In situ stratospheric measurements of CH 4 , 13 CH 4 , N 2 O, and OC 18 O using the Bliss tunable diode laser spectrometer

Simultaneous in situ measurements of stratospheric CH 4 , 13 CH 4 , N 2 O, OC 18 O, pressure, and temperature have been made from Palestine, Texas (32°N) in September 1988 with the JPL Balloon‐borne Laser In Situ Sensor (BLISS). Measurements of CH 4 and N 2 O in the altitude range 30–35 km agree well with other measurements, except for an anomalously high value for the N 2 O at 31 km. Measurements of CH 4 support earlier observations of a fold in the vertical profile. A ratio for stratospheric 13 CH 4 /CH 4 of 0.0105 ± 0.0010 implies an enrichment of δ 13 C = −45 ± 92 parts per thousand over the PDB value, in agreement with previous measurements in the troposphere. A large mixing ratio of 1.9 ± 0.2 ppmv for OC 18 O is measured, corresponding to an enrichment of δ 18 O = 280 ± 50 parts per thousand for the 18 O isotopic species over the SMOW value.