A new airborne instrument based on pulsed cavity ring-down spectroscopy for simultaneous detection of N2O5, NO3, NO2 and O3 in the upper troposphere lower stratosphere is being developed for global atmospheric monitoring. OCIS codes: 010.0010, 120.0120, 140.0140, 280.0280, 300.0300, 300.6260, 300.6360.