A quantitative analysis of grid nudging effect on each process of PM2.5 production in the Korean Peninsula

doi:10.1016/j.atmosenv.2015.10.050

Atmospheric Environment

Volume 122, December 2015, Pages 763-774

https://doi.org/10.1016/j.atmosenv.2015.10.050 Get rights and content

Highlights

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Examining the impact of grid nudging on PM_2.5 simulations in Korea.
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Validating the enhanced PM_2.5 simulation results using in-situ data.
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Investigating the change of meteorological fields by grid nudging effect.
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Clarifying impact of meteorological fields on PM_2.5 production and destruction.
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Analyzing PM2.5 production, transport, and deposition rates using process analysis.

Abstract

This study investigated the effect of assimilated meteorological fields on simulated PM_2.5 concentrations in the Korean Peninsula. Two different CMAQ simulations were conducted using base WRF run (BASE) and grid-nudged WRF run (GNG) which included a simple data assimilation method for the time period of April, 2009. The simulated PM_2.5 and PM₁₀ concentrations were compared with corresponding observations. The BASE PM_2.5 concentrations were significantly underestimated at Anmyeondo (AMD) and six Air Quality Monitoring Station (AQMS) sites in Korea, but GNG showed improved agreement with in-situ measurements due to the effect of grid nudging. The grid nudging effect was dominant under the PBL height and it appeared more clearly under the unstable synoptic condition (April 5–8) than stable condition (April 9–13). Additional quantitative analysis was conducted using the Integrated Process Rate (IPR) in the CMAQ model to investigate the effect of varied meteorological fields on each PM_2.5 production and destruction processes. The PM_2.5 production rate by aerosol process in GNG was shown to be higher than that of BASE, especially near the source region (e.g., Eastern China). The increased temperature and decreased wind speed by grid nudging effect led to increase of aerosol production rates especially during the nighttime. The change of aerosol production rates were mainly caused by increased sulfate ( ${SO}_{4}^{2 -}$ ) and nitrate ( ${NO}_{3}^{-}$ ) production rates in the day and nighttime respectively. Also, GNG provides higher PM_2.5 transport rates than BASE over the whole domain. The amount of PM_2.5 scavenged by wet deposition process in GNG was smaller than that of BASE over the Yellow Sea, reflecting the decreased water vapor mixing ratio by grid nudging. Thus, it resulted in the increase of simulated PM_2.5 concentrations. The results indicated that understanding the effects of grid nudging on PM_2.5 concentrations is crucial to enhance the performance of PM_2.5 modeling/forecasting capability over the Korean Peninsula.

Introduction

Particulate Matter (PM) is known to be a criteria pollutant with several deleterious health effects. High PM concentrations often cause a lot of environmental and health problems like visibility reduction, increase of respiratory diseases and mortality (Dockery and Stone, 2007). Especially, the fine particulate matter (PM_2.5, hereafter) is known have both direct and indirect effects on the radiative budget of the Earth (Kim et al., 2011, Ramanathan et al., 2007). These effects could be attributed to the fact that PM_2.5 has a relatively higher residence time in the atmosphere than coarse particle due to relatively smaller particle size and weight. Moreover, since PM_2.5 can easily be deposited into the human respiratory tract, it has strong propensity for inducing respiratory and cardiovascular disease (Harrison et al., 2012, Lee et al., 2003, Vaidyanathan et al., 2013).

In recent times, high PM_2.5 concentrations have become a social issue in many countries. Especially, trans-boundary transport of PM_2.5 is a contentious problem in the East Asia region, where several high emission sources are located. Investigation of the high PM_2.5 events in the East Asia region needs a significant number of in-situ measurements; however there are not enough number of in-situ PM measurement sites to cover of the entire East Asia. In order to overcome the poor spatial coverage of in-situ measured data, chemical transport models are usually employed to estimate the distribution of PM_2.5 and analyze the causes of high PM_2.5 events.

Since the concentration of PM_2.5 is determined by complicated processes such as emissions, chemical reactions, transport and deposition process (Aneja et al., 2001, Ding et al., 2004, Gelencser et al., 2007, Tie et al., 2009), its simulation results are influenced by various factors. Especially, in addition to accurate emission information, obtaining accurate meteorological input data is an essential factor for successful simulation of high PM_2.5 episodes that were induced by long range transport (Pai et al., 2000). Providing nearly real meteorological input fields to air quality model is a key factor for precise estimation of high PM_2.5 level (Otte, 2008a, Otte, 2008b), but it usually introduces some inevitable computational errors and uncertainties.

Data assimilation is an effective method which could enhance accuracy of air quality simulations. The effect of improved meteorological input fields using this technique on successful air quality simulations have been reported by various previous researches. Gilliam et al. (2012) reported that four dimensional data assimilation strategy can reduce the uncertainty in the horizontal transport in the planetary boundary layer, and Liu et al. (2012) intensively examined the differences of spectral and grid nudging effect on atmospheric simulation results. Koo (2012) reported that application of grid nudging technique can contribute to enhanced performance of PM₁₀ forecasting and Ngan et al. (2012) also showed that application of the nudging technique to meteorological and chemical transport model simulations can improve wind fields and lead to enhanced ozone modeling results. A variety of previous studies commonly asserted that nudging technique is an effective method for accurate air quality simulations. However, most of them focused on comparing two simulation results with/without grid nudging. Detailed processes that explain how meteorological fields vary by grid nudging, and how changed variables contribute to forming and transporting air pollutants have not been properly investigated over East Asia. To the best of our knowledge, there are few process analysis (PA) based studies to investigate the impact of grid analysis nudging on PM_2.5 in the Korean Peninsula.

The purpose of this study is to examine an effective optimization technique for enhancing meteorology and air quality simulation results. For this study, various CMAQ simulations were performed to quantitatively investigate the effect of grid nudging on the changes in the total PM_2.5 concentration over three different regions (Source region: Eastern China, Transport region: Yellow Sea and Receptor region: Korea) using the Integrated Process Rates (IPR) technique in CMAQ. The impacts of varied meteorological fields by employed grid nudging on individual processes (e.g., aerosol chemistry, transport and wet deposition) that contribute to changes in total PM_2.5 concentrations were analyzed.

Section snippets

The meteorological model

The Weather Research and Forecast (WRF, v3.4.1) (Skamarock et al., 2008) model was used to provide input meteorological fields for the air quality modeling set-up. As shown in Fig. 1, WRF was configured to have two nested domains with grid resolutions of 15 km (200 × 170, D1) and 5 km (310 × 259, D2), respectively. Thirty three vertical layers were set up and the 1° × 1° NCEP Final Operational Global Analysis (FNL) data were used to provide initial and boundary conditions for the simulations.

Comparisons of PM_2.5 time series

Simulated PM_2.5 concentrations were compared with measured values at KGAWC in AMD. Features of modeled PM_2.5 in BASE and GNG were compared and effect of grid nudging on PM_2.5 simulation was analyzed.

As shown in Fig. 3-(a), PM_2.5 concentration was significantly under-estimated in BASE at AMD, and the underestimation was more severe for the period of April 5–8. The daily peaks of PM_2.5 during this period could not be captured by the BASE scenario. During the period of April 5–8 (Episode Period 1:

Conclusions

Numerical simulations were performed using WRF and CMAQ model to quantitatively investigate the effect of grid nudging technique on simulated PM_2.5 concentrations in the Korean Peninsula. In-situ measured PM_2.5 and PM₁₀ data in 2009 at Anmyeondo (AMD) and six major urban air quality monitoring stations were analyzed. The time period of April 5–13, when the high PM_2.5 concentration over the regulation level was sustained for consecutive nine days, was examined to comprehensively understand the

Acknowledgments

This work is partially supported by funding from the Department of Earth and Atmosphere at the University of Houston (UH: HEAF FS 13 NSM CHOI), Texas Air Research Center (TARC) (413UHH0144A) and Air Quality Research Program (AQRP) (14-014). We would like to show specific thanks to Anirban Roy for his useful comments to this study.

References (42)

V.P. Aneja et al.
Atmospheric nitrogen compounds II: emissions, transport, transformation, deposition and assessment
Atmos. Environ.
(2001)
M.C. Day et al.
Predicted changes in summertime organic concentrations due to increased temperatures
Atmos. Environ.
(2011)
A. Ding et al.
Simulation of sea-breezes and a discussion of their implications on the transport of air pollution during a multi-day ozone episode in the Pearl River Delta of China
Atmos. Environ.
(2004)
R.C. Gilliam et al.
Improving the horizontal transport in the lower troposphere with four dimensional data assimilation
Atmos. Environ.
(2012)
B. Gomiscek et al.
Spatial and temporal variations of PM₁, PM_2.5, PM₁₀ and particle number concentration during the AUPHEP-project
Atmos. Environ.
(2004)
R.M. Harrison et al.
Processes affecting concentrations of fine particulate matter (PM_2.5) in the UK atmosphere
Atmos. Environ.
(2012)
W.-B. Jeon et al.
A study on high ozone formation mechanism associated with change of NO_x/VOCs at a rural area in the Korean Peninsula
Atmos. Environ.
(2014)
W.-B. Jeon et al.
Process analysis of the impact of atmospheric recirculation on consecutive high-O₃ episodes over the Seoul Metropolitan area in the Korean Peninsula
Atmos. Environ.
(2012)
D.J. Jacob
Heterogeneous chemistry and tropospheric ozone
Atmos. Environ.
(2000)
N.K. Kim et al.
Long-term trend of aerosol composition and direct radiative forcing due to aerosol over Gosan: TSP, PM₁₀, and PM_2.5 data between 1992 and 2008
Atmos. Environ.
(2011)

Y.-S. Koo et al.

Performance evaluation of the updated air quality forecasting system for Seoul predicting PM₁₀

Atmos. Environ.

(2012)

F. Ngan et al.

Performance assessment of retrospective meteorological inputs for use in air quality modeling during TexAQS 2006

Atmos. Environ.

(2012)

R.K. Pathak et al.

Nighttime enhancement of PM_2.5 nitrate in ammonia-poor atmospheric conditions in Beijing and Shanghai: plausible contribution of heterogeneous hydrolysis of N₂O₅ and HNO₃ partitioning

Atmos. Environ.

(2011)

A.P.K. Tai et al.

Correlations between fine particulate matter (PM_2.5) and meteorological variables in the United States: implications for the sensitivity of PM_2.5 to climate change

Atmos. Environ.

(2010)

X. Tie et al.

Measurement and modeling of O₃ variability in Shanghai, China: application of the WRF-Chem model

Atmos. Environ.

(2009)

J. Xu et al.

Process analysis of typical summertime ozone episodes over the Beijing area

Sci. Total Environ.

(2008)

J. Aw et al.

Evaluating the first-order effect of intraannual temperature variability on urban air pollution

J. Geophys. Res.

(2003)

J.H. Bowden et al.

Examining interior grid nudging techniques using two-way nesting in the WRF model for regional climate modeling

J. Clim.

(2012)

D. Byun et al.

Review of the governing equations, computational algorithms, and other components of the models-3 community multiscale air quality (CMAQ) modeling system

Appl. Mech. Rev.

(2006)

Y. Choi

The impact of satellite-adjusted NOx emissions on simulated NOx and O₃ discrepancies in the urban and outflow areas of the Pacific and Lower Middle US

Atmos. Chem. Phys.

(2014)

Y. Choi et al.

Summertime weekly cycles of observed and modeled NOx and O₃ concentrations as a function of satellite-derived ozone production sensitivity and land use types over the Continental United States

Atmos. Chem. Phys.

(2012)

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A quantitative analysis of grid nudging effect on each process of PM2.5 production in the Korean Peninsula

Highlights

Abstract

Introduction

Section snippets

The meteorological model

Comparisons of PM2.5 time series

Conclusions

Acknowledgments

Atmos. Environ.

Atmos. Environ.

Atmos. Environ.

Atmos. Environ.

Atmos. Environ.

Atmos. Environ.

Atmos. Environ.

Atmos. Environ.

Atmos. Environ.

Atmos. Environ.

Atmos. Environ.

Atmos. Environ.

Atmos. Environ.

Atmos. Environ.

Atmos. Environ.

Sci. Total Environ.

Evaluating the first-order effect of intraannual temperature variability on urban air pollution

J. Geophys. Res.

Examining interior grid nudging techniques using two-way nesting in the WRF model for regional climate modeling

J. Clim.

Review of the governing equations, computational algorithms, and other components of the models-3 community multiscale air quality (CMAQ) modeling system

Appl. Mech. Rev.

The impact of satellite-adjusted NOx emissions on simulated NOx and O3 discrepancies in the urban and outflow areas of the Pacific and Lower Middle US

Atmos. Chem. Phys.

Summertime weekly cycles of observed and modeled NOx and O3 concentrations as a function of satellite-derived ozone production sensitivity and land use types over the Continental United States

Atmos. Chem. Phys.

A quantitative analysis of grid nudging effect on each process of PM_2.5 production in the Korean Peninsula

Comparisons of PM_2.5 time series

The impact of satellite-adjusted NOx emissions on simulated NOx and O₃ discrepancies in the urban and outflow areas of the Pacific and Lower Middle US

Summertime weekly cycles of observed and modeled NOx and O₃ concentrations as a function of satellite-derived ozone production sensitivity and land use types over the Continental United States