169-897X; 2169-8996
• DOI: 10.1002/2016JD026119

The aim of this paper is to study the transport of nitrous oxide (N2O) from the Asian surface to the eastern Mediterranean Basin (MB). We used measurements from the spectrometer Thermal and Near infrared Sensor for carbon Observation Fourier transform spectrometer on board the Greenhouse gases Observing SATellite (GOSAT) over the period of 2010–2013. We also used the outputs from the chemical transport model LMDz‐OR‐INCA over the same period. By comparing GOSAT upper tropospheric retrievals to aircraft measurements from the High‐performance Instrumented Airborne Platform for Environmental Research Pole‐to‐Pole Observations, we calculated a GOSAT High‐performance Instrumented Airborne Platform for Environmental Research standard deviation (SD error) of ~2.0 ppbv for a single pixel and a mean bias of approximately −1.3 ppbv (approximately −0.4%). This SD error is reduced to ~0.1 ppbv when we average the pixels regionally and monthly over the MB. The use of nitrogen fertilizer coupled with high soil humidity during the summer Asian monsoon produces high N2O emissions, which are transported from Asian surfaces to the eastern MB. This summertime enrichment over the eastern MB produces a maximum in the difference between the eastern and the western MB upper tropospheric N2O (east‐west difference) in July in both the measurements and the model. N2O over the eastern MB can therefore be considered as a footprint of Asian summertime emissions. However, the peak‐to‐peak amplitude of the east‐west difference observed by GOSAT (~1.4 ± 0.3 ppbv) is larger than that calculated by LMDz‐OR‐INCA (~0.8 ppbv). This is due to an underestimation of N2O emissions in the model and to a relatively coarse spatial resolution of the model that tends to underestimate the N2O accumulation into the Asian monsoon anticyclone. Key Points Consistency between GOSAT N2O measurements and LMDz‐OR‐INCA model N2O results Evidence of a link between summertime Asian N2O Emissions and the Mediterranean tropospheric N2O