Returning long-range PM transport into the leeward of East Asia in 2021 after Chinese economic recovery from the COVID-19 pandemic.

Changes in the aerosol composition of sulfate (SO) and nitrate (NO) from 2012 to 2019 have been captured as a paradigm shift in the region downwind of China. Specifically, SO dramatically decreased and NO dramatically increased over downwind locations such as western Japan due to the faster reduction of SO emissions than NO emissions and the almost constant trend of NH emissions from China. Emissions from China sharply decreased during COVID-19 lockdowns in February-March 2020, after which China's economic situation seemed to recover going into 2021.

Nitrogen burden from atmospheric deposition in East Asian oceans in 2010 based on high-resolution regional numerical modeling.

East Asian oceans are possibly affected by a high nitrogen (N) burden because of the intense anthropogenic emissions in this region. Based on high-resolution regional chemical transport modeling with horizontal grid scales of 36 and 12 km, we investigated the N burden into East Asian oceans via atmospheric deposition in 2010. We found a high N burden of 2-9 kg N ha yr over the Yellow Sea, East China Sea (ECS), and Sea of Japan.

Impacts of COVID-19 lockdown, Spring Festival and meteorology on the NO variations in early 2020 over China based on in-situ observations, satellite retrievals and model simulations.

The lockdown measures due to COVID-19 affected the industry, transportation and other human activities within China in early 2020, and subsequently the emissions of air pollutants. The decrease of atmospheric NO due to the COVID-19 lockdown and other factors were quantitively analyzed based on the surface concentrations by in-situ observations, the tropospheric vertical column densities (VCDs) by different satellite retrievals including OMI and TROPOMI, and the model simulations by GEOS-Chem. The results indicated that due to the COVID-19 lockdown, the surface NO concentrations decreased by 42% ± 8% and 26% ± 9% over China in February and March 2020, respectively.

Effect of Asian dust on respiratory symptoms among children with and without asthma, and their sensitivity.

There has been little study on the effect of Asian dust exposure on respiratory symptoms among children who are vulnerable to environmental factors. In this panel study, we investigated the effect of Asian dust on respiratory symptoms among children with and without asthma, and their sensitivity. Children attending two elementary schools (137 total), and 23 children with asthma from cooperating medical institutions in Fukuoka prefecture were recruited.

Influence of the morphological change in natural Asian dust during transport: A modeling study for a typical dust event over northern China.

The effect of the nonsphericity of mineral dust aerosols on its deposition and transport was investigated based on model simulation for a typical dust event over northern China from April 6 to 12, 2018. The settling velocity related to morphological change in dust size was considered in Nested Air Quality Prediction Modeling System (NAQPMS) to simulate the dust spatial distribution. Comparison of these results with observations showed that the model reproduced the temporal variability in the mass concentration of particles along the dust plume pathway.

Paradigm shift in aerosol chemical composition over regions downwind of China.

A rapid decrease in PM concentrations in China has been observed in response to the enactment of strong emission control policies. From 2012 to 2017, total emissions of SO and NO from China decreased by approximately 63% and 24%, respectively. Simultaneously, decreases in the PM concentration in Japan have been observed since 2014, and the proportion of stations that satisfy the PM environmental standard (daily, 35 µg/m; annual average, 15 µg/m) increased from 37.

Size Distribution and Depolarization Properties of Aerosol Particles over the Northwest Pacific and Arctic Ocean from Shipborne Measurements during an R/V Cruise.

Atmospheric aerosols over polar regions have attracted considerable attention for their pivotal effects on climate change. In this study, temporospatial variations in single-particle-based depolarization ratios (δ: -polarized component divided by the total backward scattering intensity) were studied over the Northwest Pacific and the Arctic Ocean using an optical particle counter with a depolarization module. The δ value of aerosols was 0.

Dust Vortex in the Taklimakan Desert by Himawari-8 High Frequency and Resolution Observation.

The Taklimakan Desert is known to be one of the world's major sources of aeolian dust particles. Continuous images with 10-min temporal and 2-km spatial resolutions from a new-generation geostationary meteorological satellite captured the lifecycle (generation, evolution and outflow) of a previously unrecognized type of Taklimakan dust storm. The dust storm showed an anti-clockwise spiral structure and a clear core and behaved like a "dust vortex".

Seasonal variabilities in chemical compounds and acidity of aerosol particles at urban site in the west Pacific.

Mass concentrations of chemical compounds in both PM (particle aerodynamic diameter, Dp < 2.5 μm) and PM (2.5 < Dp < 10 μm), and acidity of aerosol particles were measured at an urban site in western Japan using a continuous dichotomous Aerosol Chemical Speciation Analyzer (ACSA-12) throughout 2014.

Importance of mineral dust and anthropogenic pollutants mixing during a long-lasting high PM event over East Asia.

A long-lasting high particulate matter (PM) concentration episode persisted over East Asia from May 24 to June 3, 2014. The Nested Air Quality Prediction Model System (NAQPMS) was used to investigate the mixing of dust and anthropogenic pollutants during this episode. Comparison of observations revealed that the NAQPMS successfully reproduced the time series PM and PM concentrations, as well as the nitrate and sulfate concentrations in fine (aerodynamic diameter ≤ 2.

Real-time observational evidence of changing Asian dust morphology with the mixing of heavy anthropogenic pollution.

Natural mineral dust and heavy anthropogenic pollution and its complex interactions cause significant environmental problems in East Asia. Due to restrictions of observing technique, real-time morphological change in Asian dust particles owing to coating process of anthropogenic pollutants is still statistically unclear. Here, we first used a newly developed, single-particle polarization detector and quantitatively investigate the evolution of the polarization property of backscattering light reflected from dust particle as they were mixing with anthropogenic pollutants in North China.

Chinese province-scale source apportionments for sulfate aerosol in 2005 evaluated by the tagged tracer method.

Appropriate policies to improve air quality by reducing anthropogenic emissions are urgently needed. This is typified by the particulate matter (PM) problem and it is well known that one type of PM, sulfate aerosol (SO), has a large-scale impact due to long range transport. In this study we evaluate the source-receptor relationships of SO over East Asia for 2005, when anthropogenic sulfur dioxide (SO) emissions from China peaked.

Long-term inverse modeling of Chinese CO emission from satellite observations.

Carbon monoxide (CO) emissions in China in 2005-2010 were estimated by inversion, using the Green's function method from vertical CO profiles derived from MOPITT Version 5 satellite data and a tagged CO simulation, and validated with independent in situ observations from the World Data Centre for Greenhouse Gases. Modeling with a posteriori emission successfully reproduced CO outflow from the continent to the East China Sea, Sea of Japan, and Japanese islands during winter and spring, and compensated for underestimates in central and eastern China in summer. A posteriori emissions showed large seasonal variations in which December and March emissions were on average 23% larger than August emissions, consistent with other studies.

Source contributions of sulfate aerosol over East Asia estimated by CMAQ-DDM.

We applied the decoupled direct method (DDM), a sensitivity analysis technique for computing sensitivities accurately and efficiently, to determine the source-receptor relationships of anthropogenic SO(2) emissions to sulfate aerosol over East Asia. We assessed source contributions from East Asia being transported to Oki Island downwind from China and Korea during two air pollution episodes that occurred in July 2005. The contribution from China, particularly that from central eastern China (CEC), was found to dominate the sulfate aerosols.

Field survey of trans-boundary air pollution with high time resolution at coastal sites on the Sea of Japan during winter in Japan.

An intensive field survey, with 6-h measurement intervals, of concentrations of chemical species in particulate matter and gaseous compounds was carried out at coastal sites on the Sea of Japan during winter. The concentration variation of SO(2)(g) and HNO(3)(g) were well correlated, whereas the NH(3)(g) concentration variation had no correlation with those of SO(2)(g) and HNO(3)(g). The NH(4) (+) (p)/non-sea-salt- (nss-)SO(4) (2 -)(p) ratio in particulate matter was mainly affected by the location of the sampling site.