Super dust storms reappeared in East Asia last spring after being absent for one and a half decades. Accurate simulation of such super sandstorms is valuable, but challenging due to imperfect emissions. In this study, the emissions of these dust storms are estimated by assimilating multiple observations. The results reveal that emissions originated from both China and Mongolia. However, for northern China, long-distance transport from Mongolia contributes much more dust than Chinese deserts.

Biogenic volatile organic compounds are intensely emitted by forests and crops and react with the nitrate radical during the nighttime to form functionalized products. The purpose of this study is to furnish kinetic and mechanistic data for terpinolene and β-caryophyllene, using simulation chamber experiments. Rate constants have been measured using both relative and absolute methods, and mechanistic studies have been conducted in order to identify and quantify the main reaction products.

Airborne particles were i) collected in an agricultural fields and ii) generated in the laboratory from agricultural soil samples to analyze their ice nucleating abilities. It was found that the size and chemical composition of the Mexican agricultural dust particles influence their ice nucleating behavior, where the organic components are likely responsible for their efficiency as INPs. The INP concentrations from the present study are comparable to those from higher latitudes.

Light-absorbing brown carbon (BrC) plays an important role in climate change and atmospheric chemistry. Here we investigated the seasonal and diurnal variations in water-soluble BrC in PM_2.5 in the megacity Tianjin in coastal China. Results of the source apportionments from the combination with organic molecular compositions and optical properties of water-soluble BrC reveal a large contribution from primary bioaerosol particles to BrC in the urban atmosphere.

This study investigates the modulation of daily PM_2.5 over three major populated regions in China by regional meteorology and large-scale circulation during winter. These results demonstrate the benefits of considering the large-scale circulation for air quality studies. The novel circulation indices proposed here can explain a considerable fraction of the day-to-day variability of PM_2.5 and can be combined with regional meteorology to improve our capability to predict the variability of PM_2.5.

Mobile measurement techniques (e.g., instruments placed in cars) are often employed to identify and quantify individual sources of greenhouse gases. Due to road restrictions, those observations are often sparse (temporally and spatially). We performed high-resolution simulations of plume dispersion, with realistic weather conditions encountered in the field, to reproduce the measurement process of a methane plume emitted from an oil well and provide additional information about the plume.

The intraseasonal NAAA usually establishes quickly on day −3 with a life span of 8 days. Further results revealed that the probability of regional PM_2.5 pollution related to the NAAA for at least 2 days in the NCP is 80% in NDJ period 2000–2021. Particularly, air quality in the NCP tends to deteriorate on day 2 prior to the peak day of the NAAA and reaches a peak on day −1 with a life cycle of 4 days. The corresponding meteorological conditions support these conclusions.

Heatwaves (HWs) paired with higher ozone (O₃) concentration at surface level pose a serious threat to human health. Taking Beijing as an example, three unfavorable synoptic weather patterns were identified to dominate the compound HW and O₃ pollution events. Under the synergistic stress of HWs and O₃ pollution, public mortality risk increased, and synoptic patterns and urbanization enhanced the compound risk of events in Beijing by 33.09 % and 18.95 %, respectively.

The movement of air masses and the trace gases they contain from the Earth’s surface into the upper troposphere and lower stratosphere (UTLS) can have important implications for the radiative and chemical balance of the atmosphere. In this study we build on recent techniques and use new ones to estimate a range of transport diagnostics based on simultaneously measured trace gases in the UTLS during the monsoon season in North America.

This study examines how cities and their surroundings influence turbulent exchange processes responsible for weather and climate. Analysis of a 4-year observational dataset for the Alpine city of Innsbruck reveals several similarities with other (flat) city centre sites. However, the mountain setting leads to characteristic daily and seasonal flow patterns (valley winds) and downslope windstorms that have a marked effect on temperature, wind speed, turbulence and pollutant concentration.

Observations of ammonia made using the satellite-borne CrIS instrument were used to improve the ammonia emissions used in the GEM-MACH model. These observations were used to refine estimates of the monthly mean ammonia emissions over North America for May to August 2016. The updated ammonia emissions reduced biases of GEM-MACH surface ammonia fields with surface observations and showed some improvements in the forecasting of species involved in inorganic particulate matter formation.

In the atmosphere over the Indian Ocean, intense anthropogenic pollution from Southeast Asia mixes with pristine oceanic air. During the winter monsoon, high pollution levels are regularly observed over the entire northern Indian Ocean, while during the summer monsoon, clean air dominates. Here, we review current progress in detecting and understanding atmospheric gas-phase composition over the Indian Ocean and its impacts on the upper atmosphere, oceanic biogeochemistry, and marine ecosystems.

Ice clouds in the stratosphere (SICs) greatly affect the water vapor balance and radiation budget in the upper troposphere and lower stratosphere (UTLS). We quantified the global SICs and analyzed their relationships with tropopause temperature, double tropopauses, UTLS clouds, gravity waves, and stratospheric aerosols. The correlations between SICs and all abovementioned processes indicate that the occurrence of and variability in SICs are spatiotemporally dependent on different processes.

From balloon measurements, we detected unprecedented, extremely powerful, electron precipitation over the middle latitudes. The robustness of this event is confirmed by satellite observations of electron fluxes and chemical composition, as well as by ground-based observations of the radio signal propagation. The applied chemistry–climate model shows the almost complete destruction of ozone in the mesosphere over the region where high-energy electrons were observed.

Long-lived cold-layer clouds at subzero temperatures are observed to be remarkably persistent in their generation of ice particles and snow precipitation. There is uncertainty about why this is so. This motivates the present lab study to observe the long-term ice-nucleating ability of aerosol samples from the real troposphere. Time dependence of their ice nucleation is observed to be weak in lab experiments exposing the samples to isothermal conditions for up to about 10 h.

How sea spray aerosols may affect cloud and precipitation over the region by acting as ice-nucleating particles (INPs) is unknown. We explored the effects of INPs from marine aerosols on orographic cloud and precipitation for an atmospheric river event observed during the 2015 ACAPEX field campaign. The marine INPs enhance the formation of ice and snow, leading to less shallow warm clouds but more mixed-phase and deep clouds. This work suggests models need to consider the impacts of marine INPs.

Aerosol hygroscopicity is critical when evaluating its effect on visibility and climate. Here, the size-resolved particle hygroscopicity at five sites in China is characterized using field measurements. We show the distinct behavior of hygroscopic particles during pollution evolution among the five sites. Moreover, different hygroscopic behavior during NPF events were also observed. The dataset is helpful for understanding the spatial variability in particle composition and formation mechanisms.

Using AIRS and TROPOMI sulfur dioxide retrievals and the Lagrangian transport model MPTRAC, we present an improved reconstruction of injection parameters of the 2019 Raikoke eruption. Reconstructions agree well between using AIRS nighttime and TROPOMI daytime retrievals, showing the potential of our approach to create a long-term volcanic sulfur dioxide inventory from nearly 20 years of AIRS retrievals.

This paper is intended to accomplish two goals: 1) describe a new algorithm by which remotely sensed measurements of methane or other tracers can be used to not just quantify methane fluxes, but also attribute these fluxes to specific sources and regions and characterize their uncertainties, and 2) use this new algorithm to provide methane emissions by sector and country in support of the global stock take.

Long-term trends in column ozone have been determined from five merged total ozone datasets spanning the period 1978–2020. We show that ozone recovery due to the decline in stratospheric halogens after the 1990s (as regulated by the Montreal Protocol) is evident outside the tropical region and amounts to half a percent per decade. The ozone recovery in the Northern Hemisphere is however compensated for by the negative long-term trend contribution from atmospheric dynamics since the year 2000.

Monitoring the long-term evolution of ozone and the evaluation of trends is essential to assess the efficacy of the Montreal Protocol and its amendments. The first signs of recovery as a consequence of decreasing amounts of ozone-depleting substances have been reported, but the impact needs to be investigated in more detail. In the Southern Hemisphere significant positive trends were found, but in the Northern Hemisphere the expected increase is still not yet visible.

The trades are home to a plethora of small cumulus clouds that are often barely visible to the human eye and difficult to detect with active and passive remote sensing methods. With the help of a new method and by means of high-resolution data we can detect small and particularly thin clouds. We find that optically thin clouds are a common phenomenon in the trades, covering a large area and influencing the radiative effect of clouds if they are undetected and contaminate the cloud-free signal.

Greenhouse gas methane in the Arctic atmosphere has not been accurately reported for 1900–1980 from either direct observations or ice core reconstructions. By using trace gas data from firn (compacted snow layers above ice sheet), air samples at two Greenland sites, and a firn air transport model, this study suggests a likely range of the Arctic methane reconstruction for the 20th century. Atmospheric scenarios from two previous studies are also evaluated for consistency with the firn data sets.

We conducted field observation employing Fourier transform ion cyclotron resonance mass spectrometry to characterize the molecular composition and major formation pathways or sources of organosulfur compounds in Guangzhou, where is heavily influenced by biogenic–anthropogenic interactions and has high relative humidity and temperature. We suggested that heterogeneous reactions such as SO₂ uptake and heterogeneous oxidations are important to the molecular variations of organosulfur compounds.

The understanding of secondary organic aerosols is hindered by the aerosol–gas evolution by different oxidation mechanisms. By concurrently measuring detailed mass spectra of aerosol and gas phases in a megacity online, we identified the primary and secondary source sectors and investigated the transformation between gas and aerosol phases influenced by photooxidation and moisture. The results will help us to understand the respective evolution of major sources in a typical urban environment.

The atmospheric O₂ / N₂ ratio and CO₂ concentration over the western North Pacific are presented. We found significant modification of the seasonal APO cycle in the middle troposphere due to the interhemispheric mixing of air. APO driven by the net marine biological activities indicated annual sea–air O₂ flux during El Niño. Terrestrial biospheric and oceanic CO₂ uptakes during 2012–2019 were estimated to be 1.8 and 2.8 Pg C a⁻¹, respectively.

The gas–particle partitioning process of glyoxal and methylglyoxal could contribute to secondary organic aerosol formation. Here, we launched five observations in different seasons and simultaneously measured glyoxal and methylglyoxal in the gas and particle phases. Compared to reversible pathways, irreversible pathways played a dominant role with a proportion of more than 90 % in the ambient atmosphere, and the proportion was influenced by relative humidity and inorganic components in aerosols.

This work explores the kinetics and reactivity of epoxides towards the OH radical using two different simulation chambers. Estimation of the rate coefficients has also been made using different structure–activity relationship (SAR) approaches. The results indicate a direct influence of the structural and geometric properties of the epoxides not considered in SAR estimations, influencing the reactivity of these compounds. The outcomes of this work are in very good agreement with previous studies.

This paper presents the first OH and HO₂ radical observations made in the Yangtze River Delta in China, and strong oxidation capacity is discovered based on direct measurements. The impacts of new OH regeneration mechanisms, monoterpene oxidation, and HO₂ uptake processes are examined and discussed. The sources and the factors to sustain such strong oxidation are the key to understanding the ozone pollution formed in this area.

Oxidative potential (OP), a biologically relevant metric for particulate matter (PM), was linked to PM₁₀ and PM_2.5 sources and constituents across Switzerland between 2018 and 2019. Wood burning and non-exhaust traffic emissions were identified as key processes that led to enhanced OP. Therefore, the make-up of the PM mix was very important for OP. The results highlight the importance of the management of wood burning and non-exhaust emissions to reduce OP, and presumably biological harm.

We measured the gas-phase reactivity of the NO₃ radical on the summit (825 m a.s.l.) of a semi-rural mountain in southwestern Germany in July 2021. The impact of VOC-induced NO₃ losses (mostly monoterpenes) competing with a loss by reaction with NO and photolysis throughout the diel cycle was estimated. Besides chemistry, boundary layer dynamics and plant-physiological processes presumably have a great impact on our observations, which were compared to previous NO₃ measurements at the same site.

Significant decreases in annual mean NO_x from 2011 to 2016 and SO₂ from 2008 to 2016 confirm the effectiveness of relevant control measures on the reduction in NO_x and SO₂ emissions in the North China Plain (NCP). NO_x at SDZ had a weaker influence than SO₂ on the emission reduction in Beijing and other areas in the NCP. An increase in the number of motor vehicles and weak traffic restrictions have caused vehicle emissions of NO_x, which indicates that NO_x emission control should be strengthened.