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

Ruixue Lei,Robert Talbot,Mark Estes,Sing-Chun Wang,Yuxuan Wang

doi:10.3390/atmos9050159

Ruixue Lei, Robert Talbot + Show 3 more

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https://doi.org/10.3390/atmos9050159

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Abstract

We investigated the impacts of cold fronts on area-wide peak O3 and regional backgroundO3 mixing ratios on a daily scale over the Houston-Galveston-Brazoria (HGB) area of southeasternTexas during the O3 seasons (April–October) of 2003–2016. Back trajectories showed that an 18h timelag existed between arrival of cold fronts in the HGB area and onset of a predominately northerlyflow. Cold fronts showed increasing effects on both peak and background O3 over the HGB area.Compared to no front days, average peak O3 mixing ratios during the cold front 1st days, coldfront 2+ days, and post frontal days increased 0.7, 5.9, and 9.0 ppbv, respectively while averagebackground O3 increased 2.9, 6.8, and 8.6 ppbv, respectively. The change in wind direction fromsoutherly to northerly was the most important factor causing increasing O3 levels. Wind directionshifts caused variation of other meteorological factors (i.e., wind speed, precipitation, temperature,cloud cover, and relative humidity) and tended to overshadow their effects on O3 over the HGB area.On a long-term and large-scale view, cold fronts over the HGB area could be regarded as interruptionsin the cleansing effects of predominantly marine southerly flow from the Gulf of Mexico.

Highlights

O3 mixing ratios depending upon initial conditions: (1) In winter, O3 mixing ratios usually increased after a cold front passage because of downward mixing of O3 -enriched air from the stratosphere into the troposphere by tropopause folding; (2) When folding was less common in summer, O3 might decrease due to advection of clean air masses or to enhanced cloudiness preventing photochemical production of O3, chemical destruction by nitrogen oxides, and heterogeneous chemistry in clouds; (3) O3 concentrations could remain nearly constant or have a temporary decrease followed by a similar increase when folding was missing
We investigated the impacts of cold fronts on surface peak and background O3 calculated by the Texas Commission on Environmental Quality (TCEQ) on a daily scale over the HGB area using North American Regional Reanalysis (NARR) meteorology reanalysis data, Weather Prediction Center (WPC) cold front archive, and Hybrid Single Particle Lagrangian
We investigated the impacts of cold fronts on surface peak and background O3 calculated by TCEQ method on a daily scale using NARR meteorology reanalysis data, the WPC

Summary

Introduction

The influence of cold fronts on surface ozone (O3 ) is complicated since it can be positive or negative depending on multiple factors such as cold front structure, stage, season, and location.Kunz and Speth [1] discussed three cold front vertical structures and their developments of near-groundO3 mixing ratios depending upon initial conditions: (1) In winter, O3 mixing ratios usually increased after a cold front passage because of downward mixing of O3 -enriched air from the stratosphere into the troposphere by tropopause folding; (2) When folding was less common in summer, O3 might decrease due to advection of clean air masses or to enhanced cloudiness preventing photochemical production of O3 , chemical destruction by nitrogen oxides, and heterogeneous chemistry in clouds;(3) O3 concentrations could remain nearly constant or have a temporary decrease followed by a similar increase when folding was missing.The influence of cold fronts on surface O3 exhibits various results in different areas. The influence of cold fronts on surface ozone (O3 ) is complicated since it can be positive or negative depending on multiple factors such as cold front structure, stage, season, and location. O3 mixing ratios depending upon initial conditions: (1) In winter, O3 mixing ratios usually increased after a cold front passage because of downward mixing of O3 -enriched air from the stratosphere into the troposphere by tropopause folding; (2) When folding was less common in summer, O3 might decrease due to advection of clean air masses or to enhanced cloudiness preventing photochemical production of O3 , chemical destruction by nitrogen oxides, and heterogeneous chemistry in clouds;. Atmosphere 2018, 9, 159 the summer planetary boundary layer (PBL) and limiting downward mixing of stratospheric air helping to preserve low surface O3 associated with passages of cold fronts that preceded stratospheric intrusions.

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