Since the 1970s, China has continuously improved air pollution treatment and emission standards, but polluted weather still occurs frequently in some areas, especially haze weather. At present, most of the research on haze weather focuses on particulate matter, while ignoring the mechanism of aerosol-radiation-surface ozone interaction under haze weather. Therefore, this paper analyses the relationship between aerosol-radiation-surface ozone with the help of the (SBDART) model for the Guangdong-Hong Kong-Macao Greater Bay Area (GBA), using 2013-2021 as the time line. The results show similar trends in total column ozone and tropospheric ozone, and separate trends in surface ozone. Total column ozone and tropospheric ozone concentrations are at high values in spring and summer and low values in fall and winter; surface ozone is higher in summer and fall and lower in winter and spring. In contrast, Absorbing aerosol index (AAI) had high values in both spring and winter, and low values in summer and autumn. AAI, PM10 and Black carbon (BC) showed negative relations with ozone overall, but AAI and tropospheric ozone reached high values simultaneously in spring, indicating a rapid increase of pollutants caused by meteorological factors and human activities. Ozone concentration decreases from high values when precipitable water increases significantly. The analysis of potential sources of AAI indicated that local sources centered in Guangzhou were the primary source of AAI in the urban agglomeration of GBA, while other potential sources include biomass sources in the south and ozone sources in the northeast. The photolysis rate of fine-grained urban/industrial aerosols did not decrease significantly, leading to an increase in surface ozone concentration. Therefore, low aerosol radiative forcing (ARF) may increase surface ozone concentrations in the fine-particle aerosol mode.

Air pollutants can be transported to the pristine regions such as the Tibetan Plateau, by monsoon and stratospheric intrusion. The Tibetan Plateau region has limited local anthropogenic emissions, while this region is influenced strongly by transport of heavy emissions mainly from South Asia. We conducted a comprehensive study on various air pollutants (PM2.5, total gaseous mercury, and surface ozone) at Nam Co Station in the inland Tibetan Plateau. Monthly mean PM2.5 concentration at Nam Co peaked in April before monsoon season, and decreased during the whole monsoon season (June-September). Monthly mean total gaseous mercury concentrations at Nam Co peaked in July and were in high levels during monsoon season. The Indian summer monsoon acted as a facilitator for transporting gaseous pollutants (total gaseous mercury) but a suppressor for particulate pollutants (PM2.5) during the monsoon season. Different from both PM2.5 and total gaseous mercury variabilities, surface ozone concentrations at Nam Co are primarily attributed to stratospheric intrusion of ozone and peaked in May. The effects of the Indian summer monsoon and stratospheric intrusion on air pollutants in the inland Tibetan Plateau are complex and require further studies. (C) 2021 China University of Geosciences (Beijing) and Peking University. Production and hosting by Elsevier B.V.

There has been renewed interest in developing commercial supersonic transport aircraft due to the increased overall demands by the public for air travel, the aspiration for more intercontinental travel, and the desire for shorter flight times. Various companies and academic institutions have been actively considering the designs of such supersonic aircraft. As these new designs are developed, the environmental impact on ozone and climate of these fleets need to be explored. This study examines one such proposed commercial supersonic fleet of 55-seater that is projected to fly at Mach 2.2, corresponding to cruise altitudes of 17-20 km, and which would burn 122.32 Tg of fuel and emit 1.78 Tg of NOx each year. Our analyses indicate this proposed fleet would cause a 0.74% reduction in global column ozone (similar to 2 Dobson Units), which is mainly attributed to the large amounts of nitrogen oxides released in the atmosphere from the supersonic aircraft. The maximum ozone loss occurs at the tropics in the fall season, with a reduction of -1.4% in the total column ozone regionally. The stratospheric-adjusted radiative forcing on climate from this fleet was derived based on changes in atmospheric concentrations of ozone (59.5 mW/m(2)), water vapor (10.1 mW/m(2)), black carbon (-3.9 mW/m(2)) and sulfate aerosols (-20.3 mW/m(2)), resulting in a net non-CO2, non-contrail forcing of 45.4 mW/m(2), indicating an overall warming effect. Plain Language Summary With the general public's increased demand for air travel, a desire for more intercontinental travel with shorter flight times, there has been renewed interest in developing commercial supersonic transport aircraft. Various companies and academic institutions have been actively considering the design of such a supersonic aircraft. As these new designs are developed, the environmental impact of these realistic fleets on ozone and climate needs to be explored. This study looked at one such supersonic fleet, expected to fly at Mach 2.2, corresponding to a cruising altitude of 17-20 km, that would burn 122.32 Tg of fuel and emit 1.78 Tg of NOx per year. Our analysis shows that this proposed fleet would result in a 0.74% reduction in global columnar ozone (approximately 2 Dobson units), mainly due to the large atmospheric release of nitrogen oxides by supersonic aircraft. The impact on climate from this fleet was derived to have a net forcing of 45.4 mW/m(2), indicating an overall warming effect.

This study evaluates the performance of a newly developed atmospheric chemistry-climate model, BCCAGCM_CUACE2.0 (Beijing Climate Center Atmospheric General Circulation Model_China Meteorological Administration Unified Atmospheric Chemistry Environment) model, for determining past (2010) and future (2050) tropospheric ozone (O-3) levels. The radiative forcing (RF), effective radiative forcing (ERF), and rapid adjustments (RAs, both atmospheric and cloud) due to changes in tropospheric O-3 are then simulated by using the model. The results show that the model reproduces the tropospheric O-3 distribution and the seasonal changes in O-3 surface concentration in 2010 reasonably compared with site observations throughout China. The global annual mean burden of tropospheric O-3 is simulated to have increased by 14.1 DU in 2010 relative to pre-industrial time, particularly in the Northern Hemisphere. Over the same period, tropospheric O-3 burden has increased by 21.1 DU in China, with the largest increase occurring over Southeast China. Although the simulated tropospheric O-3 burden exhibits a declining trend in global mean in the future, it increases over South Asia and Africa, according to the Representative Concentration Pathway (RCP) 4.5 and 8.5 scenarios. The global annual mean ERF of tropospheric O-3 is estimated to be 0.25 W m(-2) in 1850-2010, and it is 0.50 W m(-2) over China. The corresponding atmospheric and cloud RAs caused by the increase of tropospheric O-3 are estimated to be 0.02 and 0.03 W m(-2), respectively. Under the RCP2.6, RCP4.5, RCP6.0, and RCP8.5 scenarios, the annual mean tropospheric O-3 ERFs are projected to be 0.29 (0.24), 0.18 (0.32), 0.23 (0.32), and 0.25 (0.01) W m-2 over the globe (China), respectively.

In this work, the influence of South Asian biomass burning emissions on O-3 and PM2.5 concentrations over the Tibetan Plateau (TP) is investigated by using the regional climate chemistry transport model WRF-Chem. The simulation is validated by comparing meteorological fields and pollutant concentrations against in situ observations and gridded datasets, providing a clear perspective on the spatiotemporal variations of O-3 and PM2.5 concentrations across the Indian subcontinent, including the Tibetan Plateau. Further sensitivity simulations and analyses show that emissions from South Asian biomass burning mainly affect local O-3 concentrations. For example, contribution ratios were up to 20% in the Indo-Gangetic Plain during the pre-monsoon season but below 1% over the TP throughout the year 2016. In contrast, South Asian biomass burning emissions contributed more than 60% of PM2.5 concentration over the TP during the pre-monsoon season via significant contribution of primary PM2.5 components (black carbon and organic carbon) in western India that were lofted to the TP by westerly winds. Therefore, it is suggested that cutting emissions from South Asian biomass burning is necessary to alleviate aerosol pollution over the TP, especially during the pre-monsoon season.

Downward transport of stratospheric air into the troposphere (identified as stratospheric intrusions) could potentially modify the radiation budget and chemical of the Earth's surface atmosphere. As the highest and largest plateau on earth, the Tibetan Plateau including the Himalayas couples to global climate, and has attracted widespread attention due to rapid warming and cryospheric shrinking. Previous studies recognized strong stratospheric intrusions in the Himalayas but are poorly understood due to limited direct evidences and the complexity of the meteorological dynamics of the third pole. Cosmogenic S-35 is a radioactive isotope predominately produced in the lower stratosphere and has been demonstrated as a sensitive chemical tracer to detect stratospherically sourced air mass in the planetary boundary layer. Here, we report 6-month (April-September 2018) observation of S-35 in atmospheric sulfate aerosols ((SO42-)-S-35) collected from a remote site in the Himalayas to reveal the stratospheric intrusion phenomenon as well as its potential impacts in this region. Throughout the sampling campaign, the (SO42-)-S-35 concentrations show an average of 1,070 +/- 980 atoms/m(3). In springtime, the average is 1,620 +/- 730 atoms/m(3), significantly higher than the global existing data measured so far. The significant enrichments of (SO42-)-S-35 measured in this study verified the hypothesis that the Himalayas is a global hot spot of stratospheric intrusions, especially during the springtime as a consequence of its unique geology and atmospheric couplings. In combined with the ancillary evidences, e.g., oxygen-17 anomaly in sulfate and modeling results, we found that the stratospheric intrusions have a profound impact on the surface ozone concentrations over the study region, and potentially have the ability to constrain how the mechanisms of sulfate oxidation are affected by a change in plateau atmospheric properties and conditions. This study provides new observational constraints on stratospheric intrusions in the Himalayas, which would further provide additional information for a deeper understanding on the environment and climatic changes over the Tibetan Plateau.

Detailed examination of the impact of modern space launches on the Earth's atmosphere is crucial, given booming investment in the space industry and an anticipated space tourism era. We develop air pollutant emissions inventories for rocket launches and re-entry of reusable components and debris in 2019 and for a speculative space tourism scenario based on the recent billionaire space race. This we include in the global GEOS-Chem model coupled to a radiative transfer model to determine the influence on stratospheric ozone (O-3) and climate. Due to recent surge in re-entering debris and reusable components, nitrogen oxides from re-entry heating and chlorine from solid fuels contribute equally to all stratospheric O-3 depletion by contemporary rockets. Decline in global stratospheric O-3 is small (0.01%), but reaches 0.15% in the upper stratosphere (similar to 5 hPa, 40 km) in spring at 60-90 degrees N after a decade of sustained 5.6% a(-1) growth in 2019 launches and re-entries. This increases to 0.24% with a decade of emissions from space tourism rockets, undermining O-3 recovery achieved with the Montreal Protocol. Rocket emissions of black carbon (BC) produce substantial global mean radiative forcing of 8 mW m(-2) after just 3 years of routine space tourism launches. This is a much greater contribution to global radiative forcing (6%) than emissions (0.02%) of all other BC sources, as radiative forcing per unit mass emitted is similar to 500 times more than surface and aviation sources. The O-3 damage and climate effect we estimate should motivate regulation of an industry poised for rapid growth.

Permafrost landscapes are particularly susceptible to the observed climate change due to the presence of ice in the ground. This paper presents the results of the mapping and assessment of landscapes and their vulnerability to potential human impact and further climate change in the remote region of Eastern Chukotka. The combination of field studies and remote sensing data analysis allowed us to identify the distribution of landscapes within the study polygon, reveal the factors determining their stability, and classify them by vulnerability to the external impacts using a hazard index, H. In total, 33 landscapes characterized by unique combinations of vegetation cover, soil type, relief, and ground composition were detected within the 172 km(2) study polygon. The most stable landscapes of the study polygon occupy 31.7% of the polygon area; they are the slopes and tops of mountains covered with stony-lichen tundra, alpine meadows, and the leveled summit areas of the fourth glacial-marine terrace. The most unstable areas cover 19.2% of the study area and are represented by depressions, drainage hollows, waterlogged areas, and places of caterpillar vehicle passage within the terraces and water-glacial plain. The methods of assessment and mapping of the landscape vulnerability presented in this study are quite flexible and can be adapted to other permafrost regions.

Australian wildfires burning from December 2019 to January 2020 injected approximately 0.9 Tg of smoke into the stratosphere; this is the largest amount observed in the satellite era. A comparison of numerical simulations to satellite observations of the plume rise suggests that the smoke mass contained 2.5% black carbon. Model calculations project a 1 K warming in the stratosphere of the Southern Hemisphere midlatitudes for more than 6 months following the injection of black-carbon containing smoke. The 2020 average global mean clear sky effective radiative forcing at top of atmosphere is estimated to be -0.03 W m(-2) with a surface value of -0.32 W m(-2). Assuming that smoke particles coat with sulfuric acid in the stratosphere and have similar heterogeneous reaction rates as sulfate aerosol, we estimate a smoke-induced chemical decrease in total column ozone of 10-20 Dobson units from August to December in mid-high southern latitudes.

Knowledge of aerosol size and composition is very important for investigating the radiative forcing impacts of aerosols, distinguishing aerosol sources, and identifying harmful particulate types in air quality monitoring. The ability to identify aerosol type synoptically would greatly contribute to the knowledge of aerosol type distribution at both regional and global scales, especially where there are no data on chemical composition. In this study, aerosol classification techniques were based on aerosol optical properties from remotely-observed data from the Ozone Monitoring Instrument (OMI) and Aerosol Robotic Network (AERONET) over Saudi Arabia for the period 2004-2016 and validated using data from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO). For this purpose, the OMI-based Aerosol Absorption Optical Depth (AAOD) and UltraViolet Aerosol Index (UVAI), and AERONET-based AAOD, Angstrom Exponent (AE), Absorption Angstrom Exponent (AAE), Fine Mode Fraction (FMF), and Single Scattering Albedo (SSA) were obtained. Spatial analysis of the satellite-based OMI-AAOD showed the dominance of absorbing aerosols over the study area, but with high seasonal variability. The study found significant underestimation by OMI AAOD suggesting that the OMAERUV product may need improvement over bright desert surfaces such as the study area. Aerosols were classified into (i) Dust, (ii) Black Carbon (BC), and (iii) Mixed (BC and Dust) based on the relationships technique, between the aerosol absorption properties (AAE, SSA, and UVAI) and size parameters (AE and FMF). Additionally, the AE vs. UVAI and FMF vs. UVAI relationships misclassified the aerosol types over the study area, and the FMF vs. AE, FMF vs. AAE and FMF vs. SSA relationships were found to be robust. As expected, the dust aerosol type was dominant both annually and seasonally due to frequent dust storm events. Also, fine particulates such as BC and Mixed (BC and Dust) were observed, likely due to industrial activities (cement, petrochemical, fertilizer), water desalination plants, and electric energy generation. This is the first study to classify aerosol types over Saudi Arabia using several different aerosol property relationships, as well as over more than one site, and using data over a much longer time-period than previous studies. This enables classification and recognition of specific aerosol types over the Arabian Peninsula and similar desert regions.