Ground-based measurements of tropospheric CO, C2H6, and HCN from Australiaat 34 degrees S latitude during 1997-1998

High spectral resolution (0.004 cm(-1)) infrared solar absorption measureme nts Of CO, C2H6, and HCN have been recorded with the Fourier transform spec trometer located at the Network for the Detection of Stratospheric Change c omplementary station at the University of Wollongong, Australia (34.45 degr eesS, 150.88 degreesE, 30 m above sea level). The time series covers March 1997 to February 1998. Profile retrievals with maximum sensitivity in the u pper troposphere show distinct seasonal cycles for all three molecules with maxima during October-December 1997. Best fits to the time series of daily averages yield peak 0.03-14 km columns (molecules cm(-2)) of 1.54 X 10(18) for CO, 8.56 X 10(15) for C2H6, and 6.56 X 10(15) for HCN during austral s pring. Mixing ratio profiles of all three molecules during this time show m axima in the upper troposphere. Isentropic back trajectories suggest the el evated CO, C2H6, and HCN columns above Wollongong originated from southern Africa or South America with no significant contribution from the intense t ropical Asian emissions during the strong El Nino event of 1997-1998.