Increasing synoptic scale variability in atmospheric CO2 at Hateruma Island associated with increasing East Asian emissions
1Atmospheric Environment Division, National Institute for Environmental Studies, Tsukuba, Japan
2Center for Global Environmental Research, National Institute for Environmental Studies, Tsukuba, Japan
3Research Institute for Global Change, JAMSTEC, Yokohama, Japan
Abstract. In-situ observations of atmospheric CO2 and CH4 at Hateruma Island, Japan show large synoptic scale variations during a 6-month period from November to April, when the sampled air is predominantly of continental origin due to the Asian winter monsoon. Synoptic scale variations are extracted from the daily averaged values for the years between 1996 and 2007, along with the annual standard deviations (σCO2 and σCH4 for CO2 and CH4, respectively) for the relevant 6-month period. The temporal change in σCO2 shows a systematically increasing trend over the 12-year period, with elevated excursions in 1998 and 2003; there is no clear trend in σCH4. We also find that the σCO2/σCH4 ratio increases gradually from 1996 to 2002 and rapidly thereafter 2002 without any extreme deviations that characterized σCO2. The σCO2/σCH4 ratio correlates closely with the recent rapid increase in fossil carbon emission from China, as indicated in the CDIAC data. This methodology can be applied for tracking overall changes in regional emissions by measuring multiple chemical tracers.