SONEX Airborne Mission and Coordinated POLINAT-2 Activity: Overview and Accomplishments

The SASS (Subsonic Assessment) Ozone and NO(x) Experiment (SONEX) was an airborne field campaign conducted in October-November 1997 in the vicinity of the North Atlantic Flight Corridor Lo study the impact of aircraft emissions on NOx and ozone (03). A fully instrumented NASA DC-8 aircraft was used as the primary SONEX platform. SONEX activities were closely coordinated with the European POLINAT-2 (Pollution from Aircraft Emissions in the North Atlantic Flight Corridor) program, which used a Falcon-20 aircraft and an instrumented in-service Swissair B-747. Both campaigns focused on the upper troposphere/"lowermost" stratosphere (UT/LS) as the region of greatest interest. Specific sampling goals were achieved with the aid of a state-of-the art modeling and meteorological support system, which allowed targeted sampling of air parcels with desired characteristics. A substantial impact of aircraft emissions on NO(x) and O3 in the UT/LS of the study region is shown to be present. It is further shown that the NO(x)- HO(x)-O3 relationships are highly nonlinear and must be accurately simulated to make meaningful future predictions with global models. SONEXIPOLINAT-2 results are being published in Special Sections of GRL and JGR. Here we provide a brief overview of SONEX design, implementation, and expected results to provide a context within which these publications can be understood.