Table 1. The UMD-CTM Simulations With Different Sources of NOx Emissions Simulation Name Anthropogenic NOxa Lightning NOxb Period Simulated L0 CEMS 2004 OTD/LIS (240) May-Aug 2004 L1 (standard) CEMS 2002, CEMS 2004 NLDN-based (240) May-Aug 2002, May-Aug 2004 L2 (doubled lightning) CEMS 2004 NLDN-based (480) May-Aug 2004 noAnthro-NAc none NLDN-based (240) May-Aug 2002, May-Aug 2004 noL-NAc CEMS 2002, CEMS 2004 none May-Aug 2002, May-Aug 2004 no NOx SIP Call CEMS 2002 NLDN-based (240) May-Aug 2004 aEmission inventory used for the power plant sector for the contiguous United States (CONUS). bObserved flash rates used to adjust the model-calculated flash rates over the CONUS; lightning NO moles produced per flash over the CONUS are in parentheses. cNorth America is defined as Canada, the CONUS, Mexico, and the Gulf of Mexico.