OBSERVATIONS OF AEROSOL BY THE HALOE EXPERIMENT ONBOARD UARS - A PRELIMINARY VALIDATION

The HALOE experiment measures vertical profiles of aerosol extinction at five infrared wavelengths. Four of these observations are obtained using a combination of gas filter and broadband radiometer measurement s in bands of HF, HCl, CH4, and NO centered at wavelengths of 2.45, 3. 40, 3.45, and 5.26 mum, respectively. The fifth is obtained using broa dband radiometer measurements Of CO2 transmission at 2.79 mum. Error a nalysis shows that the random extinction uncertainties are generally l ess than 10% in the aerosol layer, increasing to over 20% at the profi le tops. HALOE spectral extinction measurements are shown to be consis tent with predicted spectral extinction for stratospheric sulfate aero sol. Profile comparisons between HALOE and independent sources result in generally good agreement in the shape and magnitude of peak extinct ion and the altitude where the peak extinction occurs. In addition, gl obal aerosol distributions obtained from the data are consistent with expected aerosol morphology. Although the validation is preliminary, t he HALOE aerosol data appear to be of excellent quality and to accurat ely represent optical characteristics and distribution of the aerosols .