Japan Geoscience Union Meeting 2018

Presentation information

[EJ] Poster

A (Atmospheric and Hydrospheric Sciences) » A-AS Atmospheric Sciences, Meteorology & Atmospheric Environment

[A-AS06] Atmospheric Chemistry

Wed. May 23, 2018 1:45 PM - 3:15 PM Poster Hall (International Exhibition Hall7, Makuhari Messe)

convener:Yoko Iwamoto(Graduate School of Biosphere Science, Hiroshima University), Tomoki Nakayama(Graduate School of Fisheries and Environmental Sciences, Nagasaki University), Sakae Toyoda(東京工業大学物質理工学院, 共同), Nawo Eguchi(Kyushu University)

[AAS06-P01] Forward and backward model analyses on high CH4 events observed over the western North Pacific

*Yosuke Niwa1, Toshinobu Machida2, Yousuke Sawa1, Taku Umezawa2, Kazuhiro Tsuboi1, Kazuyuki Saito3, Hidekazu Matsueda1, Nobuko Saigusa2 (1.Meteorological Research Institute, 2.National Institute for Environmental Studies, 3.Japan Meteorological Agency)

Keywords:CH4, aircraft, model

Methane (CH4) is one of important greenhouse gases and a large part of the global total CH4 emission exists in Asia. Over the western North Pacific, which locates at the downwind side of the Asia continent, enhanced CH4 concentrations are frequently observed not only at surface stations but also by aircraft in the mid- to upper-troposphere. Especially, high CH4 events observed by aircraft during summer are noteworthy because they are likely emitted through highly uncertain biogenic processes and such observational data could provide valuable constraints on biogenic CH4 emission estimates in inverse modeling. However, its transport mechanism and the model uncertainty should be investigated for an effective use of those observational data. In this study, we have conducted forward and backward model analyses using the atmospheric transport model NICAM-TM and its adjoint mode in order to evaluate the transport model uncertainties and also to investigate the detailed transport pathway from the continent to the western North Pacific. The aircraft observational data we use are from the research project of Comprehensive Observation Network for Trace gases by Airliner (CONTRAIL) and from the operational observation program by Japan Meteorological Agency (JMA). The CONTRAIL project uses commercial airliners connecting Japan and Australia/Bangkok, and the JMA aircraft observation is conducted with the C-130 aircraft connecting the Japan main island and Minamitorishima.