Influence of Cold Fronts on Variability of Daily Surface O3 over the Houston-Galveston-Brazoria Area in Texas USA during 2003–2016

Abstract

Abstract:We investigated the impacts of cold fronts on area-wide peak O 3 and regional background O 3 mixing ratios on a daily scale over the Houston-Galveston-Brazoria (HGB) area of southeastern Texas during the O 3 seasons (April-October) of [2003][2004][2005][2006][2007][2008][2009][2010][2011][2012][2013][2014][2015][2016]. Back trajectories showed that an 18h time lag existed between arrival of cold fronts in the HGB area and onset of a predominately northerly flow. Cold fronts showed increasing effects on both peak and background O 3 over the HGB area. Compared to no front days, average peak O 3 mixing ratios during the cold front 1st days, cold front 2+ days, and post frontal days increased 0.7, 5.9, and 9.0 ppbv, respectively while average background O 3 increased 2.9, 6.8, and 8.6 ppbv, respectively. The change in wind direction from southerly to northerly was the most important factor causing increasing O 3 levels. Wind direction shifts caused variation of other meteorological factors (i.e., wind speed, precipitation, temperature, cloud cover, and relative humidity) and tended to overshadow their effects on O 3 over the HGB area. On a long-term and large-scale view, cold fronts over the HGB area could be regarded as interruptions in the cleansing effects of predominantly marine southerly flow from the Gulf of Mexico.

Traffic, transport, and vegetation drive VOC concentrations in a major urban area in Texas

“…The high O 3 days (May 13 and 14) had transport of continental airmass from the North. Previous studies have shown that long-range transport of the northern continental air mass contributes to an elevated regional O 3 background in Texas (Lei et al, 2019(Lei et al, , 2018. May 24 and 25 also had continental airmass from the North but these days did not have the high actinic flux required for the peak O 3 production (Fig.…”

Identification of Sea Breeze Recirculation and Its Effects on Ozone in Houston, TX, During DISCOVER‐AQ 2013

“…MDA8 ozone level is in the middle for Oscillation and Northerly Cluster with the mean values of 37.60 ppbv and 35.40 ppbv in HGB and of 42.93 ppbv and 41.01 ppbv in SA, respectively. Both Northerly and Oscillation Cluster bring polluted continental air masses to the region which can elevate background ozone (Lei et al, 2018; Rappenglück et al, 2008). Oscillation Cluster has slightly higher ozone concentrations than Northerly Cluster because the higher temperature in Oscillation Cluster can result in more production of ozone.…”

Meteorological Conditions During an Ozone Episode in Dallas‐Fort Worth, Texas, and Impact of Their Modeling Uncertainties on Air Quality Prediction

“…In summer, westward extension of the Bermuda subtropical high favors the development of a southerly low‐level jet over the Southern Great Plains, while transient processes (e.g., passages of frontal systems) may disturb such flow patterns at times (Klein et al, ; Lei et al, ; Zhu & Liang, ). During summer months, O 3 over the Southern Great Plains shows correlation with the Bermuda High variations: a stronger/weaker Bermuda High leads to lower/higher summer mean O 3 in the region with a magnitude of variation of around 6 ppbv (Zhu & Liang, ).…”