Clustering Surface Ozone Diurnal Cycles to Understand the Impact of Circulation Patterns in Houston, Texas
Abstract
The diurnal cycle of surface ozone is directly influenced by the chemistry and meteorological processes which affect a region. This study uniquely employs clustering analysis to examine the complete diurnal pattern of surface ozone for the Houston-Galveston-Brazoria (HGB) region and links the identified patterns to meteorological regimes for June, July, and August (JJA) of three years (2011, 2014, 2015). Four features, representing times of the day when surface ozone is directly influenced by meteorological and chemical processes, were implemented into the clustering algorithm: decreasing slope during the early morning, daily minimum just before sunrise, increasing slope after the sun rises, and an average of consistently higher concentrations during the afternoon. The clustering results yielded four individual clusters, ranging from a less variable, mostly flat diurnal pattern with low mixing ratios (~ 20 ppbv) that barely deviate from the mean, to a more variable, pronounced diurnal cycle with very high mixing ratios (> 70 ppbv) in the afternoon. The four cluster-derived groups are characterized by distinctive circulation patterns and by well-known regional meteorological processes that affect the HGB region, including the southerly low-level jet and the Bermuda High. The clustering analysis linked to the meteorological regimes helps elucidate ozone interannual variability for the three years. This study reveals how the shape of the diurnal pattern and the morning ozone concentrations have prediction capabilities for the coming afternoon hours. This study demonstrates the value of using a clustering method to comprehend diurnal ozone cycle variability of a region for a better understanding of how and why surface ozone behaves due to meteorological processes on both daily and interannual timescales.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.A21G2650B
- Keywords:
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- 0305 Aerosols and particles;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0317 Chemical kinetic and photochemical properties;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0345 Pollution: urban and regional;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0365 Troposphere: composition and chemistry;
- ATMOSPHERIC COMPOSITION AND STRUCTURE