GROUND-BASED REMOTE-SENSING OF METHANE HEIGHT PROFILES WITH A TUNABLEDIODE-LASER HETERODYNE SPECTROMETER

Height distributions of methane in the troposphere and stratosphere we re derived from high resolution absorption spectra observed with a gro und-based tunable diode laser heterodyne spectrometer. The center wave number of the measured methane absorption line is 1223.1561 cm-1. In t he retrieval of methane height profiles, a volume mixing ratio of meth ane was assumed to have a constant value in the troposphere and to dec rease with a constant rate in the stratosphere. The tropospheric mixin g ratio and the decreasing rate in stratosphere were derived to be 1.7 +/- 0.1 ppmv and -0.06 ppmv/km, respectively, for measurements at Tsu kuba (36.0-degrees-N, 140.1-degrees-E) on December 17 and 20, 1991.