Summertime tropospheric ozone enhancement associated with a cold front passage due to stratosphere‐to‐troposphere transport and biomass burning: Simultaneous ground‐based lidar and airborne measurements

Abstract

Stratosphere‐to‐troposphere transport (STT) and biomass burning (BB) are two important natural sources for tropospheric ozone that can result in elevated ozone and air‐quality episode events. High‐resolution observations of multiple related species are critical for complex ozone source attribution. In this article, we present an analysis of coinciding ground‐based and airborne observations, including ozone lidar, ozonesonde, high spectral resolution lidar (HSRL), and multiple airborne in situ measurements, made on 28 and 29 June 2013 during the Southeast Nexus field campaign. The ozone lidar and HSRL reveal detailed ozone and aerosol structures as well as the temporal evolution associated with a cold front passage. The observations also captured two enhanced (+30 ppbv) ozone layers in the free troposphere (FT), which were determined from this study to be caused by a mixture of BB and stratospheric sources. The mechanism for this STT is tropopause folding associated with a cutoff upper level low‐pressure system according to the analysis of its potential vorticity structure. The depth of the tropopause fold appears to be shallow for this case compared to events observed in other seasons; however, the impact on lower tropospheric ozone was clearly observed. This event suggests that strong STT may occur in the southeast United States during the summer and can potentially impact lower troposphere during these times. Statistical analysis of the airborne observations of trace gases suggests a coincident influence of BB transport in the FT impacting the vertical structure of ozone during this case study.

Ozone Variability and Anomalies Observed During SENEX and SEAC4RS Campaigns in 2013

“…The average STT layer occurrence frequency for these months (Table ) is 31%. Tropopause folding, the most important mechanism for STT (Sprenger et al, ), occurs predominantly at midlatitudes, approximately between 40° and 60° according to Liang et al (); however, it eventually affects the subtropics through quasi‐isentropic descent (Kuang et al, , ). According to Sprenger & Wernli (), the STT events that affect the tropospheric ozone in SEUS primarily originate from the cross‐tropopause flux over British Columbia, Canada, and the northwestern U.S.…”

A Case Study of Ozone Diurnal Variation in the Convective Boundary Layer in the Southeastern United States Using Multiple Observations and Large-Eddy Simulation

“…Observations were collected on 6 September 2013 during the SEAC 4 RS field campaign, which included ozone and meteorological fields from multiple platform instruments located on the campus of the University of Alabama in Huntsville (UAH 34.724 • N, 86.645 • W) [3,30]. Local standard time in Huntsville, Alabama (USA central time zone) is 5 h earlier (GMT-5) according to the universal time coordinate (UTC).…”

Evaluation of potential sources of a priori ozone profiles for TEMPO tropospheric ozone retrievals

“…These three sites were selected due to data availability (http://www-air.larc.nasa.gov/ missions/TOLNet/data.html) and to represent differing parts of North America, which will be observed by TEMPO, with varying topography, meteorology, and atmospheric chemistry conditions (overview information for each station is presented in Table 1). The RO3QET system is located in the southeast US where the air quality is impacted by both anthropogenic and natural emission sources, complex chemistry, and multiple transport pathways (e.g., Hidy et al, 2014;Johnson et al, 2016;Kuang et al, 2017). During the summer of 2014 this lidar system measured O 3 profiles from the surface to ∼ 5 km a.g.l.…”

“…For this study, we use the linear estimate approach to perform theoretical TEMPO re- trievals and evaluate the impact of a priori profiles on these retrievals. This linear estimation approach is a good firstorder approximation of non-linear satellite retrievals and has been used in numerous research studies (e.g., Bowman et al, 2002;Worden et al, 2007;Kulawik et al, 2006Kulawik et al, , 2008Zhang et al, 2010;Natraj et al, 2011;Zoogman et al, 2014). In this approach, shown in Eq.…”