The summer of 2020 recorded a record-breaking flood due to excessive mei-yu rain falling over the Yangtze River Valley(YRV).Using the Lagrangian model FLEXPART,this paper investigates moisture sources and transport pr...The summer of 2020 recorded a record-breaking flood due to excessive mei-yu rain falling over the Yangtze River Valley(YRV).Using the Lagrangian model FLEXPART,this paper investigates moisture sources and transport processes behind this extreme event.Based on climate data from 1979 to 2019,the air-particle(an infinitesimally small air parcel)trajectories reaching the YRV show sectors that correspond to five main moisture sources:the Indian monsoon region(IND,27.5%of the total rainfall),the local evaporation(27.4%),the Western Pacific Ocean(WPO,21.3%),the Eurasian continent(8.5%)and Northeast Asia(4.4%).In the 2020 mei-yu season,moisture from all source regions was above normal except that from Northeast Asia.A record-breaking moisture source from the IND and WPO dominated this extreme mei-yu flood in 2020,which was 1.5 and 1.6 times greater than the climate mean,respectively.This study reveals a significant relationship between the moisture source with three moisture transport processes,i.e.,trajectory density,moisture content,and moisture uptake of air-particles.A broad anomalous anticyclonic circulation over the Indo-Northwestern Pacific(Indo-NWP)provides a favorable environment to enhance the moisture transport from the IND and WPO into the YRV.In the 2020 mei-yu season,a record-breaking Indo-NWP anomalous anticyclonic circulation contributed to a higher trajectory density as well as higher moisture content and moisture uptake of air-particles from the IND and WPO regions.This collectively resulted in unprecedented moisture transport from source origins,thus contributing to the mei-yu flood over the YRV in 2020.展开更多
Changes in monsoon precipitation have profound social and economic impacts as more than two-thirds of the world’s population lives in monsoon regions.Observations show a significant reduction in global land monsoon p...Changes in monsoon precipitation have profound social and economic impacts as more than two-thirds of the world’s population lives in monsoon regions.Observations show a significant reduction in global land monsoon precipitation during the second half of the 20 th century.Understanding the cause of this change,especially possible anthropogenic origins,is important.Here,we compare observed changes in global land monsoon precipitation during 1948–2005 with those simulated by 5 global climate models participating in the Coupled Model Inter-comparison Project-phase 5(CMIP5)under different external forcings.We show that the observed drying trend is consistent with the model simulated response to anthropogenic forcing and to anthropogenic aerosol forcing in particular.We apply the optimal fingerprinting method to quantify anthropogenic influences on precipitation and find that anthropogenic aerosols may have contributed to 102%(62–144%for the 5–95%confidence interval)of the observed decrease in global land monsoon precipitation.A moisture budget analysis indicates that the reduction in precipitation results from reduced vertical moisture advection in response to aerosol forcing.Since much of the monsoon regions,such as India and China,have been experiencing rapid developments with increasing aerosol emissions in the past decedes,our results imply a further reduction in monsoon precipitation in these regions in the future if effective mitigations to reduce aerosol emissions are not deployed.The observed decline of aerosol emission in China since 2006 helps to alleviate the reducing trend of monsoon precipiptaion.展开更多
It has been of interest in seeking electrocatalysts that could exercise equally high-efficient and durable hydrogen evolution upon nonselective electrolytes in both acidic and alkaline environments. Herein, we report ...It has been of interest in seeking electrocatalysts that could exercise equally high-efficient and durable hydrogen evolution upon nonselective electrolytes in both acidic and alkaline environments. Herein, we report a facile strategy to fabricate cobalt tungsten phosphides (CoxW2−xP2/C) hollow polyhedrons with tunable composition based on metal-organic frameworks (MOFs) template method. By the deliberate control of W doping, the synthesized catalyst with the composition of Co0.9W1.1P2/C is found to be able to achieve a current density of 10 mA·cm^(−2) at overpotentials of 35 and 54 mV in acidic and alkaline media, respectively. This combined electrochemical property stands atop the state-of-the-art electrocatalyst counterparts. To unveil the peculiar behavior of the structure, density functional theory (DFT) calculation was implemented and reveals that the surface W-doping facilitates the optimization of hydrogen absorption free energy (ΔGH*) as well as the thermodynamic and kinetics barriers for water dissociation, which is coupled with the hollow structure of Co-W phosphides, leading to the prominent HER catalytic performance.展开更多
The catalysis of Au thin film could be improved by fabrication of array structures in large area.In this work,nanoimprint lithography has been developed tofabricate flexible Au micro-array(MA)electrodes with~100%cover...The catalysis of Au thin film could be improved by fabrication of array structures in large area.In this work,nanoimprint lithography has been developed tofabricate flexible Au micro-array(MA)electrodes with~100%coverage.Advanced electron microscopy characterisations have directly visualised the atomic-scale three-dimensional(3D)nanostructures with a maximum depth of 6 atomic layers.In-situ observation unveils the crystal growth in the form of twinning.High double layer capacitance brings about large number of active sites on the Au thin film and has a logarithmic relationship with mesh grade.Electrochemistry testing shows that the Au MAs perform much better ethanol oxidation reaction than the planar sample;MAs with higher mesh grade have a greater active site utilisation ratio(ASUR),which is important to build electrochemical double layer for efficient charge transfer.Further improvement on ASUR is expected for greater electrocatalytic performance and potential application in direct ethanol fuel cell.展开更多
基金This paper was supported by the National Natural Science Foundation of China(Grant No.42075037)the Ministry of Science and Technology of China(Grant No.2018YFA0606501)the Program of International S&T Cooperation(Grant No.2018YFE0196000).
文摘The summer of 2020 recorded a record-breaking flood due to excessive mei-yu rain falling over the Yangtze River Valley(YRV).Using the Lagrangian model FLEXPART,this paper investigates moisture sources and transport processes behind this extreme event.Based on climate data from 1979 to 2019,the air-particle(an infinitesimally small air parcel)trajectories reaching the YRV show sectors that correspond to five main moisture sources:the Indian monsoon region(IND,27.5%of the total rainfall),the local evaporation(27.4%),the Western Pacific Ocean(WPO,21.3%),the Eurasian continent(8.5%)and Northeast Asia(4.4%).In the 2020 mei-yu season,moisture from all source regions was above normal except that from Northeast Asia.A record-breaking moisture source from the IND and WPO dominated this extreme mei-yu flood in 2020,which was 1.5 and 1.6 times greater than the climate mean,respectively.This study reveals a significant relationship between the moisture source with three moisture transport processes,i.e.,trajectory density,moisture content,and moisture uptake of air-particles.A broad anomalous anticyclonic circulation over the Indo-Northwestern Pacific(Indo-NWP)provides a favorable environment to enhance the moisture transport from the IND and WPO into the YRV.In the 2020 mei-yu season,a record-breaking Indo-NWP anomalous anticyclonic circulation contributed to a higher trajectory density as well as higher moisture content and moisture uptake of air-particles from the IND and WPO regions.This collectively resulted in unprecedented moisture transport from source origins,thus contributing to the mei-yu flood over the YRV in 2020.
基金supported as part of the Energy Exascale Earth System Model(E3SM)project,funded by the U.S.Department of Energy,Office of Science,Office of Biological and Environmental Researchsupported by the CAS Strategic Priority Research Program(Grant No.XDA20060102)+1 种基金China MOST Program(Grant No.2018YFC1507701)the National Natural Science Foundation of China(Grant No.41775091)。
文摘Changes in monsoon precipitation have profound social and economic impacts as more than two-thirds of the world’s population lives in monsoon regions.Observations show a significant reduction in global land monsoon precipitation during the second half of the 20 th century.Understanding the cause of this change,especially possible anthropogenic origins,is important.Here,we compare observed changes in global land monsoon precipitation during 1948–2005 with those simulated by 5 global climate models participating in the Coupled Model Inter-comparison Project-phase 5(CMIP5)under different external forcings.We show that the observed drying trend is consistent with the model simulated response to anthropogenic forcing and to anthropogenic aerosol forcing in particular.We apply the optimal fingerprinting method to quantify anthropogenic influences on precipitation and find that anthropogenic aerosols may have contributed to 102%(62–144%for the 5–95%confidence interval)of the observed decrease in global land monsoon precipitation.A moisture budget analysis indicates that the reduction in precipitation results from reduced vertical moisture advection in response to aerosol forcing.Since much of the monsoon regions,such as India and China,have been experiencing rapid developments with increasing aerosol emissions in the past decedes,our results imply a further reduction in monsoon precipitation in these regions in the future if effective mitigations to reduce aerosol emissions are not deployed.The observed decline of aerosol emission in China since 2006 helps to alleviate the reducing trend of monsoon precipiptaion.
基金This work was supported by the National Science Foundation for Young Scientists of China (No. 51901018)China Postdoctoral Science Foundation (No. 2019M660456)+4 种基金the National Natural Science Foundation of China (Nos. 51771027 and 21676216)Young Elite Scientists Sponsorship Program by China Association for Science and Technology (YESS, 2019QNRC001)the Fundamental Research Funds for the Central Universities (No. FRF-MP-19-001)National Key Research and Development Program of China (No. 2017YFB0702100)Singapore MOE AcRF Tier 1 grant M4011528.
文摘It has been of interest in seeking electrocatalysts that could exercise equally high-efficient and durable hydrogen evolution upon nonselective electrolytes in both acidic and alkaline environments. Herein, we report a facile strategy to fabricate cobalt tungsten phosphides (CoxW2−xP2/C) hollow polyhedrons with tunable composition based on metal-organic frameworks (MOFs) template method. By the deliberate control of W doping, the synthesized catalyst with the composition of Co0.9W1.1P2/C is found to be able to achieve a current density of 10 mA·cm^(−2) at overpotentials of 35 and 54 mV in acidic and alkaline media, respectively. This combined electrochemical property stands atop the state-of-the-art electrocatalyst counterparts. To unveil the peculiar behavior of the structure, density functional theory (DFT) calculation was implemented and reveals that the surface W-doping facilitates the optimization of hydrogen absorption free energy (ΔGH*) as well as the thermodynamic and kinetics barriers for water dissociation, which is coupled with the hollow structure of Co-W phosphides, leading to the prominent HER catalytic performance.
基金the MOE AcRF Tier 1 grant M4011528.The XRD and FEG-TEM characterisations were performed at Facility for Analysis,Characterisation,Testing and Simulation(FACTS)Labthe FEG-SEM/FIB characterisations were carried out at Microelectronics Reliability and Characterisation(MRC)Lab.
文摘The catalysis of Au thin film could be improved by fabrication of array structures in large area.In this work,nanoimprint lithography has been developed tofabricate flexible Au micro-array(MA)electrodes with~100%coverage.Advanced electron microscopy characterisations have directly visualised the atomic-scale three-dimensional(3D)nanostructures with a maximum depth of 6 atomic layers.In-situ observation unveils the crystal growth in the form of twinning.High double layer capacitance brings about large number of active sites on the Au thin film and has a logarithmic relationship with mesh grade.Electrochemistry testing shows that the Au MAs perform much better ethanol oxidation reaction than the planar sample;MAs with higher mesh grade have a greater active site utilisation ratio(ASUR),which is important to build electrochemical double layer for efficient charge transfer.Further improvement on ASUR is expected for greater electrocatalytic performance and potential application in direct ethanol fuel cell.