Comparison of HALOE O3 and H2O Observations from UARS with Ground and Balloonborne Measurements

The HALOE experiment was launched on the UARS satellite by the Space Shuttle Discovery at 7:11:04 EDT on September 12, 1991. After allowing for a period of outgassing, HALOE began taking routine science observations on October 11. HALOE uses the experiment approach of solar occultation and the gas filter and broad band radiometer instrument techniques to measure vertical profiles of HCℓ, HF, CH4, NO, NO2, H2O, O3, aerosol, and temperature versus pressure. The measurements cover a broad altitude range from the upper troposphere in some cases to the lower thermosphere in the case of nitric oxide. Latitude coverage provided by the occultation geometry ranges from 80 ° S to 80 °N over the course of one year. The experiment has operated essentially without flaw for more than three years. Instrument stability over this time, as judged by the maximum signal change when viewing the sun exoatmospherically, is ≤ 2 to 3 %.