HCl and ClO profiles inside the Antarctic vortex as observed by SMILES in November 2009: comparisons with MLS and ACE-FTS instruments

Abstract

Abstract. We present vertical profiles of hydrogen chloride (HCl) and chlorine monoxide (ClO) as observed by the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) inside the Antarctic vortex on 19–24 November 2009. The SMILES HCl value reveals 2.8–3.1 ppbv between 450 and 500 K levels in potential temperature (PT). The high value of HCl is highlighted since it is suggested that HCl was a main component of the total inorganic chlorine (Cly), defined as Cly ≃ HCl + ClO + chlorine nitrate (ClONO2) inside the Antarctic vortex in spring, owing to low ozone values. To confirm the quality of two SMILES Level 2 (L2) data products provided by Japan Aerospace Exploration Agency (JAXA) and National Institute of Information and Communications Technology (NICT) from a view point of the partitioning of Cly, comparisons are made using other satellite data, from the Aura Microwave Limb Sounder (MLS) and Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS). HCl values from the SMILES NICT L2 product agree to within 10% with the MLS HCl data between 425 and 650 K levels in PT and with the ACE-FTS HCl data between 425 and 575 K, respectively. The SMILES JAXA L2 product is 10 to 20% smaller than that from MLS (ACE-FTS) between 400 (500 K) and 700 K. For ClO in daytime, the difference between SMILES (JAXA and NICT) and MLS was less than ±0.05 ppbv between 500 and 650 K with the ClO values less than 0.2 ppbv. ClONO2 values as measured by ACE-FTS also reveal 0.2 ppbv at 475–500 K level, resulting in the HCl/Cly ratios of 0.91–0.95. The high HCl value and HCl/Cly ratio found from the three satellite instruments agree with the past observations inside the Antarctic vortex at this time (October to November) of year in the lower stratosphere.