INFRARED SPECTROSCOPIC MEASUREMENTS OF THE ETHANE (C2H6) TOTAL COLUMNABUNDANCE ABOVE MAUNA-LOA, HAWAII - SEASONAL-VARIATIONS

About 200 i.r. solar spectra recorded at 0.01 cm(-1) resolution on 71 days between November 1991 and July 1993 at the Network for the Detect ion of Stratospheric Change (NDSC) station at Mauna Loa, Hawaii (latit ude 19.53 degrees N, longitude 155.58 degrees W, elevation 3.459 km) h ave been analyzed with a nonlinear least-squares spectral fitting tech nique to study temporal variations in the total column of atmospheric ethane (C2H6) above the site. The results were derived from the analys is of the unresolved v(7) band (P)Q(3) subbranch at 2976.8 cm(-1) A di stinct seasonal cycle is observed with a factor of 2 variation, a maxi mum total column of 1.16 x 10(16)mol.cm(-2) at the end of winter, and a minimum total column of 0.53 x 10(16) mol.cm(-2) at the end of summe r. Our measurements are compared with previous observations and model predictions.