1. Source analysis of the ozone-induced vegetation loss in the US using the GEOS-Chem adjoint Kateryna Lapina, Daven Henze, Jana Milford (CU Boulder) Acknowledgments: NASA AQAST for funding Source: NPS IGC7 May 6, 2015

2. Estimating tree & crop loss Previous studies estimated present/future crop yield loss due to O 3 [e.g., Wang & Mauzerall 2004, Avnery et al., 2011,13; Tai et al., 2014], and explored LRT effects for crop losses in Northern Hemisphere [e.g., Hollaway et al., 2012] Crop loss: f (M12/M7), f (W126), f (AOT40) [Wang & Mauzerall 2004,Van Dingenen et al. 2009] Tree loss: f (W126) [ EPA 2015] Crop/tree loss Crop production/tree basal area (BA) O 3 exposure during 3 month growing season Exposure : response  Tree & crop loss Aspen BA (Source: FHTET) Wheat Production (Source: USDA) What are the main sources of O 3 -induced vegetation loss in US?

3. Modeled exposure: wheat  Agreement between model and observations is worse for cumulative metrics (W126 & AOT40) XXXXXX O 3 metricmean (Obs/Model) AOT40 W126 M7 Crop loss [%] Apr-May-Jun 2010 Data source: AQS, CASTNET  O 3 concentrations adjusted to canopy height prior to bias correction [Van Dingenen et al., 2009, Zhang et al., 2012]  Canopy adjustment reduced M7 by 3%, on avg [ppm-hr] [ppb] Exposure- response mean

4. National aggregated tree & crop loss Ponderosa pine, aspen Estimates of national aggregated vegetation loss agree well between 2 o x 2.5 o and 0.5 o x 0.667 o Wheat, soybean avg WheatSoy AspenPonderosa Pine 2 o x2.5 o 0.5 o x0.667 o Before correction Crop loss [%] Tree loss [%

5. Global source regions: wheat CropLoss US adjoint sensitivities to anthropogenic CO CropLoss US adjoint sensitivities to anthropogenic NO x  Anthropogenic emissions of NO x dominate influence on crop/tree loss  Chinese influence comparable to US influence for CO

6. State-based analysis: wheat %NO x influence %NO x influence–%NO x emissions %NO x influence–%Wheat loss  Most of crop loss is in Kansas, the highest contributor is NO x from Texas  Contribution of Texas NO x to wheat loss exceeds Texas’s share of emissions Texas “exports” wheat loss % Production % Wheat loss % NO x emissions

7. Conclusions  National aggregated ozone-induced losses vary between 2.4% for aspen to 10% for soybean.  Model agreement with observations improves when O 3 concentrations are adjusted to monitor height.  Bias correction is important for estimating biomass loss, sensitivity results.  GEOS-Chem adjoint shows US anthropogenic emissions dominate the crop/tree loss.  Influence of anthropogenic CO from China exceeds CO domestic influence for loss of Ponderosa pine.  Large differences between the state’s contribution to the loss in crops/trees and the state’s own emissions.