Atmospheric response to SST variability was estimated using generalized equilibrium feedback analysis （GEFA） in the SST EOF space with synthesis data from an idealized climate model. Results show that the GEFA atmos...Atmospheric response to SST variability was estimated using generalized equilibrium feedback analysis （GEFA） in the SST EOF space with synthesis data from an idealized climate model. Results show that the GEFA atmospheric response to the leading SST EOF modes is much more accurate and robust than the GEFA feedback matrix in physical space. Therefore, GEFA provides a practical method for assessing atmospheric response to large-scale SST anomalies in terms of the leading EOFs.展开更多
Atmospheric dimethyl sulfide(DMS,CH_(3)SCH_(3))and methanethiol(MeSH,CH_(3)SH)have been widely studied and recognized to significantly constrain the atmospheric sulfur budget.Nevertheless,while the role of DMS and MeS...Atmospheric dimethyl sulfide(DMS,CH_(3)SCH_(3))and methanethiol(MeSH,CH_(3)SH)have been widely studied and recognized to significantly constrain the atmospheric sulfur budget.Nevertheless,while the role of DMS and MeSH remains largely uncertain in inland regions,learning about dimethyl disulfide(DMDS,CH_(3)SSCH_(3))is also limited.In this study,we measured atmospheric DMS,MeSH and DMDS in winter,from 19 December 2022 to 30 January 2023,and spring,from 24 April to 2 June 2023 with a Vocus proton-transfer-reaction time-offlightmass spectrometer(Vocus PTR-TOF)at the Dianshan Lake(DSL)Air QualityMonitoring Supersite in a suburban area of Shanghai,China.The mixing ratios of DMS,MeSH and DMDS exhibited clear diurnal cycles,and were characterized by average and interquartile range values of 22.6(10.1-29.7),14.9(6.5-19.4)and 9.8(6.0-10.7)pptv,respectively,in the spring campaign,which are approximately twice as high as those in winter.MeSH and DMDS were found to be well correlated with DMS in the two campaigns.Wind analysis suggests that three reduced-sulfur compounds owned common sources from the DSL.Furthermore,the sulfur dioxide(SO_(2))production quantity fromthe three reduced-sulfur compounds over the DSL inMay 2023 was estimated to be 1.42±0.74 t with 84.8%originating fromDMDS,which was comparable to the monthly SO_(2) emissions fromships over the DSL.Our results highlight the prominent role of atmospheric DMDS in SO_(2) production when compared to DMS and MeSH in the suburban area of Shanghai,soliciting further investigation and consideration of DMDS in the sulfur budget.展开更多
The entrainment flux ratio Ae and the inversion layer （IL） thickness are two key parameters in a mixed layer model. Ae is defined as the ratio of the entrainment heat flux at the mixed layer top to the surface heat ...The entrainment flux ratio Ae and the inversion layer （IL） thickness are two key parameters in a mixed layer model. Ae is defined as the ratio of the entrainment heat flux at the mixed layer top to the surface heat flux. The IL is the layer between the mixed layer and the free atmosphere. In this study, a parameterization of Ae is derived from the TKE budget in the first- order model for a well-developed CBL under the condition of linearly sheared geostrophic velocity with a zero value at the surface. It is also appropriate for a CBL under the condition of geostrophic velocity remaining constant with height. LESs are conducted under the above two conditions to determine the coefficients in the parameterization scheme. Results suggest that about 43% of the shear-produced TKE in the IL is available for entrainment, while the shear-produced TKE in the mixed layer and surface layer have little effect on entrainment. Based on this scheme, a new scale of convective turbulence velocity is proposed and applied to parameterize the IL thickness, The LES outputs for the CBLs under the condition of linearly sheared geostrophic velocity with a non-zero surface value are used to verify the performance of the parameterization scheme. It is found that the parameterized Ae and IL thickness agree well with the LES outputs.展开更多
Organic acids are important contributors to the acidity of atmospheric precipitation,but their existence in the Chinese atmosphere is largely unclear.In this study,twelve atmospheric gaseous organic acids,including C_...Organic acids are important contributors to the acidity of atmospheric precipitation,but their existence in the Chinese atmosphere is largely unclear.In this study,twelve atmospheric gaseous organic acids,including C_(1)-C_(9) alkanoic acids,methacrylic acid,pyruvic acid,and benzoic acid,were observed in the suburb of Wangdu,Hebei Province,a typical rural site in the northern China plain from 16^(th) December,2018 to 22^(nd) January,2019,using a Vocus■ Proton-Transfer-Reaction time-of-flight mass spectrometer(Vocus PTR-ToF).The quantification of C_(2)-C_(4) alkanoic acids by the Vocus PTR-ToF was calibrated according to the titration of a NaOH solution by C_(2)-C_(4) alkanoic acids from home-made permeation sources,and the other organic acids except for formic acid were quantified based on the k_(cap)-sensitivity linearity in the Vocus PTR-ToF,whereas formic acid was not quantified because our instrument setting led to a significant underestimation in its concentration.The average total concentration of eleven gaseous organic acids was 6.96±5.20 ppbv(parts per billion by volume).The average concentration of acetic acid was the highest(3.86±3.00 ppbv),followed by propanoic acid,butyric acid,and methacrylic acid.Domestic straw burning was likely the dominant source of the observed gaseous organic acids according to the good correlations between acetonitrile and organic acids and between particulate K+and organic acids,and traffic emissions could also have contributed.During episodes with continuously high concentrations of organic acids,short-distance transport dominated in Wangdu according to the backward trajectory analysis.Baoding,Shijiazhuang,and Hengshui areas were the main source areas based on potential source contribution function and concentration weighing track analysis.展开更多
Following the parameterization of sheared entrainment obtained in the companion paper, Liu et al. （2016）, the present study aims to further investigate the characteristics of entrainment, and develop a simple model ...Following the parameterization of sheared entrainment obtained in the companion paper, Liu et al. （2016）, the present study aims to further investigate the characteristics of entrainment, and develop a simple model for predicting the growth rate of a well-developed and sheared CBL. The relative stratification, defined as the ratio of the stratification in the free atmosphere to that in the entrainment zone, is found to be a function of entrainment flux ratio （Ae）. This leads to a simple expression of the entrainment rate, in which Ae needs to be parameterized. According to the results in Liu et al. （2016）, Ae can be simply expressed as the ratio of the convective velocity scale in the sheared CBL to that in the shear-free CBL. The parameterization of the convective velocity scale in the sheared CBL is obtained by analytically solving the bulk model with several assumptions and approximations. Results indicate that the entrainment process is influenced by the dynamic effect, the interaction between mean shear and environmental stratification, and one other term that includes the Coriolis effect. These three parameterizations constitute a simple model for predicting the growth rate of a well-developed and sheared CBL. This model is validated by outputs of LESs, and the results show that it performs satisfactorily. Compared with bulk models, this model does not need to solve a set of equations for the CBL. It is more convenient to apply in numerical models.展开更多
Climate changes in Guangdong are studied based on temperature data of 86 meteorological stations in Guangdong Province during 1961 – 2000, temperature data in Guangzhou during 1908 – 2002, and sea level data in the ...Climate changes in Guangdong are studied based on temperature data of 86 meteorological stations in Guangdong Province during 1961 – 2000, temperature data in Guangzhou during 1908 – 2002, and sea level data in the South China Sea during 1958 – 2001. Significant climate warming and sea level rise in Guangdong is demonstrated. Possible influences of climate warming on agriculture in Guangdong are discussed in terms of thermal resources, crop and breed layout, crop yield, diseases, insect pests and weeds as well as agrometeorological disasters, etc. In the final part, agricultural strategies of mitigating and adapting to the climate changes are given.展开更多
The effects of different Planetary Boundary Layer（PBL） structures on pollutant dispersion processes within two idealized street canyon configurations and a realistic urban area were numerically examined by a Computa...The effects of different Planetary Boundary Layer（PBL） structures on pollutant dispersion processes within two idealized street canyon configurations and a realistic urban area were numerically examined by a Computational Fluid Dynamics（CFD） model. The boundary conditions of different PBL structures/conditions were provided by simulations of the Weather Researching and Forecasting model. The simulated results of the idealized 2D and 3D street canyon experiments showed that the increment of PBL instability favored the downward transport of momentum from the upper flow above the roof to the pedestrian level within the street canyon. As a result, the flow and turbulent fields within the street canyon under the more unstable PBL condition are stronger. Therefore, more pollutants within the street canyon would be removed by the stronger advection and turbulent diffusion processes under the unstable PBL condition. On the contrary, more pollutants would be concentrated in the street canyon under the stable PBL condition. In addition, the simulations of the realistic building cluster experiments showed that the density of buildings was a crucial factor determining the dynamic effects of the PBL structure on the flow patterns. The momentum field within a denser building configuration was mostly transported from the upper flow, and was more sensitive to the PBL structures than that of the sparser building configuration. Finally, it was recommended to use the Mellor-Yamada-Nakanishi-Niino（MYNN） PBL scheme, which can explicitly output the needed turbulent variables, to provide the boundary conditions to the CFD simulation.展开更多
This study investigates the effects of Fe on the oxygen-evolution reaction(OER)in the presence of Au.Two distinct areas of OER were identified:the first associated with Fe sites at low overpotential(~330 mV),and the s...This study investigates the effects of Fe on the oxygen-evolution reaction(OER)in the presence of Au.Two distinct areas of OER were identified:the first associated with Fe sites at low overpotential(~330 mV),and the second with Au sites at high overpotential(~870 mV).Various factors such as surface Fe concentration,electrochemical method,scan rate,potential range,concentration,method of adding K_(2)Fe O_(4),nature of Fe,and temperature were varied to observe diverse behaviors during OER for Fe O_(x)H_(y)/Au.Trace amounts of Fe ions had a significant impact on OER,reaching a saturation point where the activity did not increase further.Strong electronic interaction between Fe and Au ions was indicated by X-ray photoelectron spectroscopy(XPS)and electron paramagnetic resonance(EPR)analyses.In situ visible spectroscopy confirmed the formation of Fe O_(4)^(2-)during OER.In situ Mossbauer and surfaceenhanced Raman spectroscopy(SERS)analyses suggest the involvement of Fe-based species as intermediates during the rate-determining step of OER.A lattice OER mechanism based on Fe O_(x)H_(y)was proposed for operation at low overpotentials.Density functional theory(DFT)calculations revealed that Fe oxide,Fe-oxide clusters,and Fe doping on the Au foil exhibited different activities and stabilities during OER.The study provides insights into the interplay between Fe and Au in OER,advancing the understanding of OER mechanisms and offering implications for the design of efficient electrocatalytic systems.展开更多
The explosive spread of the 2019 novel coronavirus(COVID-19)provides a unique chance to rethink the relationship between human activity and air pollution.Though related studies have revealed substantial reductions in ...The explosive spread of the 2019 novel coronavirus(COVID-19)provides a unique chance to rethink the relationship between human activity and air pollution.Though related studies have revealed substantial reductions in primary emissions,obvious differences do exist in the responses of secondary pollutants,like ozone(0_(3))pollution.However,the regional disparities of O_(3)responses and their causes have still not been fully investigated.To better elucidate the interrelationship between anthropogenic emissions,chemical production,and meteorological conditions,O_(3)responses caused by lockdowns over different regions were comprehensively explored at a global scale.Observational signals of air-quality change were derived from multi-year surface measurements and satellite retrievals.With similar substantial drops in nitrogen dioxide(NO_(2)),ozone shows rising signals in most areas of both East Asia and Europe,even up to~14 ppb,while a non-negligible declining signal exists in North America,by about 2-4 ppb.Furthermore,the drivers behind the different O_(3)responses are discussed based on meteorological analysis and O_(3)sensitivity diagnosis.On the one hand,O_(3)responses to NO_(2)declines can be affected by the primary dependence on its precursors.On the other hand,it is also highly dependent on meteorological factors,especially temperature.Our study further highlights the great importance of taking into consideration both the regional disparities and synergistic effects of precursor reductions and meteorological influence for scientific mitigation of O_(3)pollution.展开更多
This work presents an overall introduction to the Station for Observing Regional Processes of the EarthSystem - SORPES in Nanjing, East China, and gives an overview about main scientific findings instudies of air poll...This work presents an overall introduction to the Station for Observing Regional Processes of the EarthSystem - SORPES in Nanjing, East China, and gives an overview about main scientific findings instudies of air pollution-weather/climate interactions obtained since 2011. The main results summarizedin this paper include overall characteristics of trace gases and aerosols, chemical transformationmechanisms for secondary pollutants like O3, HONO andsecondary ingrganic aerosols, and the airpollution- weather/climate interactions and feedbacks in mixed air pollution plumes from sources likefossil fuel combustion, biomass burning and dust storms. The future outlook of the development plan on instrumentation, networking and data-sharing for the SORPES station is also discussed.展开更多
Global temperature has increased at a rapid rate in recent decades,and the warming rate at night is observed higher than that during the daytime among different regions.Nighttime anomalous high temperatures may pose a...Global temperature has increased at a rapid rate in recent decades,and the warming rate at night is observed higher than that during the daytime among different regions.Nighttime anomalous high temperatures may pose an additional risk to human health and society.Nevertheless,less research has explored the spatiotemporal trend and the local atmospheric mechanism of nocturnal temperature anomaly around the world.Here,we investigate the spatiotemporal trend of nighttime temperature anomaly(NTA)from 1961 to 2023,and analyze the underlying physical mechanism related to different extents of positive temperature anomaly.We find that NTA showed a significantly increased trend worldwide,with an increasing rate of0.21°C/decade.At the continental scale,NTA has increased faster in North America,Asia,and Europe.The occurrence of positive NTA is generally associated with local increased cloud cover,precipitation,and humidity,which contribute to enhanced downward longwave radiation and greenhouse effect at night.On the inter-annual scale,NTA is positively related to the preceding winter Oceanic Ni?o Index,indicating the possible modulation of El Ni?o-Southern Oscillation on the global nocturnal temperature.Our results could help to understand the variation and influence mechanism of anomalous nighttime temperature in recent decades,and inform the forecast of and response to hot nights.展开更多
China, as the biggest GHG emitter and the largest developing country, has been urged by international society to take responsibilities for reducing GHG, especially in the post-Kyoto commitment period. Currently, the U...China, as the biggest GHG emitter and the largest developing country, has been urged by international society to take responsibilities for reducing GHG, especially in the post-Kyoto commitment period. Currently, the United Nations Framework Convention on Climate Change （UNFCCC） assigns the responsibility to parties who produce the pollution, using the production-based GHG emissions inventories. In this article, we analyze the difference between China＇s production- and consumption- based emission inventories and conclude that consumption-based GHG emission inventories are preferred; as it is fair that whoever consumes the emission should pay for their consumption. In addition, in order to consider environmental justice, policy-makers should take both economic and administrative measures to support poor provinces for reducing C02 emissions.展开更多
Tropospheric O3 is an important pollutant harmful to human health and ecosystem productivity[1,2].It plays a major role in oxidation processes determining the oxidizing capacity of the troposphere and is also an impor...Tropospheric O3 is an important pollutant harmful to human health and ecosystem productivity[1,2].It plays a major role in oxidation processes determining the oxidizing capacity of the troposphere and is also an important greenhouse gas contributing to global warming[3].Ground-level O3 pollution is formed by complex photochemical reactions involving anthropogenic and biogenic emitted volatile organic compounds(VOCs)and nitrogen oxides(NOx).Severe O3 pollution episodes have been reported frequently in eastern China,especially in the Yangtze River Delta[4,5].展开更多
Because of overfitting and the improvement of generalization capability (GC)available in the construction of forecasting models using artificial neural network (ANN), a newmethod is proposed for model establishment by...Because of overfitting and the improvement of generalization capability (GC)available in the construction of forecasting models using artificial neural network (ANN), a newmethod is proposed for model establishment by means of making a low-dimension ANN learning matrixthrough principal component analysis (PCA). The results show that the PC A is able to construct anANN model without the need of finding an optimal structure with the appropriate number ofhidden-layer nodes, thus avoids overfitting by condensing forecasting information, reducingdimension and removing noise, and GC is greatly raised compared to the traditional ANN and stepwiseregression techniques for model establishment.展开更多
Weather prediction is essential to the daily life of human beings.Current numerical weather prediction models such as the Global Forecast System(GFS)are still subject to substantial forecast biases and rarely consider...Weather prediction is essential to the daily life of human beings.Current numerical weather prediction models such as the Global Forecast System(GFS)are still subject to substantial forecast biases and rarely consider the impact of atmospheric aerosol,despite the consensus that aerosol is one of the most important sources of uncertainty in the climate system.Here we demonstrate that atmospheric aerosol is one of the important drivers biasing daily temperature prediction.By comparing observations and the GFS prediction,we find that the monthly-averaged bias in the 24-h temperature forecast varies between±1.5℃in regions influenced by atmospheric aerosol.The biases depend on the properties of aerosol,the underlying land surface,and aerosol–cloud interactions over oceans.It is also revealed that forecast errors are rapidly magnified over time in regions featuring high aerosol loadings.Our study provides direct‘‘observational"evidence of aerosol’s impacts on daily weather forecast,and bridges the gaps between the weather forecast and climate science regarding the understanding of the impact of atmospheric aerosol.展开更多
Organic aerosol(OA)is a major component of atmospheric particulate matter(PM)with complex composition and formation processes influenced by various factors.Emission reduction can alter both precursors and oxidants whi...Organic aerosol(OA)is a major component of atmospheric particulate matter(PM)with complex composition and formation processes influenced by various factors.Emission reduction can alter both precursors and oxidants which further affects secondary OA formation.Here we provide an observational analysis of secondary OA(SOA)variation properties in Yangtze River Delta(YRD)of eastern China in response to large scale of emission reduction during Chinese New Year(CNY)holidays from 2015 to 2020,and the COVID-19 pandemic period from January to March,2020.We found a 17%increase of SOA proportion during the COVID lockdown.The relative enrichment of SOA is also found during multi-year CNY holidays with dramatic reduction of anthropogenic emissions.Two types of oxygenated OA(OOA)influenced by mixed emissions and SOA formation were found to be the dominant components during the lockdown in YRD region.Our results highlight that these emission-reduction-induced changes in organic aerosol need to be considered in the future to optimize air pollution control measures.展开更多
Land-use significantly affects soil organic carbon(SOC)and nitrogen cycling,eventually leading to global climate change.The cold and arid climate conditions in Tibet are not conducive to transformation of SOC and nitr...Land-use significantly affects soil organic carbon(SOC)and nitrogen cycling,eventually leading to global climate change.The cold and arid climate conditions in Tibet are not conducive to transformation of SOC and nitrogen.Hence,research on SOC and nitrogen distribution under different land-use patterns in Tibet is an important basis to assess the soil carbon and nitrogen potential in the land ecosystem of this area.This study aims to explain the effects of two land-use patterns,namely,farmland and grassland,on SOC and nitrogen contents in the cold regions of Tibet.This study also seeks to provide a scientific basis for the agricultural and grass production system.To achieve these goals,the changing features of total nitrogen(TN),mineralized nitrogen(nitrate nitrogen(NN)and ammonium nitrogen(AN)),and SOC were analyzed in different soil depths(0-5,5-10,10-20,20-30,30-40,and 40-50 cm)in farmland and adjacent natural grassland.The differences in carbon and nitrogen contents between the farmland and grassland of the main agricultural area of Tibet were determined through combined field survey and lab analysis.Results showed that the contents of SOC,TN and mineralized nitrogen in the grassland and farmland decreased with increasing soil depth mainly in the surface with depth of 0-20 cm.The effects of the different land-use patterns on the contents of SOC and TN were primarily evident in the 0-10 cm surface layer.The contents of SOC and TN in the farmland were significantly lower than those in the grassland,with mean reduction by 28.36%for SOC and 20.76%for TN.When the soil layer is deeper than 10 cm,the contents of SOC and TN in the farmland were greater than those in the grassland.This finding indicated that the transformation from grassland to farmland in Tibet mainly influenced the SOC and TN in the 0-10 cm surface layer.Moreover,the results showed that the increment of carbon in the deep soil layers of the farmland partially offsets the SOC loss from the surface because of cultivation.The ratio of mineralized nitrogen to TN in the farmland was significantly higher than that in the grassland(p<0.001).Mineralized nitrogen in the farmland mainly existed in the form of NN,with a mean content of 2.7%in the 0-50 cm surface layer.By contrast,the difference in the ratio of AN to TN between the grassland and farmland was not significant.The results revealed that the land-use pattern in extremely cold agricultural areas mainly affects the contents of SOC and nitrogen in the 0-10 cm surface layer,and agricultural management is beneficial in increasing the SOC content in the deeper layers.展开更多
Based on observation data from urban observation stations in Nanjing and Suzhou at two heights in the roughness sublayer above the canopy and observation data at three heights in the SORPES station at the Xianlin Camp...Based on observation data from urban observation stations in Nanjing and Suzhou at two heights in the roughness sublayer above the canopy and observation data at three heights in the SORPES station at the Xianlin Campus of Nanjing University in a suburban area,the of land-atmosphere turbulent flux exchange and the energy balance over complex underlying surfaces were analyzed.The results indicated that in the roughness sublayer above the canopy,the nearsurface momentum flux,sensible heat flux,and latent heat flux increase with height,and the observation value of the surface albedo increases with height.However,the observation value of the net radiation decreases with height,thus resulting in a change in the urban surface energy budget with height.At the SORPES station in the Xianlin Campus of Nanjing University located in a hilly area,the momentum flux,sensible heat flux,and latent heat flux of the ground observation field significantly differed from those of the two heights on the tower,while the two heights on the tower were extremely close.These results indicate that the flux observation over the complex underlying surface exhibits adequate local only when it is conducted at a higher altitude above the ground.The turbulent flux observation results at a lower altitude in urban areas are underestimated,while the turbulent flux observation results near the surface produce a large deviation over the underlying hilly complex.展开更多
We tested two questions:(i)whether the climatic conditions of the Azorean Islands in Portugal may have restricted the invasion of Harmonia axyridis across this archipelago and(ii)determine what population of this spec...We tested two questions:(i)whether the climatic conditions of the Azorean Islands in Portugal may have restricted the invasion of Harmonia axyridis across this archipelago and(ii)determine what population of this species could have a higher probability of invading the islands.We used MaxEnt to project the climate requirements of different H.axyridis populations from three regions of the world,and the potential global niche of the species in the Azorean islands.Then we assessed the suitability of the islands for each of the three H.axyridis populations and global potential niche through histograms analysis,Principal Component Analysis(PCA)of climate variables,and a variable-by-variable assessment of the suitability response curves compared with the climatic conditions of the Azores.Climatic conditions of the Azores are less suitable for the U.S.and native Asian populations of H.axyridis,and more suitable for European populations and the global potential niche.The PCA showed that the climatic conditions of the islands differed from the climatic requirements of H.axyridis.This difference is mainly explained by precipitation of the wettest month,isothermality,and the minimum temperature of the coldest month.We concluded that the climatic conditions of the Azores could have influenced the establishment and spread of H.axyridis on these islands from Europe.Our results showed that abiotic resistance represented by the climate of the potentially colonizable zones could hinder the establishment of invasive insects,but it could vary depending of the origin of the colonizing population.展开更多
China has announced an ambitious goal of peaking its carbon emissions before 2030 and achieving carbon neutrality before 2060.To realize carbon neutrality,China’s total electricity consumptions are projected to doubl...China has announced an ambitious goal of peaking its carbon emissions before 2030 and achieving carbon neutrality before 2060.To realize carbon neutrality,China’s total electricity consumptions are projected to double to 15 PW h(1 PW h=1012 kW h)by 2060,which would be mainly supported by renewable energies via a 16-fold increase in solar power and a 9-fold increase in wind power[1].展开更多
基金supported by National Natural Science Foundation of China 40830106the 111 Project of China (No. B07036)+1 种基金Ministry of Science and Technology of China (No. GYHY200906016)US Department of Environment (DOE 144 KQ65)
文摘Atmospheric response to SST variability was estimated using generalized equilibrium feedback analysis （GEFA） in the SST EOF space with synthesis data from an idealized climate model. Results show that the GEFA atmospheric response to the leading SST EOF modes is much more accurate and robust than the GEFA feedback matrix in physical space. Therefore, GEFA provides a practical method for assessing atmospheric response to large-scale SST anomalies in terms of the leading EOFs.
基金supported by the National Natural Science Foundation of China(Nos.21925601 and 22127811).
文摘Atmospheric dimethyl sulfide(DMS,CH_(3)SCH_(3))and methanethiol(MeSH,CH_(3)SH)have been widely studied and recognized to significantly constrain the atmospheric sulfur budget.Nevertheless,while the role of DMS and MeSH remains largely uncertain in inland regions,learning about dimethyl disulfide(DMDS,CH_(3)SSCH_(3))is also limited.In this study,we measured atmospheric DMS,MeSH and DMDS in winter,from 19 December 2022 to 30 January 2023,and spring,from 24 April to 2 June 2023 with a Vocus proton-transfer-reaction time-offlightmass spectrometer(Vocus PTR-TOF)at the Dianshan Lake(DSL)Air QualityMonitoring Supersite in a suburban area of Shanghai,China.The mixing ratios of DMS,MeSH and DMDS exhibited clear diurnal cycles,and were characterized by average and interquartile range values of 22.6(10.1-29.7),14.9(6.5-19.4)and 9.8(6.0-10.7)pptv,respectively,in the spring campaign,which are approximately twice as high as those in winter.MeSH and DMDS were found to be well correlated with DMS in the two campaigns.Wind analysis suggests that three reduced-sulfur compounds owned common sources from the DSL.Furthermore,the sulfur dioxide(SO_(2))production quantity fromthe three reduced-sulfur compounds over the DSL inMay 2023 was estimated to be 1.42±0.74 t with 84.8%originating fromDMDS,which was comparable to the monthly SO_(2) emissions fromships over the DSL.Our results highlight the prominent role of atmospheric DMDS in SO_(2) production when compared to DMS and MeSH in the suburban area of Shanghai,soliciting further investigation and consideration of DMDS in the sulfur budget.
基金sponsored by the National Natural Science Foundation of China(Grant No.40975004)the State Key Basic Program(973)Program(Grant No.2013CB430100)
文摘The entrainment flux ratio Ae and the inversion layer （IL） thickness are two key parameters in a mixed layer model. Ae is defined as the ratio of the entrainment heat flux at the mixed layer top to the surface heat flux. The IL is the layer between the mixed layer and the free atmosphere. In this study, a parameterization of Ae is derived from the TKE budget in the first- order model for a well-developed CBL under the condition of linearly sheared geostrophic velocity with a zero value at the surface. It is also appropriate for a CBL under the condition of geostrophic velocity remaining constant with height. LESs are conducted under the above two conditions to determine the coefficients in the parameterization scheme. Results suggest that about 43% of the shear-produced TKE in the IL is available for entrainment, while the shear-produced TKE in the mixed layer and surface layer have little effect on entrainment. Based on this scheme, a new scale of convective turbulence velocity is proposed and applied to parameterize the IL thickness, The LES outputs for the CBLs under the condition of linearly sheared geostrophic velocity with a non-zero surface value are used to verify the performance of the parameterization scheme. It is found that the parameterized Ae and IL thickness agree well with the LES outputs.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.21925601,91644213)the National Key R&D Program of China(No.2017YFC0209505).
文摘Organic acids are important contributors to the acidity of atmospheric precipitation,but their existence in the Chinese atmosphere is largely unclear.In this study,twelve atmospheric gaseous organic acids,including C_(1)-C_(9) alkanoic acids,methacrylic acid,pyruvic acid,and benzoic acid,were observed in the suburb of Wangdu,Hebei Province,a typical rural site in the northern China plain from 16^(th) December,2018 to 22^(nd) January,2019,using a Vocus■ Proton-Transfer-Reaction time-of-flight mass spectrometer(Vocus PTR-ToF).The quantification of C_(2)-C_(4) alkanoic acids by the Vocus PTR-ToF was calibrated according to the titration of a NaOH solution by C_(2)-C_(4) alkanoic acids from home-made permeation sources,and the other organic acids except for formic acid were quantified based on the k_(cap)-sensitivity linearity in the Vocus PTR-ToF,whereas formic acid was not quantified because our instrument setting led to a significant underestimation in its concentration.The average total concentration of eleven gaseous organic acids was 6.96±5.20 ppbv(parts per billion by volume).The average concentration of acetic acid was the highest(3.86±3.00 ppbv),followed by propanoic acid,butyric acid,and methacrylic acid.Domestic straw burning was likely the dominant source of the observed gaseous organic acids according to the good correlations between acetonitrile and organic acids and between particulate K+and organic acids,and traffic emissions could also have contributed.During episodes with continuously high concentrations of organic acids,short-distance transport dominated in Wangdu according to the backward trajectory analysis.Baoding,Shijiazhuang,and Hengshui areas were the main source areas based on potential source contribution function and concentration weighing track analysis.
基金sponsored by the National Natural Science Foundation of China(Grant No.40975004)the State Key Basic Program(973)(Grant No.2013CB430100)
文摘Following the parameterization of sheared entrainment obtained in the companion paper, Liu et al. （2016）, the present study aims to further investigate the characteristics of entrainment, and develop a simple model for predicting the growth rate of a well-developed and sheared CBL. The relative stratification, defined as the ratio of the stratification in the free atmosphere to that in the entrainment zone, is found to be a function of entrainment flux ratio （Ae）. This leads to a simple expression of the entrainment rate, in which Ae needs to be parameterized. According to the results in Liu et al. （2016）, Ae can be simply expressed as the ratio of the convective velocity scale in the sheared CBL to that in the shear-free CBL. The parameterization of the convective velocity scale in the sheared CBL is obtained by analytically solving the bulk model with several assumptions and approximations. Results indicate that the entrainment process is influenced by the dynamic effect, the interaction between mean shear and environmental stratification, and one other term that includes the Coriolis effect. These three parameterizations constitute a simple model for predicting the growth rate of a well-developed and sheared CBL. This model is validated by outputs of LESs, and the results show that it performs satisfactorily. Compared with bulk models, this model does not need to solve a set of equations for the CBL. It is more convenient to apply in numerical models.
基金Key Research Planning Project of the National Natural Science Foundation (90211010)
文摘Climate changes in Guangdong are studied based on temperature data of 86 meteorological stations in Guangdong Province during 1961 – 2000, temperature data in Guangzhou during 1908 – 2002, and sea level data in the South China Sea during 1958 – 2001. Significant climate warming and sea level rise in Guangdong is demonstrated. Possible influences of climate warming on agriculture in Guangdong are discussed in terms of thermal resources, crop and breed layout, crop yield, diseases, insect pests and weeds as well as agrometeorological disasters, etc. In the final part, agricultural strategies of mitigating and adapting to the climate changes are given.
基金supported by the China Meteorological Administration Special Public Welfare Research Fund (No. GYHY201106033)the National Natural Science Foundation of China (No. 41175004)
文摘The effects of different Planetary Boundary Layer（PBL） structures on pollutant dispersion processes within two idealized street canyon configurations and a realistic urban area were numerically examined by a Computational Fluid Dynamics（CFD） model. The boundary conditions of different PBL structures/conditions were provided by simulations of the Weather Researching and Forecasting model. The simulated results of the idealized 2D and 3D street canyon experiments showed that the increment of PBL instability favored the downward transport of momentum from the upper flow above the roof to the pedestrian level within the street canyon. As a result, the flow and turbulent fields within the street canyon under the more unstable PBL condition are stronger. Therefore, more pollutants within the street canyon would be removed by the stronger advection and turbulent diffusion processes under the unstable PBL condition. On the contrary, more pollutants would be concentrated in the street canyon under the stable PBL condition. In addition, the simulations of the realistic building cluster experiments showed that the density of buildings was a crucial factor determining the dynamic effects of the PBL structure on the flow patterns. The momentum field within a denser building configuration was mostly transported from the upper flow, and was more sensitive to the PBL structures than that of the sparser building configuration. Finally, it was recommended to use the Mellor-Yamada-Nakanishi-Niino（MYNN） PBL scheme, which can explicitly output the needed turbulent variables, to provide the boundary conditions to the CFD simulation.
基金the National Elite Foundationthe Institute for Advanced Studies in Basic Sciences for their financial supportfinancially supported by the National Natural Science Foundation of China(22173026,22350410386,22375200,U22A202175,21961142006)。
文摘This study investigates the effects of Fe on the oxygen-evolution reaction(OER)in the presence of Au.Two distinct areas of OER were identified:the first associated with Fe sites at low overpotential(~330 mV),and the second with Au sites at high overpotential(~870 mV).Various factors such as surface Fe concentration,electrochemical method,scan rate,potential range,concentration,method of adding K_(2)Fe O_(4),nature of Fe,and temperature were varied to observe diverse behaviors during OER for Fe O_(x)H_(y)/Au.Trace amounts of Fe ions had a significant impact on OER,reaching a saturation point where the activity did not increase further.Strong electronic interaction between Fe and Au ions was indicated by X-ray photoelectron spectroscopy(XPS)and electron paramagnetic resonance(EPR)analyses.In situ visible spectroscopy confirmed the formation of Fe O_(4)^(2-)during OER.In situ Mossbauer and surfaceenhanced Raman spectroscopy(SERS)analyses suggest the involvement of Fe-based species as intermediates during the rate-determining step of OER.A lattice OER mechanism based on Fe O_(x)H_(y)was proposed for operation at low overpotentials.Density functional theory(DFT)calculations revealed that Fe oxide,Fe-oxide clusters,and Fe doping on the Au foil exhibited different activities and stabilities during OER.The study provides insights into the interplay between Fe and Au in OER,advancing the understanding of OER mechanisms and offering implications for the design of efficient electrocatalytic systems.
基金This research was supported by the National Natural Science Foundation of China[grant numbers 91744311 and 41922038]the International Cooperation project of Jiangsu Provincial Science and Technology Agency[grant number BZ2017066].
文摘The explosive spread of the 2019 novel coronavirus(COVID-19)provides a unique chance to rethink the relationship between human activity and air pollution.Though related studies have revealed substantial reductions in primary emissions,obvious differences do exist in the responses of secondary pollutants,like ozone(0_(3))pollution.However,the regional disparities of O_(3)responses and their causes have still not been fully investigated.To better elucidate the interrelationship between anthropogenic emissions,chemical production,and meteorological conditions,O_(3)responses caused by lockdowns over different regions were comprehensively explored at a global scale.Observational signals of air-quality change were derived from multi-year surface measurements and satellite retrievals.With similar substantial drops in nitrogen dioxide(NO_(2)),ozone shows rising signals in most areas of both East Asia and Europe,even up to~14 ppb,while a non-negligible declining signal exists in North America,by about 2-4 ppb.Furthermore,the drivers behind the different O_(3)responses are discussed based on meteorological analysis and O_(3)sensitivity diagnosis.On the one hand,O_(3)responses to NO_(2)declines can be affected by the primary dependence on its precursors.On the other hand,it is also highly dependent on meteorological factors,especially temperature.Our study further highlights the great importance of taking into consideration both the regional disparities and synergistic effects of precursor reductions and meteorological influence for scientific mitigation of O_(3)pollution.
基金The work was supported by the National Natural Science Foundation of China （Grant Nos. D0512/91544231, D0512/ 41422504, and D0510/41505109）, National Key Research and Development Program in China （No. 2016YFC0200506）, and Jiangsu Provincial Science Fund （No. BK20140021）. We thank L.F. Zheng, Z.N. Xu, L.S. Jin, E. Herrmann, Y.N. Xie, X.M. Qi, A. Virkkula, Z. Peng, Y.C. Shen, J.P. Wang, H. Shi, L. Wang, C.J. Zhu and H. Shi for their contributions on instrumental maintenance and field campaigns.
文摘This work presents an overall introduction to the Station for Observing Regional Processes of the EarthSystem - SORPES in Nanjing, East China, and gives an overview about main scientific findings instudies of air pollution-weather/climate interactions obtained since 2011. The main results summarizedin this paper include overall characteristics of trace gases and aerosols, chemical transformationmechanisms for secondary pollutants like O3, HONO andsecondary ingrganic aerosols, and the airpollution- weather/climate interactions and feedbacks in mixed air pollution plumes from sources likefossil fuel combustion, biomass burning and dust storms. The future outlook of the development plan on instrumentation, networking and data-sharing for the SORPES station is also discussed.
基金supported by the National Natural Science Foundation of China(Grant No.42475191)the Fundamental Research Funds for the Central Universities-Cemac‘Geo X’Interdisciplinary Program(Grant No.2024300245)the Postgraduate Research&Practice Innovation Program of Jiangsu Province。
文摘Global temperature has increased at a rapid rate in recent decades,and the warming rate at night is observed higher than that during the daytime among different regions.Nighttime anomalous high temperatures may pose an additional risk to human health and society.Nevertheless,less research has explored the spatiotemporal trend and the local atmospheric mechanism of nocturnal temperature anomaly around the world.Here,we investigate the spatiotemporal trend of nighttime temperature anomaly(NTA)from 1961 to 2023,and analyze the underlying physical mechanism related to different extents of positive temperature anomaly.We find that NTA showed a significantly increased trend worldwide,with an increasing rate of0.21°C/decade.At the continental scale,NTA has increased faster in North America,Asia,and Europe.The occurrence of positive NTA is generally associated with local increased cloud cover,precipitation,and humidity,which contribute to enhanced downward longwave radiation and greenhouse effect at night.On the inter-annual scale,NTA is positively related to the preceding winter Oceanic Ni?o Index,indicating the possible modulation of El Ni?o-Southern Oscillation on the global nocturnal temperature.Our results could help to understand the variation and influence mechanism of anomalous nighttime temperature in recent decades,and inform the forecast of and response to hot nights.
基金the National Basic Research Program of China(973 Program)(No.2012CB955904)National Natural Science Foundation(No.40905062)
文摘China, as the biggest GHG emitter and the largest developing country, has been urged by international society to take responsibilities for reducing GHG, especially in the post-Kyoto commitment period. Currently, the United Nations Framework Convention on Climate Change （UNFCCC） assigns the responsibility to parties who produce the pollution, using the production-based GHG emissions inventories. In this article, we analyze the difference between China＇s production- and consumption- based emission inventories and conclude that consumption-based GHG emission inventories are preferred; as it is fair that whoever consumes the emission should pay for their consumption. In addition, in order to consider environmental justice, policy-makers should take both economic and administrative measures to support poor provinces for reducing C02 emissions.
基金supported jointly by the National Natural Science Foundation of China (41705023)the Postdoctoral Science Foundation of China (017M610319)the Foundation for Innovative Research Groups of the National Natural Science Foundation of China (41621005).
文摘Tropospheric O3 is an important pollutant harmful to human health and ecosystem productivity[1,2].It plays a major role in oxidation processes determining the oxidizing capacity of the troposphere and is also an important greenhouse gas contributing to global warming[3].Ground-level O3 pollution is formed by complex photochemical reactions involving anthropogenic and biogenic emitted volatile organic compounds(VOCs)and nitrogen oxides(NOx).Severe O3 pollution episodes have been reported frequently in eastern China,especially in the Yangtze River Delta[4,5].
基金This work is sponsored by the Ministry of Science and Technology of China Project "2004 DIB3J122"
文摘Because of overfitting and the improvement of generalization capability (GC)available in the construction of forecasting models using artificial neural network (ANN), a newmethod is proposed for model establishment by means of making a low-dimension ANN learning matrixthrough principal component analysis (PCA). The results show that the PC A is able to construct anANN model without the need of finding an optimal structure with the appropriate number ofhidden-layer nodes, thus avoids overfitting by condensing forecasting information, reducingdimension and removing noise, and GC is greatly raised compared to the traditional ANN and stepwiseregression techniques for model establishment.
基金supported by the National Natural Science Foundation of China(41725020 and 41922038)。
文摘Weather prediction is essential to the daily life of human beings.Current numerical weather prediction models such as the Global Forecast System(GFS)are still subject to substantial forecast biases and rarely consider the impact of atmospheric aerosol,despite the consensus that aerosol is one of the most important sources of uncertainty in the climate system.Here we demonstrate that atmospheric aerosol is one of the important drivers biasing daily temperature prediction.By comparing observations and the GFS prediction,we find that the monthly-averaged bias in the 24-h temperature forecast varies between±1.5℃in regions influenced by atmospheric aerosol.The biases depend on the properties of aerosol,the underlying land surface,and aerosol–cloud interactions over oceans.It is also revealed that forecast errors are rapidly magnified over time in regions featuring high aerosol loadings.Our study provides direct‘‘observational"evidence of aerosol’s impacts on daily weather forecast,and bridges the gaps between the weather forecast and climate science regarding the understanding of the impact of atmospheric aerosol.
基金supported by National Natural Science Foundation of China(No.42005082).
文摘Organic aerosol(OA)is a major component of atmospheric particulate matter(PM)with complex composition and formation processes influenced by various factors.Emission reduction can alter both precursors and oxidants which further affects secondary OA formation.Here we provide an observational analysis of secondary OA(SOA)variation properties in Yangtze River Delta(YRD)of eastern China in response to large scale of emission reduction during Chinese New Year(CNY)holidays from 2015 to 2020,and the COVID-19 pandemic period from January to March,2020.We found a 17%increase of SOA proportion during the COVID lockdown.The relative enrichment of SOA is also found during multi-year CNY holidays with dramatic reduction of anthropogenic emissions.Two types of oxygenated OA(OOA)influenced by mixed emissions and SOA formation were found to be the dominant components during the lockdown in YRD region.Our results highlight that these emission-reduction-induced changes in organic aerosol need to be considered in the future to optimize air pollution control measures.
基金The research financial was supported by the National Natural Science Foundations of China(Grant No.41161052,41461054,41561052)the Project of Promote Plan for Ecology Research Team,and the Support Program for the Backbone of the Young Teachers of Agricultural and Animal Husbandry College,Tibet University.
文摘Land-use significantly affects soil organic carbon(SOC)and nitrogen cycling,eventually leading to global climate change.The cold and arid climate conditions in Tibet are not conducive to transformation of SOC and nitrogen.Hence,research on SOC and nitrogen distribution under different land-use patterns in Tibet is an important basis to assess the soil carbon and nitrogen potential in the land ecosystem of this area.This study aims to explain the effects of two land-use patterns,namely,farmland and grassland,on SOC and nitrogen contents in the cold regions of Tibet.This study also seeks to provide a scientific basis for the agricultural and grass production system.To achieve these goals,the changing features of total nitrogen(TN),mineralized nitrogen(nitrate nitrogen(NN)and ammonium nitrogen(AN)),and SOC were analyzed in different soil depths(0-5,5-10,10-20,20-30,30-40,and 40-50 cm)in farmland and adjacent natural grassland.The differences in carbon and nitrogen contents between the farmland and grassland of the main agricultural area of Tibet were determined through combined field survey and lab analysis.Results showed that the contents of SOC,TN and mineralized nitrogen in the grassland and farmland decreased with increasing soil depth mainly in the surface with depth of 0-20 cm.The effects of the different land-use patterns on the contents of SOC and TN were primarily evident in the 0-10 cm surface layer.The contents of SOC and TN in the farmland were significantly lower than those in the grassland,with mean reduction by 28.36%for SOC and 20.76%for TN.When the soil layer is deeper than 10 cm,the contents of SOC and TN in the farmland were greater than those in the grassland.This finding indicated that the transformation from grassland to farmland in Tibet mainly influenced the SOC and TN in the 0-10 cm surface layer.Moreover,the results showed that the increment of carbon in the deep soil layers of the farmland partially offsets the SOC loss from the surface because of cultivation.The ratio of mineralized nitrogen to TN in the farmland was significantly higher than that in the grassland(p<0.001).Mineralized nitrogen in the farmland mainly existed in the form of NN,with a mean content of 2.7%in the 0-50 cm surface layer.By contrast,the difference in the ratio of AN to TN between the grassland and farmland was not significant.The results revealed that the land-use pattern in extremely cold agricultural areas mainly affects the contents of SOC and nitrogen in the 0-10 cm surface layer,and agricultural management is beneficial in increasing the SOC content in the deeper layers.
基金supported by the National Key R&D Program of China(Grant No.2016YFC0200500)the Youth Project of National Natural Science Foundation of China(Grant No.41805007)。
文摘Based on observation data from urban observation stations in Nanjing and Suzhou at two heights in the roughness sublayer above the canopy and observation data at three heights in the SORPES station at the Xianlin Campus of Nanjing University in a suburban area,the of land-atmosphere turbulent flux exchange and the energy balance over complex underlying surfaces were analyzed.The results indicated that in the roughness sublayer above the canopy,the nearsurface momentum flux,sensible heat flux,and latent heat flux increase with height,and the observation value of the surface albedo increases with height.However,the observation value of the net radiation decreases with height,thus resulting in a change in the urban surface energy budget with height.At the SORPES station in the Xianlin Campus of Nanjing University located in a hilly area,the momentum flux,sensible heat flux,and latent heat flux of the ground observation field significantly differed from those of the two heights on the tower,while the two heights on the tower were extremely close.These results indicate that the flux observation over the complex underlying surface exhibits adequate local only when it is conducted at a higher altitude above the ground.The turbulent flux observation results at a lower altitude in urban areas are underestimated,while the turbulent flux observation results near the surface produce a large deviation over the underlying hilly complex.
文摘We tested two questions:(i)whether the climatic conditions of the Azorean Islands in Portugal may have restricted the invasion of Harmonia axyridis across this archipelago and(ii)determine what population of this species could have a higher probability of invading the islands.We used MaxEnt to project the climate requirements of different H.axyridis populations from three regions of the world,and the potential global niche of the species in the Azorean islands.Then we assessed the suitability of the islands for each of the three H.axyridis populations and global potential niche through histograms analysis,Principal Component Analysis(PCA)of climate variables,and a variable-by-variable assessment of the suitability response curves compared with the climatic conditions of the Azores.Climatic conditions of the Azores are less suitable for the U.S.and native Asian populations of H.axyridis,and more suitable for European populations and the global potential niche.The PCA showed that the climatic conditions of the islands differed from the climatic requirements of H.axyridis.This difference is mainly explained by precipitation of the wettest month,isothermality,and the minimum temperature of the coldest month.We concluded that the climatic conditions of the Azores could have influenced the establishment and spread of H.axyridis on these islands from Europe.Our results showed that abiotic resistance represented by the climate of the potentially colonizable zones could hinder the establishment of invasive insects,but it could vary depending of the origin of the colonizing population.
基金supported by the National Natural Science Foundation of China(41988101 and 42171360)the National Key Research and Development Program of China(2017YFA0603604)。
文摘China has announced an ambitious goal of peaking its carbon emissions before 2030 and achieving carbon neutrality before 2060.To realize carbon neutrality,China’s total electricity consumptions are projected to double to 15 PW h(1 PW h=1012 kW h)by 2060,which would be mainly supported by renewable energies via a 16-fold increase in solar power and a 9-fold increase in wind power[1].
