Using a New Top‐Down Constrained Emissions Inventory to Attribute the Previously Unknown Source of Extreme Aerosol Loadings Observed Annually in the Monsoon Asia Free Troposphere

Abstract

 New constrained emissions provide the best daily to weekly scale model fit with independent measurements in space, time, and magnitude. Increases in BC emissions from 6.6 to 11.9 times are required to match the observed aerosol loadings in free tropospheric Monsoon Asia. A new spatiotemporal pathway is observed to transport aerosols far to both the southwest and east to match extreme aerosol events.

Inferring Polluted Asian Absorbing Aerosol Properties Using Decadal Scale AERONET Measurements and a MIE Model

“…Therefore, it is important to identify the source (urban, biomass burning, long‐range transport), size (nucleation, fine, coarse, etc.) and mixing state, including internal, external, and Core‐Shell mixing, of existing aerosol particles in order to accurately assess their direct and indirect effects on the atmosphere (i.e., Cohen & Wang, 2014; Kim et al., 2008; Kodros et al., 2018; Wang et al., 2021).…”

“…Most current chemical transport models (CTMs), general circulation models and reanalysis products (such as WRF‐Chem, GEOS‐Chem, CESM‐3, MERRA, NCEP, etc.) assume a non‐Core‐Shell approximation (Ichoku & Ellison, 2014; Kim et al., 2015; Nordmann et al., 2014; Yu et al., 2012), meaning that while CTMs can resolve the atmospheric composition of unmixed aerosols reasonably well, there are intrinsic problems in terms of being able to predict the composition of aerosols under polluted conditions or which have undergone long‐range transport, and further tend to underestimate their overall absorption of radiation (Cohen et al., 2011; Kajino et al., 2012; Wang et al., 2021). The use of the Core‐Shell model in this work is intended to aid elucidating how changes in measured atmospheric absorption and overall radiative properties of aerosols of different sizes and mixing ratios, can provide more insight into the sources and in‐situ processing of observed BC.…”

Dramatic decline of observed atmospheric CO2 and CH4 during the COVID-19 lockdown over the Yangtze River Delta of China

“…During 2011–2019, the average concentrations of △CO 2 , △CO and △CH 4 decreased from 3.0 ppm, 160.6 ppb and 12.5 ppb in IOP-1 to 0.8 ppm, 68.1 ppb and 0 ppb in IOP-2, then increased to 6.2 ppm, 114.7 ppb and 18.7 ppb in IOP-3, and ultimately reduced to 5.6 ppm, 64.8 ppb and 16.1 ppb in IOP-4, respectively. The one-trough mode was mainly due to the significant reduction in anthropogenic activities during the CNY holiday (IOP-2) ( Ding et al., 2013 ), and the slight variation in △CO 2 , △CO and △CH 4 as the time transitioned from IOP-3 to IOP-4 was probably due to high frequency changes in synoptic events, short-term changes in industrial and transportation emissions, or changes in the uptake of terrestrial ecosystems ( Wang et al., 2007 ; Peters et al., 2017 ; Wang et al., 2021 ; Deng et al., 2021). Furthermore, the lower △CO 2 /△CO slope and higher △CO during IOP-1 relative to post-CNY period (i.e., IOP-3 and IOP-4) was partly attributed to the high transportation emissions from “spring travel rush” in the beginning of the CNY holiday, as emissions sources from transportation often lead to lower △CO 2 /△CO compared to large, efficient power plants ( Turnbull et al., 2011 ; Wang et al., 2010 ).…”

“…Wide-spread improvement in air quality has been widely reported following lockdown in the world's most polluted cities ( Shrestha et al., 2020 ). Nevertheless, sporadic air pollution episodes frequently occurred in eastern China during COVID-19 ( Chang et al., 2020 ; Su et al., 2020 ; Wang et al., 2020 ), which were attributed to a wide range of causes, including much shallower boundary layer ( Su et al., 2020 ), regional transboundary transport ( Huang et al., 2020 ), the enhanced conversion of NOx to particulate nitrate ( Chang et al., 2020 ), aerosol heterogeneous chemistry promoted by high humidity ( Le et al., 2020 ), and enhanced biomass burning ( Wang et al., 2021 ).…”

Regulation of Synoptic Circulation in Regional PM2.5 Transport for Heavy Air Pollution: Study of 5‐year Observation Over Central China

“…The high temporal and spatial resolutions of air pollutant emissions could improve our understanding on air quality change with the contribution of regional air pollutant transport. It is more thoughtful and scientific to use 3‐D constrained emission inventory to investigate the heavy air pollution events (Wang, Cohen, et al., 2021), which can help to understand how air pollutants from source areas impact the environment from a more widespread perspective and also provide a pathway to explore previously untraceable air pollution events.…”