HCFC‐22 flux estimates over East Asia by inverse modeling from hourly observations at Hateruma monitoring station

Abstract

A series of high‐frequency observations of chlorodifluoromethane (HCFC‐22) at Hateruma Island (latitude 24.1°N, longitude 123.8°E) was used to evaluate the strength of various sources in East Asia by a tracer transport inversion. The forward calculation was conducted with a regional meteorological model using an online tracer transport scheme, and the inversion calculation used a Bayesian approach. On the basis of winter observations during 2005–2007, we estimated the annual HCFC‐22 emission from China to be 32 Gg, which is nine times current estimates. The total uncertainty of the Chinese emission was reduced from 50% (a priori) to 15% (a posteriori) by the inversion calculation. A sensitivity study showed that the a posteriori values for China showed little dependency on the a priori values, whereas those for Japan, Korea, and Taiwan were considerably affected by the a priori values used. This can be explained by the more frequent high‐concentration events from China observed at the Hateruma site. The a posteriori emission estimates from central China accounted for half of the total emissions from China.