The Convective Transport of Active Species in the Tropics (CONTRAST) Experiment

Abstract

The Convective Transport of Active Species in the Tropics (CONTRAST) experiment was conducted from Guam (13.5° N, 144.8° E) during January-February 2014. Using the NSF/NCAR Gulfstream V research aircraft, the experiment investigated the photochemical environment over the tropical western Pacific (TWP) warm pool, a region of massive deep convection and the major pathway for air to enter the stratosphere during Northern Hemisphere (NH) winter. The new observations provide a wealth of information for quantifying the influence of convection on the vertical distributions of active species. The airborne in situ measurements up to 15 km altitude fill a significant gap by characterizing the abundance and altitude variation of a wide suite of trace gases. These measurements, together with observations of dynamical and microphysical parameters, provide significant new data for constraining and evaluating global chemistry climate models. Measurements include precursor and product gas species of reactive halogen compounds that impact ozone in the upper troposphere/lower stratosphere. High accuracy, in-situ measurements of ozone obtained during CONTRAST quantify ozone concentration profiles in the UT, where previous observations from balloon-borne ozonesondes were often near or below the limit of detection. CONTRAST was one of the three coordinated experiments to observe the TWP during January-February 2014. Together, CONTRAST, ATTREX and CAST, using complementary capabilities of the three aircraft platforms as well as ground-based instrumentation, provide a comprehensive quantification of the regional distribution and vertical structure of natural and pollutant trace gases in the TWP during NH winter, from the oceanic boundary to the lower stratosphere.

The O2/N2 Ratio and CO2 Airborne Southern Ocean Study

“…Mixing ratios of VOCs with known continental sources observed during ORCAS were very low in comparison to measurements made over the tropical and midlatitude Pacific Ocean using the same instrumentation during previous January and February field campaigns, Tropical Ocean Troposphere Exchange of Reactive Halogen Species and Oxygenated VOC (TORERO; Volkamer et al 2015) and Convective Transport of Active Species in the Tropics (CONTRAST; Pan et al 2016; Fig. 9).…”

An observationally constrained evaluation of the oxidative capacity in the tropical western Pacific troposphere

“…The CONTRAST campaign [ Pan et al ., ] was based in Guam (13.5°N, 144.8°E) during January and February 2014. Observations were obtained by a suite of chemical, meteorological, microphysical, and radiative instruments on board the NSF/NCAR Gulfstream V (GV) aircraft.…”

“…We use data collected during the CONTRAST aircraft campaign [ Pan et al ., ], conducted during January and February 2014 from Guam (13.5°N, 144.8°E), to model the abundance of OH in the TWP. While OH was not observed during CONTRAST, a multitude of chemical species, radiative variables, and meteorological parameters needed to model the in situ production and loss of OH were measured.…”

A comparison of very short lived halocarbon (VSLS) and DMS aircraft measurements in the tropical west Pacific from CAST, ATTREX and CONTRAST

“…Sample processing time was 2 min. More details can be found in Apel et al (2003). The system was calibrated with NOAA standards SX-3515 and SX 3562 prior to deployment.…”

“…However, major uncertainties exist regarding the relative contribution of individual sources (Carpenter and Liss, 2000). Global distributions and controls of VSLS emissions are also not well known, exacerbated by large spatial variability in sea-air fluxes (Carpenter et al, 2005;Archer et al, 2007;Ziska et al, 2013;Stemmler et al, 2013;Orlikowska and Schulz-Bull, 2009). These are important considerations as deep convection in the tropics can rapidly transport VSLSs to the upper tropospherelower stratosphere (UTLS) and make a significant contribution to photochemical ozone depletion (Von Glasow et al, 2004;Salawitch et al, 2005;Yang et al, 2005;Montzka et al, 2011;Saiz-Lopez et al, 2012;Feng et al, 2007;Laube et al, 2008;Sinnhuber and Meul, 2015).…”