The effect of lightning NO<sub>x</sub> production on surface ozone in the continental United States

Abstract

Abstract.Lightning NO x emissions calculated using the US National Lightning Detection Network data were found to account for 30% of the total NO x emissions for July-August 2004, a period chosen both for having higher lightning NO x production and high ozone levels, thus maximizing the likelihood that such emissions could impact peak ozone levels. Including such emissions led to modest, but sometimes significant increases in simulated surface ozone when using the Community Multi-scale Air Quality Model (CMAQ). Three model simulations were performed, two with the addition of lightning NO x emissions, and one without. Domain-wide daily maximum 8-h ozone changes due to lightning NO x were less than 2 ppbv in 71% of the cases with a maximum of 10 ppbv; whereas the difference in 1-h ozone was less than 2 ppbv in 77% of the cases with a maximum of 6 ppbv. Daily maximum 1-h and 8-h ozone for grids containing O 3 monitoring stations changed slightly, with more than 43% of the cases differing less than 2 ppbv. The greatest differences were 42 ppbv for both 1-h and 8-h O 3 , though these tended to be on days of lower ozone. Lightning impacts on the seasonwide maximum 1-h and 8-h averaged ozone decreased starting from the 1st to 4th highest values (an average of 4th highest, 8-h values is used for attainment demonstration in the US). Background ozone values from the y-intercept of O 3 versus NO z curve were 42.2 and 43.9 ppbv for simulations without and with lightning emissions, respectively. Results from both simulations with lightning NO x suggest that while North American lightning production of NO x can lead to significant local impacts on a few occasions, they will have a

Modeling natural emissions in the Community Multiscale Air Quality (CMAQ) Model–I: building an emissions data base

“…Nitrogen in the form of NO x is far greater than that emitted as ammonia or nitryl chloride (the latter is confined to marine coastal areas). The data suggest that lightning could occasionally make significant contributions to ozone formation in summer over the southern US, consistent with that reported by Kaynak et al (2008). Lightning NO x also has the greatest potential to contribute to nitrogen deposition in summer over the southern and eastern US.…”

“…The US National Aeronautics and Space Administration (NASA) is experimenting with using remote sensing of atmospheric chemical signatures to estimate lightning NO x for use in real-time air quality forecasting (http://nasascience.nasa.gov/earth-science/ applied-sciences/resources/CMAQr1.pdf). The method used here is very similar to that of Kaynak et al (2008) who used lightning flash data from the National Lightning Detection Network (NLDN). Kaynak et al (2008) horizontally allocated lightning-derived NO x based on whether clouds were simulated to occur in the CMAQ model grid cell associated with the measured lightning flash or in adjacent cells whenever no clouds were simulated in the flash cell.…”

“…The method used here is very similar to that of Kaynak et al (2008) who used lightning flash data from the National Lightning Detection Network (NLDN). Kaynak et al (2008) horizontally allocated lightning-derived NO x based on whether clouds were simulated to occur in the CMAQ model grid cell associated with the measured lightning flash or in adjacent cells whenever no clouds were simulated in the flash cell. The latter occurrence was very rare (<1.5% at most).…”

“…There are disadvantages to neglecting certain classes of emissions as reported by Chameides et al (1988), Novak and Pierce (1993), DeCaria et al (2000), Guenther et al (2000), Tonnesen et al (2006), Kaynak et al (2008), Koo et al (2010) and others. First, neglected emissions may, at some times and in some places, play significant roles in the photochemical evolution of the atmosphere even in the presence of anthropogenic emissions.…”

“…Vertical allocation of emissions was based on published lightning profiles and modeled cloud top heights. Kaynak et al (2008) made CMAQ model simulations for July-August 2004 with and without lightning NO x and found that lightning could contribute significantly to ground level ozone in some circumstances. Another recent study that also determined that lightning could contribute significantly to ozone levels, particularly in the southeastern US, is the work performed by Koo et al (2010).…”