Airborne Fourier transform spectrometer observations in support of EOS Aura validation

Nearly coincident observations of HNO3, HCl, N2O, and H2O in the vicinity of the northern polar vortex during the NASA Polar Aura Validation Experiment (PAVE) in January and February 2005 have shown reasonably good agreement between aircraft-borne infrared spectrometer results and results from High Resolution Dynamics Limb Sounder (HIRDLS), Microwave Limb Sounder (MLS), and Tropospheric Emission Spectrometer (TES) instruments aboard the EOS Aura satellite. Mixing ratio profile and column results show that special attention must be given to retrievals that may be disturbed by the dynamics and chemical processing of the polar vortex. Largest differences occur on days when observations were made in regions of the vortex with large gradients in wind and potential vorticity, and the differences were especially noticeable in results for HNO3 and HCl, whose profiles may be dramatically changed by vortex activity. The mean difference between coincident column observations by MLS and the Fourier transform spectrometer (FTS) is 2.4%, VMR profile amounts generally are in good agreement between the satellite observations where they are available. The average difference between coincident HCl column observations by MLS and the FTS is 4.6%.