New Measurements of Stratospheric HOx from Aura MLS and Balloon

The Aura MLS instrument measures OH near 2512 GHz and HO₂ near 660 GHz. The OH bands have sensitivity to obtain daily maps for 30-80 km. The HO₂ band has sensitivity to obtain monthly zonal means for 30 - 75 km. Since launch, the MLS OH and HO₂ bands have been performing to predicted sensitivity levels. Data will be presented concerning the HOx dilemma in the upper stratosphere and mesosphere. Additionally, a balloon precursor to the MLS OH instrument has had three scientific flights over the last four years. In September 2003, the balloon instrument flew from noon until 2 AM the next morning and showed a very slow decay of OH above 45 km. The MLS OH and HO₂ bands can also probe this long-lived HOx from measurements on the dark side of the orbit. These observations of night-time HOx put further constraints on the chemistry.