The CONvective TRansport of Active Species in the Tropics (CONTRAST) Experiment

Abstract:

The CONTRAST experiment was conducted from Guam (13.5° N, 144.8° E) using the NSF/NCAR Gulfstream V (GV) research aircraft during January and February 2014. The main objective of the experiment was to investigate the impact of deep convection on chemical composition and ozone photochemical budget. The experiment was part of three coordinated experiments to target the tropical Western Pacific during Northern Hemisphere winter, when and where the most extensive deep convection in Earth’s climate system develops. The partner missions were ATTREX (Airborne Tropical Tropopause Experiment), which deployed the high-altitude NASA Global Hawk, and CAST (Coordinated Airborne Studies in the Tropics), which used the UK FAAM BAe 146 research aircraft to investigate the lower to mid-troposphere of the Western Pacific. A total of 16 research flights were conducted using the GV, with measurement of ozone, CO, CH₄, and CO_2, as well as a large suite of chemical tracer measurements including organic and inorganic halogen species, NMHCs, and OVOCs. The research flights from Guam covered 20°S to 40°N latitude, 130°E to 165°E longitude, and 0.1 to 15.2 km ASL in altitude, successfully sampled the recent and aged outflows from active deep convective storms and defined the background chemical conditions of the tropical western Pacific during boreal winter. The results are expected to bring new insights into the ozone and halogen budgets of the tropical troposphere. These airborne observations, especially in combination with the CAST and ATTREX data, provide key measurements and diagnostics for evaluating and constraining chemistry-climate models. Highlights of the experiment and initial findings will be presented.