1. Bottom-up and top-down estimates of ammonia emissions over China Lin Zhang 1 (zhanglg@pku.edu.cn), Yuanhong Zhao 1, Youfan Chen 1, Yuepeng Pan 2, Yuesi Wang 2, Daven Henze 3 The GEIA 2015 Conference 18-20 November 2015 1. Peking U. 2. Chinese Academy of Sciences 3. U. of Colorado, Boulder Key messages: Top-down NH 3 emission estimates over China suggest a strong seasonality with emission in summer much higher than winter. We provide a new bottom-up estimate of Chinese NH 3 emissions from fertilizer use which better quantifies the fertilizer application procedure to improve the emission seasonality.

2. Large uncertainties in bottom-up Asian NH 3 emissions Base year Total emissions (Tg NH 3 a -1 ) Fertilizer useOthers Streets et al.(2003)200013.66.76.9 S. Wang et al.(2009)1980-200513.45.18.3 Dong et al.(2010)200616.18.77.4 Huang et al.(2012)20069.83.26.6 REAS 2.1(2013)2000-200814.88.46.4 Paulot et al.(2014)2005-20088.43.05.4 P. Xu et al.(2015)201010.74.56.2 NH 3 emissions from REAS-2 (Kurokawa ACP 2013) Differences with Streets et al. (JGR 2003) 50%-100% difference

3. Bayesian inversion of NH 3 emissions over the North China using measurements of concentrations and wet deposition fluxes Observations (2007-2010) GEOS-Chem (REAS-2 no seasonality) GEOS-Chem (Optimized) NH 4 + wet NH 3 concentration 10 sites from CAS

4. Adjoint inversion of Asian NH 3 emissions for July using the TES satellite measurements Scaling factors 1.3 2.1 1.4 r = 0.56 bias=-43% r = 0.29 bias=-65% r = 0.59 bias=-38% r = 0.63 bias=-0.1% r = 0.49 bias=-9% r = 0.62 bias=-14% The inversion results show large sensitivity to the prior emissions used and the model horizontal resolution. Inverse results for July would give a range of 1.62-2.61 Tg.

5. Revisiting bottom-up NH 3 emission estimates from fertilizer use Total fertilizer application rates over China in 2008 for 18 crop types Needs to better quantify how fertilizers are applied in China over different agricultural crops (more practical timing and magnitude of fertilizer use)

6. Improved seasonality of Chinese NH 3 emissions from fertilizer use 2008 fertilizer use over China: spatial and seasonal variations 2008 NH 3 emissions from fertilizer use over China Annual total 4.95 Tg NH 3, peaking in late spring and early summer [Zhang et al. in prepare]