Ceilometer Monitoring of Boundary-Layer Height and Its Application in Evaluating the Dilution Effect on Air Pollution

Junhong Lee, Je Woo Hong, Keunmin Lee, Jinkyu Hong, Erik Velasco, Yong Jae Lim, Jae Bum Lee, Kipyo Nam, Jihoon Park

Research output: Contribution to journalArticle

Abstract

The dilution effect caused by boundary-layer evolution over land has strong influences on air quality. Accurate and continuous measurements of the boundary-layer height over urban areas are therefore needed for complete air-quality assessments. Commercial ceilometers, in combination with reliable and simple methodologies, can be used to retrieve the mixed-layer height, and represent a means of obtaining information on vertical mixing and atmospheric structure above cities. Here, we evaluate various retrieval algorithms based on the gradient method against high-temporal-resolution radiosonde observations. Based on the results, we propose a simple algorithm by using the gradient method, the correction of background noise and the moving averages, with the minimum number of parameters that need to be adjusted to the local properties and the instrument itself. The algorithm is adjusted for Seoul, Korea, and improves the retrieval performance by reducing high-frequency noise. The algorithm is used to investigate the relationship between the evolution of the daytime mixed-layer height and air pollution under a two-layer mixing model where changes in concentration depend only on the urban boundary-layer growth and air entrainment from the free atmosphere. Using 2 months of ceilometer retrievals of mixed-layer height and air-quality data from across the city, we find strong negative correlations for primary emitted pollutants such as NO2, CO, SO2, and particulate matter smaller than 10 µm, and a modest positive correlation for O3. The results provide insight into the significant influence of urban boundary-layer evolution on Seoul’s air quality.

Original languageEnglish
Pages (from-to)435-455
Number of pages21
JournalBoundary-Layer Meteorology
Volume172
Issue number3
DOIs
Publication statusPublished - 2019 Sep 15

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air quality
dilution
atmospheric pollution
boundary layer
mixed layer
monitoring
atmospheric structure
vertical mixing
radiosonde
entrainment
particulate matter
urban area
methodology
effect
pollutant
atmosphere
air
method
city

All Science Journal Classification (ASJC) codes

  • Atmospheric Science

Cite this

Lee, Junhong ; Hong, Je Woo ; Lee, Keunmin ; Hong, Jinkyu ; Velasco, Erik ; Lim, Yong Jae ; Lee, Jae Bum ; Nam, Kipyo ; Park, Jihoon. / Ceilometer Monitoring of Boundary-Layer Height and Its Application in Evaluating the Dilution Effect on Air Pollution. In: Boundary-Layer Meteorology. 2019 ; Vol. 172, No. 3. pp. 435-455.
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Ceilometer Monitoring of Boundary-Layer Height and Its Application in Evaluating the Dilution Effect on Air Pollution. / Lee, Junhong; Hong, Je Woo; Lee, Keunmin; Hong, Jinkyu; Velasco, Erik; Lim, Yong Jae; Lee, Jae Bum; Nam, Kipyo; Park, Jihoon.

In: Boundary-Layer Meteorology, Vol. 172, No. 3, 15.09.2019, p. 435-455.

Research output: Contribution to journalArticle

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