Rebecca Hornbrook1,*, Eric Apel1, Alan Hills1, Lucy Carpenter2, Stephen Andrews2, Jean-Francois Lamarque1, Doug Kinnison1, Simone Tilmes1, Brad Pierce3, Rainer Volkamer4, and the TORERO Science Team

1Atmospheric Chemistry Division, NCAR, Boulder, CO, *rsh@ucar.edu; 2Department of Chemistry, University of York, York, United Kingdom; 3NOAA/NESDIS Center for Satellite Applications and Research, Cooperative Institute for Meteorological Satellite Studies, Madison, WI, 4CIRES, University of Colorado Boulder, Boulder, CO

A51E-0117

The primary objective of TORERO was to study the release and transport of halogenated gases and oxidized VOCs in the Eastern Tropical Pacific during the season of high biologic productivity. Many halogenated gases, also called very short-lived species (VSLS; t < 6 mo.) are emitted from the ocean and can impact marine boundary layer (MBL) O3, as well as stratospheric O3 due to convection to the UT/LS. Despite efforts to quantify these species, uncertainties remain as to the regional distribution of sources and sinks of these compounds and their impact on MBL chemistry.

TORERO

Tropical Ocean tRoposphere

Exchange of Reactive halogen

species and Oxygenated VOC

TORERO motivation

Several VSLS were measured in situ using GC/MS on board the NCAR/NSF GV using the NCAR Trace Organic Gas Analyzer (TOGA), and from the NOAA RV Ka’imimoana by the University of York.

Organohalogen measurements

Figure 2. Observations of DMS and several organohalogens during three TORERO flights in both oligotrophic (RF05) and nutrient-rich environments.

Marine Boundary Layer Organohalogens

Figure 1. Flight tracks of the 17 research flights flown from Antofagasta, Chile and San Jose, Costa Rica, 19-Jan to 29-Feb-2012.

Chl-a

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RF15, UTC 22-Feb-2012

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Comparison with WACCM/CAM-chem Model output from the global CAM-chem chemistry-climate model, with recently integrated observations of very short-lived (VSL) halocarbons and reactive iodine and bromine species (Saiz-Lopez et al., 2012), are compared against several of the VSLS observed by TOGA during TORERO.

Saiz-Lopez, A., et al., ACP, 12, 3939, doi:10.5194/acp-12-3939-2012, 2012.

Summary

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Figure 3. TOGA data from the MBL (< 500 m) and U. of York data on surface maps of MODIS sea surface temperatures (SST) and Chlorophyll-a (Chl-a).

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Ratios of Halogenated Species Ratios of pairs of halogenated species, i.e., CHBr3/CH2Br2, are indicators or MBL influence. τCHBr3 ≈ 1 mo. τCH2Br2 ≈ 4 mo. τCH3I ≈ 1 week τCH2ClI ≈ 2 hours τCH2I2 ≈ 5 min τDMS ≈ 1 day

Figure 4. RAQMS model curtain plots showing MBL exposure, with observed CHBr3/CH2Br2 ratios.

Figure 5. CAM-chem modeled and observed VSLS from three TORERO flights.

Figure 6. CAM-chem curtain plots and observed CHBr3.

• VSLS emissions from the east-tropical Pacific Ocean are tied to factors involving SST and biologically active chlorophyll-a production, but differ from DMS.

• MBL ship- and aircraft-based observations of most VSLS are in good agreement. • Ratios of VSLS are indicators of recent influence of MBL air to the free

troposphere and of aging within the free troposphere. • Initial comparisons of observations to WACCM/CAM-chem model output show

reasonable agreement with CHBr3, CH2Br2 and CHBr2Cl.