VALIDATION OF TEMPERATURE-MEASUREMENTS FROM THE HALOGEN OCCULTATION EXPERIMENT

The Halogen Occultation Experiment (HALOE) onboard UARS measures profi les of limb path solar attenuation in eight infrared bands. These meas urements are used to infer profiles of temperature, gas mixing ratios of seven species, and aerosol extinction at five wavelengths. The obje ctive of this paper is to validate profiles of temperature retrieved f rom atmospheric transmission measurements in the 2.80-mu m CO2 band. T emperatures are retrieved fur levels above where aerosol affects the s ignals (35 km) to altitudes where the signal-to-noise decreases to uni ty (similar to 85 km). At altitudes from 45 to 35 km the profile under goes a gradual transition from retrieved to National Meteorological Ce nter (NMC) temperatures and below 35 km the profile is strictly from t he NMC. This validation covers the uncertainty analysis, internal vali dations, and comparisons with independent measurements. Monte Carlo ca lculations using all known random and systematic errors determine typi cal measurement uncertainties of 5 K for altitudes below 80 km. Compar isons of coincident HALOE sunrise and sunset measurements are an indic ator of the upper limit of measurement uncertainty. The sunrise-sunset comparisons have random and systematic differences which are less tha n 10 K for altitudes below 80 km. Comparisons of HALOE to lidar and ro cket measurements typically have random differences of similar to 5 K for altitudes below 65 km. The mean differences for the correlative co mparisons indicate that HALOE temperatures have a cold bias (2 to 5 K) in the upper stratosphere and stratopause.