Measurements of Reactive Nitrogen Compounds (NO, NOX, NOY) During SHARP

Concentrations of reactive nitrogen species were measured atop the Moody Tower at the University of Houston from April 15-May 31, 2009 as part of the Study of Houston Atmospheric Radicals Program (SHARP). A research-grade three channel instrument simultaneously measured concentrations of NO, NO_X (NO_X = NO + NO₂), and NO_Y (NO_Y = NO_X + HNO₃ + PAN + HONO + HO₂NO₂ + NO₃ + 2*N₂O₅+ p-NO₃^- + ....) at parts per trillion sensitivity and 1 second time resolution. NO₂ was selectively photolyzed to NO using a solid state light source. Heated molybdenum screen (375°C) was used to reduce NO_Y species to NO. Results will be compared with results from the 2006 TEXAQS-II study, and will be discussed in the context of emission source regions, diurnal variations, and correlations with other primary and secondary trace species.