Diurnal variations of BrONO2 observed by MIPAS-B in the Arctic and at mid-latitudes

Despite being much less abundant, the contribution of bromine to stratospheric ozone depletion is similar to that of chlorine. Moreover, against the background of abating levels of chlorine in the stratosphere, bromine will become more and more important due to its natural sources. The two major inorganic bromine species in the lower stratosphere are bromine oxide (BrO) and bromine nitrate (BrONO2) - the relative abundances of which are mainly controlled by photochemical processes. While BrO has first been observed around 20 years ago, BrONO2 has been detected by satellite limb observations in the mid-infrared spectral region only recently (in 2008). Two Arctic flights of the balloon-borne Michelson Interferometer for Passive Atmospheric Sounding (MIPAS-B) were carried out from Kiruna (68 °N, Sweden) in January 2010 and March 2011 inside the stratospheric polar vortices. Diurnal variations of BrONO2 around sunrise are measured by MIPAS-B for the first time. Dedicated to the simultaneous observation of BrO and BrONO2 including their diurnal variability, a balloon campaign took place from Timmins (49 °N, Canada) in September 2014. The remote sounding instrumentation consisted of three spectrometers covering the UV-VIS, the mid-infrared and the sub-mm/microwave spectral region. In this contribution we present the first results from MIPAS-B: time- and height-dependent distributions of BrONO2 and NO2 volume mixing ratios together with a comprehensive error estimation and further diagnostic parameters of the inversion procedure. All results will be compared to the Chemistry Climate Model EMAC (ECHAM5/MESSy Atmospheric Chemistry).