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  1. Article ; Online: Impacts of Horizontal Resolution on Global Data Assimilation of Satellite Measurements for Tropospheric Chemistry Analysis

    Takashi Sekiya / Kazuyuki Miyazaki / Koji Ogochi / Kengo Sudo / Masayuki Takigawa / Henk Eskes / K. Folkert Boersma

    Journal of Advances in Modeling Earth Systems, Vol 13, Iss 6, Pp n/a-n/a (2021)

    2021  

    Abstract: Abstract We present the results from a global 0.56°‐resolution chemical data assimilation that integrates satellite observations of ozone, NO2, CO, HNO3, and SO2 from OMI, GOME‐2, SCIAMACHY, TES, MOPITT, and MLS. The assimilation is based on an ensemble ... ...

    Abstract Abstract We present the results from a global 0.56°‐resolution chemical data assimilation that integrates satellite observations of ozone, NO2, CO, HNO3, and SO2 from OMI, GOME‐2, SCIAMACHY, TES, MOPITT, and MLS. The assimilation is based on an ensemble Kalman filter technique and simultaneously optimizes ozone precursor emissions and concentrations of various species. The data assimilation at 0.56° resolution reduced model errors against independent surface, aircraft, and ozonesonde observations, which was larger than at coarser resolutions for many cases. By the data assimilation, surface model errors over major polluted regions were reduced by 33%–75% for NO2 and by 15%–18% for ozone. Agreements against assimilated observations for NO2 were improved using the data assimilation at 0.56° resolution by a factor of 1.5–3 compared to 2.8° resolution over major polluted regions. The estimated global total NOx emission over medium and strong source areas were smaller by 15% at 0.56° resolution than at 2.8° resolution associated with resolving small‐scale transport and chemistry processes, while 2%–26% smaller emissions were found for regional total emissions over Europe, the United States, China, India, and South Africa, with larger differences over megacities such as Los Angeles (−41%). The estimated ship emissions were 5%–7% smaller at 0.56° resolution over the Pacific and Atlantic. The 0.56°‐resolution data assimilation provides globally consistent analyses of the emissions and concentrations on a megacity scale, which benefit studies on air quality and its impact on human health at various spatial scales over different regions of the world.
    Keywords atmospheric chemistry ; data assimilation ; emission inversion ; Physical geography ; GB3-5030 ; Oceanography ; GC1-1581
    Subject code 551
    Language English
    Publishing date 2021-06-01T00:00:00Z
    Publisher American Geophysical Union (AGU)
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article ; Online: Assessing Lagrangian inverse modelling of urban anthropogenic CO2 fluxes using in situ aircraft and ground-based measurements in the Tokyo area

    Ignacio Pisso / Prabir Patra / Masayuki Takigawa / Toshinobu Machida / Hidekazu Matsueda / Yousuke Sawa

    Carbon Balance and Management, Vol 14, Iss 1, Pp 1-

    2019  Volume 23

    Abstract: Abstract Background In order to use in situ measurements to constrain urban anthropogenic emissions of carbon dioxide (CO2), we use a Lagrangian methodology based on diffusive backward trajectory tracer reconstructions and Bayesian inversion. The ... ...

    Abstract Abstract Background In order to use in situ measurements to constrain urban anthropogenic emissions of carbon dioxide (CO2), we use a Lagrangian methodology based on diffusive backward trajectory tracer reconstructions and Bayesian inversion. The observations of atmospheric CO2 were collected within the Tokyo Bay Area during the Comprehensive Observation Network for TRace gases by AIrLiner (CONTRAIL) flights, from the Tsukuba tall tower of the Meteorological Research Institute (MRI) of the Japan Meteorological Agency and at two surface sites (Dodaira and Kisai) from the World Data Center for Greenhouse Gases (WDCGG). Results We produce gridded estimates of the CO2 emissions and calculate the averages for different areas within the Kanto plain where Tokyo is located. Using these inversions as reference we investigate the impact of perturbing different elements in the inversion system. We modified the observations amount and location (surface only sparse vs. including aircraft CO2 observations), the background representation, the wind data used to drive the transport model, the prior emissions magnitude and time resolution and error parameters of the inverse model. Conclusions Optimized fluxes were consistent with other estimates for the unperturbed simulations. Inclusion of CONTRAIL measurements resulted in significant differences in the magnitude of the retrieved fluxes, 13% on average for the whole domain and of up to 21% for the spatiotemporal cells with the highest fluxes. Changes in the background yielded differences in the retrieved fluxes of up to 50% and more. Simulated biases in the modelled transport cause differences in the retrieved fluxes of up to 30% similar to those obtained using different meteorological winds to advect the Lagrangian trajectories. Perturbations to the prior inventory can impact the fluxes by ~ 10% or more depending on the assumptions on the error covariances. All of these factors can cause significant differences in the estimated flux, and highlight the challenges in estimating ...
    Keywords Environmental sciences ; GE1-350
    Subject code 551
    Language English
    Publishing date 2019-05-01T00:00:00Z
    Publisher BMC
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  3. Article ; Online: Nitrogen oxides concentration and emission change detection during COVID-19 restrictions in North India

    Prakhar Misra / Masayuki Takigawa / Pradeep Khatri / Surendra K. Dhaka / A. P. Dimri / Kazuyo Yamaji / Mizuo Kajino / Wataru Takeuchi / Ryoichi Imasu / Kaho Nitta / Prabir K. Patra / Sachiko Hayashida

    Scientific Reports, Vol 11, Iss 1, Pp 1-

    2021  Volume 11

    Abstract: Abstract COVID-19 related restrictions lowered particulate matter and trace gas concentrations across cities around the world, providing a natural opportunity to study effects of anthropogenic activities on emissions of air pollutants. In this paper, the ...

    Abstract Abstract COVID-19 related restrictions lowered particulate matter and trace gas concentrations across cities around the world, providing a natural opportunity to study effects of anthropogenic activities on emissions of air pollutants. In this paper, the impact of sudden suspension of human activities on air pollution was analyzed by studying the change in satellite retrieved NO2 concentrations and top-down NOx emission over the urban and rural areas around Delhi. NO2 was chosen for being the most indicative of emission intensity due to its short lifetime of the order of a few hours in the planetary boundary layer. We present a robust temporal comparison of Ozone Monitoring Instrument (OMI) retrieved NO2 column density during the lockdown with the counterfactual baseline concentrations, extrapolated from the long-term trend and seasonal cycle components of NO2 using observations during 2015 to 2019. NO2 concentration in the urban area of Delhi experienced an anomalous relative change ranging from 60.0% decline during the Phase 1 of lockdown (March 25–April 13, 2020) to 3.4% during the post-lockdown Phase 5. In contrast, we find no substantial reduction in NO2 concentrations over the rural areas. To segregate the impact of the lockdown from the meteorology, weekly top-down NOx emissions were estimated from high-resolution TROPOspheric Monitoring Instrument (TROPOMI) retrieved NO2 by accounting for horizontal advection derived from the steady state continuity equation. NOx emissions from urban Delhi and power plants exhibited a mean decline of 72.2% and 53.4% respectively in Phase 1 compared to the pre-lockdown business-as-usual phase. Emission estimates over urban areas and power-plants showed a good correlation with activity reports, suggesting the applicability of this approach for studying emission changes. A higher anomaly in emission estimates suggests that comparison of only concentration change, without accounting for the dynamical and photochemical conditions, may mislead evaluation of lockdown impact. ...
    Keywords Medicine ; R ; Science ; Q
    Subject code 333
    Language English
    Publishing date 2021-05-01T00:00:00Z
    Publisher Nature Portfolio
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  4. Article ; Online: PM2.5 diminution and haze events over Delhi during the COVID-19 lockdown period

    Surendra K. Dhaka / Chetna / Vinay Kumar / Vivek Panwar / A. P. Dimri / Narendra Singh / Prabir K. Patra / Yutaka Matsumi / Masayuki Takigawa / Tomoki Nakayama / Kazuyo Yamaji / Mizuo Kajino / Prakhar Misra / Sachiko Hayashida

    Scientific Reports, Vol 10, Iss 1, Pp 1-

    an interplay between the baseline pollution and meteorology

    2020  Volume 8

    Abstract: Abstract Delhi, a tropical Indian megacity, experiences one of the most severe air pollution in the world, linked with diverse anthropogenic and biomass burning emissions. First phase of COVID-19 lockdown in India, implemented during 25 March to 14 April ...

    Abstract Abstract Delhi, a tropical Indian megacity, experiences one of the most severe air pollution in the world, linked with diverse anthropogenic and biomass burning emissions. First phase of COVID-19 lockdown in India, implemented during 25 March to 14 April 2020 resulted in a dramatic near-zeroing of various activities (e.g. traffic, industries, constructions), except the “essential services”. Here, we analysed variations in the fine particulate matter (PM2.5) over the Delhi-National Capital Region. Measurements revealed large reductions (by 40–70%) in PM2.5 during the first week of lockdown (25–31 March 2020) as compared to the pre-lockdown conditions. However, O3 pollution remained high during the lockdown due to non-linear chemistry and dynamics under low aerosol loading. Notably, events of enhanced PM2.5 levels (300–400 µg m−3) were observed during night and early morning hours in the first week of April after air temperatures fell close to the dew-point (~ 15–17 °C). A haze formation mechanism is suggested through uplifting of fine particles, which is reinforced by condensation of moisture following the sunrise. The study highlights a highly complex interplay between the baseline pollution and meteorology leading to counter intuitive enhancements in pollution, besides an overall improvement in air quality during the COVID-19 lockdown in this part of the world.
    Keywords Medicine ; R ; Science ; Q ; covid19
    Subject code 333
    Language English
    Publishing date 2020-08-01T00:00:00Z
    Publisher Nature Portfolio
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  5. Article: Mapping ozone risks for rice in China for years 2000 and 2020 with flux-based and exposure-based doses

    Tang, Haoye / Gang Liu / Gongxuan Zhang / Jianguo Zhu / Jing Pang / Kazuhiko Kobayashi / Masayuki Takigawa

    Atmospheric environment. 2014 Apr., v. 86

    2014  

    Abstract: We parameterized a multiplicative model of stomatal conductance (gsto) for O3 uptake by rice leaves with the field measurements in a fully open-air ozone (O3) fumigation experiment. The estimated gsto compared well with the observed one (r2 = 0.79). By ...

    Abstract We parameterized a multiplicative model of stomatal conductance (gsto) for O3 uptake by rice leaves with the field measurements in a fully open-air ozone (O3) fumigation experiment. The estimated gsto compared well with the observed one (r2 = 0.79). By using the gsto model for O3 uptake, we estimated a flux-based O3 risk (POD6, accumulated stomatal flux of O3 above a threshold of 6 nmol m−2 s−1) for rice across China in years 2000 and 2020, and compared it with the exposure-based O3 risk (AOT40, accumulated hourly O3 concentration above 40 ppb during daytime) for the same period. For the year 2000, both POD6 and AOT40 indicated the middle and lower reaches of Yangtze River and the south China being at the highest O3 risk. From the years 2000–2020, the O3 risks are projected to double (POD6) or triple (AOT40) in a majority of rice producing areas in the above two regions. Among three major rice cropping in the middle and lower reaches of Yangtze River, double-late rice is projected to have lower O3 risk than double-early rice and single rice on the either O3 risk measure in both 2000 and 2020. In south China, on the other hand, the O3 risks for double-late rice are comparable to that for early double-rice. In this study, the O3 risk was not measured as yield loss but as O3 flux and O3 exposure. The crop loss estimation would require a relationship between O3 flux and yield loss for major rice production regions across China.
    Keywords atmospheric chemistry ; crop losses ; crop production ; fumigation ; leaves ; models ; ozone ; rice ; risk ; stomatal conductance ; China ; Yangtze River
    Language English
    Dates of publication 2014-04
    Size p. 74-83.
    Publishing place Elsevier Ltd
    Document type Article
    ZDB-ID 216368-8
    ISSN 0004-6981 ; 1352-2310
    ISSN 0004-6981 ; 1352-2310
    DOI 10.1016/j.atmosenv.2013.11.078
    Database NAL-Catalogue (AGRICOLA)

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