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A field campaign (29 May to 14 June 2018) was conducted at a mountain site in central China. The chemical composition of non‐refractory submicron particulate matter (NR‐PM1) and the particle number size distribution (PNSD) were measured, respectively. The mean NR‐PM1 mass concentration was 20.94 ± 10.14 μg m−3, among which organics (47%) was the most abundant component, followed by sulfate (37%), ammonium (11%), nitrate (4%), and chloride (1%). Notably, sulfate accounted for more than 70% of the secondary inorganic aerosols. Positive matrix factorization (PMF) analysis of the composition data resulted in three organic aerosol (OA) factors: hydrocarbon‐like OA (HOA), oxygenated OA I (OOA‐I), and oxygenated OA II (OOA‐II). The secondary organic aerosol (SOA) composed of the latter two factors (SOA: OOA‐I + OOA‐II) was dominant in OA (80.7%). The PMF analysis of the PNSD data yielded three factors: new particle formation related mode, growth mode, and accumulation mode, among which the last factor dominated both number and volume ratios. The sulfate formation was characterized by the sulfur oxidation ratio (SOR), heterogeneous sulfate production rate (Phet), and gaseous sulfuric acid concentration, representing secondary sulfate transformation, heterogeneous reactions, and gas phase reactions, respectively. The results showed that Phet was well correlated with both sulfate concentrations and SOR, especially during the polluted periods. Our study demonstrates that photochemically‐driven heterogeneous reactions contribute dominantly to the sulfate formation and SOA is formed predominantly by photochemical oxidation of volatile organic compounds under high temperatures and ultraviolet (UV) intensities, and NOX concentrations on Mt. Wudang during the campaign period. Plain Language Summary: In this study, the chemical composition and size distribution of submicron aerosols were measured at a mountain site in central China (Mt. Wudang), and the sources as well as controlling factors were further investigated. Our results reveal that photochemical reactions play an important role in both sulfate and secondary organic aerosol formation. For sulfate, heterogeneous reactions were dominant during the polluted periods, whereas gas‐phase reactions are more pronounced during the clean periods. Key Points: Organics and sulfate account for more than 80% mass concentration of submicron aerosols on Mt. WudangHeterogenous reactions lead to sulfate formation on Mt. Wudang during the polluted periodsSecondary organic aerosol was mainly formed by photochemical reactions on Mt. Wudang [ABSTRACT FROM AUTHOR]

Amines affect particle formation, aerosol acidity, nitrogen cycle, and climate change. However, little is known about the temporal and spatial differences in the composition, source, and formation process of amines in fine particulate matter (PM2.5) in different regions of China. Seven amines (amine salts) were investigated in PM2.5 collected in the Yangtze River Delta (YRD, Shanghai and Nanjing), Pearl River Delta (PRD, Guangzhou), northern China (Xi'an and Haerbin), and background (Puding) areas in winter 2017–2018. Methylamine was the dominant amine species at the YRD, northern China, and background sites, while diethylamine dominated at the PRD site; moreover, the mass concentration and fraction of diethylamine were the lowest at the background site. These results could be attributed to changes in sources and atmospheric processes. Further, coal combustion and biomass burning were found to be important contributors of amines in northern cities in winter. The contribution of biomass and coal combustion to amines was weakened in other urban sites. In contrast, the amine abundance at the background site was largely controlled by biogenic sources. Acid‐base chemistry and displacement mechanism were tightly associated with the formation of amine salts at all sites. In particular, the atmospheric degradation of amines by hydroxyl radical (•OH) was significant at the Nanjing, Guangzhou, Xi'an, and Haerbin sites. The insignificant photochemical degradation of amines at the Shanghai and background sites can be explained by differentiated amine sources, meteorological conditions, and •OH levels. Overall, our findings deepen the understanding of the origins and atmospheric processes of amines. Plain Language Summary: Concentrations, compositions, potential sources, and major atmospheric processes of amines in winter PM2.5 in different regions of China were systematically investigated for the first time. The concentrations and compositions of amines in PM2.5 showed significant spatial differences, with the dominance of diethylamine at the Guangzhou site and the dominance of methylamine at other sites (Nanjing, Shanghai, Xi'an, Haerbin, and background sites). The influence of coal combustion associated with heating and industry was a typical feature that distinguishes the difference of amine sources between the coastal and northern areas. Moreover, the overall amine abundance at the background site was largely controlled by biogenic sources. Acid‐base chemistry and displacement mechanism were tightly associated with the formation of amine salts in PM2.5 at all sites. The atmospheric processes related to •OH exerted a significant impact on the removal of amines at the Nanjing, Guangzhou, Xi'an, and Haerbin sites. The insignificant photochemical degradation of amines in the Shanghai and background areas was associated with varied amine sources, meteorological conditions, and •OH levels. The overall results improve the current understanding on the temporal and spatial variations in the composition, source, and atmospheric process of amines in China. Key Points: Changes in the source led to large differences in the concentration and composition of amines in winter PM2.5 across regionsAcid‐base chemistry contributed significantly to the formation of amine salts in PM2.5 at all study sitesThe atmospheric degradation of amines by •OH was significant only at the Nanjing, Guangzhou, Xi'an, and Haerbin sites [ABSTRACT FROM AUTHOR]

Proteinaceous matter (PrM) is a substantial constituent in bioaerosols. However, the sources and atmospheric processes of PrM remain large uncertainties. The characterizations, sources, and potential atmospheric processes of free amino acids (FAAs) and combined amino acids (CAAs) were investigated via a set of 1‐year fine particle (PM2.5) samples collected in suburban Guiyang (a hilly basin area in Southwest China). The annual average concentrations of FAAs and CAAs were 156.31 ± 41.52 and 315.36 ± 147.66 ng m−3, respectively. The dominant FAA and CAA species were proline, which was different from previous observations with glycine as a major species. The results indicated that the sources or atmospheric processes of aerosol PrM at this study site were different from previous observations in the urban and suburban areas. The analysis of AA‐nitrogen isotope compositions and air mass back trajectories suggested that the abundances of aerosol FAAs and CAAs were highly controlled by primary sources (particularly plants) with less impact from long‐range transport. Furthermore, the contributions of PrM degradation by ozone‐ and hydroxyl radical‐related processes to total FAAs were found to be minor. The overall results suggested that the long‐range transport and atmospheric degradation of PrM were insignificant factors affecting aerosol PrM abundance in this suburban area with the weak atmospheric oxidation capacity, high cloud cover rate, and frequent precipitation. Thus, the findings improve our understanding of the sources and atmospheric processes of aerosol PrM. Plain Language Summary: Aerosol proteinaceous matter (PrM) consists of free amino acids (FAAs) and combined amino acids (CAAs). It is well documented that FAAs and CAAs have a large variety of natural sources. Moreover, the atmospheric degradation of CAAs has been regarded as a new potential source of aerosol FAAs. However, the relative contribution of primary and secondary sources to FAAs remains poorly understood. Based on a 1‐year investigation of PrM in PM2.5 collected in suburban Guiyang (a hilly basin area in Southwest China), we found that proline was the dominant species in both FAAs and CAAs. This result was different from previous observations with glycine as a major species. Further, our analysis showed that aerosol PrM in this hilly basin area was mainly derived from local primary sources (particularly plants) with less influence from long‐range transport of PrM. Moreover, the contribution of oxidative degradation of PrM to total FAAs was found to be minor. In general, the long‐range transport and atmospheric degradation of PrM have an insignificant contribution to aerosol PrM abundance in this hilly basin area. Our findings provide new insights into the sources and atmospheric transformation of aerosol PrM. Key Points: Proline is the dominant species in both free amino acids and combined amino acidsAerosol Proteinaceous matter (PrM) was largely originated from local primary sources with less impact from long‐range transportThe oxidative degradation of aerosol PrM was insignificant in suburban Guiyang [ABSTRACT FROM AUTHOR]

Modern meteorology is a very practical science necessary for social life. Most meteorologists model weather and climate forecasts, while others work for government and military organizations as well as private companies, providing forecasts for aviation, navigation, agriculture, construction, and radio and television broadcasting. In many countries, meteorology is often called "atmospheric physics", and ordinary meteorologists deal more with complex mathematical formulas and calculations that model physical and physico-chemical processes in the Earth's atmosphere. However, since the latter is closely related to all other envelopes, the work of meteorologists also has a distinct geographic element, since only geography needs to be taken into account for weather forecasting and modeling of atmospheric processes. In addition, the conditions of the atmosphere and the processes that take place in it differ in different parts of the globe due to geographic patterns (regions, altitude bands, etc.). Long-term weather conditions in a certain area are called climate. So, climatology is a science that studies such issues as climate formation, description and classification of the global climate, and the impact of human activity on the climate. By its nature, it is more closely related to other geographical disciplines. Modern research in the field of meteorology and climatology is at the center of mass media reports, as it sheds light on the future of our planet and life on it in light of actual and potential climate change. This is their mission today. they can only answer questions posed as elements of the system of geographic science. The article contains basic provisions on the environment, aspects of life in various regions, especially natural areas and objects subject to special protection. The work on environmental impact assessment is characterized. The article covers some issues of human bioclimatology, synrheological effects of individual meteorological variables and atmospheric factors and methods of assessing the complex impact of weather on the human body. The influence of climate warming on the health of the population and adaptation to climate change in Ukraine are mentioned. [ABSTRACT FROM AUTHOR]

Interactions in urban environment were investigated using a multidisciplinary model combination, with focus on traffic, emissions and atmospheric particles. An agent-based model was applied to simulate the evolution of unsustainable human behavior (usage of combustion-based personal vehicles) as a function of pro-environmental affordances (opportunities for sustainable choices). Scenarios regarding changes in multi-pollutant emissions were derived, and the non-linear implications to atmospheric particles were simulated with a box model. Based on the results for a Nordic city, increasing pro-environmental affordances by 10%, 50% or 100% leads to emission reductions of 15%, 30% and 40% within 2 years. To reduce ambient particle mass, emissions from traffic should decrease by > 15%, while the lung deposited surface area decreases in all scenarios ( - 23 % , - 32 % and - 36 % , correspondingly). The presented case is representative of one season, but the approach is generic and applicable to simulating a full year, given meteorological and pollution data that reflects seasonal variation. This work emphasizes the necessity to consider feedback mechanisms and non-linearities in both human behavior and atmospheric processes, when predicting the outcomes of changes in an urban system. [ABSTRACT FROM AUTHOR]

The multiyear variability of ice conditions in the Russian Arctic seas and the ice area of the Arctic Ocean (AO) is analyzed. It is shown that the ice conditions of the Russian Arctic seas are largely determined by large-scale atmospheric processes and the development of ice cover in the AO. It is shown that there are significant changes in the nature of the variability of the ice coverage of the Russian Arctic seas, which make it possible to distinguish two different periods: 1946–2004 and 2005–2021. It is found that in the past 17-year period, the frequency of complete cleansing of the water area of the Russian Arctic seas has significantly increased compared to previous periods. [ABSTRACT FROM AUTHOR]

The transformation of aerosol proteinaceous matter (PrM) has potentially adverse environmental and health effects. The origins and atmospheric processes of PrM have obtained an increasing interest, but there are still large uncertainties. Although aerosol liquid water (ALW) has been found to be vital in numerous atmospheric processes, its impact on atmospheric degradation of PrM remains poorly understood. ALW, proteins, and low molecular weight PrM (LMW PrM, <10 kDa) were investigated in fine aerosols (PM2.5) collected in urban and suburban Nanchang (Eastern China) over a 1‐year period. The average concentrations of proteins and LMW PrM in the urban center were higher than those in the suburban area. Urban PrM tended to increase from cool season to warm season, which was opposite to the case of suburban PrM. These differences could be attributed to varied sources and atmospheric processes of PrM. Increase in ALW was prominent from the suburban site to the urban site, which was attributable to increased anthropogenic nitrate and sulfate. LMW PrM can be degraded from higher molecular weight PrM by ozone. Furthermore, correlation analysis between LMW PrM and ozone and ALW suggested that the enhanced ALW in the urban center facilitated the ozone‐induced LMW PrM release. The ALW‐related protein degradation was further supported by ozone exposure experiments with bovine serum albumin and PM2.5 samples under dry condition. Our findings suggest that ALW is a crucial promoter during PrM degradation by ozone, providing new insights into atmospheric transformation of proteins. Plain Language Summary: Recent observation‐based studies on interactions between aerosol proteins and ozone have suggested that free amino acids in fine aerosols (PM2.5) can be degraded from proteins under the influence of ozone. Here, proteins, low molecular weight (LMW) proteinaceous matter (PrM), and aerosol liquid water (ALW) were investigated in PM2.5 collected in urban and suburban Nanchang (Eastern China) over a 1‐year period. Interestingly, we found that alone ozone cannot explain the production of LMW PrM in this study. Specifically, LMW PrM was found to be largely degraded from higher molecular weight PrM by ozone in the urban center (high ALW), whereas this degradation process was insignificant in the suburban area (low ALW). Correlation analysis between LMW PrM and ozone and ALW suggested that increased ALW in the urban center may promote the production of LMW PrM from ozone‐related aqueous‐phase reactions. This consideration was also supported by ozone exposure experiments with bovine serum albumin and PM2.5 samples under dry condition. The overall results suggest that ALW plays an important role in PrM degradation by ozone. Therefore, this study provides new insights into the fate of proteins in the atmosphere. Key Points: The significant increase in aerosol liquid water (ALW) from the urban center to the suburban area is attributable to increased anthropogenic nitrates and sulfatesAtmospheric degradation of high molecular weight proteinaceous matter (PrM) by ozone is an important secondary source of low molecular weight (LMW) PrM, especially in the urban areaThe increased ALW in the urban area promotes the ozone‐related LMW PrM release [ABSTRACT FROM AUTHOR]

A multi-experiment ensemble is performed using the WRF (Weather Research and Forecasting) model at high spatial resolution (1 km) over the Antisana glacier region (Ecuador), during the year 2005. Our goal is to identify the best model configurations to simulate atmospheric processes at diurnal and seasonal scales. The model is able to reproduce the complex zonal gradient of precipitation between the wet Amazon and the drier inter-Andean region. The main precipitation biases are (i) an overestimation in the afternoon (up to 6 mm/day) in the Antisana region related to local surface circulation patterns and (ii) a nighttime overestimation (up to 20 mm/day) in the Andes-Amazon transition zone associated with the regional circulation. Changing the microphysics scheme and/or the cumulus scheme primarily affect nighttime processes, while changing the topography forcing and activating slope radiation and shading options mostly affects afternoon processes. An adequate choice of the model configuration allows a correct representation of the diurnal cycle of precipitation, and in particular: (i) the mid-level easterly regional flow, (ii) the local moisture transport along and across the valleys, and (iii) the orographic mountain waves on the Antisana summit. For this specific area and year, the best configuration retained defined as "dSRTM_LRad" shows nighttime (daytime) precipitation biases smaller than 2 mm/day (3 mm/day); it is based on non-smoothed SRTM digital elevation model (dSRTM), Lin Purdue microphysics (L), and slope and shading radiation options (Rad). This 1-km resolution configuration requires the activation of the cumulus scheme, that improves the regional nighttime convection induced by the easterly regional flow on the Amazon-Andes transition region. It allows also a realistic strengthening of the daytime upward moisture transport. This study demonstrates that in the Antisana region, 1 km is a resolution still too coarse to deactivate cumulus schemes for a correct representation of cloud convection. [ABSTRACT FROM AUTHOR]

The state of the natural environment of the marginal seas of the Northwest Pacific is largely controlled by the interaction of the atmospheric and hydrophysical processes. Tropical cyclones (typhoons), originating in the tropical zone of the Northwest Pacific and over the South China Sea basin, occupy a special place among atmospheric processes. The main destructive impact of typhoons falls on Southeast Asia. However, a significant number of are moving to the Russian Far East. The region of the South China Sea plays a significant role in the formation of tropical cyclones. This determines the importance of studying hydrometeorological processes not only in the Far East, but also in the South China Sea, and the need for cooperation between Vietnamese and Russian scientists. The main hydrodynamic structure of the western South China Sea is the Vietnamese Coastal Current (Western Boundary current), which depends not only on the seasonal monsoons but also on typhoons. The paper presents the results of joint Russian–Vietnamese studies of the dependence of the vertical structure of the Vietnamese Coastal Current on the Pacific tropical cyclones that form in the South China Sea. The study is done with numerical modeling. The period from April to June 1999 was used for modeling, provided with the necessary field data. The simulation results showed that, in general, the structure of water masses depends on the trajectories of tropical cyclones. In all cases considered, the Vietnamese Coastal Current is not a single flow, but represents a zone of eddy structures of different directions. An exception is the only situation in the condition of a tropical cyclone in the central region of the South China Sea when this current acquired the form of a single continuous flow directed from north to south only in the 200-m layer. The general patterns of changes in the dynamic structure of the Vietnamese Coastal Current for all the considered tropical cyclone trajectories include the following: areas with water transport in the northern direction prevail on the surface, while the rest of the water mass continues to flow generally in the southern direction. This transport of surface waters may be due to the influence of the emerging summer monsoon, and the rest of the water mass, which is less exposed to the still weak atmospheric processes of the monsoon type, continues to flow in the winter regime. [ABSTRACT FROM AUTHOR]

Experimental studies are key to investigating the physical and chemical processes that drive cloud and haze formation from gas and solid phase molecular precursors in (exo)planetary environments, and validating the theoretical calculations used in models of (exo)planetary atmospheres. They allow characterizing the physical, optical, and chemical properties of laboratory-generated analogs, hence providing critical input parameters to models for observational data analysis. In this paper, we present examples of (1) experiments performed with different facilities to produce analogs of Titan and exoplanet atmospheric aerosols from gas phase molecular precursors, and (2) the characterization of these analogs to provide information on their composition, morphology, and optical constants to the scientific community. We also introduce the recently launched NASA Center for Optical Constants (NCOC), which will provide this critical data to the scientific community for (exo)planetary-relevant ices and organic refractory materials produced in the laboratory from the irradiation of gas and ice precursors. [ABSTRACT FROM AUTHOR]

Since 2013, China has taken a series of actions to relieve serious PM _2.5 pollution. As a result, the annual PM _2.5 concentration decreased by more than 50% from 2013 to 2021. However, ozone pollution has become more pronounced, especially in the North China Plain. Here, we review the impacts of anthropogenic emissions, meteorology, and atmospheric processes on ambient PM _2.5 loading and components and O _3 pollution in China. The reported influence of interannual meteorological changes on PM _2.5 and O _3 pollution during 2013–2019 ranged from 10%–20% and 20%–40%, respectively. During the same period, the anthropogenic emissions of NO _x , SO _2 , primary PM _2.5 , NMVOC and NH _3 are estimated to decrease by 38%, 51%, 35%, 11% and 17%, respectively. Such emission reduction is the main cause for the decrease in PM _2.5 concentration across China. However, the imbalanced reductions in various precursors also result in the variation in nitrate gas-particle partitioning and hence an increase in the nitrate fraction in PM _2.5 . The increase of ozone concentration and the enhancement of atmospheric oxidation capacity can also have substantial impact on the secondary components of PM _2.5 , which partly explained the growth of organic aerosols during haze events and the COVID-19 shutdown period. The uneven reduction in NO _x and NMVOC is suggested to be the most important reason for the rapid O _3 increase after 2013. In addition, the decrease in PM _2.5 may also have affected O _3 formation via radiation effects and heterogeneous reactions. Moreover, climate change is expected to influence both anthropogenic emissions and atmospheric processes. However, the extent and pathways of the PM _2.5 -O _3 interplay and how it will be impacted by the changing emission and atmospheric conditions making the synergetic control of PM _2.5 and O _3 difficult. Further research on the interaction of PM _2.5 and O _3 is needed to provide basis for a scientifically-grounded and effective co-control strategy.

Drop-on-demand inkjet printing is an easily upscalable, rapid, and digital deposition technique that allows thin film formation with a high material utilization rate as ideally needed for solar cell production. Herein, a method is reported to prepare inkjet-printed compact TiO2 thin films that are further assessed as an electron transport layer (ETL) for perovskite solar cells and compared to reference dip-coated TiO2 layers. Through ink formula engineering and adjustment of the printing parameters, reliable process control is achieved, leading to a homogeneous TiO2 coating of the fluorine-doped tin oxide substrate. Perovskite solar cells with an inkjet-printed TiO2 ETL yields efficiencies of up to 13.7%, outperforming the efficiency and the process repeatability of devices prepared with the dip-coated TiO2 reference. Together with other recent contributions on inkjet-printed perovskite solar cells, this work contributes to highlight the processability of thin film solar cells using digital inkjet printing for next-generation photovoltaic applications. [ABSTRACT FROM AUTHOR]

Tropical cyclones play a significant role in the formation of the hydrodynamic regime of the South China Sea, including its western part, which is bordered by the coast of Vietnam. In this region, the main hydrodynamic structure is the Vietnamese (western boundary) Current. Its structure depends on both seasonal monsoons and tropical cyclones. Therefore, the study of this dependence is an important task for Vietnamese scientists. The results of these studies are not only of scientific, but also of great practical importance, because the social and economic development of Vietnam largely depends on the activity and variability of synoptic and hydrodynamic processes in this region. This paper presents the results of joint Russian–Vietnamese studies on the dependence of the vertical structure of the Vietnamese current on tropical Pacific cyclones in the north of the South China Sea during the interseasonal winter–summer period. This study is based on numerical modeling. The calculations were performed for April–June 1999, for which the necessary initial field data are available. The simulation results indicated that the Vietnamese Current during this time period is not a uniform stream of water masses. Instead, the structure of water masses in this region is governed by a strong anticyclonic circulation and a deep cyclonic circulation, which are responsible for the complex pattern of the Vietnamese Current. The Vietnamese Current transfers coastal water masses in the summer mode (from south to north) within the anticyclonic circulation and in the winter mode (from north to south) within the cyclonic circulation. [ABSTRACT FROM AUTHOR]

Variations of cosmogenic (7Be), primordial (40K), radiogenic (210Pb) and anthropogenic (137Cs) in Bratislava air were studied during 2001–2019 using a weekly sampling and HPGe gamma-spectrometry. While 7Be variations were associated with transport of air masses from the lower stratosphere to the ground level air, an inverse trend was observed for 210Pb variations due to infiltration of radon from the soil. The 137Cs activity concentrations (excluding the Chernobyl and Fukushima accidents) were decreasing with half-life of 1.9 years, however, during recent years they were almost constant. The increased atmospheric 40K levels were due to soil resuspension and radionuclide transport by winds. [ABSTRACT FROM AUTHOR]

Proteinaceous compounds are particularly interesting because of their ubiquity and importance in many atmospheric processes. We investigated hydrolyzed amino acid (HAA), dissolved organic nitrogen (DON), nitrate (NO 3 −) and ammonium (NH 4 +) concentrations in precipitation samples collected in a suburban site in Guiyang over a 12 month period. Annually averaged total HAA, DON, NO 3 − and NH 4 + concentrations were 3.7 μmol L−1, 151.1 μmol L−1, 68.9 μmol L−1 and 117.3 μmol L−1, respectively. Regarding the HAAs in precipitation, glutamic acid, glycine and proline were present in relatively high concentrations, followed by aspartic acid and alanine. The concentrations of total HAAs in precipitation showed a clear seasonal cycle, with a minimum level in winter and a maximum level in spring. Based on seasonal variations of total HAAs together with back-trajectory analysis, the air mass origins did not significantly impact the precipitation HAA levels. The NO 3 − concentrations recorded a better positive correlation (P < 0.01) with both the DON and total HAA concentrations than the NH 4 + concentrations, possibly revealing that the sources for precipitation amino acids in suburban Guiyang were more linked with NO 3 − sources (from biomass burning, microbial activities and agricultural activities) than with NH 4 + sources (from biomass burning and agricultural activities). In particular, in some specific periods, such as spring, abundant pollen releases may have been responsible for the relatively high precipitation amino acid concentrations. The average air temperature and the highest air temperature showed a positive correlation with the total HAA levels in precipitation. Clearly, the increase in precipitation total HAAs with higher air temperatures may indicate the enhanced temperature-induced degradation of high molecular weight atmospheric proteinaceous matter. Moreover, the volume-weighted precipitation glycine and total HAA levels were positively correlated with the product of atmospheric ozone and nitrogen dioxide, indicating that atmospheric proteinaceous matter may be inextricably bound up with both ozone- and nitrogen dioxide-related atmospheric processes. In conclusion, this study improves current knowledge on the origins and atmospheric processes of atmospheric proteinaceous compounds. Image 1 • Annual cycle of precipitation HAAs at an inland suburban site was first investigated. • The main sources of precipitation HAAs in suburban Guiyang were revealed. • Precipitation HAA levels are linked to O 3 -/NO x -related atmospheric processes. [ABSTRACT FROM AUTHOR]

An important part of the water supply in California and the western United States is derived from runoff fed by mountain snow melt. Snow accumulation responds to both precipitation and temperature variations, and forms an interesting climatic index, since it integrates these influences over the entire late fall-spring period. The study area includes the Sierra Nevada, which accumulates most of the snow pack and comprises a major portion of the water-bearing region of California. The purpose of this study is to shed light upon the link between climate and year-to-year variability in the snow pack. Specifically, we wanted to determine (a) the dependence of snow pack and streamflow upon natural climate variability, and (b) if the relationships linking snow and streamflow to climate variations are stable over the history of instrumental records by using pre-1948 historical records to test the results from 1948-present. The basis of the study will be several long series of historical observations containing observed variability over daily-toseasonal time scales. Our focus is on measurements on/around April 1, when snow accumulation is typically greatest. The primary data is from a network of mountainous snow courses; many have records of six decades or more. For any given year, the spring snow water equivalent (SWE) anomaly at a particular snow course is likely to be 25-60% of its long-term average. Although effects vary with region and with elevation, in general, the anomalous winter precipitation has the strongest influence on spring SWE fluctuations. Anomalous temperature has a weaker effect overall, but it has great influence in lower elevations such as in the coastal Northwest, and during spring in higher elevations. Patterns of the precipitation, temperature, and snow anomalies extend over broad regional areas, much larger than individual watersheds. These surface anomalies are organized by the atmospheric circulation, with primary anomaly centers over the North Pacific Ocean as well as over western North America. For most of the regions, anomalously low SWE is associated with a winter circulation resembling the PNA pattern. With a strong low in the central North Pacific and high pressure over the Pacific Northwest, this pattern diverts North Pacific storms northward, away from the region. Both warm and cool phases of ENSO tend to produce regional patterns with out-of-phase SWE anomalies in the Northwest and the Southwest.

Large volcanic eruptions have strong impacts on both atmospheric and ocean dynamics that can last for decades. Numerical models have attempted to reproduce the effects of major volcanic eruptions on climate; however, there are remarkable inter-model disagreements related to both short-term dynamical response to volcanic forcing and long-term oceanic evolution. The lack of robust simulated behaviour is related to various aspects from model formulation to simulated background internal variability to the eruption details. Here, we use the Norwegian Earth System Model version 1 to calculate interactively the volcanic aerosol loading resulting from SO2 emissions of the second largest high-latitude volcanic eruption in historical time (the Laki eruption of 1783). We use two different approaches commonly used interchangeably in the literature to generate ensembles. The ensembles start from different background initial states, and we show that the two approaches are not identical on short-time scales (

The evolution of black carbon (BC) particles during atmospheric aging led to the complexity of their environmental and climate effect assessment. This study simultaneously measured the heterogeneous distribution of multi-level microphysical properties of BC-containing particles (i.e., BC mass concentration, coating amounts, and morphology) by a suite of state-of-the-art instruments, and investigated how atmospheric processing influence these heterogeneities. Our field measurements show that the mixing states of atmospheric BC-containing particles exhibit a clear dependence on BC core diameters. The particles with small BC core sizes (80-160 nm) are coated and reshaped more rapidly in real atmosphere, with coating-to-BC mass ratios (M R ) and non-spherical fractions of 5.1 ± 1.2 and 61 ± 19 %, respectively. Conversely, the particles with large core sizes (240-320 nm) are thinly coated and fractal, with M R and non-spherical fractions of 4.0 ± 0.3 and 74 ± 15 %, respectively. Furthermore, primary emissions result in low heterogeneity in coating amount but great heterogeneity in morphology between BC-containing particles of different sizes, while photochemical processing would enhance heterogeneity in coating amount but weaken the heterogeneity in morphology. Overall, our field measurement of multi-level microphysical properties highlights that BC core size and atmospheric processing are the key factors that drive the heterogeneity evolution of BC-containing particles in real atmosphere., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier B.V.)

The Mediterranean region is a unique area characterized by a large spectrum of atmospheric phenomena, some of which have a high impact on many aspects of human activities, safety and wellbeing. The area is long considered as a hot spot of such atmospheric phenomena deserving multidisciplinary scientific attention. The scientific research that has been carried out on these high impact atmospheric processes that occur in the Mediterranean area is indeed widespread and the available international literature is very extensive. The paper touches initially the temperature and precipitation regimes, followed by a discussion of floods and droughts. The exciting cyclogenetic patterns of explosive cyclones and medicanes are presented in separate sections. The lightning activity and the presence of dust and other pollutants are also presented herein. The atmospheric chemistry of the region which is increasingly becoming of utmost importance for the area under study is distinctly discussed. Attempts to modify the weather (the precipitation, in particular) are outlined too. The effects of climatic change on various atmospheric processes are considered throughout this paper, in addition to a dedicated section on temperature and precipitation. [ABSTRACT FROM AUTHOR]

In this paper, the features and possible causes of sea surface temperature (SST) biases over the Northwest Pacific are investigated based on a mixed-layer heat budget analysis in 21 coupled general circulation models (CGCMs) from phase 5 of the Coupled Model Inter-comparison Project (CMIP5). Most CMIP5 models show cold SST biases throughout the year over the Northwest Pacific. The largest biases appear during summer, and the smallest biases occur during winter. These cold SST biases are seen at the basin scale and are mainly located in the inner region of the low and mid-latitudes. According to the mixed-layer heat budget analysis, overestimation of upward net sea surface heat fluxes associated with atmospheric processes are primarily responsible for the cold SST biases. Among the different components of surface heat fluxes, overestimated upward latent heat fluxes induced by the excessively strong surface winds contribute the most to the cold SST biases during the spring, autumn, and winter seasons. Conversely, during the summer, overestimated upward latent heat fluxes and underestimated downward solar radiations at the sea surface are equally important. Further analysis suggests that the overly strong surface winds over the Northwest Pacific during winter and spring are associated with excessive precipitation over the Maritime Continent region, whereas those occurring during summer and autumn are associated with the excessive northward extension of the intertropical convergence zone (ITCZ). The excessive precipitation over the Maritime Continent region and the biases in the simulated ITCZ induce anomalous northeasterlies, which are in favor of enhancing low-level winds over the North Pacific. The enhanced surface wind increases the sea surface evaporation, which contributes to the excessive upward latent heat fluxes. Thus, the SST over the Northwest Pacific cools. [ABSTRACT FROM AUTHOR]

The Arctic is undergoing dramatic climatic changes that cause profound transformations in its terrestrial ecosystems and consequently in the microbial communities that inhabit them. The assembly of these communities is affected by aeolian deposition. However, the abundance, diversity, sources and activity of airborne microorganisms in the Arctic are poorly understood. We studied bacteria in the atmosphere over southwest Greenland and found that the diversity of bacterial communities correlated positively with air temperature and negatively with relative humidity. The communities consisted of 1.3X10³ ± 1.0X10³ cells m-3, which were aerosolized from local terrestrial environments or transported from marine, glaciated and terrestrial surfaces over long distances. On average, airborne bacterial cells displayed a high activity potential, reflected in the high 16S rRNA copy number (590 ± 300 rRNA cell-1), that correlated positively with water vapor pressure. We observed that bacterial clades differed in their activity potential. For instance, a high activity potential was seen for Rubrobacteridae and Clostridiales, while a low activity potential was observed for Proteobacteria. Of those bacterial families that harbor ice-nucleation active species, which are known to facilitate freezing and may thus be involved in cloud and rain formation, cells with a high activity potential were rare in air, but were enriched in rain. [ABSTRACT FROM AUTHOR]

To better understand the formation and characteristics of secondary organic aerosols (SOA) in coastal areas, a four-season observation of PM 2.5 -bound SOA tracers was conducted on a coastal island in southeastern China. Typical organic tracers, including the tracer for biomass burning (levoglucosan) and tracers from isoprene (SOA I), α / β pinene (SOA M), β -caryophyllene (SOA C), and toluene (SOA A), were analyzed by GC-MS. The total concentrations of SOA tracers were found to be higher in the fall and summer compared to spring and winter. The highest concentration among the SOA tracers was observed for SOA I (12.96 ± 17.89 ng m−3), followed by SOA M (6.66 ± 6.03 ng m−3), SOA A (1.76 ± 1.73 ng m−3), and SOA C (1.52 ± 1.11 ng m−3). The study revealed that the production of SOA I was significantly influenced by the HO 2 channel. Compared with the first generation products and the later generation products of α / β -pinene, we found the aerosols in the study area were relatively fresh. In summer, the majority of SOA tracers showed strong positive correlations with SO 4 2−, H+, and O x (O 3 +NO 2), indicating the influence of acid sulfate and photochemical oxidation. However, based on the LEV/K+ ratio, it was concluded that crop residue burning has a substantial influence on SOA in winter and mostly comes from regional transportation. During biomass burning transport episodes, the concentration of β -caryophyllenic acid (CPA) increased along with LEV and K+. The average concentration of total secondary organic carbon (SOC) estimated from the SOA-tracer method was found to be 0.399 μg C m−3, with SOC A constituting the majority (0.220 ± 0.216 μg C m−3). Isoprene contributed the most to biogenic SOA (BSOA) in summer (42.1%), whereas sesquiterpene had the largest contribution (66.8%) in winter. This study provides valuable insights into the characteristics and formation mechanisms of SOA in coastal areas with low anthropogenic emissions. • A four-season PM 2.5 -bound SOA tracer was investigated on a coastal island. • Atmospheric processes in summer affected the formation of SOA. • Biomass combustion in winter affected the formation of SOA. • A biomass combustion transport episode has been distinguished. [ABSTRACT FROM AUTHOR]

The Western Mediterranean is a climate change hotspot subject to generalized drying together with an increased torrentiality in precipitation with future scenarios pointing toward an extremization of these conditions. Projections indicate a further enhancement of differences between dry summers and wet autumns that already characterize this region. However, relevant uncertainties and discrepancies among projections exist including contrasting results complicating planification for future adaptation to climate change impacts in the Western Mediterranean. Both, the water supply for ecosystems and communities as well as the safety and well-being of the inhabitants are in danger. Detailed knowledge of the regional-to-local precipitation variability and evolution in the present climate together with an improved understanding of the underlying mechanisms, which is the objective of this investigation, will provide a better comprehension of projected future trends in the region. In this context, the present study provides a comprehensive evaluation of precipitation spatiotemporal characteristics and trends for the period 1951–2020 employing novel high-resolution gridded observations (SPAIN02) with a focus in eastern Spain, Hydrographic Confederations of Ebro (EBRO), Júcar-Segura (CHJS) and the Mediterranean Basins of Andalusia (CMA) that conform it from north to south. Particular attention is on the analysis of the Júcar-Segura (CHJS) basin. Results indicate a marked precipitation seasonality along the Spanish Mediterranean coast, with localized areas showing increasing trends, and a substantial drying during summer in the last seven decades reinforcing the already remarkable interseasonal variability characterizing the region. In contrast, moderate-to-heavy precipitation events have intensified in the last three decades for all seasons over central regions. Non-significant seasonal trends are identified for the winter, spring and autumn for the period under study, however, substantial intraseasonal variability dominates precipitation changes in these periods, particularly a significant mean precipitation decrease is observed in March and June. Interestingly, in the last two decades, summer precipitation presents a non-significant negative trend, with some areas over central regions showing an increase in precipitation contrasting with the general mean decrease observed during the period 1951–2020. The detailed analysis of the underlying mechanisms responsible for interseasonal and intraseasonal precipitation variations in the period 2000–2020 indicates that a frequency increase and intensification of orographically induced summer storms drive the observed summer precipitation increase in the Júcar-Segura basin. While the main changes during winter, spring, and autumn are principally linked to an intensification of precipitation events as a consequence of changes in moisture advection from the Mediterranean. Ongoing variability in this region can represent a mirror of the changes to come over similar areas around the world as a consequence of global warming. • Analysis of precipitation changes using a high-resolution dataset in eastern Spain. • This study provides improved knowledge of local-to-regional precipitation changes and associated underlying mechanisms. • Spring precipitation has increased and intensified in the last 35 years. • Main precipitation variations are connected to changes in the dynamics of atmospheric moisture. [ABSTRACT FROM AUTHOR]

Ozone and methane are chemically active climate-forcing agents affected by climate–chemistry interactions in the atmosphere. Key chemical reactions and processes affecting ozone and methane are presented. It is shown that climate-chemistry interactions have a significant impact on the two compounds. Ozone, which is a secondary compound in the atmosphere, produced and broken down mainly in the troposphere and stratosphre through chemical reactions involving atomic oxygen (O), NOx compounds (NO, NO2), CO, hydrogen radicals (OH, HO2), volatile organic compounds (VOC) and chlorine (Cl, ClO) and bromine (Br, BrO). Ozone is broken down through changes in the atmospheric distribution of the afore mentioned compounds. Methane is a primary compound emitted from different sources (wetlands, rice production, livestock, mining, oil and gas production and landfills).Methane is broken down by the hydroxyl radical (OH). OH is significantly affected by methane emissions, defined by the feedback factor, currently estimated to be in the range 1.3 to 1.5, and increasing with increasing methane emission. Ozone and methane changes are affected by NOx emissions. While ozone in general increase with increases in NOx emission, methane is reduced, due to increases in OH. Several processes where current and future changes have implications for climate-chemistry interactions are identified. It is also shown that climatic changes through dynamic processes could have significant impact on the atmospheric chemical distribution of ozone and methane, as we can see through the impact of Quasi Biennial Oscillation (QBO). Modeling studies indicate that increases in ozone could be more pronounced toward the end of this century. Thawing permafrost could lead to important positive feedbacks in the climate system. Large amounts of organic material are stored in the upper layers of the permafrost in the yedoma deposits in Siberia, where 2 to 5% of the deposits could be organic material. During thawing of permafrost, parts of the organic material that is deposited could be converted to methane. Furthermore, methane stored in deposits under shallow waters in the Arctic have the potential to be released in a future warmer climate with enhanced climate impact on methane, ozone and stratospheric water vapor. Studies performed by several groups show that the transport sectors have the potential for significant impacts on climate-chemistry interactions. There are large uncertainties connected to ozone and methane changes from the transport sector, and to methane release and climate impact during permafrost thawing.

In 2018, NASA will launch InSight, a single-station suite of geophysical instruments, designed to characterise the martian interior. We investigate the seismo-acoustic signal generated by a bolide entering the martian atmosphere and exploding in a terminal airburst, and assess this phenomenon as a potential observable for the SEIS seismic payload. Terrestrial analogue data from four recent events are used to identify diagnostic airburst characteristics in both the time and frequency domain. In order to estimate a potential number of detectable events for InSight, we first model the impactor source population from observations made on the Earth, scaled for planetary radius, entry velocity and source density. We go on to calculate a range of potential airbursts from the larger incident impactor population. We estimate there to be ${\sim}\,1000$ events of this nature per year on Mars. To then derive a detectable number of airbursts for InSight, we scale this number according to atmospheric attenuation, air-to-ground coupling inefficiencies and by instrument capability for SEIS. We predict between 10-200 detectable events per year for InSight. [ABSTRACT FROM AUTHOR]

To investigate the climate change in the next 30 years over a complex terrain in southwestern Germany, simulations performed with the regional climate model COSMO-CLM at convection-permitting resolution are compared to simulations at 7 km resolution with parameterised convection. An earlier study has shown the main benefits of convection-permitting resolution in the hourly statistics and the diurnal cycle of precipitation intensities. Here, we investigate whether the improved simulation of precipitation in the convection-permitting model is affecting future climate projections in summer. Overall, the future scenario (ECHAM5 with A1B forcing) brings weak changes in mean precipitation, but stronger hourly intensities in the morning and less frequent but more intense daily precipitation. The two model simulations produce similar changes in climate, despite differences in their physical characteristics linked to the formation of convective precipitation. A significant increase in the morning precipitation probably due to large-scale forced convection is found when considering only the most extreme events (above 50 mm/day). In this case, even the diurnal cycles of precipitation and convection-related indices are similar between resolutions, leading to the conclusion that the 7 km model sufficiently resolves the most extreme convective events. In this region and time periods, the 7 km resolution is deemed sufficient for most assessments of near future precipitation change. However, conclusions could be dependent on the characteristics of the region of investigation. [ABSTRACT FROM AUTHOR]

In the last years, the use of radio occultation (RO) technique to observe the terrestrial atmosphere and the climate takes advantage of the occultation of the Sun, the Moon, the stars and principally of artificial satellites of low height (LEO). In the latter case, crossed signs between LEO and GPS satellites are used. The application of RO's technology using transmitters of the GPS system in high orbits and recipients on board of low orbit satellites, has provided profiles of atmospheric refractivity very precise. The basic idea of a RO is to observe how waves emitted by a GPS are propagated in the atmosphere. The ray trajectory associated to a radio wave between a GPS and a LEO, while these are hiding themselves mutually due to the interposition of the Earth, is deviated due to refractivity gradients. The ray bending angle is obtained from a change in the phase (Doppler shift) of the signal received by the LEO. Assuming spherical symmetry, the deviation information may be inverted by an Abel transformation to obtain a vertical profile of the index of refraction. From atmospheric profiles of refractivity and an atmospheric model, several parameters are obtained: from temperature (T), pressure, geopotential height and water vapor to minor species as aerosols, cloud liquid water and ionospheric electron density. The enormous advantage offered by the coverage in the whole planet, above the continental and oceanic territories, the 1K T resolution, the long term stability and mainly the absence of any restriction imposed by climatic conditions, makes the GPS RO technique unique among different remote sensing atmospheric systems. Up to now, hundreds of thousands of soundings have been processed, from the first satellites to recent (SAC-C, CHAMP, GRACE, COSMIC, TerraSAR-X, MetOp). In the present work, examples of global and regional water vapor and atmospheric wave energy distributions will be shown. It will be put on special emphasis on the mountainous regions of the Andes Range at middle latitudes and the Antarctic Peninsula and case studies will be analyzed. This analysis will be complemented by WRF model simulations and with measured T profiles in the regions of interest. In particular it will be shown: i) the spatial distribution of stationary gravity waves, ii) their propagation in the lower and middle atmospheres, and iii) the possible relevance of mountain waves as a triggering mechanism of seep convection processes with hail production. Key words: satellite radio occultation, gravity waves.