Abstract
Over the past decade, the number of studies that investigate aerosol–cloud interactions has increased considerably. Although tremendous progress has been made to improve the understanding of ...basic physical mechanisms of aerosol–cloud interactions and reduce their uncertainties in climate forcing, there is still poor understanding of 1) some of the mechanisms that interact with each other over multiple spatial and temporal scales, 2) the feedbacks between microphysical and dynamical processes and between local-scale processes and large-scale circulations, and 3) the significance of cloud–aerosol interactions on weather systems as well as regional and global climate. This review focuses on recent theoretical studies and important mechanisms on aerosol–cloud interactions and discusses the significances of aerosol impacts on radiative forcing and precipitation extremes associated with different cloud systems. The authors summarize the main obstacles preventing the science from making a leap—for example, the lack of concurrent profile measurements of cloud dynamics, microphysics, and aerosols over a wide region on the observation side and the large variability of cloud microphysics parameterizations resulting in a large spread of modeling results on the modeling side. Therefore, large efforts are needed to escalate understanding. Future directions should focus on obtaining concurrent measurements of aerosol properties and cloud microphysical and dynamic properties over a range of temporal and spatial scales collected over typical climate regimes and closure studies, as well as improving understanding and parameterizations of cloud microphysics such as ice nucleation, mixed-phase properties, and hydrometeor size and fall speed.
This study highlights the significance of high-quality development of energy (EHQD) in achieving carbon neutrality. Researchers have explored how to successfully achieve carbon neutrality, but few ...studies have examined the impact of the EHQD on carbon neutrality. Accordingly, while considering the high-quality development of China’s economy, this study constructs a comprehensive evaluation index system for China’s EHQD using the technique for order preference by similarity to an ideal solution (TOPSIS) method based on entropy weight to measure the EHQD level of energy in 30 provinces in China from 2004 to 2019. Considering the possibility of endogeneities, the two-stage least squares (2SLS) regression is applied to empirically analyze the impact of the EHQD on carbon neutrality. Cointegration tests show a long-term cointegration relationship between the EHQD, real GDP per capita, urbanization, traffic pressure, industrial structure, and CO2 emissions (CE). The 2SLS method empirically shows that the EHQD has a significant negative impact on CE. The EHQD can significantly reduce CE, which is conducive for China to achieve the goal of carbon neutrality. The results of this study indicate that to reduce CE and enable China to successfully achieve its goal of carbon neutrality by 2060, policymakers should take effective measures to promote the EHQD.
Based on the PM2.5 concentration data of 253 prefecture-level cities, it empirically investigated the effect of urban density on PM2.5 concentration in China using spatial econometric regression ...method. The results show that there is a spatial spillover effect of PM2.5 concentration in China. The coefficient of urban density is significantly negative, and the increase in urban density will reduce haze pollution. In order to reduce haze pollution in Chinese cities, it is necessary to continue to implement regional joint prevention and control measures. The eastern region should focus on building small blocks and high-density networks to reduce haze pollution. The central region should focus on urban greening, increase green coverage, and reduce the heat island effect. While improving the level of greening in the western region, we should increase urban density, reduce urban sprawl, and build compact cities.
Mineral dust plays an important role in the primary formation of ice crystals in mixed‐phase clouds by acting as ice nucleating particles (INPs). It can influence the cloud phase transition and ...radiative forcing of mixed‐phase clouds, both of which are crucial to global energy budget and climate. In this study, we investigate the dust indirect effects on mixed‐phase clouds through heterogeneous ice nucleation with the U.S. Department of Energy (DOE) Energy Exascale Earth System Model (E3SM). Dust and INP concentrations simulated from two versions of E3SM with three ice nucleation parameterizations were evaluated against observations in the Northern Hemisphere. Constrained by these observations, E3SM shows that dust INPs induce a global mean net cloud radiative effect of 0.05 to 0.26 W/m2 with the predominant warming appearing in the Northern Hemisphere midlatitudes. However, a cooling effect is found in the Arctic due to reduced longwave cloud forcing.
Plain Language Summary
Mineral dust is one of the most important ice nucleating particles in the atmosphere. In other words, it can initiate ice crystal formation in cold clouds. This process has large impacts on cloud liquid and ice content and cloud radiative forcing, which are crucial to global energy budget and climate. In this study, we investigate the dust indirect effects on mixed‐phase clouds through the freezing of cloud water using global climate models. Dust and ice nucleating particle concentrations from model simulations were evaluated against observations focusing on the Northern Hemisphere. Constrained by these observations, the model results indicate that dust induces a global mean net warming cloud effect. The warming is found predominantly in the Northern Hemisphere midlatitudes, whereas a cooling effect is found in the Arctic.
Key Points
Dust indirect effects on mixed‐phase clouds by acting as ice nucleating particles are investigated with global climate models
Dust induces a global mean net warming cloud radiative effect
The dust warming effect is located predominantly in the Northern Hemisphere midlatitudes, while a cooling effect is found in the Arctic
Data envelopment analysis cross-efficiency evaluation has been widely accepted as a useful tool for performance evaluation and ranking of decision making units. However, the non-uniqueness of optimal ...weights is a problem that has reduced the usefulness of this powerful method. In addition, current studies generally have not considered the situation in which undesirable outputs appear in the data envelopment analysis cross-efficiency evaluation. To solve these problems, firstly, we present an equitable model for efficiency evaluation of decision-making units with undesirable outputs and introduce a technique for cross-efficiency evaluation considering undesirable outputs. Then, a ranking priority model is proposed considering the decision making units' intentions of pursuing the best ranking positions. In addition, an aggressive model is given to guarantee the uniqueness of the optimal solution. The proposed approach can not only solve the problem of non-uniqueness of optimal weights in data envelopment analysis cross-efficiency evaluation but also considers undesirable outputs and ranking preferences of the decision-making units. Finally, the proposed approach is applied for eco-efficiency analysis of coal-fired power plants in a big data environment, and the results show that most coal-fired power plants in China have not performed well.
•The undesirable output is considered in DEA cross-efficiency evaluation.•An equitable model is given for measuring efficiency.•The ranking preference of each DMU is regarded as the secondary goal.•An aggressive model is given to guarantee the uniqueness of the optimal solution.•A case study of eco-efficiency analysis of coal-fired power plants is presented.
It is essential to understand the factors driving the recent decline of dust activity in East Asia for future dust projections. Using a physically-based dust emission model, here we show that the ...weakening of surface wind and the increasing of vegetation cover and soil moisture have all contributed to the decline in dust activity during 2001 to 2017. The relative contributions of these three factors to the dust emission reduction during 2010-2017 relative to 2001 are 46%, 30%, and 24%, respectively. Much (78%) of the dust emission reduction is from barren lands, and a small fraction (4.6%) of the reduction is attributed to grassland vegetation increase that is partly ascribed to the ecological restoration. This suggests that the ecological restoration plays a minor role in the decline of dust activity. Rather, the decline is mainly driven by climatic factors, with the weakening of surface wind playing the dominant role.
Coronaviruses (CoVs) are by far the largest group of known positive‐sense RNA viruses having an extensive range of natural hosts. In the past few decades, newly evolved Coronaviruses have posed a ...global threat to public health. The immune response is essential to control and eliminate CoV infections, however, maladjusted immune responses may result in immunopathology and impaired pulmonary gas exchange. Gaining a deeper understanding of the interaction between Coronaviruses and the innate immune systems of the hosts may shed light on the development and persistence of inflammation in the lungs and hopefully can reduce the risk of lung inflammation caused by CoVs. In this review, we provide an update on CoV infections and relevant diseases, particularly the host defense against CoV‐induced inflammation of lung tissue, as well as the role of the innate immune system in the pathogenesis and clinical treatment.
Highlights
This highlights the importance of immune responses under coronavirus infection and improve the understanding of the features of CoV‐induced inflammatory response.
Biomass burning (BB) aerosols exert a strong surface cooling effect over the southeast Atlantic (SEA) via aerosol‐radiation and aerosol‐cloud interactions. The reduction of the sea surface ...temperature (SST) can trigger the SST‐low cloud feedback. Whether this feedback can amplify the surface cooling effect is examined. The modeling results from the Community Earth System Model version 2 (CESM2) demonstrate that counterintuitively the cloud radiative effect (CRE) caused by the BB aerosols is weaker if SST‐low cloud feedback is considered compared to fixed‐SST simulation (−2.99 W m−2 vs. −4.79 W m−2). This is caused by (a) stronger sea breeze due to larger sea‐land temperature contrast causing less smoke transport over SEA and (b) less moisture supply from surface due to colder SST. Changes in SST also lead to counterclockwise rotation of ocean circulation anomalies. Consequently, the excess heat transport from the equator reverses the direction of SST‐cloud feedback in this region.
Plain Language Summary
Biomass burning aerosols can modulate the cloud macro‐ and microphysical properties over the Southeast Atlantic and induce a strong cooling effect at the surface. As a result, sea surface temperature will decrease, which can further promote cloudiness in this region (a positive SST‐low cloud feedback). Our study demonstrates that the cooling effect caused by biomass burning aerosols is actually smaller when the SST‐low cloud feedback is considered, because of stronger sea breeze that reduces the transport of biomass burning aerosols and weaker surface moisture supply. In addition, the ocean current changes can determine the direction of this SST‐low cloud feedback.
Key Points
Sea surface temperature‐low cloud feedback reduces the magnitude of the cloud radiative effect (CRE) caused by the BB aerosols over Southeast Atlantic
Weaker CRE is due to stronger sea breeze and less moisture supply from the ocean
The excess heat transport associated with counterclockwise rotation of ocean circulation anomalies stops the amplification of CRE
Surface enhanced Raman scattering (SERS) is a fingerprint spectral technique whose performance is highly dependent on the physicochemical properties of the substrate materials. In addition to the ...traditional plasmonic metal substrates that feature prominent electromagnetic enhancements, boosted SERS activities have been reported recently for various categories of non-metal materials, including graphene, MXenes, transition-metal chalcogens/oxides, and conjugated organic molecules. Although the structural compositions of these semiconducting substrates vary, chemical enhancements induced by interfacial charge transfer are often the major contributors to the overall SERS behavior, which is distinct from that of the traditional SERS based on plasmonic metals. Regarding charge-transfer-induced SERS enhancements, this short review introduces the basic concepts underlying the SERS enhancements, the most recent semiconducting substrates that use novel manipulation strategies, and the extended applications of these versatile substrates.
•Surface-enhanced Raman scattering (SERS) is a fingerprint spectral technique highly dependent on the substrate materials.•Charge transfer transitions are commonly the major contributors to the boosted SERS activities in non-metal substrates.•Novel manipulation strategies and extended applications of the versatile substrates are illustrated on the basis of interfacial charge transfer.
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The dust cycle is an important component of the Earth system and has been
implemented in climate models and Earth system models (ESMs). An
assessment of the dust cycle in these models is vital to ...address their
strengths and weaknesses in simulating dust aerosol and its interactions
with the Earth system and enhance the future model developments. This study
presents a comprehensive evaluation of the global dust cycle in 15 models
participating in the fifth phase of the Coupled Model Intercomparison
Project (CMIP5). The various models are compared with each other and with an aerosol reanalysis as well as station observations. The results show that the global dust emission in these models varies by a factor of 4–5 for the same size range. The models generally agree with each other and observations in reproducing the “dust belt”, which extends from North Africa, the Middle East, Central and South Asia to East Asia, although they differ greatly in the spatial extent of this dust belt. The models also differ in other dust source regions such as North America and Australia. We suggest that the coupling of dust emission with dynamic vegetation can enlarge the range of simulated dust emission. For the removal process, all the models estimate that wet deposition is
smaller than dry deposition and wet deposition accounts for 12 %–39 % of
total deposition. The models also estimate that most (77 %–91 %) dust
particles are deposited onto continents and 9 %–23 % of dust particles are deposited
into oceans. Compared to the observations, most models reproduce the dust
deposition and dust concentrations within a factor of 10 at most stations,
but larger biases by more than a factor of 10 are also noted at specific
regions and for certain models. These results highlight the need for further
improvements of the dust cycle especially on dust emission in climate models.
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