Nitrous acid at Concordia (inland site) and Dumont d'Urville (coastal site), East Antarctica

Abstract

During the austral summer 2010/2011, nitrous acid (HONO) was investigated for the first time at Concordia (75°06′S, 123°33′E) and Dumont D'Urville (66°40′S, 140°01′E), two sites located in East Antarctica. Hereby, for the first time in Antarctica, HONO was measured by deploying a long path absorption photometer (LOPAP). At Concordia, HONO mixing ratios at 1 m above the snow surface ranged between 5 and 60 pptv from end of December 2010 to mid January 2011. Lowest levels were observed under cloudy conditions. Levels exhibit a diurnal cycle with a maximum in the morning (around 06:00) and in the evening (around 21:00). At Dumont d'Urville, background mixing ratios remained close to 2 pptv in February 2011. No clear diurnal cycles were detected at that site but several events of air masses export from inland Antarctica were encountered with enhanced HONO levels (10 pptv) at night. These first HONO data gained in East Antarctica are discussed in terms of sources and sinks along with synoptic weather conditions.