Enhanced NO2 at Okinawa Island, Japan caused by rapid air-mass transport from China as observed by MAX-DOAS

doi:10.1016/j.atmosenv.2010.10.055

Atmospheric Environment

Volume 45, Issue 15, May 2011, Pages 2593-2597

https://doi.org/10.1016/j.atmosenv.2010.10.055 Get rights and content

Abstract

Since March 2007, continuous NO₂ profile observations have been performed using ground-based Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) at Cape Hedo (26.87°N, 128.25°E) on Okinawa Island, Japan. NO₂ observations show particularly low values of less than 0.3 ppbv at 0–1 km in most cases during the northern summer, whereas higher concentrations of more than 1 ppbv were occasionally observed during winter and spring. Trajectory analysis using meteorological analysis data showed that the high NO₂ concentrations were caused mainly by rapid air-mass transport in the marine boundary layer, with strong westerly winds bringing the air mass from coastal China to the study site within ∼24 h. Such rapid transport is a major cause of NO₂ variations at Cape Hedo, even though the region is located approximately 700 km from China.

Highlights

► NO₂ profile observations have been performed by MAX-DOAS at Cape Hedo, Japan. ► Higher NO₂ concentrations were occasionally observed during winter and spring. ► The high concentrations were caused by rapid air-mass transport from coastal China.

Introduction

In recent years, satellite observations have revealed increasing concentrations of tropospheric nitrogen dioxide (NO₂) over Asia, including China, due to changes in anthropogenic emissions (e.g., Irie et al., 2005, Richter et al., 2005). To enhance our knowledge of tropospheric chemistry, it is important to gain a quantitative understanding of the impact of the emission on chemical balance over the source area and remote regions. However, neither tropospheric chemistry nor spatial and temporal variations in NO₂ are fully understood, partly because NO₂ generally shows large spatio-temporal variations and its photochemical lifetime is much shorter than the typical interval of satellite observations. To quantitatively clarify the role of NO₂ in tropospheric chemistry, it is necessary to conduct continuous ground-based measurements.

Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) is a new technique designed for atmospheric aerosol and gas profile measurements from the ground (e.g., Hönninger et al., 2004, Wagner et al., 2004, Sinreich et al., 2005, Frieβ et al., 2006, Hendrick et al., 2006, Vigouroux et al., 2009). In recent years, continuous NO₂ profile measurements have been conducted using MAX-DOAS at several sites in Asia (e.g., Irie et al., 2008b, Irie et al., 2009). Because NO₂ concentrations are much higher near the surface, ground-based MAX-DOAS is useful for quantifying tropospheric NO₂ and for measuring a priori profiles for satellite retrievals. In addition, as described below, MAX-DOAS has the potential to retrieve NO₂ profiles even under cloudy conditions, when satellites are generally unable to perform measurements below the cloud layer.

MAX-DOAS measurements have been conducted at Cape Hedo, located at the northernmost point of Okinawa Island in Japan (26.87°N, 128.25°E), since March 2007. This location allows for observations of polluted or clean air masses from China or the Pacific Ocean, respectively, depending on the meteorological conditions (e.g., Takashima et al., 2009), and is suitable for investigating long-range transport from China. Although long-range transport of NO₂ in the free troposphere has previously been studied using satellite measurements (e.g., Spichtinger et al., 2001, Stohl et al., 2003), long-range transport within the marine boundary layer (MBL) has not yet been fully investigated. Here, we report our first attempt at long-term measurements of NO₂ by MAX-DOAS in a relatively clean region located far from pollution sources. In particular, we focus on long-range transport in the MBL and show that NO₂ enhancement at Cape Hedo is controlled by transboundary air pollution in the MBL, even though Cape Hedo is located ∼700 km southeast of the coast of China, the source area of the NO₂.

Section snippets

Observations

The MAX-DOAS instrument at Cape Hedo consists of two main parts: an outdoor telescope unit and an indoor miniaturized UV/visible spectrometer (USB4000, Ocean Optics), connected to each other by a 5-m fiber-optic bundle cable (Takashima et al., 2009). The azimuth angle of the observations was set to −14° from north (the minus sign indicates a counterclockwise direction). A movable mirror turns through six different elevation angles (ELs; 3°, 5°, 10°, 20°, 30°, and 70°) every 30 min, with a field

NO₂ variations at Cape Hedo and rapid air-mass transport from China in the MBL

Fig. 2a shows a time series of the NO₂ mixing ratio at 0–1 km at Cape Hedo for the period March 2007 to April 2008, as observed by MAX-DOAS. Table 1 quantifies the NO₂ variation at Cape Hedo. Although the NO₂ concentration was low throughout the year, an annual cycle is apparent, with a minimum during the northern summer (generally <0.3 ppbv) and a maximum during the northern winter and spring, when higher concentrations (>1 ppbv) were sometimes observed. These seasonal variations are

Discussion

Using MAX-DOAS NO₂ measurements and meteorological analysis data, we showed that NO₂ enhancement over Cape Hedo is controlled by rapid air-mass transport from China. Although the observation site is located about 700 km from China, NO₂ concentration was enhanced when air masses were transported from coastal China within ∼24 h.

To gain a quantitative understanding of the NO₂ enhancement, two factors during advection should be considered. First, the NO₂ concentration within an air mass decreases

Acknowledgments

The authors would like to thank the three anonymous reviewers for their constructive comments and suggestions. The authors thank Prof. I. Uno of Kyushu University for his useful comments. The MAX-DOAS observations at Cape Hedo were supported by the Japan Earth Observation System (EOS) Promotion Program of the Ministry of Education, Culture, Sports, Science and Technology (MEXT). This study was partially supported by the MEXT Grant-in-Aid for Young Scientists' Start-up (KAKENHI) 20840052. The

References (27)

K. Bogumil
Measurements of molecular absorption spectra with the SCIAMACHY pre-flight model: instrument characterization and reference data for atmospheric remote-sensing in the 230–2380 nm region
J. Photoch. Photobio.
(2003)
L. Rothman
The HITRAN molecular spectroscopic database: edition of 2000 including updates through 2001
J. Quant. Spectrosc. Radiat. Transfer
(2003)
A. Vandaele et al.
Measurements of the NO₂ absorption cross-section from 42,000 cm⁻¹ to 10,000 cm⁻¹ (238–1000 nm) at 220 K and 294 K
J. Quant. Spectrosc. Ra.
(1998)
K. Chance et al.
Ring effect studies: Rayleigh scattering, including molecular parameters for rotational Raman scattering, and the Fraunhofer spectrum
Appl. Opt.
(1997)
U. Frieβ et al.
MAX-DOAS O4 measurements: a new technique to derive information on atmospheric aerosols: 2. Modeling studies
J. Geophys. Res.
(2006)
J. Grainger et al.
Anomalous Fraunhofer line profiles
Nature
(1962)
G. Greenblatt et al.
Absorption measurements of oxygen between 330 and 1140 nm
J. Geophys. Res.
(1990)
F. Hendrick
Intercomparison exercise between different radiative transfer models used for the interpretation of ground-based zenith-sky and multi-axis DOAS observations
Atmos. Chem. Phys.
(2006)
G. Hönninger et al.
Multi axis differential optical absorption spectroscopy (MAX-DOAS)
Atmos. Chem. Phys.
(2004)
H. Irie
Evaluation of long-term tropospheric NO₂ data obtained by GOME over East Asia in 1996–2002
Geophys. Res. Lett.
(2005)

H. Irie et al.

First retrieval of tropospheric aerosol profiles using MAX-DOAS and comparison with lidar and sky radiometer measurements

Atmos. Chem. Phys.

(2008)

H. Irie et al.

Validation of OMI tropospheric NO₂ column data using MAX-DOAS measurements deep inside the north China Plain in June 2006: Mount Tai Experiment 2006

Atmos. Chem. Phys.

(2008)

H. Irie et al.

Characterization of OMI tropospheric NO₂ measurements in East Asia based on a robust validation comparison

SOLA

(2009)

Cited by (18)

Observing decoupling processes of NO<inf>2</inf> pollution and GDP growth based on satellite observations for Los Angeles and Tokyo
2023, Atmospheric Environment
Nitrogen dioxide (NO₂) pollution is mainly caused by anthropogenic processes such as burning of fossil fuels. Due to its severe impact on health as well as the environment in general, it is important to monitor the amount of NO₂ pollution especially in areas with a high population density. Therefore, the aim of this study is to investigate to what extent spatiotemporal fluctuations in the tropospheric NO₂ column density can map variations in economic output. To do so, we analyzed satellite based tropospheric NO₂ column observations obtained from the ERS-2, ENVISAT, MetOp-A and MetOp-B satellite missions covering the period from 1996 to 2017 for Tokyo, Japan and Los Angeles, United States. Within our studies, a harmonic analysis was carried out in order to exclude meteorological influences. Afterwards, the NO₂ time series were further investigated through a wavelet analysis method to characterize the fluctuations, that is the temporal variability of the NO₂. These fluctuations have been shown to be a particularly sensitive measure of the change in NO₂ pollution. We further use the gross domestic product (GDP) for the metropolitan areas as an indicator for economic performance. The results for the study area of Los Angeles shows a substantial reduction in NO₂ variability starting in 2007. The NO₂ variability for the period during the global financial crisis (December 2007–April 2012), dropped by around 77% in comparison to the previous period (January 1997–November 2007). However, a second period from May 2012 to December 2016 presents a further reduction of the NO₂ variability of around 82% in contrast to the period from 2007 to 2012. Contrary to this, continuous economic growth can be observed during the second period. A similar picture emerges for the metropolitan region of Tokyo. A significant decline in NO₂ variability of around 73% can be detected from October 2003 to January 2012. Additionally, a second period with a strong decline in NO₂ variability of around 80% can be identified from February 2012 to December 2016. A plunge in GDP during 2008 reflects that year's global financial crisis, but cannot independently explain the following sharp decline in NO₂ variability. Those results suggest that Tokyo as well as Los Angeles managed to substantially decouple its NO₂ pollution from the economic growth due to strict air quality policies.
Atmospheric chemistry in Asia: Need of integrated approach
2021, Asian Atmospheric Pollution: Sources, Characteristics and Impacts
Growing anthropogenic emissions have a severe impact on the atmospheric composition. This has various atmospheric implications such as poor air quality, biogeochemical changes, global warming, biodiversity loss, acid deposition, human health effects, extreme events, etc. The damage due to these issues varies from one region to another. In this chapter, some of the key issues related to the atmospheric processes, air pollution sources, their transformation, transportation, and impacts on the Asian region have been highlighted. In Asia, different regions have different kinds of atmospheric problems associated with the different pollution sources, meteorology, and policies. South Asian countries suffer from poor air quality due to high dust loading. East Asia suffers from acid rain, high ozone, and transboundary pollution problems. Central Asia suffers from frequent dust storms that cause poor air quality. Some of the areas in Southeast Asia are prone to forest fire emissions. Some of these regions commonly contribute to larger issues such as atmospheric brown clouds and monsoon. The issue can be tackled through an integrated approach to avoid unforeseen crisis in the future. There is a need for the promotion of comprehensive emission reduction plans to improve the air quality, utilizing cleaner energies, such as natural gas, efficient fuel burning, solar, hydro, wind, and geothermal energy sources, some of the best ways to lead with present atmospheric issues.
Long-term observations of tropospheric NO<inf>2</inf>, SO<inf>2</inf> and HCHO by MAX-DOAS in Yangtze River Delta area, China
2018, Journal of Environmental Sciences (China)
Citation Excerpt :
A type of passive DOAS system, MAX-DOAS was used in the recent decade to measure column density and vertical distribution of trace gases (SO2, NO2, O3, HCHO, HONO, BrO, OClO, IO, and CHOCHO) (Frieß et al., 2011; Wagner et al., 2013; Pinardi et al., 2013; Kanaya et al., 2014). To date, MAX-DOAS atmospheric detection networks developed by international academic organizations, including the Belgian Institute for Space Aeronomy (BIRA-IASB, http://uv-vis.aeronomie.be/groundbased/), Bremian DOAS network for atmospheric measurements (BREDOM, http://www.doas-bremen.de/groundbased_data.htm), long-term NO2-monitoring network based on MAX-DOAS over Russia and Asia by Japan (MADRAS, http://ebcrpa.jamstec.go.jp/maxdoashp/) (Lee et al., 2009; Takashima et al., 2011), and Network for Observation of Volcanic and Atmospheric Change by the European Union (NOVAC, http://www.novac-project.eu/), which are mainly used to verify satellite data and chemical models (Irie et al., 2009; Arellano et al., 2008; Bani et al., 2009). Surface concentrations of SO2, NO2, PM10, O3, CO, and PM2.5 are monitored by the Air Quality Network operated by the China National Environmental Monitoring Center.
Yangtze River Delta (YRD) area is one of the important economic zones in China. However, this area faces increasing environmental problems. In this study, we use ground-based multi-axis differential optical absorption spectroscopy (MAX-DOAS) network in Eastern China to retrieve variations of NO₂, SO₂, and formaldehyde (HCHO) in the YRD area. Three cities of YRD (Hefei, Nanjing, and Shanghai) were selected for long-term observations. This paper presents technical performance and characteristics of instruments, their distribution in YRD, and results of vertical column densities (VCDs) and profiles of NO₂, SO₂, and HCHO. Average diurnal variations of tropospheric NO₂ and SO₂ in different seasons over the three stations yielded minimum values at noon or in the early afternoon, whereas tropospheric HCHO reached the maximum during midday hours. Slight reduction of the pollutants in weekends occurred in all the three sites. In general trace gas concentrations gradually reduced from Shanghai to Hefei. Tropospheric VCDs of NO₂, SO₂, and HCHO were compared with those from Ozone Monitoring Instrument (OMI) satellite observations, resulting in R² of 0.606, 0.5432, and 0.5566, respectively. According to analysis of regional transports of pollutants, pollution process happened in YRD under the north wind with the pollution dissipating in the southeast wind. The feature is significant in exploring transport of tropospheric trace gas pollution in YRD, and provides basis for satellite and model validation.
An overview of emissions of SO<inf>2</inf> and NO<inf>x</inf> and the long-range transport of oxidized sulfur and nitrogen pollutants in East Asia
2016, Journal of Environmental Sciences (China)
Citation Excerpt :
The levels of reactive nitrogen in the continental air mass were found to be significantly higher during PEM-West B than during PEM-West A (Kondo et al., 1997). Some studies have attempted to apply backward trajectory models to identify the long-range transport and sources of observed polluted air masses that may affect air quality in South Korea and Japan (He et al., 2003; Kang et al., 2010, 2013; Kitayama et al., 2010; Takashima et al., 2011; Sakata et al., 2013; Zaizen et al., 2014). The backward trajectories in winter and spring, which were attributed to enhanced emissions and dominant westerly winds, were considered to carry more oxidized S and N pollutants than in summer and autumn.
The long-range transport of oxidized sulfur (sulfur dioxide (SO₂) and sulfate) and oxidized nitrogen (nitrogen oxides (NO_x) and nitrate) in East Asia is an area of increasing scientific interest and political concern. This paper reviews various published papers, including ground- and satellite-based observations and numerical simulations. The aim is to assess the status of the anthropogenic emissions of SO₂ and NO_x and the long-range transport of oxidized S and N pollutants over source and downwind region. China has dominated the emissions of SO₂ and NO_x in East Asia and urgently needs to strengthen the control of their emissions, especially NO_x emissions. Oxidized S and N pollutants emitted from China are transported to Korea and Japan, due to persistent westerly winds, in winter and spring. However, the total contributions of China to S and N pollutants across Korea and Japan were not found to be dominant over longer time scales (e.g., a year). The source–receptor relationships for oxidized S and N pollutants in East Asia varied widely among the different studies. This is because: (1) the nonlinear effects of atmospheric chemistry and deposition processes were not well considered, when calculating the source–receptor relationships; (2) different meteorological and emission data inputs and solution schemes for key physical and chemical processes were used; and (3) different temporal and spatial scales were employed. Therefore, simulations using the same input fields and similar model configurations would be of benefit, to further evaluate the source–receptor relationships of the oxidized S and N pollutants.
Seasonal variations of biogenic secondary organic aerosol tracers in Cape Hedo, Okinawa
2016, Atmospheric Environment
Secondary organic aerosol (SOA) substantially contributes to particulate organic matter affecting the regional and global air quality and the climate. Total suspended particle (TSP) samples were collected in October 2009 to February 2012 on a weekly basis at Cape Hedo, Okinawa, Japan in the western North Pacific Rim, an outflow region of Asian aerosols and precursors. The TSP samples were analyzed for SOA tracers derived from biogenic volatile organic compounds (BVOCs). Total isoprene-SOA tracers showed a maximum in summer (2.12 ± 2.02 ng m⁻³) and minimum in winter (1.16 ± 0.92 ng m⁻³). This seasonality is mainly controlled by isoprene emission from the local subtropical forest, followed by regional scale emission of isoprene from the surrounding seas and long-range transported air masses. Total monoterpene-SOA tracers peaked in March (3.38 ± 2.03 ng m⁻³) followed by October (2.95 ± 1.62 ng m⁻³). In contrast, sesquiterpene-SOA tracer, β-caryophyllinic acid, showed winter maximum (1.63 ± 1.18 ng m⁻³) and summer minimum (0.20 ± 0.46 ng m⁻³). The variations of the monoterpene- and sesquiterpene-SOA tracers are likely related to the continental outflow of oxidation products of BVOC. Using a tracer-based method, we estimated the total biogenic SOC of 0.25–157 ng m⁻³ (mean 35.8 ng m⁻³) that accounts for 0.01–9.8% (mean 2.7%) of aerosol organic carbon. Our study suggests that SOA formation in the western North Pacific Rim is involved with not only local but also regional emissions followed by long-range atmospheric transport.
Spatiotemporal inhomogeneity in NO<inf>2</inf> over Fukuoka observed by ground-based MAX-DOAS
2015, Atmospheric Environment
Citation Excerpt :
In this step, the vertical NO2 profile shape was uniquely determined within each layer, and we used the lowest 0–100 m layer data (in the 0–1 km layer) to compare in situ surface measurements. Details of the retrieval algorithm have been described elsewhere (e.g., Irie et al., 2008, 2011; Takashima et al., 2009, 2011; Kanaya et al., 2014). We estimated the error in NO2 measurements for random and systematic uncertainties in aerosol retrievals reported by Irie et al. (2008) and Takashima et al. (2009).
Continuous NO₂ profile observations have been made using ground-based Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) at Fukuoka (33.55°N, 130.36°E), an urban area in Japan. Throughout the year, NO₂ variations measured by MAX-DOAS (0–100 m) are in good agreement with in situ surface NO₂ measurements on several-day, week-to-week, and seasonal timescales. We investigated the spatiotemporal inhomogeneity in NO₂ over Fukuoka by observing at two azimuth angles: the Tenjin (towards the city center) and Itoshima (away from the city center) directions. In terms of diurnal variations, NO₂ in both directions show clear morning maxima, on account of local emissions in the morning and the development of a boundary layer. The concentrations in the early morning are nearly the same in both directions, but they are higher in the Tenjin direction during most of the daytime on average. Variability in both directions, as well as spatial inhomogeneity, is large during most of the daytime except for in the morning. The diurnal maximum for 0–1 km between 10 and 13 LT is sometimes observed in the Tenjin direction; in some cases, 1 h after this maximum, a maximum is also observed in the Itoshima direction. The NO₂ maxima for the upper level (1–2 km) in both directions are also delayed from the maximum in the Tenjin direction for 0–1 km. Analysis of the surface wind field indicates that the NO₂ inhomogeneity is strongly related to vertical/horizontal transport of high concentrations of NO₂ from the city center, and to horizontal transport of low concentrations from the ocean via a land–sea breeze. Three-dimensional continuous observations by MAX-DOAS are potentially a powerful tool for increasing our understanding of pollutant transport and mixing in urban areas.

View all citing articles on Scopus

¹: Present address. Asia Center for Air Pollution Research (ACAP), Nigata, Japan.

View full text

Enhanced NO2 at Okinawa Island, Japan caused by rapid air-mass transport from China as observed by MAX-DOAS

Abstract

Highlights

Introduction

Section snippets

Observations

NO2 variations at Cape Hedo and rapid air-mass transport from China in the MBL

Discussion

Acknowledgments

J. Photoch. Photobio.

J. Quant. Spectrosc. Radiat. Transfer

J. Quant. Spectrosc. Ra.

Ring effect studies: Rayleigh scattering, including molecular parameters for rotational Raman scattering, and the Fraunhofer spectrum

Appl. Opt.

MAX-DOAS O4 measurements: a new technique to derive information on atmospheric aerosols: 2. Modeling studies

J. Geophys. Res.

Anomalous Fraunhofer line profiles

Nature

Absorption measurements of oxygen between 330 and 1140 nm

J. Geophys. Res.

Intercomparison exercise between different radiative transfer models used for the interpretation of ground-based zenith-sky and multi-axis DOAS observations

Atmos. Chem. Phys.

Multi axis differential optical absorption spectroscopy (MAX-DOAS)

Atmos. Chem. Phys.

Evaluation of long-term tropospheric NO2 data obtained by GOME over East Asia in 1996–2002

Geophys. Res. Lett.

First retrieval of tropospheric aerosol profiles using MAX-DOAS and comparison with lidar and sky radiometer measurements

Atmos. Chem. Phys.

Validation of OMI tropospheric NO2 column data using MAX-DOAS measurements deep inside the north China Plain in June 2006: Mount Tai Experiment 2006

Atmos. Chem. Phys.

Characterization of OMI tropospheric NO2 measurements in East Asia based on a robust validation comparison

SOLA

Enhanced NO₂ at Okinawa Island, Japan caused by rapid air-mass transport from China as observed by MAX-DOAS

NO₂ variations at Cape Hedo and rapid air-mass transport from China in the MBL

Evaluation of long-term tropospheric NO₂ data obtained by GOME over East Asia in 1996–2002

Validation of OMI tropospheric NO₂ column data using MAX-DOAS measurements deep inside the north China Plain in June 2006: Mount Tai Experiment 2006

Characterization of OMI tropospheric NO₂ measurements in East Asia based on a robust validation comparison