ILAS for stratospheric ozone layer monitoring: outline of data processing (Version 3.00 and 3.10) and validation experiments

The Improved Limb Atmospheric Spectrometer (ILAS) developed by the Environment Agency of Japan was successfully flown in space on board the Sun synchronous polar-orbiting satellite ADEOS (Advanced Earth Observing Satellite) on August 17, 1996, ADEOS, with ILAS and other sensors on board, performed successfully until June 30, 1997, after which an unexpected sudden failure of the ADEOS satellite solar battery system prevented further measurements. ILAS made over 6700 measurements of the stratospheric ozone layer with the solar occultation technique, producing vertical profiles of ozone, other ozone-chemistry related gases, aerosol extinction coefficients, temperature, and pressure in the high-latitude stratosphere. The ILAS data processing software so far used was Version 3.00, and algorithm tests are currently being made for the improved Version 3.10 software which includes correction of nongas contribution due to aerosols and polar stratospheric clouds (PSCs). The present paper describes mainly the status of data processing and validation and the results of validation and comparison with other independent data sets.