Japan Geoscience Union Meeting 2016

Presentation information

International Session (Oral)

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

[A-AS01] Global Carbon Cycle Observation and Analysis

Tue. May 24, 2016 1:45 PM - 3:15 PM A03 (APA HOTEL&RESORT TOKYO BAY MAKUHARI)

Convener:*Nobuko Saigusa(National Institute for Environmental Studies), Prabir Patra(Research Institute for Global Change, JAMSTEC), Toshinobu Machida(National Institute for Environmental Studies), Satoru Chatani(National Institute for Environmental Studies), Chair:Toshinobu Machida(National Institute for Environmental Studies)

3:00 PM - 3:15 PM

[AAS01-06] Fine-scale CO2 variations over the Tokyo megacity observed by CONTRAIL

*Taku Umezawa1, Hidekazu Matsueda2, Toshinobu Machida1, Yousuke Sawa2, Yosuke Niwa2 (1.National Institute for Environmental Studies, 2.Meteorological Research Institute)

Keywords:Megacity, CO2, Aircraft measurements

Urban areas are considered to account for ~70% of the global anthropogenic carbon emissions. Many cities now take actions to reduce their carbon emissions. However, atmospheric CO2 measurement networks capable of verifying carbon emissions from large cities are still far from sufficient. CONTRAIL, an ongoing project to measure trace gases with instruments onboard aircraft of Japan Airlines, has obtained millions of CO2 data over worldwide large cities since 2005. In general, we have observed increases of CO2 concentration approaching down to the airports, indicating presence of CO2 plume over metropolitan areas. We found vertical gradient of CO2 concentration (i.e. difference between the free troposphere and the lowermost layer) larger for large megacities, suggesting that CO2 plume correlates with size of the city. This infers that the CONTRAIL measurements may have potential to assess city’s carbon emission trends. In this study, we focus on detailed analysis of CO2 distributions over Tokyo, currently the world largest megacity. Analyzing thousands of vertical profiles of CO2 over the Narita and Haneda airports over the last 10 years, we found CO2 levels significantly different between areas over Haneda and north and south of Narita. This likely reflects different catchments of CO2 plumes over the respective areas.