TY - JOUR

T1 - Reconciling Observed and Predicted Tropical Rainforest OH Concentrations

AU - Jeong, Daun

AU - Seco, Roger

AU - Emmons, Louisa

AU - Schwantes, Rebecca

AU - Liu, Yingjun

AU - McKinney, Karena A.

AU - Martin, Scot T.

AU - Keutsch, Frank N.

AU - Gu, Dasa

AU - Guenther, Alex B.

AU - Vega, Oscar

AU - Tota, Julio

AU - Souza, Rodrigo A. F.

AU - Springston, Stephen R.

AU - Watson, Thomas B.

AU - Kim, Saewung

N1 - Funding Information: Institutional support was provided by the Central Office of the Large Scale Biosphere Atmosphere Experiment in Amazonia (LBA), the National Institute of Amazonian Research (INPA), and Amazonas State University (UEA). The authors acknowledge the Atmospheric Radiation Measurement (ARM) Climate Research Facility, a user facility of the United States Department of Energy, Office of Science, sponsored by the Office of Biological and Environmental Research, and support from the Atmospheric System Research (ASR) program of that office. Funding was obtained from the United State Department of Energy (DOE, DESC00011122), the Amazonas State Research Foundation (FAPEAM), the Sao Paulo Research Foundation (FAPESP), the Brazilian Scientific Mobility Program (CsF/CAPES), and the United States National Science Foundation (NSF). The research was conducted under Scientific License 001030/2012-4 of the Brazilian National Council for Scientific and Technological Development (CNPq). This material is based upon work supported by the National Center for Atmospheric Research, which is a major facility sponsored by the NSF under Cooperative Agreement No. 1852977. The AP-CIMS deployed for this field campaign was loaned by National Center for Atmospheric Research (NCAR) in Boulder, Colorado, USA. The authors would like to thank Dr. Glenn M. Wolfe at NASA GSFC for the discussions on the manuscript and model simulations and Dr. Camille Mouchel-Vallon and Dr. Duseong Jo at NCAR ACOM for help on the NCAR box model BOXMOX. Funding Information: Institutional support was provided by the Central Office of the Large Scale Biosphere Atmosphere Experiment in Amazonia (LBA), the National Institute of Amazonian Research (INPA), and Amazonas State University (UEA). The authors acknowledge the Atmospheric Radiation Measurement (ARM) Climate Research Facility, a user facility of the United States Department of Energy, Office of Science, sponsored by the Office of Biological and Environmental Research, and support from the Atmospheric System Research (ASR) program of that office. Funding was obtained from the United State Department of Energy (DOE, DESC00011122), the Amazonas State Research Foundation (FAPEAM), the Sao Paulo Research Foundation (FAPESP), the Brazilian Scientific Mobility Program (CsF/CAPES), and the United States National Science Foundation (NSF). The research was conducted under Scientific License 001030/2012‐4 of the Brazilian National Council for Scientific and Technological Development (CNPq). This material is based upon work supported by the National Center for Atmospheric Research, which is a major facility sponsored by the NSF under Cooperative Agreement No. 1852977. The AP‐CIMS deployed for this field campaign was loaned by National Center for Atmospheric Research (NCAR) in Boulder, Colorado, USA. The authors would like to thank Dr. Glenn M. Wolfe at NASA GSFC for the discussions on the manuscript and model simulations and Dr. Camille Mouchel‐Vallon and Dr. Duseong Jo at NCAR ACOM for help on the NCAR box model BOXMOX. Publisher Copyright: © 2021. American Geophysical Union. All Rights Reserved.

PY - 2022

Y1 - 2022

N2 - We present OH observations made in Amazonas, Brazil during the Green Ocean Amazon campaign (GoAmazon2014/5) from February to March of 2014. The average diurnal variation of OH peaked with a midday (10:00–15:00) average of 1.0 × 106 (±0.6 × 106) molecules cm−3. This was substantially lower than previously reported in other tropical forest photochemical environments (2–5 × 106 molecules cm−3) while the simulated OH reactivity was lower. The observational data set was used to constrain a box model to examine how well current photochemical reaction mechanisms can simulate observed OH. We used one near-explicit mechanism (MCM v3.3.1) and four condensed mechanisms (i.e., RACM2, MOZART-T1, CB05, CB6r2) to simulate OH. A total of 14 days of analysis shows that all five chemical mechanisms were able to explain the measured OH within instrumental uncertainty of 40% during the campaign in the Amazonian rainforest environment. Future studies are required using more reliable NOx and VOC measurements to further investigate discrepancies in our understanding of the radical chemistry in the tropical rainforest.

AB - We present OH observations made in Amazonas, Brazil during the Green Ocean Amazon campaign (GoAmazon2014/5) from February to March of 2014. The average diurnal variation of OH peaked with a midday (10:00–15:00) average of 1.0 × 106 (±0.6 × 106) molecules cm−3. This was substantially lower than previously reported in other tropical forest photochemical environments (2–5 × 106 molecules cm−3) while the simulated OH reactivity was lower. The observational data set was used to constrain a box model to examine how well current photochemical reaction mechanisms can simulate observed OH. We used one near-explicit mechanism (MCM v3.3.1) and four condensed mechanisms (i.e., RACM2, MOZART-T1, CB05, CB6r2) to simulate OH. A total of 14 days of analysis shows that all five chemical mechanisms were able to explain the measured OH within instrumental uncertainty of 40% during the campaign in the Amazonian rainforest environment. Future studies are required using more reliable NOx and VOC measurements to further investigate discrepancies in our understanding of the radical chemistry in the tropical rainforest.

KW - F0AM

KW - hydroxyl radical

KW - isoprene

KW - photochemistry

U2 - 10.1029/2020JD032901

DO - 10.1029/2020JD032901

M3 - Journal article

AN - SCOPUS:85122749715

VL - 127

JO - Journal of Geophysical Research: Solid Earth

JF - Journal of Geophysical Research: Solid Earth

SN - 0148-0227

IS - 1

M1 - e2020JD032901

ER -