H. Irie

Chiba University, Tiba, Chiba, Japan

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Publications (103)216.01 Total impact

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    ABSTRACT: NO2 vertical column densities (VCDs) over East Asia in June and December 2007 were simulated by the Community Multi-scale Air Quality (CMAQ) version 4.7.1 using an updated and more elaborate version of the Regional Emission Inventory in Asia (REAS) version 2. The modeling system could reasonably capture observed spatiotemporal changes of NO2 VCDs by satellite sensors, the Global Ozone Monitoring Experiment-2 (GOME-2), the Scanning Imaging Absorption Spectrometer for Atmospheric Cartography (SCIAMACHY), and the Ozone Monitoring Instrument (OMI), even at the coarsest horizontal resolution of 80 km. The CMAQ simulations were performed in a sequence of three horizontal resolutions (80 km, 40 km, and 20 km) for June and December 2007 to investigate the influence of changes of horizontal resolution on the obtained NO2 VCDs. CMAQ-simulated NO2 VCDs generally increased with improvements in resolution from 80 km to 40 km and then to 20 km. Increases in the CMAQ-simulated NO2 VCDs were greater for the change from 80 km to 40 km than for those from 40 km and 20 km, in which the increases of NO2 VCDs due to the improvement of horizontal resolution were approached convergence at the horizontal resolution of approximately 20 km. Conversely, no clear convergences in NO2 VCDs changes were found at near Tokyo and over the East China Sea. The biases of the NO2 VCDs simulated at a resolution of 20 km against the satellite retrievals were -36% near Beijing (CHN1) and -78% near Shanghai (CHN2) in summer; these errors were found to be comparable to the horizontal resolution-dependent errors, which were 18-25% at CHN1 and 44-58% at CHN2 from 80 km to 40 km. Conversely, the influence of changes of horizontal resolution in winter was relatively less compared to that in summer. Implications: NO2 VCDs over East Asia in June and December 2007 were simulated using CMAQ version 4.7.1 and REAS version 2. The modeling system could reasonably capture observed spatiotemporal changes of NO2 VCDs by satellite sensors. The CMAQ simulations were performed in a sequence of three horizontal resolutions, 80, 40, and 20 km, to investigate the influence of changes of horizontal resolution on the obtained NO2 VCDs. The results suggested that the influence of changes of horizontal resolution was larger in summer compared to that in winter. The magnitude of the influence was comparable to the biases of the NO2 VCDs simulated at a resolution of 20 km against the satellite retrievals.
    Journal of the Air & Waste Management Association (1995) 04/2014; 64(4):436-44. · 1.20 Impact Factor
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    ABSTRACT: We investigated the effect of surface reflectance anisotropy, Bidirectional Reflectance Distribution Function (BRDF), on satellite retrievals of tropospheric NO2. We assume the geometry of geostationary measurements over Tokyo, which is one of the worst air-polluted regions in the East Asia. We calculated air mass factors (AMF) and box AMFs (BAMF) for tropospheric NO2 to evaluate the effect of BRDF by using the radiative transfer model SCIATRAN. To model the BRDF effect, we utilized the Moderate Resolution Imaging Spectroradiometer (MODIS) products (MOD43B1 and MOD43B2), which provide three coefficients to express the RossThick-LiSparseReciprocal model, a semi-empirical and kernel-based model of BRDF. Because BRDF depends on the land cover type, we also utilized the High Resolution Land-Use and Land-Cover Map by the Advanced Land Observing Satellite (ALOS)/Advanced Visible and Near Infrared Radiometer type 2 (AVNIR-2), which classifies the ground pixels over Tokyo into six main types: water, urban, paddy, crop, deciduous forest and evergreen forest. We first develop an empirical model of the three BRDF coefficients for each land cover type over Tokyo, and then apply the model to the calculation of land cover type dependent AMFs and BAMFs. Results show that the variability of AMF among the land types is up to several tens percent, and if we neglect the reflectance anisotropy, the difference from BRDF's AMF reaches 10% or more. The evaluation of the BAMFs calculated shows that not to consider variations in BRDF will cause large errors if the concentration of NO2 is high close to the surface, although the importance of BRDF for AMFs decreases for large aerosol optical depth (AOD).
    03/2014; 7(4).
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    ABSTRACT: Retrievals of tropospheric nitrogen dioxide (NO2) from the Ozone Monitoring Instrument (OMI) are subject to errors in the treatments of aerosols, surface reflectance anisotropy, and vertical profile of NO2. Here we quantify the influences over China via an improved retrieval process. We explicitly account for aerosol optical effects (simulated by nested GEOS-Chem at 0.667° long. × 0.5° lat. and constrained by aerosol measurements), surface reflectance anisotropy, and high-resolution vertical profiles of NO2 (simulated by GEOS-Chem). Prior to the NO2 retrieval, we derive the cloud information using consistent ancillary assumptions. We compare our retrieval to the widely used DOMINO v2 product, using MAX-DOAS measurements at three urban/suburban sites in East China as reference and focusing the analysis on the 127 OMI pixels (in 30 days) closest to the MAX-DOAS sites. We find that our retrieval reduces the interference of aerosols on the retrieved cloud properties, thus enhancing the number of valid OMI pixels by about 25%. Compared to DOMINO v2, our retrieval better captures the day-to-day variability in MAX-DOAS NO2 data (R2 = 0.96 versus 0.72), due to pixel-specific radiative transfer calculations rather than the use of a look-up table, explicit inclusion of aerosols, and consideration of surface reflectance anisotropy. Our retrieved NO2 columns are 54% of the MAX-DOAS data on average, reflecting the inevitable spatial inconsistency between the two types of measurement, errors in MAX-DOAS data, and uncertainties in our OMI retrieval related to aerosols and vertical profile of NO2. Sensitivity tests show that excluding aerosol optical effects can either increase or decrease the retrieved NO2 for individual OMI pixels with an average increase by 14%. Excluding aerosols also complexly affects the retrievals of cloud fraction and particularly cloud pressure. Employing various surface albedo data sets slightly affects the retrieved NO2 on average (within 10%). The retrieved NO2 columns increase when the NO2 profiles are taken from MAX-DOAS retrievals (by 19% on average) or TM4 simulations (by 13%) instead of GEOS-Chem simulations. Our findings are also relevant to retrievals of other pollutants (e.g., sulfur dioxide, ormaldehyde, glyoxal) from UV-visible backscatter satellite instruments.
    01/2014; 14(3).
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    ABSTRACT: We conducted long-term network observations using standardized Multi-Axis Differential optical absorption spectroscopy (MAX-DOAS) instruments in Russia and ASia (MADRAS) from 2007 onwards. At seven locations (Cape Hedo, Fukue, and Yokosuka in Japan, Hefei in China, Gwangju in Korea, and Tomsk and Zvenigorod in Russia) with different levels of pollution, we obtained 80 927 retrievals of tropospheric NO2 vertical column density (TropoNO2VCD) and aerosol optical depth (AOD). In the technique, the optimal estimation of the TropoNO2VCD and its profile was performed using aerosol information derived from O4 absorbances simultaneously observed at 460-490 nm. This large data set was used to analyze NO2 climatology systematically, including temporal variations from the seasonal to the diurnal scale. The results were compared with Ozone Monitoring Instrument (OMI) satellite observations and global model simulations. Two NO2 retrievals of OMI satellite data (NASA ver. 2.1 and Dutch OMI NO2 (DOMINO) ver. 2.0) generally showed close correlations with those derived from MAX-DOAS observations, but had low biases of ~50%. The bias was distinct when NO2 was abundantly present near the surface and when the AOD was high, suggesting that the aerosol shielding effect could be important, especially for clean sites where the difference could not be attributed to the spatial inhomogeneity. Except for constant biases, the satellite observations showed nearly perfect seasonal agreement with MAX-DOAS observations, suggesting that the analysis of seasonal features of the satellite data were robust. The prevailing seasonal patterns with a wintertime maximum implied the dominance of anthropogenic emissions around our sites. The presence of weekend reductions at Yokosuka and Gwangju suggested the dominance of emissions from diesel vehicles, with significant weekly cycles, whereas the absence of such a reduction at Hefei suggested the importance of other sources. A global chemical transport model, MIROC-ESM-CHEM, was validated for the first time with respect to background NO2 column densities during summer at Cape Hedo and Fukue in the clean marine atmosphere.
    12/2013; 14(2).
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    Dataset: zieger2011
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    ABSTRACT: Gaseous and particulate semi-volatile carbonyl compounds were determined every three hours in the atmosphere of Mount Tai (elevation, 1534 m) in the North China Plain during 2-5, 23-24 and 25 June 2006 under clear sky conditions. Using a two-step filter cartridge in a series, particulate carbonyls were first collected on a quartz filter and then gaseous carbonyls were collected on a quartz filter impregnated with O-benzylhydroxylamine (BHA). After the two-step derivatization with BHA and N,O-Bis(trimethylsilyl)trifluoroacetamide (BSTFA), carbonyl derivatives were measured using a gas chromatography. The gaseous concentrations were obtained as follow: glycolaldehyde (range 0-826 ng m-3, average 303 ng m-3), hydroxyacetone (0-579 ng m-3, 126 ng m-3), glyoxal (46-1200 ng m-3, 487 ng m-3), methylglyoxal (88-2690 ng m-3, 967 ng m-3), n-nonanal (0-500 ng m-3, 89 ng m-3), and n-decanal (0-230 ng m-3, 39 ng m-3). These concentrations are among the highest ever reported in the urban and forest atmosphere. We found that gaseous α-dicarbonyls (glyoxal and methylglyoxal) are more than 20 times more abundant than particulate carbonyls and that glycolaldehyde is one order of magnitude more abundant than in aerosol phase. In contrast, hydroxyacetone and normal aldehydes (nonanal and decanal) are equally present in both phases. Time-resolved variations of carbonyls did not show any a clear diurnal pattern, except for hydroxyacetone. We found that glyoxal, methylglyoxal and glycolaldehyde positively correlated with levoglucosan (a tracer of biomass burning), suggesting that a contribution from field burning of agricultural wastes (wheat crops) is significant for the bifunctional carbonyls in the atmosphere of Mt. Tai. Upward transport of the pollutants to the mountaintop from the low lands in the North China Plain is a major process to control the distributions of carbonyls in the upper atmosphere over Mt. Tai.
    ATMOSPHERIC CHEMISTRY AND PHYSICS 05/2013; 13(10):5369-5380. · 5.51 Impact Factor
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    ABSTRACT: Despite the importance of the role of nitrogen dioxide (NO2) in tropospheric chemistry, the causes leading to the discrepancy between satellite-derived and modeled tropospheric NO2 vertical column densities (VCDs) over East Asia remain unclear. Here the reproducibility of satellite tropospheric NO2 VCD data by a regional chemical transport model (CMAQ) with the Regional Emission inventory in ASia (REAS) Version 2 is evaluated from the viewpoint of the diurnal variation of tropospheric NO2 VCDs, where satellite observations at different local times (SCIAMACHY/ENVISAT, OMI/Aura, and GOME-2/Metop-A) are utilized considering literature validation results. As a case study, we concentrate on June and December 2007 for a detailed evaluation based on various sensitivity simulations, for example with different spatial resolutions (80, 40, 20, and 10 km) for CMAQ. For June, CMAQ generally reproduces absolute values of satellite NO2 VCDs and their diurnal variations over all 12 selected diagnostic regions in East Asia. In contrast, a difficulty arises in interpreting the significant disagreement between satellite and CMAQ values over most of the diagnostic regions in December. The disagreement cannot be explained by any of the sensitivity simulations performed in this study. To address this, more investigations, including further efforts for satellite validations in wintertime, are needed.
    Atmospheric Chemistry and Physics 05/2013; 13(5):14037-14067. · 4.88 Impact Factor
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    ABSTRACT: Satellite observations of the tropospheric NO2 vertical column density (VCD) are closely correlated to surface NOx emissions and can thus be used to estimate the latter. In this study, the NO2 VCDs simulated by a regional chemical transport model with data from the updated Regional Emission inventory in ASia (REAS) version 2.1 were validated by comparison with multi-satellite observations (GOME, SCIAMACHY, GOME-2, and OMI) between 2000 and 2010. Rapid growth in NO2 VCD driven by expansion of anthropogenic NOx emissions was revealed above the central eastern China region, except during the economic downturn. In contrast, slightly decreasing trends were captured above Japan. The modeled NO2 VCDs using the updated REAS emissions reasonably reproduced the annual trends observed by multi-satellites, suggesting that the NOx emissions growth rate estimated by the updated inventory is robust. On the basis of the close linear relationship of modeled NO2 VCD, observed NO2 VCD, and anthropogenic NOx emissions, the NOx emissions in 2009 and 2010 were estimated. It was estimated that the NOx emissions from anthropogenic sources in China beyond doubled between 2000 and 2010, reflecting the strong growth of anthropogenic emissions in China with the rapid recovery from the economic downturn during late 2008 and mid-2009.
    Atmospheric Chemistry and Physics 04/2013; 13(4):11247-11268. · 4.88 Impact Factor
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    ABSTRACT: We present intercomparison results for formaldehyde (HCHO) slant column measurements performed during the Cabauw Intercomparison campaign of Nitrogen Dioxide measuring Instruments (CINDI) that took place in Cabauw, the Netherlands, in summer 2009. During two months, nine atmospheric research groups simultaneously operated MAXDOAS (MultiAXis Differential Optical Absorption Spectroscopy) instruments of various designs to record UVvisible spectra of scattered sunlight at different elevation angles that were analysed using common retrieval settings. The resulting HCHO data set was found to be highly consistent, the mean difference between instruments generally not exceeding 15% or 7.5×1015 molec cm−2, for all viewing elevation angles. Furthermore, a sensitivity analysis was performed to investigate the uncertainties in the HCHO slant column retrieval when varying key input parameters such as the molecular absorption cross sections, correction terms for the Ring effect or the width and position of the fitting interval. This study led to the identification of potentially important sources of errors associated with crosscorrelation effects involving the Ring effect, O4, HCHO and BrO cross sections and the DOAS closure polynomial. As a result, a set of updated recommendations was formulated for HCHO slant column retrieval in the 336.5–359 nm wavelength range. To conclude, an error budget is proposed which distinguishes between systematic and random uncertainties. The total systematic error is estimated to be of the order of 20% and is dominated by uncertainties in absorption cross sections and related spectral cross-correlation effects. For a typical integration time of one minute, random uncertainties range between 5 and 30 %, depending on the noise level of individual instruments.
    Atmospheric Measurement Techniques 02/2013; 6(2):219-219. · 3.21 Impact Factor
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    ABSTRACT: Gaseous and particulate semi-volatile carbonyl compounds were determined every three hours in the atmosphere of Mount Tai (elevation, 1534 m) in the North China Plain during 2-5, 23-24 and 25 June, 2006 under a clear sky condition. Using two-step filter cartridge in a series, particulate carbonyls were first collected on a quartz filter and then gaseous carbonyls were collected on a quartz filter impregnated with O-benzylhydroxylamine (BHA). After the two-step derivatization with BHA and N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA), carbonyl derivatives were measured using a gas chromatography. The gaseous concentrations were obtained as follow: glycolaldehyde (range 0-1271 ng m-3, average 555 ng m-3), hydroxyacetone (0-707 ng m-3, 163 ng m-3), glyoxal (198-1396 ng m-3, 720 ng m-3), methylglyoxal (410-3170 ng m-3, 1376 ng m-3), n-nonanal (0-236 ng m-3, 71 ng m-3), and n-decanal (0-159 ng m-3, 31 ng m-3). These concentrations are among the highest ever reported in the urban and forest atmosphere. We found that gaseous carbonyls are more than 10 times more abundant than particulate carbonyls. Time-resolved variations of carbonyls did not show any a clear diurnal pattern, except for hydroxyacetone. We found that glyoxal, methylglyoxal and glycolaldehyde positively correlated with levoglucosan (a tracer of biomass burning), suggesting that a contribution from field burning of agricultural wastes (wheat crops) is significant for the bifunctional carbonyls in the atmosphere of Mt. Tai. Upward transport of the pollutants to the mountaintop from the low lands in the North China Plain is a major process to control the distributions of carbonyls in the upper atmosphere over Mt. Tai.
    Atmospheric Chemistry and Physics 01/2013; 13(1):2725-2758. · 4.88 Impact Factor
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    ABSTRACT: We conducted an intensive field campaign at the summit of Mt. Tai (1534 m a.s.l.), Shandong Province, located at the center of Central East China, during the period 28 May to 30 June 2006, to study seasonal maxima of regional air pollution with respect to ozone (O3) and aerosols. The specific objectives, campaign design, and major findings are summarized. High concentrations of O3 and its precursors, and aerosols, were detected and studied in the context of annual variations. Most importantly, we identified that emissions from regional-scale open crop residue burning after the harvesting of winter wheat, together with photochemical aging, strongly increased the concentrations of O3, aerosols, and primary species relevant to air quality in this month of the year. Studies of in-situ photochemical activity, regional source attribution of O3, O3-aerosol interactions, validation of satellite observations of tropospheric NO2, behaviors of volatile organic compounds, organic/inorganic aerosol species, loss rates of black carbon (BC), and instrument inter-comparisons are also summarized. The observed BC levels must have a strong impact on the regional climate.
    Atmospheric Chemistry and Physics 01/2013; 13(1):1527-1573. · 4.88 Impact Factor
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    ABSTRACT: Intensive open crop residue burning (OCRB) has a great impact on regional air quality and climate. A field observation campaign in a rural area of the Yangtze River Delta Region (YRDR) was performed during the harvest season, and Elemental carbon (ECa), organic carbon (OC), black carbon (BCe), carbon monoxide (CO), carbon dioxide (CO2) and PM2.5mass were concurrently measured. During the observation period, urban pollution and OCRB-impact episodes were classified. The emission ratio of ECa mass (defined as the ΔECa/ΔCO ratio) from OCRB was estimated to be 18.2 ± 4.6 ng/m3/ppbv, much higher than that (3.0 ± 0.3 ng/m3/ppbv) of urban pollution from the YRDR. A significant amount of OC was emitted from OCRB with ΔOC/ΔCO ratio of 101.3 ± 41.6 ng/m3/ppbv. The value found in the present study was near the upper limit of OC emission ratios in the literature, implying great impacts from combustion conditions, types of biomass burned and subsequent evolution. Regarding urban pollution episodes, the ΔOC/ΔCO ratio was found to be 23.7 ± 2.4 ng/m3/ppbv, and secondary organics accounted for the major fraction of OC mass. Combustions phases of OCRB were classified according to a modified combustion efficiency (MCE, defined as ΔCO2/(ΔCO + ΔCO2)). Our results support the view that ECa tend to be produced in flaming combustions (MCE > 0.95) than in smoldering combustions (MCE < 0.95), whereas OC is emitted preferentially from smoldering combustions. Based on our observed carbonaceous aerosol correlations, we estimate that the ECa and OC emissions from OCRB in East Asia might be underestimated by at least 50%.
    Journal of Geophysical Research 11/2012; 117(D22):22304-. · 3.17 Impact Factor
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    ABSTRACT: In the present study, we aim at developing an empirical model of BRDF over Tokyo, Japan, which is one of the most polluted areas in Asia, to evaluate the effect of the surface albedo on air-pollution monitoring from space. We used the RossThick-LiSparseReciprocal model with MODIS data to retrieve BRDF information. The BRDF had a strong dependence on season and local time, and the magnitude of the seasonal and local time change was up to 50%.
    Proc SPIE 10/2012;
  • Kazuyo Yamaji, Itsushi Uno, Hitoshi Irie
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    ABSTRACT: To illuminate the issue of trans-boundary O3 pollution and regional O3 reduction policies in East Asia, we have investigated the East Asian ozone (O3) response to perturbations caused by Chinese anthropogenic emissions using the Community Multiscale Air Quality (CMAQ) model, a regional chemical transport model. The O3 responses have been examined for the range between −100 and +100% changes from the Chinese emissions level in 2004 in 10% intervals. We have found that springtime and summertime O3 responses both at the source and at the downwind areas can be regarded as linear over the range between −30 and +100% changes from the current emissions level. We therefore suggest that the perturbation between −30 and +100% is sufficiently small to avoid nonlinear chemical influence on O3 formation in a model experiment to investigate East Asian scale O3 source-receptor relationships. On the other hand, the O3 response is strongly nonlinear in April at Hong Kong, where the current NMVOCs/NOx ratio is low and the O3 production regime is easily moved to the NMVOCs sensitive region. The O3 responses to the NOx emission changes have been investigated using surface O3 concentrations at remote Japanese sites and tropospheric NO2 vertical column density (NO2 VCD) over central east China both with observations and with model simulations in springtime during 2003–2009. Analysis of satellite data shows that the observed range of NO2 VCD over central east China in 2003–2009 is the range between −25 and +34% from the 2004 level, which corresponds approximately to an emission variation between −21 and +29%. The O3 concentration in the downwind region during 2003–2009 responds linearly to a change of the NO2 VCD over central east China both in the model and in the observation. The corresponding O3 responses derived from surface observations at remote Japanese sites show linear features consistent with this expectation. The doubling of emissions, i.e., approximately 1.9-fold increase in the NO2 VCD from 2004, leads to O3 increments of 5 ppbv and 8 ppbv in the model and in the observation, respectively. The modeled O3 increase due to changes in NOx emission explains approximately 60% of the observed O3 trend at remote Japanese sites. Thus, approximately 40% of the observed O3 increase is unaccounted for by the NOx emissions growth.
    Atmospheric Environment 08/2012; 55:475–482. · 3.11 Impact Factor
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    ABSTRACT: To investigate the feasibility of new satellite observations, including air quality (AQ) observations from geostationary (GEO) orbit, it is essential to link the measurement precision (ε) with sensor specifications in advance. The present study attempts to formulate the linkage between ε and specifications of a UV/visible sensor (signal-to-noise ratio (SNR), full width at half maximum (FWHM) of the slit function, and sampling ratio (SR)) on a GEO satellite. A sophisticated radiative transfer model (JACOSPAR) is used to calculate synthetic radiance spectra that would be measured by a UV/visible sensor observing the atmosphere over Tokyo (35.7°N, 139.7°E) from GEO orbit at 120°E longitude. The spectra, modified according to given sensor specifications, are analyzed by the differential optical absorption spectroscopy technique to estimate the ε for slant column densities of O3 and NO2. We find clear relationships: for example, the ε of the O3 slant column density (molecules cm−2) and SNR at 330 nm are linked by the equation log(ε) = −1.06 · log(SNR) + 20.71 in the UV region, and the ε of the NO2 slant column density and SNR at 450 nm are linked by log(ε) = −0.98 · log(SNR) + 18.00, at a FWHM = 0.6 nm (for the Gaussian slit function) and SR = 4. The relationships are mostly independent of other specifications (e.g., horizontal and temporal resolutions), as they affect ε primarily through SNR, providing constraints in determining the optimal SNR (and alternatively FWHM and SR) for similar UV/visible sensors dedicated for AQ studies.
    Advances in Space Research 06/2012; 49(12):1743–1749. · 1.18 Impact Factor
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    ABSTRACT: We present the results of a formaldehyde slant column intercomparison performed during the Cabauw Intercomparison Campaign of Nitrogen Dioxide measuring Instruments (CINDI) which took place in Cabauw (52°N, 5°E), The Netherlands, during summer 2009. Results from nine MAX-DOAS instruments (from BIRA-IASB, INTA, Bremen, Heidelberg, JAMSTEC, NASA, WSU, Toronto and Mainz research groups) are compared after application of common DOAS settings. To reduce instrumental and atmospheric noises, the slant columns are averaged over intervals of 30-minutes, and subsequently compared to a reference dataset. The intercomparison shows a good agreement, with differences from the reference dataset generally within 15% for off-axis elevations. In a second part of the study, sensitivity tests are performed to investigate the systematic uncertainties in the HCHO slant columns retrieval. Input parameters such as the molecular absorption cross-sections, corrections terms for the Ring effect, the polynomial closure terms and the width of the fitting interval are tested. In general, HCHO slant columns were found to be moderately sensitive to changes in the retrieval settings. However larger differences exceeding 15-20% were found to be related to uncertainties on the Ring effect corrections as well as to the O4 absorption cross-sections. The contribution from random uncertainties (ranging between 5 and 30% of the total error) was found to be highly dependent on the performance of individual measuring systems.
    04/2012;
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    ABSTRACT: Anthropogenic SO2 emissions increased alongside economic development in China at a rate of 12.7% yr-1 from 2000 to 2005. However, under new Chinese government policy, SO2 emissions declined by 3.9% yr-1 between 2005 and 2009. Between 2000 and 2010, we found that the variability in the fine-mode (submicron) aerosol optical depth (AOD) over the oceans adjacent to East Asia increased by 3-8% yr-1 to a peak around 2005-2006 and subsequently decreased by 2-7% yr-1, based on observations by the Moderate Resolution Imaging Spectroradiometer (MODIS) on board NASA's Terra satellite and simulations by a chemical transport model. This trend is consistent with ground-based observations of aerosol particles at a mountainous background observation site in central Japan. These fluctuations in SO2 emission intensity and fine-mode AOD are thought to reflect the widespread installation of fuel-gas desulfurization (FGD) devices in power plants in China, because aerosol sulfate is a major determinant of the fine-mode AOD in East Asia. Using a chemical transport model, we confirmed that the contribution of particulate sulfate to the fine-mode AOD is more than 70% of the annual mean and that the abovementioned fluctuation in fine-mode AOD is caused mainly by changes in SO2 emission rather than by other factors such as varying meteorological conditions in East Asia. A strong correlation was also found between satellite-retrieved SO2 vertical column density and bottom-up SO2 emissions, both of which were also consistent with observed fine-mode AOD trends. We propose a simplified approach for evaluating changes in SO2 emissions in China, combining the use of modeled sensitivity coefficients that describe the variation of fine-mode AOD with changes in SO2 emissions and satellite retrieval. Satellite measurements of fine-mode AOD above the Sea of Japan marked a 4.1% yr-1 decline between 2007 and 2010, which corresponded to the 9% yr-1 decline in SO2 emissions from China during the same period.
    ATMOSPHERIC CHEMISTRY AND PHYSICS 03/2012; 12(5):2631-2640. · 5.51 Impact Factor
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    ABSTRACT: From June to July 2009 more than thirty different in-situ and remote sensing instruments from all over the world participated in the Cabauw Intercomparison campaign for Nitrogen Dioxide measuring Instruments (CINDI). The campaign took place at KNMI's Cabauw Experimental Site for Atmospheric Research in the Netherlands. Its main objectives were to determine the accuracy of state-of-the-art ground-based measurement techniques for the detection of atmospheric nitrogen dioxide (both in-situ and remote sensing), and to investigate their usability in satellite data validation. The expected outcomes are recommendations regarding the operation and calibration of such instruments, retrieval settings, and observation strategies for the use in ground-based networks for air quality monitoring and satellite data validation. Twenty-four optical spectrometers participated in the campaign, of which twenty-one had the capability to scan different elevation angles consecutively, the so-called Multi-axis DOAS systems, thereby collecting vertical profile information, in particular for nitrogen dioxide and aerosol. Various in-situ samplers simultaneously characterized the variability of atmospheric trace gases and the physical properties of aerosol particles. A large data set of continuous measurements of these atmospheric constituents has been collected under various meteorological conditions and air pollution levels. Together with the permanent measurement capability at the Cabauw site characterizing the meteorological state of the atmosphere, the CINDI campaign provided a comprehensive observational data set of atmospheric constituents in a highly polluted region of the world during summertime. First detailed comparisons performed with the CINDI data show that slant column measurements of NO2, O4 and HCHO with MAX-DOAS agree within 5 to 15%, vertical profiles of NO2 derived from several independent instruments agree within 25%, and MAX-DOAS aerosol optical thickness agrees within 20-30% with AERONET data. For the in-situ NO2 instrument using a molybdenum converter, a bias was found as large as 5 ppbv during day time, when compared to the other in-situ instruments using photolytic converters.
    Atmospheric Measurement Techniques 01/2012; 5(2):457-485. · 3.21 Impact Factor
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    ABSTRACT: For the intercomparison of tropospheric nitrogen dioxide (NO2) vertical column density (VCD) data from three different satellite sensors (SCIAMACHY, OMI, and GOME-2), we use a common standard to quantitatively evaluate the biases for the respective data sets. As the standard, a regression analysis using a single set of collocated ground-based Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) observations at several sites in Japan and China from 2006-2011 is adopted. Examinations of various spatial coincidence criteria indicates that the slope of the regression line can be influenced by the spatial distribution of NO2 over the area considered. While the slope varies systematically with the distance between the MAX-DOAS and satellite observation points around Tokyo in Japan, such a systematic dependence is not clearly seen and correlation coefficients are generally higher in comparisons at sites in China. On the basis of these results, we focus mainly on comparisons over China and estimate the biases in SCIAMACHY, OMI, and GOME-2 data (TM4NO2A and DOMINO version 2 products) against the MAX-DOAS observations to be -5 ± 14%, -10 ± 14%, and +1 ± 14%, respectively, which are all small and insignificant. We suggest that these small biases now allow for analyses combining these satellite data for air quality studies, which are more systematic and quantitative than previously possible.
    Atmospheric Measurement Techniques 01/2012; 5(10):2403-2411. · 3.21 Impact Factor
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    ABSTRACT: Reducing uncertainties associated with measurements of black carbon (BC) particles is critical for improved quantification of their impacts on climate and health. We compared BC measurements using a continuous soot-monitoring system (COSMOS) and a multi-angle absorption photometer (MAAP) to assess their uncertainties. We found that measurements by COSMOS and MAAP instruments correlate strongly to each other, and their hourly ratio showed minimal temporal variations, but the MAAP values were systematically higher by a factor of 1.56 ± 0.19 (1σ), based on simultaneous observations on Fukue, a remote island in Japan, for about a year. This factor was almost independent of the air mass origins and seasons. Measurements in central Tokyo for about 2 months also yielded a similar relationship, with a systematic difference factor of ∼1.8. It is likely that the systematic differences are caused by differences in the conditions/protocols in the thermal/optical BC determinations used for calibration of each optical instrument. Based on results from the COSMOS instrument calibrated using an elemental carbon and organic carbon analyzer with thermal/optical transmittance correction, the MAAP absorption cross-section (6.6 m g) needs to be systematically increased to 10.3 m g at 639 nm for Fukue when babs values derived from the built-in software are used. Small temporal fluctuations in the ratios of MAAP-derived BC to COSMOS-derived BC were possibly caused by humidity effects and temporal variations in the optical properties of the measured particles. For MAAP, we also found that low filter- transmittance (0.2–0.5) could either increase or decrease the BC reading. The current best recommendations with the MAAP instrument are to use an increased cross-section, to use data with high filter-transmittance (>0.5) only, and to control humidity.
    Aerosol Science and Technology 01/2012; · 2.78 Impact Factor

Publication Stats

732 Citations
216.01 Total Impact Points

Institutions

  • 2012–2014
    • Chiba University
      • Center for Environmental Remote Sensing (CEReS)
      Tiba, Chiba, Japan
  • 2005–2013
    • Japan Agency for Marine-Earth Science Technology
      • Research Institute for Global Change
      Yokohama, Kanagawa, Japan
  • 2010–2012
    • Asia-Pacific Network for Global Change Research
      Kōbe, Hyōgo, Japan
  • 2002–2004
    • National Institute for Environmental Studies
      Tsukuba, Ibaraki, Japan
    • The University of Tokyo
      Edo, Tōkyō, Japan
  • 2000
    • Nagoya University
      • Solar-Terrestrial Environment Laboratory
      Nagoya, Aichi, Japan