Lidar detection of high concentrations of ozone and aerosol transported from northeastern Asia over Saga, Japan

Uchino, Osamu; Sakai, Tetsu; Izumi, Toshiharu; Nagai, Tomohiro; Morino, Isamu; Yamazaki, Akihiro; Deushi, Makoto; Yumimoto, Keiya; Mäki, T.; Tanaka, Taichu Y.; Akaho, Taiga; Okumura, Hiroshi; Arai, Kohei; Nakatsuru, Takahiro; Matsunaga, Tsuneo; Yokota, Tatsuya

doi:10.5194/acp-17-1865-2017

Cited by 9 publications

(6 citation statements)

References 46 publications

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“…inaccuracies in the CTM simulations. The emission inventory used within FARM likely underestimates the real emissions, as also reported in other cases, and for different models, in the scientific literature (e.g., EMEP, 2016;Uchino et al, 2017). In particular, the boundary conditions could not be accurate enough for our aims owing to the abrupt change of the national emission inventory grid resolution (12 km) to the local scale (1 km).…”

Section: Model-measurement Discrepanciesmentioning

confidence: 84%

Transport of Po Valley aerosol pollution to the northwestern Alps. Part 1: phenomenology

Diémoz¹,

Barnaba²,

Magri³

et al. 2018

Preprint

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Abstract. Mountainous regions are often considered pristine environments, however they can be affected by pollutants emitted in more populated and industrialised areas, transported by regional winds. Based on experimental evidence, further supported by modelling tools, we demonstrate and quantify here the impact of air masses transported from the Po Valley, a European atmospheric pollution hotspot, to the northwestern Alps. This is achieved through a detailed investigation of the phenomenology of near-range (few hundreds km), trans-regional transport, exploiting synergies of multi-sensor observations mainly focussed on particulate matter. The explored dataset includes vertically-resolved data from atmospheric profiling techniques (Automated LiDAR-Ceilometers, ALC), vertically-integrated aerosol properties from ground (sun photometer) and space, and in situ measurements (PM10 and PM2.5, relevant chemical analyses, and aerosol size distribution). During the frequent advection episodes from the Po basin, all the physical quantities observed by the instrumental setup are found to significantly increase: the scattering ratio from ALC reaches values > 30, AOD triplicates, surface PM10 reaches concentrations > 100 µg/m3 even in rural areas, secondary inorganic compounds such as nitrate, ammonium and sulfate increase up to 28 %, 8 % and 17 % of the total PM10 mass, respectively. Results also indicate that the advected aerosol is smaller in size and less light-absorbing compared to the aerosol type locally-emitted in the northwestern Italian Alps, and hygroscopic. In this work, the phenomenon is exemplified through detailed analysis and discussion of three case studies, selected for their clarity and relevance within the wider dataset, the latter being fully exploited in a companion paper quantifying the impact of this phenomenology over the long-term (Diémoz et al., 2018). For the three case studies investigated, a high-resolution numerical weather prediction model (COSMO) and a lagrangian tool (LAGRANTO) are employed to understand the meteorological mechanisms favouring the transport and to demonstrate the Po Valley origin of the air masses. In addition, a chemical transport model (FARM) is used to further support the observations and to partition the contributions of local and non-local sources. Results show that the simulations are not able to adequately reproduce the measurements (with modelled PM10 concentrations 4–5 times lower than the ones retrieved from the ALC, and maxima anticipated by 6–7 hours), likely owing to deficiencies in the emission inventory and particle water uptake not fully taken into account. The advected aerosol is shown to remarkably degrade the air quality of the Alpine region, with potential negative effects on human health, climate and ecosystems, as well as on the touristic development of the investigated area. The findings of the present study could also help design mitigation strategies at the trans–regional scale in the Po basin, and suggest an observations-based approach to evaluate the outcome of their implementation.

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Section: Model-measurement Discrepanciesmentioning

confidence: 84%

Transport of Po Valley aerosol pollution to the northwestern Alps. Part 1: phenomenology

Diémoz¹,

Barnaba²,

Magri³

et al. 2018

Preprint

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“…The depolarization signals we measured may have been closer to those reported by Heese et al [54], i.e., a mix of particles from biomass and industrial burning. Also, following an analysis from Uchino et al [44], the main aerosol component we detected in this period might have been sub-micrometer-sized spherical particles, because the depolarization signal was small and the backscatter-related Ångström exponent is on the order of 1-2 ( Figure 5, middle panel).…”

Section: Discussionmentioning

confidence: 59%

“…The integrated backscattering coefficients (IBCs) of stratospheric aerosols from the tropopause level to 33 km were 6.81 × 10 −5 sr and 7.58 × 10 −5 sr on 26 January and 28 February, respectively. From here, we determined the stratospheric AOD by assuming that the LiDAR ratio for stratospheric aerosols is 50 sr −1 [44]. This yields stratospheric AODs of 0.0034 on 26 January and 0.0038 on 28 February 2017.…”

Section: Lidar Resultsmentioning

confidence: 99%

TCCON Philippines: First Measurement Results, Satellite Data and Model Comparisons in Southeast Asia

et al. 2017

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Abstract:The Total Carbon Column Observing Network (TCCON) is a global network dedicated to the precise and accurate measurements of greenhouse gases (GHG) in the atmosphere. The TCCON station in Burgos, Ilocos Norte, Philippines was established with the primary purpose of validating the upcoming Greenhouse gases Observing SATellite-2 (GOSAT-2) mission and in general, to respond to the need for reliable ground-based validation data for satellite GHG observations in the region. Here, we present the first 4 months of data from the new TCCON site in Burgos, initial comparisons with satellite measurements of CO 2 and model simulations of CO. A nearest sounding from Japan's GOSAT as well as target mode observations from NASA's Orbiting Carbon Observatory 2 (OCO-2) showed very good consistency in the retrieved column-averaged dry air mole fractions of CO 2 , yielding TCCON -satellite differences of 0.86 ± 1.06 ppm for GOSAT and 0.83 ± 1.22 ppm for OCO-2. We also show measurements of enhanced CO, probably from East Asia. GEOS-Chem model simulations were used to study the observed CO variability. However, despite the model capturing the pattern of the CO variability, there is an obvious underestimation in the CO magnitude in the model. We conclude that more measurements and modeling are necessary to adequately sample the variability over different seasons and to determine the suitability of current inventories.

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“…Analysis of multiple AERONET sites in East Asia during the 2001-2010 period showed that the area is dominated by mineral dust during spring months, likely transported from the Gobi and Taklamakan Deserts (Eck et al, 2005;Huang et al, 2008;Logan et al, 2013). The dominance of these outflowing aerosols continues to be observed as far away as Japan (Ikeda et al, 2014;Uchino et al, 2017). shows certain similarity, but is higher in general.…”

Section: Case Studymentioning

confidence: 99%

Analysis of Global Three-Dimensional Aerosol Structure with Spectral Radiance Matching

Liu¹,

Chen²,

Barker³

et al. 2019

Preprint

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Abstract. A method is assessed which expands aerosol vertical profiles inferred from nadir-pointing lidars to cross-track locations next to nadir columns. This is achieved via matching of passive radiances at off-nadir locations with their counterparts that are collocated with lidar data. This spectral radiance matching (SRM) method is tested using profiles inferred from CALIPSO lidar observations and collocated MODIS passive imagery for the periods 10–25 April and 14–29 September 2015. CALIPSO profiles are expanded out to 100 km on both sides of the daytime ground-track. Reliability of constructed profiles that are removed from the ground-track by N km are tested by requiring the algorithm to reconstruct profiles using only profiles that are removed from it along-track by more than N km. When sufficient numbers of pixels/columns are available, the SRM method can correctly match ~ 75 % and ~ 68 % of aerosol vertical structure at distances of 30 km and 100 km from the ground-track, respectively. The construction algorithm is applied to the east coast of Asia during spring 2015. Vertical distributions of different aerosol subtypes indicate that the region was dominated by dust and polluted dust transported from the continent. It is shown that aerosol optical depths inferred from ground-based measurements agree with those constructed by the SRM method better than direct observation from CALIPSO, and close to those inferred from MODIS radiances.

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Lidar detection of high concentrations of ozone and aerosol transported from northeastern Asia over Saga, Japan

Cited by 9 publications

References 46 publications

Transport of Po Valley aerosol pollution to the northwestern Alps. Part 1: phenomenology

Transport of Po Valley aerosol pollution to the northwestern Alps. Part 1: phenomenology

TCCON Philippines: First Measurement Results, Satellite Data and Model Comparisons in Southeast Asia

Analysis of Global Three-Dimensional Aerosol Structure with Spectral Radiance Matching

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