TY - JOUR

T1 - Sulfuric acid in the Amazon basin

T2 - measurements and evaluation of existing sulfuric acid proxies

AU - Myers, Deanna C.

AU - Kim, Saewung

AU - Sjostedt, Steven

AU - Guenther, Alex B.

AU - Seco, Roger

AU - Vega Bustillos, Oscar

AU - Tota, Julio

AU - Souza, Rodrigo A. F.

AU - Smith, James N.

N1 - Funding Information: Financial support. This research has been supported by the Office of Science (grant nos. DE-SC0011122 and DE-SC0019000). Funding Information: 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) and the local Research Support Foundation (FA-PEAM/GOAMAZON). We also acknowledge support from 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; grant nos. DE-SC0011122 and DE-SC0019000) program of that office. James N. Smith acknowledges support from a Brazilian Science Mobility Program (Programa Ciência sem Fron- teiras) Special Visiting Researcher Scholarship. Roger Seco acknowledges grants RYC2020-029216-I and CEX2018-000794-S funded by MCIN/AEI/10.13039/501100011033 and by “ESF Investing in your future”. The authors would also like to thank Michelia Dam, Hayley Glicker, Adam Thomas, and Jeremy Wakeen, for their contributions to discussions regarding this project. Publisher Copyright: © 2022 Deanna C. Myers et al.

PY - 2022

Y1 - 2022

N2 - Sulfuric acid is a key contributor to new particle formation, though measurements of its gaseous concentrations are difficult to make. Several parameterizations to estimate sulfuric acid exist, all of which were constructed using measurements from the Northern Hemisphere. In this work, we report the first measurements of sulfuric acid from the Amazon basin. These measurements are consistent with concentrations measured in Hyytiälä, Finland, though, unlike Hyytiälä, there is no clear correlation of sulfuric acid with global radiation. There was a minimal difference in sulfuric acid observed between the wet and dry seasons in the Amazon basin. We also test the efficacy of existing proxies to estimate sulfuric acid in this region. Our results suggest that nighttime sulfuric acid production is due to both a stabilized Criegee intermediate pathway and oxidation of SO2 by OH, the latter of which is not currently accounted for in existing proxies. These results also illustrate the drawbacks of the common substitution of radiation for OH concentrations. None of the tested proxies effectively estimate sulfuric acid measurements at night. For estimates at all times of day, a recently published proxy based on data from the boreal forest should be used. If only daytime estimates are needed, several recent proxies that do not include the Criegee pathway are sufficient. More investigation of nighttime sulfuric acid production pathways is necessary to close the gap between measurements and estimates with existing proxies.

AB - Sulfuric acid is a key contributor to new particle formation, though measurements of its gaseous concentrations are difficult to make. Several parameterizations to estimate sulfuric acid exist, all of which were constructed using measurements from the Northern Hemisphere. In this work, we report the first measurements of sulfuric acid from the Amazon basin. These measurements are consistent with concentrations measured in Hyytiälä, Finland, though, unlike Hyytiälä, there is no clear correlation of sulfuric acid with global radiation. There was a minimal difference in sulfuric acid observed between the wet and dry seasons in the Amazon basin. We also test the efficacy of existing proxies to estimate sulfuric acid in this region. Our results suggest that nighttime sulfuric acid production is due to both a stabilized Criegee intermediate pathway and oxidation of SO2 by OH, the latter of which is not currently accounted for in existing proxies. These results also illustrate the drawbacks of the common substitution of radiation for OH concentrations. None of the tested proxies effectively estimate sulfuric acid measurements at night. For estimates at all times of day, a recently published proxy based on data from the boreal forest should be used. If only daytime estimates are needed, several recent proxies that do not include the Criegee pathway are sufficient. More investigation of nighttime sulfuric acid production pathways is necessary to close the gap between measurements and estimates with existing proxies.

U2 - 10.5194/acp-22-10061-2022

DO - 10.5194/acp-22-10061-2022

M3 - Journal article

AN - SCOPUS:85135617311

VL - 22

SP - 10061

EP - 10076

JO - Atmospheric Chemistry and Physics

JF - Atmospheric Chemistry and Physics

SN - 1680-7316

IS - 15

ER -