HCHO measurements during CHABLIS in coastal Antarctica

Gas phase formaldehyde concentrations were measured during the 2004-5 CHABLIS campaign at Halley research station, Antarctica. Data coverage span from March 2004 through to January 2005 thus capturing the majority of the year. Factors controlling HCHO concentration include local chemical sources and sinks, and exchange with the 5 snow surface. The measured seasonality is in line with previous observations from Neumayer station, with maximum in summer and minimum during the winter months, but with lower absolute concentrations throughout the year. Steady state calculations show oxidation of methane to be the overwhelming source of formaldehyde during the summer, with destruction dominated by photolysis and reaction with Br atoms.