Temperature Dependence of Air-Broadening and Shift Coefficients of O3Lines in the ν1Band

Abstract

High-resolution Fourier transform absorption spectra of ozone broadened by dry air have been recorded at a number of temperatures from −63°C to 29°C. Using a multispectrum nonlinear least-squares procedure, we fit 29 of these spectra simultaneously to determine the air-broadening and shift coefficients and their temperature dependences for 450 lines in the 9-μm region; most of these belong to the ν1band. Partial air-broadening results were obtained for 104 additional lines, and room-temperature self-broadening coefficients were also determined for most of the 554 lines measured. These results cover a wide range of rotational quantum numbers, particularly in theRbranch, withJ″ ≤ 55 andKa″≤ 12. The variation of the retrieved broadening and shift parameters with the rotational quantum numbers has been examined; particularly interesting behavior of the broadening coefficients is noted as the value ofKa″approaches that ofJ″. The broadening and shift coefficients compare well with previous room-temperature measurements in the ν1and other bands. The temperature-dependence results are also consistent (within the stated uncertainties) with the few previous measurements of the temperature dependence of air- and N2-broadening coefficients in other O3bands, but disagree with the mean value given in the HITRAN compilation.