Measurement report: In situ observations of deep convection without lightning during the tropical cyclone Florence 2018

Nussbaumer, Clara M.; Tadić, Ivan; Dienhart, Dirk; Wang, Nijing; Edtbauer, Achim; Ernle, Lisa; Williams, Jonathan; Obersteiner, Florian; Gutiérrez-Álvarez, I.; Harder, Hartwig; Lelieveld, J.; Fischer, H.

doi:10.5194/acp-21-7933-2021

Cited by 6 publications

(5 citation statements)

References 72 publications

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“…Lightning was lowest over the remote Pacific Ocean during ATom, in line with our understanding of lightning formation, which is thought to require solid particles for the formation of light ice particles. In fact, solid particles, such as dust or sand, are usually more abundant over or in proximity to land masses, which makes lighting strongest over the (tropical) continents (Christian et al., 2003; Nussbaumer, Tadic, et al., 2021; Verma et al., 2021). Pan et al.…”

Section: Resultsmentioning

confidence: 99%

Ozone Formation Sensitivity to Precursors and Lightning in the Tropical Troposphere Based on Airborne Observations

Nussbaumer,

Kohl,

Pozzer

et al. 2024

JGR Atmospheres

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Tropospheric ozone (O3) is an important greenhouse gas that is also hazardous to human health. The formation of O3 is sensitive to the levels of its precursors NOx (≡NO + NO2) and peroxy radicals, for example, generated by the oxidation of volatile organic compounds (VOCs). A better understanding of this sensitivity will show how changes in the levels of these trace gases could affect O3 levels today and in the future, and thus air quality and climate. In this study, we investigate O3 sensitivity in the tropical troposphere based on in situ observations of NO, HO2 and O3 from four research aircraft campaigns between 2015 and 2023. These are OMO (Oxidation Mechanism Observations), ATom (Atmospheric Tomography Mission), CAFE Africa (Chemistry of the Atmosphere Field Experiment in Africa) and CAFE Brazil, in combination with simulations using the EMAC atmospheric chemistry—climate model. We use the metric α(CH3O2) together with NO to investigate the O3 formation sensitivity. We show that O3 formation is generally NOx‐sensitive in the lower and middle tropical troposphere and is in a transition regime in the upper troposphere. By distinguishing observations impacted by lightning or not we show that NO from lightning is the most important driver of O3 sensitivity in the tropics. NOx‐sensitive chemistry predominates in regions without lightning impact, with α(CH3O2) ranging between 0.56 and 0.82 and observed average O3 levels between 35 and 55 ppbv. Areas affected by lightning exhibit strongly VOC‐sensitive O3 chemistry with α(CH3O2) of about 1 and average O3 levels between 55 and 80 ppbv.

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Section: Resultsmentioning

confidence: 99%

Ozone Formation Sensitivity to Precursors and Lightning in the Tropical Troposphere Based on Airborne Observations

Nussbaumer,

Kohl,

Pozzer

et al. 2024

JGR Atmospheres

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“…Additionally, diurnal variations of hBL lead to entrainment of free tropospheric air into the MBL, in particular during the early morning (Fischer et al, 2015;Fischer et al, 2019). While vertical profiles of HCHO mixing ratios decrease with height (Anderson et al, 2017;Klippel et al, 2011;Heikes et al, 2001), H2O2 and MHP mixing ratios increase up to a local maximum above the boundary layer (Allen et al, 2022;Nussbaumer et al, 2021a;Klippel et al, 2011). Therefore, intrusion of air masses from the lower troposphere will most likely result in a decrease of HCHO in the MBL, while peroxide mixing ratios would likely increase as shown in Fischer et al (2015).…”

Section: Photochemical Production and Loss Of H2o2mentioning

confidence: 99%

“…With its lifetime of several hours, H2O2 enables horizontal or vertical transport of HOx by e.g. advection/convection of air masses (Nussbaumer et al, 2021a). However, H2O2 also transitions readily into the liquid phase and thus also acts as a net sink for HOx radicals via its dry and wet deposition.…”

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confidence: 99%

“…In the MBL, H2O2 concentration gradients are small, so that horizontal transport becomes unimportant. Additionally, the MBL height is relatively constant with no significant diel variation and thus vertical transport is weak, except close to convective clouds (Nussbaumer et al 2021a, Fischer et al, 2015. Therefore, the H2O2 distribution in the MBL depends largely on net photochemical tendencies and deposition processes (Fischer et al, 2015).…”

mentioning

confidence: 99%

“…due to oxidation of isoprene and anthropogenic emissions) and seasonal variability (Zhu et al, 2020;De Smedt et al, 2018;De Smedt et al, 2015;De Smedt et al, 2012;Marbach et al, 2009). HCHO measurements are currently used as HCHO / NOx ratios for O3 sensitivity studies (i.e., NOx or VOC limitation) and global mapping of OH variability in remote air (Nussbaumer et al, 2021a;Nussbaumer et al, 2022;Tadic et al, 2020;Wolfe et al, 2019;Schroeder et al, 2017;Wolfe et al, 2016). In very clean conditions like the remote MBL or the free troposphere, HCHO production is dominated by the photo-oxidation of methane (R5), with the bimolecular self-reaction of methyl peroxy radicals the rate limiting factor (R11) (Nussbaumer et al, 2021b;Wagner et al, 2001).…”

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confidence: 99%

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Formaldehyde and hydroperoxide distribution around the Arabian Peninsula – evaluation of EMAC model results with ship-based measurements

Dienhart

Brendel

Crowley

et al. 2022

Preprint

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Abstract. Formaldehyde (HCHO) and hydrogen peroxide (H2O2) play a key role in atmospheric oxidation processes. They act as sources and sinks for HOx radicals (OH + HO2), with OH as the primary oxidant that governs the atmospheric self-cleaning capacity. Measurements of these species allow evaluation of global chemistry-transport models which need to account for multifarious source distributions, transport and mixing, complex photochemical reaction pathways and deposition processes. HCHO is an intermediate produced during the oxidation of VOCs and is an indicator of photochemical activity and combustion related emissions. Due to its many production pathways and its rather short lifetime of only several hours at noon, accurate modelling of this species is challenging. In this study, we use in situ observations in the marine boundary layer (MBL) to evaluate results of the general circulation model EMAC (ECHAM5/MESSy2 Atmospheric Chemistry). The dataset was obtained during the AQABA ship campaign around the Arabian Peninsula in summer 2017. This region is characterized by high mixing ratios of photochemical air pollution, high humidity and strong solar irradiation, especially in the area around the Suez Canal and the Arabian Gulf. We find that EMAC fails to predict absolute mixing ratios of HCHO, especially during high pollution events, but it reproduces most of the HCHO variability seen in the different regions, while it systematically overestimates H2O2. This is mainly attributed to missing primary VOC emissions and the overestimation of HOx radicals, and also related to the models coarse spatial resolution.

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Formaldehyde and hydroperoxide distribution around the Arabian Peninsula – evaluation of EMAC model results with ship-based measurements

et al. 2023

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Abstract. Formaldehyde (HCHO), hydrogen peroxide (H2O2) and organic hydroperoxides (ROOH) play a key role in atmospheric oxidation processes. They act as sources and sinks for HOx radicals (OH + HO2), with OH as the primary oxidant that governs the atmospheric self-cleaning capacity. Measurements of these species allow for evaluation of chemistry-transport models which need to account for multifarious source distributions, transport, complex photochemical reaction pathways and deposition processes of these species. HCHO is an intermediate during the oxidation of volatile organic compounds (VOCs) and is an indicator of photochemical activity and combustion-related emissions. In this study, we use in situ observations of HCHO, H2O2 and ROOH in the marine boundary layer (MBL) to evaluate results of the general circulation model EMAC (ECHAM5/MESSy2 Atmospheric Chemistry; European Center HAMburg, Modular Earth Submodel System). The dataset was obtained during the Air Quality and Climate Change in the Arabian Basin (AQABA) ship campaign around the Arabian Peninsula in summer 2017. This region is characterized by high levels of photochemical air pollution, humidity and solar irradiation, especially in the areas around the Suez Canal and the Arabian Gulf. High levels of air pollution with up to 12 ppbv HCHO, 2.3 ppbv ROOH and relatively low levels of H2O2 (≤0.5 ppbv) were detected over the Arabian Gulf. We find that EMAC failed to predict absolute mixing ratios of HCHO and ROOH during high-pollution events over the Arabian Gulf, while it reproduced HCHO on average within a factor of 2. Dry deposition velocities were determined for HCHO and H2O2 at night with 0.77±0.29 cm s−1 for HCHO and 1.03±0.52 cm s−1 for H2O2 over the Arabian Sea, which were matched by EMAC. The photochemical budget of H2O2 revealed elevated HOx radical concentrations in EMAC, which resulted in an overestimation of H2O2 by more than a factor of 5 for the AQABA dataset. The underestimated air pollution over the Arabian Gulf was related to EMAC's coarse spatial resolution and missing anthropogenic emissions in the model.

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Measurement report: In situ observations of deep convection without lightning during the tropical cyclone Florence 2018

Cited by 6 publications

References 72 publications

Ozone Formation Sensitivity to Precursors and Lightning in the Tropical Troposphere Based on Airborne Observations

Ozone Formation Sensitivity to Precursors and Lightning in the Tropical Troposphere Based on Airborne Observations

Formaldehyde and hydroperoxide distribution around the Arabian Peninsula – evaluation of EMAC model results with ship-based measurements

Formaldehyde and hydroperoxide distribution around the Arabian Peninsula – evaluation of EMAC model results with ship-based measurements

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