Scientific information recovered from the partially obstructed HIRDLS instrument

The High Resolution Dynamics Limb Sounder (HIRDLS) instrument was designed to advance on previous infrared limb sounders in 5 ways, by; retrieving many species (10, plus PSC's, stratospheric aerosols and thin cirrus), sounding down to the tropopause and into the upper troposphere, retrieving with high vertical resolution (1km), obtaining data at high horizontal resolution (~5° in longitude), and obtaining data for 5-6 years or more. During the Aura launch a piece of plastic placed to maintain cleanliness of the optics ruptured, and ended up in front of the scan mirror, limiting the available views of the atmosphere to one partial beam width at the most extreme angle from the orbital plane. Of the capabilities originally envisaged, only the ability to sample at multiple azimuths is now lost.

This paper will briefly explain how the HIRDLS team is correcting for the effects of the blockage and the reduced aperture by applying revised algorithms, adapted to the new instrument configuration. Results of retrievals obtained using these revised algorithms will be shown for temperature and some of the major species, with an assessment of their characteristics. Remaining problems and approaches to them will be outlined. Projections of future data quality will be presented, with a discussion of the use of these data in middle atmosphere scientific investigations.