m s -1 METDOT3D VWIND v-component of horizontal wind (cell corners) m s -1 METDOT3D UHAT_JD contravariant U-component wind×density×Jacobian kg m -1 s -1 METDOT3D VHAT_JD contravariant V-component wind×density×Jacobian kg m -1 s -1 METDOT3D UWINDC u-component



  Figure S1: The geographical distribution of the δ 15 N value of atmospheric NOx in per mil (‰) from 10 UTC to 22 UTC on Apr 13, 2002 near the northwest corner of the study domain, simulated by CMAQ, based on NEI-2002 and 2016 meteorology. 


Figure S2 :

 S2 Figure S2: The geographical distribution of the δ 15 N value of atmospheric NOx in per mil (‰) from 04 UTC to 13 UTC on Dec 8, 2002 near the northwest corner of the study domain, simulated by CMAQ, based on NEI-2002 and 2016 meteorology. 


Figure S3 :

 S3 Figure S3: The geographical distribution of the δ 15 N value of total NOx emissions in each season (Winter: Jan-Mar; Spring: Apr-Jun; Summer: Jul-Sep; Fall: Oct-Dec) in per mil (‰) throughout the Midwest simulated by SMOKE, based on NEI-2002. 


Figure S4 :

 S4 Figure S4: The geographical distribution of the planetary boundary layer (PBL) height in meters during each season (Winter: Jan-Mar; Spring: Apr-Jun; Summer: Jul-Sep; Fall: Oct-Dec) of 2016 throughout the Midwest. 


Figure S5 :

 S5 Figure S5: The geographical distribution of the planetary boundary layer (PBL) height in meters during each season (Winter: Jan-Mar; Spring: Apr-Jun; Summer: Jul-Sep; Fall: Oct-Dec) of 2002 throughout the Midwest. 


Figure S6 :

 S6 Figure S6: The geographical distribution of the δ 15 N value of atmospheric NOx in each season (Winter: Jan-Mar; Spring: Apr-Jun; Summer: Jul-Sep; Fall: Oct-Dec) in per mil (‰) throughout the Midwest simulated by CMAQ, based on NEI-2002 and 2002 meteorology. 


Figure S7 :

 S7 Figure S7: The geographical distribution of the δ 15 N value of atmospheric NOx in each season (Winter: Jan-Mar; Spring: Apr-Jun; Summer: Jul-Sep; Fall: Oct-Dec) in per mil (‰) throughout the Midwest simulated by CMAQ, based on NEI-2016 and 2016 meteorology. 


Figure S8 :

 S8 Figure S8: The geographical distribution of the δ 15 N value of atmospheric NOx in each season (Winter: Jan-Mar; Spring: Apr-Jun; Summer: Jul-Sep; Fall: Oct-Dec) in per mil (‰) throughout the Midwest simulated by CMAQ, based on NEI-2002 and 2016 meteorology, under the "amplified deposition" scenario. 


Figure S9 :

 S9 Figure S9: The nested-domain simulation of the δ 15 N value of atmospheric NOx in each season (Winter: Jan-Mar; Spring: Apr-Jun; Summer: Jul-Sep; Fall: Oct-Dec) in per mil (‰) within IN, IL, OH, and KY, based on NEI-2002 and 2016 meteorology.