View in EDS

Reconciling Observed and Predicted Tropical Rainforest OH Concentrations.

Saved in:
Bibliographic Details
Title: Reconciling Observed and Predicted Tropical Rainforest OH Concentrations.
Authors: Jeong, Daun1,2, Seco, Roger1,3, Emmons, Louisa4, Schwantes, Rebecca4,5,6, Liu, Yingjun7,8, McKinney, Karena A.7, Martin, Scot T.7,9, Keutsch, Frank N.7,10,11, Gu, Dasa1,12, Guenther, Alex B.1, Vega, Oscar13, Tota, Julio14, Souza, Rodrigo A. F.15, Springston, Stephen R.16, Watson, Thomas B.16, Kim, Saewung1 saewungk@uci.edu
Source: Journal of Geophysical Research. Atmospheres. Jan2022, Vol. 127 Issue 1, p1-18. 18p.
Subject Terms: *Nitric oxide, *Volatile organic compounds, *Photochemistry, Hydroxyl group, Diurnal atmospheric pressure variations, Tropical forests
Abstract: 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. Key Points: OH observations with a chemical ionization mass spectrometer during the GoAmazon2014/5 study were lower than some previous studiesBox model simulations of OH were carried out with five different chemical mechanismsObserved and model‐predicted OH concentrations agree to within measurement uncertainty of 40% [ABSTRACT FROM AUTHOR]
Copyright of Journal of Geophysical Research. Atmospheres is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
Database: GreenFILE
Description
Abstract: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. Key Points: OH observations with a chemical ionization mass spectrometer during the GoAmazon2014/5 study were lower than some previous studiesBox model simulations of OH were carried out with five different chemical mechanismsObserved and model‐predicted OH concentrations agree to within measurement uncertainty of 40% [ABSTRACT FROM AUTHOR]
ISSN:2169897X
DOI:10.1029/2020JD032901