Measurement of HONO Flux using Relaxed Eddy Accumulation during SHARP

Vertical HONO fluxes were measured based on the relaxed eddy accumulation (REA) technique during the Study of Houston Atmospheric Radical Precussor (SHARP) study in spring 2009 on the roof of Moody Tower. A REA sampling unit was deployed and HONO concentrations in updraft air flow and downdraft air flow were measured by a highly sensitive HONO instrumentbased on aqueous LOng Path Absorption Photometry (LOPAP). Strong upward HONO fluxes were observed, indicating strong surface HONO sources and the upward HONO transport. Diurnal pattern of HONO flux, its correlation with meteorological parameters and other chemial species, and possibler influence of th ebuilding walls to atmospheric turbulence are presented.