Spatial mapping of greenhouse gases using a UAV monitoring platform over a megacity in China.

Urban environments are recognized as main anthropogenic contributors to greenhouse gas (GHG) emissions, characterized by unevenly distributed emission sources over the urban environments. However, spatial GHG distributions in urban regions are typically obtained through monitoring at only a limited number of locations, or through model studies, which can lead to incomplete insights into the heterogeneity in the spatial distribution of GHGs. To address such information gap and to evaluate the spatial representation of a planned GHG monitoring network, a custom-developed atmospheric sampler was deployed on a UAV platform in this study to map the CO and CH mixing ratios in the atmosphere over Zhengzhou in central China, a megacity of nearly 13 million people.

A New Methodology for High Spatiotemporal Resolution Measurements of Air Volatile Organic Compounds: From Sampling to Data Deconvolution.

Monitoring of volatile organic compounds (VOCs) in air is crucial for understanding their atmospheric impacts and advancing their emission reduction plans. This study presents an innovative integrated methodology suitable for achieving semireal-time high spatiotemporal resolution three-dimensional measurements of VOCs from ground to hundreds of meters above ground. The methodology integrates an active AirCore sampler, custom-designed for deployment from unmanned aerial vehicles (UAV), a proton-transfer-reaction mass spectrometry (PTR-MS) for sample analysis, and a data deconvolution algorithm for improved time resolution for measurements of multiple VOCs in air.

Quantification of Methane Emissions from Cold Heavy Oil Production with Sand Extraction in Alberta and Saskatchewan, Canada.

Cold heavy oil production with sand (CHOPS) is an extraction process for heavy oil in Canada, with the potential to lead to higher CH venting than conventional oil sites, that have not been adequately characterized. In order to quantify CH emissions from CHOPS activities, a focused aerial measurement campaign was conducted in the Canadian provinces of Alberta and Saskatchewan in June 2018. Total CH emissions from each of 10 clusters of CHOPS wells (containing 22-167 well sites per cluster) were derived using a mass balance computation algorithm that uses in situ wind data measurement on board aircraft.

Characteristics of sub-micron aerosols above the urban canopy in Beijing during warm seasons.

To understand the characteristics of atmospheric pollution above the urban canopy in warm seasons, the characteristics of sub-micron aerosol (PM) was studied based on high-altitude observations at the Beijing 325 m meteorological tower. The PM at 260 m was 34, 29 and 21 μg m in May 2015, June 2015, and June 2017, respectively, indicating a reduction in PM pollution above the urban canopy. Meanwhile, an overall decrease was also observed in the concentrations of all PM chemical species (excluding Chl and BC) and organic aerosol (OA) factors.

A newly developed Lagrangian chemical transport scheme: Part 1. Simulation of a boreal forest fire plume.

Forest fire research over the last several decades has improved the understanding of fire emissions and impacts. Nevertheless, the evolution of forest fire plumes remains poorly quantified and understood. Here, a Lagrangian chemical transport model, the Forward Atmospheric Stochastic Transport model coupled with the Master Chemical Mechanism (FAST-MCM), has been developed to simulate the transport and chemical transformations of plumes from a boreal forest fire over several hours since their emission.

Insights into vertical differences of particle number size distributions in winter in Beijing, China.

Particle number size distribution (PNSD) is of importance for understanding the mechanisms of particle growth, haze formation and climate impacts. However, the measurements of PNSD aloft in megacities are very limited. Here we report the first simultaneous winter measurements of size-resolved particle number concentrations along with collocated gaseous species and aerosol composition at ground level and 260 m in Beijing.

Aerosol characterization in a city in central China plain and implications for emission control.

Extensive studies on aerosol chemistry have been carried out in megacities in China, however, aerosol characterization in Central China Plain (CCP) is limited. Here we conducted real-time measurements of fine particle composition with a time-of-flight aerosol chemical speciation monitor in Kaifeng, Henan province in October 2019. Our results showed that nitrate and organics constituted the major fraction of non-refractory PM for the entire study, on average accounting for 34% and 33%, respectively.

Vertical Distributions of Primary and Secondary Aerosols in Urban Boundary Layer: Insights into Sources, Chemistry, and Interaction with Meteorology.

Vertical measurements are essential for the characterization of aerosol and boundary layer interactions; yet, our knowledge of vertical profiles of primary and secondary aerosol species in megacities is limited. Here, we conducted comprehensive vertical measurements of aerosol particle composition on a 325 m meteorological tower with two aerosol chemical speciation monitors in winter in urban Beijing. The simultaneous measurements at ground level, 140, and 240 m illustrated similar aerosol bulk composition at these three heights.

Light absorption of black carbon and brown carbon in winter in North China Plain: comparisons between urban and rural sites.

The light absorption black carbon (BC) and brown carbon (BrC) are two important sources of uncertainties in radiative forcing estimate. Here we investigated the light absorption enhancement (E) of BC due to coated materials at an urban (Beijing) and a rural site (Gucheng) in North China Plain (NCP) in winter 2019 by using a photoacoustic extinctiometer coupled with a thermodenuder. Our results showed that the average (±1σ) E was 1.

Seasonal characterization of aerosol composition and sources in a polluted city in Central China.

We characterized the aerosol composition and sources of particulate matter (PM) in Sanmenxia, a polluted city located in the Fen-Wei Plain region of Central China. The PM concentration decreased by 18% from 72 μg m in 2014 to 59 μg m in 2019. All chemical species presented pronounced seasonal variations, with their highest concentrations in winter due to enhanced emissions and the frequent stagnant meteorological conditions.

Molecular composition and sources of water-soluble organic aerosol in summer in Beijing.

Water-soluble organic aerosol (WSOA) constitutes a large fraction of OA and plays an important role in formation of secondary OA (SOA). Here we characterized the sources and molecular composition of WSOA in summer in Beijing using high-resolution aerosol mass spectrometer and orbitrap mass spectrometer equipped with electrospray ionization. Our results showed that WSOA was the major fraction of OA on average accounting for 69% in summer, which is much higher than that (47%) in winter.

Contrasting mixing state of black carbon-containing particles in summer and winter in Beijing.

Black carbon (BC) exerts a large impact on climate radiative forcing and public health, and such impacts depend strongly on chemical composition and mixing state. Here a single particle aerosol mass spectrometry (SPA-MS) along with an aerosol chemical speciation monitor was employed to characterize the composition and mixing state of BC-containing particles in summer and winter in Beijing. Approximately 2 million BC-containing particles were chemically analyzed, and the particles were classified into nine and eight different types in summer and winter, respectively, according to mass spectral signatures and composition.

Monitoring land surface thermal environments under the background of landscape patterns in arid regions: A case study in Aksu river basin.

Land surface temperature (LST) is defined as an important indicator in the formation and evolution of climate. In some cases, changes in landscape patterns affect LST, even more than the contribution of greenhouse gases. Although much work has been done with respect to the correlations between urban development and thermal environment dynamics, the related questions regarding relationships between LST and landscape patterns in arid regions are not thoroughly considered.

Response of aerosol chemistry to clean air action in Beijing, China: Insights from two-year ACSM measurements and model simulations.

Despite substantial mitigation of particulate matter (PM) pollution during the past decade in Beijing, the response of aerosol chemistry to clean air action and meteorology remains less understood. Here we characterized the changes in aerosol composition as responses to emission reductions by using two-year long-term measurements in 2011/2012 and 2017/2018, and WRF-Chem model. Our results showed substantial decreases for all aerosol species except nitrate from 2011/2012 to 2017/2018.

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.

Temporal characteristics and vertical distribution of atmospheric ammonia and ammonium in winter in Beijing.

To understand the temporal characteristics and vertical distributions of ammonia (NH) and ammonium (NH) in urban Beijing, we conducted ground-based and tower-based measurements of gaseous NH and submicron aerosol composition. The average mixing ratio of NH was 16.5 ± 7.

First Chemical Characterization of Refractory Black Carbon Aerosols and Associated Coatings over the Tibetan Plateau (4730 m a.s.l).

Refractory black carbon (rBC) aerosol is an important climate forcer, and its impacts are greatly influenced by the species associated with rBC cores. However, relevant knowledge is particularly lacking at the Tibetan Plateau (TP). Here we report, for the first time, highly time-resolved measurement results of rBC and its coating species in central TP (4730 m a.

Light absorption by water-soluble organic carbon in atmospheric fine particles in the central Tibetan Plateau.

Brown carbon (BrC) has recently received much attention because of its light absorption features. The chemical compositions, optical properties, and sources of fine aerosol at a high-elevation mountain observatory (4730 m a.s.