Bottomup and topdown estimates of ammonia emissions over
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 1. Peking U. 2. Chinese Academy of Sciences 3. U. of Colorado, Boulder Key messages: n Top-down NH 3 emission estimates over China suggest a strong seasonality with emission in summer much higher than winter. n 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. The GEIA 2015 Conference 18 -20 November 2015
Large uncertainties in bottom-up Asian NH 3 emissions from REAS-2 (Kurokawa ACP 2013) Differences with Streets et al. (JGR 2003) 50%-100% difference Base year Total emissions (Tg NH 3 a-1) Fertilizer use Others Streets et al. (2003) 2000 13. 6 6. 7 6. 9 S. Wang et al. (2009) 1980 -2005 13. 4 5. 1 8. 3 Dong et al. (2010) 2006 16. 1 8. 7 7. 4 Huang et al. (2012) 2006 9. 8 3. 2 6. 6 REAS 2. 1(2013) 2000 -2008 14. 8 8. 4 6. 4 Paulot et al. (2014) 2005 -2008 8. 4 3. 0 5. 4 P. Xu et al. (2015) 2010 10. 7 4. 5 6. 2
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 10 sites from CAS NH 3 concentration
Adjoint inversion of Asian NH 3 emissions for July using the TES satellite measurements Scaling factors r = 0. 56 bias=-43% r = 0. 63 bias=-0. 1% 1. 3 r = 0. 29 bias=-65% r = 0. 49 bias=-9% 2. 1 r = 0. 59 bias=-38% r = 0. 62 bias=-14% 1. 4 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.
Revisiting bottom-up NH 3 emission estimates from fertilizer use Needs to better quantify how fertilizers are applied in China over different agricultural crops (more practical timing and magnitude of fertilizer use) Total fertilizer application rates over China in 2008 for 18 crop types
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]
- Slides: 6