Abstract

Thunderstorms can significantly influence the air composition via strong updraft and lightning nitrogen oxides (LNOx). In this study, the ozonesondes and TROPOMI nitrogen dioxide (NO2) observations for two cases are combined with model to investigate the effects of typical strong convection on vertical redistribution of air pollutants in Nanjing, southeastern China. The ozonesonde observations show higher O3 and water vapor mixing ratios in the upper troposphere (UT) after convection, indicating the strong updraft transporting lower-level airmass into the UT, and the possible downward O3-rich air near the top of UT over the convective period. During the whole convection life cycle, the UT O3 production is driven by the chemistry (> 87 %) and reduced by the LNOx (−40 %). Sensitivity tests demonstrate that neglecting LNOx in standard TROPOMI NO2 products causes overestimated air mass factors over fresh lightning regions and the opposite for outflow and aged lightning areas. Therefore, a new high-resolution retrieval algorithm is applied to estimate the LNOx production efficiency. Our work shows the demand for high-resolution modeling and satellite observations on LNOx emissions of both active and dissipated convection, especially small-scale storms.

Highlights

  • Convection can transport the surface pollutants and moisture from the planetary boundary layer to the upper troposphere (UT) in a short time, where the gaseous pollutants have a longer lifetime due to the slower reaction rates, except for photolysis, in 15 the colder environment (Dickerson et al, 1987)

  • As revealed by modeling using WRF-Chem, the dynamic contribution of O3 variation in the 2019 case was generated by mixing with the UT O3-rich air due to strong updraft, while it was caused by vertical advection of high background O3 in the 2020 case

  • The UT O3 enhancement of the 2019 case decreases by 40 % if 275 the lightning nitrogen oxides (LNOx) is included in the model, indicating the importance of the LNOx

Read more

Summary

Introduction

Convection can transport the surface pollutants and moisture from the planetary boundary layer to the upper troposphere (UT) in a short time, where the gaseous pollutants have a longer lifetime due to the slower reaction rates, except for photolysis, in 15 the colder environment (Dickerson et al, 1987). Two main methods have been proposed to distinguish LNOx from the NO2 background pollution: 1) subtracting the weighted temporal average 30 NO2 of areas with few flashes before the satellite passing time (Pickering et al, 2016; Bucsela et al, 2019; Allen et al, 2019; Lapierre et al, 2020) and 2) directly using customized lightning air mass factors (AMFs) for each convection event (Beirle et al, 2009; Zhang et al, 2020). We combine ground observations and model simulations to investigate the origin of higher UT O3 45 and water vapor mixing ratio (Qv) after convection, and we try to distinguish the contributions of physical processes, chemical reactions and LNOx. For the first time, the TROPOMI (TROPOspheric Monitoring Instrument) NO2 observations are used to identify LNOx PEs in southeastern China. Because the IC DE of all these lightning data is low in China, we conservatively used the merged CG data with a constant ratio (3:1) of IC and CG based on Wu et al (2016) and 85 Bandholnopparat et al (2020)

TROPOMI Data
Model Simulations
Model Evaluation
Relation of lightning and TROPOMI products
Estimations of LNOx
Conclusions
Findings
315 References
Full Text
Published version (Free)

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call