Airborne Measurements of Aerosol Parameters and Trace Gas Species

Measurement Description: Our Group will provide in situ measurements of aerosol parameters along with dew point and ozone aboard the NASA DC-8 during the SAGE-III Ozone Loss and Validation Experiment (SOLVE). The fast-response (~1 Hz) suite of instruments will include: condensation nuclei counters to determine the number and size of aerosols between 0.004 and 0.1 nm and the volatility of aerosols > 0.015 nm; two different aerosol scattering spectrometer probes for obtaining particle size distributions over the 0.1 to 20 nm size range; a cryogenic hygrometer to determine dew points down to -90°C; and a chemiluminescence instrument to provide O₃ mixing ratio data. The aerosol instruments provide an overall precision of ~5%, whereas the dew point and O₃ measurements are precise to about 0.3°C and 1 ppbv, respectively. This same instrument payload was successfully deployed aboard the DC-8 during the spring 1999 PEM-Tropics B mission. In flight, we will distribute the ozone, total condensation nuclei, and dew point signals to the DC-8 data acquisition and distribution system (DADS) for the viewing by the mission scientist and other investigators. Our post-mission analyses will be performed in collaboration with groups providing remote and meteorological measurements/ interpretations with the primary objectives of

1. providing data for interpolating between nadir and zenith DIAL profiles of ozone and water vapor,
2. developing "calibration" information so that multi-wavelength lidar relative aerosol scattering intensities can be inverted to provide psuedo aerosol size distributions and optical depth via vertical soundings of species,
3. addressing questions related to the impact of aviation upon upper tropospheric/lower stratospheric aerosol budgets and
4. examining the impact of heterogeneous processes on cirrus clouds on the ozone budget of the upper troposphere.