Dislocation strengthening,as one of the methods to simultaneously enhance the room temperature strength and ductility of alloys,does not achieve the desired strengthening and plasticity effect during elevated-temperat...Dislocation strengthening,as one of the methods to simultaneously enhance the room temperature strength and ductility of alloys,does not achieve the desired strengthening and plasticity effect during elevated-temperature deformation.Here,we report a novel strategy to boost the dislocation multiplication and accumulation during deformation at elevated temperatures through dynamic strain aging(DSA).With the introduction of the rare-earth element Ho in Mg-Y-Zn alloy,Ho atoms diffuse toward dislocations during deformation at elevated temperatures,provoking the DSA effect,which increases the dislocation density significantly via the interactions of mobile dislocations and Ho atoms.The resulting alloy achieves a great enhancement of dislocation hardening and obtains the dual benefits of high strength and good ductility simultaneously at high homologous temperatures.The present work provides an effective strategy to enhancing the strength and ductility for elevated-temperature materials.展开更多
Organic-inorganic hybrid perovskite solar cells(PSCs)have garnered significant attention due to their high power conversion efficiency(PCE),low cost,and solution-processability.However,a substantial gap remains in the...Organic-inorganic hybrid perovskite solar cells(PSCs)have garnered significant attention due to their high power conversion efficiency(PCE),low cost,and solution-processability.However,a substantial gap remains in the certified efficiency of single-junction PSCs,primarily due to defects in perovskite films that accelerate nonradiative recombination of carriers.In this study,we designed a multifunctional thiourea derivative,amidinethiourea(ATU),as an additive to modulate the crystallization process of perovskite films and inhibit the formation of organic cations and iodine vacancies.Our work leverages the strong hydrogen-bonding interactions between guanidinium molecules and organic amine components,as well as the robust coordination effects between the C=S bonds in thiourea and Pb^(2+)ions.We demonstrate that ATU treatment significantly enhances the crystallinity of perovskite films,reduces defects,and improves charge transport properties.The ATU-treated PSCs achieved a PCE of 25.32%,with enhanced operational stability and reduced leakage current.Additionally,the ATU-treated perovskite films exhibited superior humidity and light-soaking stability,retaining 85.2%of their initial efficiency after 1500 h of exposure to ambient conditions.展开更多
The Atmospheric Infrared Sounder(AIRS)on the Aqua satellite,along with the MWTS/MWHS Synergy(TSHS)sounding system and Atmospheric Vertical Sounder System(VASS)on the Fengyun-3D(FY-3D)satellite,provide highquality data...The Atmospheric Infrared Sounder(AIRS)on the Aqua satellite,along with the MWTS/MWHS Synergy(TSHS)sounding system and Atmospheric Vertical Sounder System(VASS)on the Fengyun-3D(FY-3D)satellite,provide highquality data for studying Arctic temperature change.The generalized cold bias of AIRS is confirmed through horizontal comparisons with Arctic land radiosonde stations.VASS corrects the warm bias of TSHS by incorporating the Hyperspectral Infrared Atmospheric Sounder-I(HIRAS-I).Vertical comparisons demonstrate that AIRS,TSHS,and VASS offer excellent temperature detection from the top of the boundary layer to the lower stratosphere(800–100 h Pa).However,the overestimation and errors of stratospheric temperatures by TSHS and VASS increase with altitude(pressures below60 h Pa).Specifically,the warm bias trends at 0.06 K hPa^(-1),reaching 2.87 K and 2.92 K at 10 h Pa.Similarly,RMSE values trend at 0.05?K h Pa^(-1),reaching 3.62?K and 3.69?K at 10 h Pa.The low correlation(R≥0.65)of TSHS near 250 h Pa in summer is significantly improved in VASS(R≥0.78)after adding HIRAS-I.The high vertical resolution due to infrared hyperspectral resolution facilitates the detection of complex temperature junctions.The retrieval error of AIRS in the boundary layer increases with cloudiness,while VASS combines microwave and infrared channel data to reduce the impact of cloud cover.Assessing the Arctic applicability of these three satellite temperature profile products will facilitate their widespread use in the Arctic region,enhance accurate climate change monitoring,and further reveal the mechanisms of Arctic warming.展开更多
Hydrogen production through solar energy is one of the most important pathways to meet the growing demand of renewable energy,and photocatalyst participation in solar hydrolytic hydrogen production has received great ...Hydrogen production through solar energy is one of the most important pathways to meet the growing demand of renewable energy,and photocatalyst participation in solar hydrolytic hydrogen production has received great attention in recent years in terms of low cost,high efficiency,and flexible design.Particularly,g-C_(3)N_(4)(Graphitic-like carbon nitride material),as a unique material,can catalyze the hydrogen production process by completing the separation and transmission of charge.The easily adjustable pore structure/surface area,dimension,band-gap modulation and defect have shown great potential for hydrogen production from water cracking.In this review,the most recent advance of g-C_(3)N_(4) including the doping of metal and non-metal elements,and the formation of semiconductor heterojunction is highlighted.The main modification strategies and approaches for the design of g-C_(3)N_(4) for hydrogen production,as well as the influence of various materials on hydrogen evolution regarding the photocatalysis mechanism and advantages brought by theoretical calculations are specially and briefly illu-strated.Potential design pathways and strategies of g-C_(3)N_(4) are discussed.In addition,current challenges of hydrogen production from g-C_(3)N_(4) water splitting are summarized and can be expected.展开更多
Perovskite solar cells(PSCs)have emerged as a promising photovoltaic technology because of their high light absorption coefficient,long carrier diffusion distance,and tunable bandgap.However,PSCs face challenges such ...Perovskite solar cells(PSCs)have emerged as a promising photovoltaic technology because of their high light absorption coefficient,long carrier diffusion distance,and tunable bandgap.However,PSCs face challenges such as hysteresis effects and stability issues.In this study,we introduced a novel approach to improve film crystallization by leveraging 4-tert-butylpyridine(TBP)molecules,thereby enhancing the performance and stability of PSCs.Our findings demonstrate the effective removal of PbI_(2)from the perovskite surface through strong coordination with TBP molecules.Additionally,by carefully adjusting the concentration of the TBP solution,we achieved enhanced film crystallinity without disrupting the perovskite structure.The TBP-treated perovskite films exhibit a low defect density,improved crystallinity,and improved carrier lifetime.As a result,the PSCs manufactured with TBP treatment achieve power conversion efficiency(PCE)exceeding 24%.Moreover,we obtained the PCE of 21.39%for the 12.25 cm^(2)module.展开更多
Natural organic matters(NOM)affect water environmental security and have posed a potential threat to human health,and thus they have long been considered as a key index to evaluate water treatment performance.Di...Natural organic matters(NOM)affect water environmental security and have posed a potential threat to human health,and thus they have long been considered as a key index to evaluate water treatment performance.Dissolved organic nitrogen is one of the NOM,which produces some disinfection byproducts having more toxic than those carbon-based materials.Coagulation is a key unit of drinking water purification and has received wide attention.However,conventional flocculation technology on removal of DON is so poor that we have to seek more effective technologies[1,2].Compared with activated carbon,biological aerated filter and sand filtration,the coagulation efficiency of removing DON is relatively low[3].展开更多
AI-driven interior design generation offers promising applications.However,current AI-based diffusion models struggle to generate indoor layouts in pixel-level alignment with the indoor structure.This study proposes a...AI-driven interior design generation offers promising applications.However,current AI-based diffusion models struggle to generate indoor layouts in pixel-level alignment with the indoor structure.This study proposes a new stable diffusion-based interior design workflow with an Interior Design Control Network(IDCN).IDCN ensures that the batchgenerated creative interior designs based on an input image of an unfurnished room match the indoor structure.Generating innovative designs and rendering images directly with the proposed method eliminates the tedious creative design and drawing work in traditional design practices.The results indicate that the proposed method with the new design approach achieves nearly real-time design generation and modiflcation and signiflcantly enhances design creativity and efflciency.Moreover,the proposed method can be generalized to other design generation tasks,thereby promoting the transformation toward intelligent design.展开更多
Because the Tibetan Plateau (TP)has the highest elevation in the world and is a key area affecting the Asian extreme weather and climate events,studies on the Tibetan Plateau meteorology have been highly concerned by ...Because the Tibetan Plateau (TP)has the highest elevation in the world and is a key area affecting the Asian extreme weather and climate events,studies on the Tibetan Plateau meteorology have been highly concerned by the international scientific community.In the late 1970s.Ye and Gao [1]reveled the climatic characteristics of the TP heating and its connection with global and regional atmospheric circulations.With the seasonal evolution from winter to summer,strong surface sensible heat regulates the timing of the establishment of the Asian summer monsoon [2].However,Boos and Kuang [3]addressed that the large-scale South Asian summer monsoon is unaffected by removal of the plateau,provided that the narrow orography of the Himalayas and adjacent mountain ranges is preserved,and revealed the domi- nance of the uplift of the Himalayas in the formation of the present South Asian summer monsoon.Then,does this indicate a weak effect of the summer TP thermal forcing on the variability of the present South Asian monsoon and larger-scale climates?Some dis- cussions have been also stimulated in Science [4].展开更多
The Tibetan Plateau(TP) is a key area affecting forecasts of weather and climate in China and occurrences of extreme weather and climate events over the world. The China Meteorological Administration, the National Nat...The Tibetan Plateau(TP) is a key area affecting forecasts of weather and climate in China and occurrences of extreme weather and climate events over the world. The China Meteorological Administration, the National Natural Science Foundation of China, and the Chinese Academy of Sciences jointly initiated the Third Tibetan Plateau Atmospheric Science Experiment(TIPEX-Ⅲ) in 2013, with an 8–10-yr implementation plan. Since its preliminary field measurements conducted in 2013, routine automatic sounding systems have been deployed at Shiquanhe, Gaize, and Shenzha stations in western TP, where no routine sounding observations were available previously. The observational networks for soil temperature and soil moisture in the central and western TP have also been established. Meanwhile, the plateau-scale and regional-scale boundary layer observations, cloud–precipitation microphysical observations with multiple radars and aircraft campaigns, and tropospheric–stratospheric air composition observations at multiple sites, were performed. The results so far show that the turbulent heat exchange coefficient and sensible heat flux are remarkably lower than the earlier estimations at grassland, meadow, and bare soil surfaces of the central and western TP. Climatologically, cumulus clouds over the main body of the TP might develop locally instead of originating from the cumulus clouds that propagate northward from South Asia. The TIPEX-Ⅲ observations up to now also reveal diurnal variations, macro-and microphysical characteristics, and water-phase transition mechanisms, of cumulus clouds at Naqu station. Moreover, TIPEX-Ⅲ related studies have proposed a maintenance mechanism responsible for the Asian "atmospheric water tower" and demonstrated the effects of the TP heating anomalies on African, Asian, and North American climates. Additionally, numerical modeling studies show that the Γ distribution of raindrop size is more suitable for depicting the TP raindrop characteristics compared to the M–P distribution, the overestimation of sensible heat flux can be reduced via modifying the heat transfer parameterization over the TP, and considering climatic signals in some key areas of the TP can improve the skill for rainfall forecast in the central and eastern parts of China. Furthermore, the TIPEX-Ⅲ has been promoting the technology in processing surface observations, soundings, and radar observations, improving the quality of satellite retrieved soil moisture and atmospheric water vapor content products as well as high-resolution gauge–radar–satellite merged rainfall products, and facilitating the meteorological monitoring, forecasting, and data sharing operations.展开更多
In summer,the Yangtze River valley(YRV)in central–eastern China frequently suffers consecutive extreme rainfall(CER)events,causing floods and huge damages.On the daily timescale,our previous study has shown that the ...In summer,the Yangtze River valley(YRV)in central–eastern China frequently suffers consecutive extreme rainfall(CER)events,causing floods and huge damages.On the daily timescale,our previous study has shown that the Pacific–Japan(PJ)teleconnection is related to the CER events over the YRV,and is a source for long-term(lead time of about 10 days)forecasts of CER events.To facilitate extended-range(lead time of about 20 days)prediction of CER,in the present study,we use the band-pass filter for the PJ teleconnection to keep only the prolonged atmospheric circulation information at the intraseasonal timescale and try to identify more advanced precursors for the CER events over the YRV.Power spectrum analysis was implemented on 9-day sliding mean of the precipitation anomalies.It is found that summer precipitation in YRV has significant 10–40-day oscillations,and the CER events over the YRV are affected by the intraseasonal oscillation(ISO)of the PJ teleconnection.When the ISO of the PJ teleconnection enters its positive phase,it is favorable for CER events to occur.Dynamic diagnoses and model experiments demonstrate that the ISO of the PJ teleconnection is attributed to the intraseasonal convective activities and diabatic heating around the Philippines,which generate significant northward energy dispersion and propagation of Rossby waves up to 16 days prior to occurrences of the CER events in the YRV.The ISO of the PJ teleconnection and the convective activities in the tropical South Asia provide significant and earlier precursors for extended-range forecasts of the CER events along the YRV.展开更多
This paper establishes the kinetic equations in atmospheric chemistry that describe the macroscopic mechanisms of secondary fine particle pollution generated by precursors during atmospheric self-purification.The dyna...This paper establishes the kinetic equations in atmospheric chemistry that describe the macroscopic mechanisms of secondary fine particle pollution generated by precursors during atmospheric self-purification.The dynamic and static solutions of these equations can be applied to calculate quantitative relationships between the concentration ratio of precursors and secondary fine particles as well as the physical clearance power of the atmosphere,chemical reaction rate,and the scale of a contaminated area.The dynamic solution presented here therefore corresponds with a theoretical formula for calculating the overall rate constant for the oxidation reaction of reducing pollutants in the actual atmosphere based on their local concentrations and meteorological monitoring data.In addition,the static solution presented in this paper reveals the functional relationship between the concentration of secondary fine particles and precursor emission rate as well as atmospheric self-purification capacity.This result can be applied to determine the atmospheric environmental capacity of a precursor.Hourly records collected over the last 40 years from 378 weather stations in China's Mainland as well as the spatiotemporal distribution sequence of overall oxidation reaction rates from precursors show that when the reference concentration limit of secondary fine particles is100μmol m-3,the atmospheric environmental capacity of total precursors canbe calculated as 24890×1010 mol yr-1.Thus,when the annual average concentration limit of given fine particles is 35μg m-3 and the ratio of sulfate and nitrate to 30%and 20%of the total amount of fine particles,the capacities of SO2,NOx and NH3 are 1255,1344,and 832(1010g yr-1),respectively.The clearance density of precursors for different return periods across China's Mainland under above conditions are also provided in this study.展开更多
基金supported by the National Key Research and Development Project(2023YFA1609100)the NSFC Funding(U2141207,52171111,52001083)+6 种基金Natural Science Foundation of Heilongjiang(YQ2023E026)China Postdoctoral Science foundation(2024M754149)Postdoctoral Fellowship Program of CPSF(GZC20242192)support from the National Science Foundation(DMR-1611180 and 1809640)with the program directors,DrsHKU Seed Fund for Collaborative Research(#2207101618)support by Croucher Senior Research Fellowship and City U Project(Project No.9229019)Shenzhen Science and Technology Program(Project No.JCYJ20220818101203007)。
文摘Dislocation strengthening,as one of the methods to simultaneously enhance the room temperature strength and ductility of alloys,does not achieve the desired strengthening and plasticity effect during elevated-temperature deformation.Here,we report a novel strategy to boost the dislocation multiplication and accumulation during deformation at elevated temperatures through dynamic strain aging(DSA).With the introduction of the rare-earth element Ho in Mg-Y-Zn alloy,Ho atoms diffuse toward dislocations during deformation at elevated temperatures,provoking the DSA effect,which increases the dislocation density significantly via the interactions of mobile dislocations and Ho atoms.The resulting alloy achieves a great enhancement of dislocation hardening and obtains the dual benefits of high strength and good ductility simultaneously at high homologous temperatures.The present work provides an effective strategy to enhancing the strength and ductility for elevated-temperature materials.
基金financial support from various entities,including the National Natural Science Foundation of China[grant number 62405005]the Natural Science Research Project of Anhui Educational Committee[2024AH050314]+1 种基金the Foundation of Anhui Science and Technology University[grant number HCYJ202201]the Anhui Science and Technology University's Student Innovation and Entrepreneurship Training Program[grant numbers S202410879115,S202410879098]。
文摘Organic-inorganic hybrid perovskite solar cells(PSCs)have garnered significant attention due to their high power conversion efficiency(PCE),low cost,and solution-processability.However,a substantial gap remains in the certified efficiency of single-junction PSCs,primarily due to defects in perovskite films that accelerate nonradiative recombination of carriers.In this study,we designed a multifunctional thiourea derivative,amidinethiourea(ATU),as an additive to modulate the crystallization process of perovskite films and inhibit the formation of organic cations and iodine vacancies.Our work leverages the strong hydrogen-bonding interactions between guanidinium molecules and organic amine components,as well as the robust coordination effects between the C=S bonds in thiourea and Pb^(2+)ions.We demonstrate that ATU treatment significantly enhances the crystallinity of perovskite films,reduces defects,and improves charge transport properties.The ATU-treated PSCs achieved a PCE of 25.32%,with enhanced operational stability and reduced leakage current.Additionally,the ATU-treated perovskite films exhibited superior humidity and light-soaking stability,retaining 85.2%of their initial efficiency after 1500 h of exposure to ambient conditions.
基金supported by the National Key R&D Program of China(Grant Nos.2022YFC2807204 and 2022YFE0106700)the Basic Research Fund of the Chinese Academy of Meteorological Sciences(Grant Nos.2023Z004,2023Z015,and 2023Y012)。
文摘The Atmospheric Infrared Sounder(AIRS)on the Aqua satellite,along with the MWTS/MWHS Synergy(TSHS)sounding system and Atmospheric Vertical Sounder System(VASS)on the Fengyun-3D(FY-3D)satellite,provide highquality data for studying Arctic temperature change.The generalized cold bias of AIRS is confirmed through horizontal comparisons with Arctic land radiosonde stations.VASS corrects the warm bias of TSHS by incorporating the Hyperspectral Infrared Atmospheric Sounder-I(HIRAS-I).Vertical comparisons demonstrate that AIRS,TSHS,and VASS offer excellent temperature detection from the top of the boundary layer to the lower stratosphere(800–100 h Pa).However,the overestimation and errors of stratospheric temperatures by TSHS and VASS increase with altitude(pressures below60 h Pa).Specifically,the warm bias trends at 0.06 K hPa^(-1),reaching 2.87 K and 2.92 K at 10 h Pa.Similarly,RMSE values trend at 0.05?K h Pa^(-1),reaching 3.62?K and 3.69?K at 10 h Pa.The low correlation(R≥0.65)of TSHS near 250 h Pa in summer is significantly improved in VASS(R≥0.78)after adding HIRAS-I.The high vertical resolution due to infrared hyperspectral resolution facilitates the detection of complex temperature junctions.The retrieval error of AIRS in the boundary layer increases with cloudiness,while VASS combines microwave and infrared channel data to reduce the impact of cloud cover.Assessing the Arctic applicability of these three satellite temperature profile products will facilitate their widespread use in the Arctic region,enhance accurate climate change monitoring,and further reveal the mechanisms of Arctic warming.
基金This work was supported by Sichuan Science and Technology Program(2021YFS0284,2018SZDZX0026,2021YFS0289)the Opening Project of Key Laboratory of Theoretical Chemistry of Environment(South China Normal University),Ministry of Education(20200103)+1 种基金the Fundamental Research Funds for the Central Universities of Southwest Jiaotong University(210824)the Opening Project of Key Laboratory of Southwest Jiaotong University(ZD2021210001).
文摘Hydrogen production through solar energy is one of the most important pathways to meet the growing demand of renewable energy,and photocatalyst participation in solar hydrolytic hydrogen production has received great attention in recent years in terms of low cost,high efficiency,and flexible design.Particularly,g-C_(3)N_(4)(Graphitic-like carbon nitride material),as a unique material,can catalyze the hydrogen production process by completing the separation and transmission of charge.The easily adjustable pore structure/surface area,dimension,band-gap modulation and defect have shown great potential for hydrogen production from water cracking.In this review,the most recent advance of g-C_(3)N_(4) including the doping of metal and non-metal elements,and the formation of semiconductor heterojunction is highlighted.The main modification strategies and approaches for the design of g-C_(3)N_(4) for hydrogen production,as well as the influence of various materials on hydrogen evolution regarding the photocatalysis mechanism and advantages brought by theoretical calculations are specially and briefly illu-strated.Potential design pathways and strategies of g-C_(3)N_(4) are discussed.In addition,current challenges of hydrogen production from g-C_(3)N_(4) water splitting are summarized and can be expected.
基金financial support from various entities,including the Foundation of Anhui Science and Technology University[HCYJ202201]the Anhui Science and Technology University’s Student Innovation and Entrepreneurship Training Program[S202310879115,202310879053]+4 种基金the Key Project of Natural Science Research in Anhui Science and Technology University[2021ZRZD07]the Chuzhou Science and Technology Project[2021GJ002]the Anhui Province Key Research and Development Program[202304a05020085]the Natural Science Research Project of Anhui Educational Committee[2023AH051877]The Opening Project of State Key Laboratory of Advanced Technology for Float Glass[2020KF06,2022KF06]。
文摘Perovskite solar cells(PSCs)have emerged as a promising photovoltaic technology because of their high light absorption coefficient,long carrier diffusion distance,and tunable bandgap.However,PSCs face challenges such as hysteresis effects and stability issues.In this study,we introduced a novel approach to improve film crystallization by leveraging 4-tert-butylpyridine(TBP)molecules,thereby enhancing the performance and stability of PSCs.Our findings demonstrate the effective removal of PbI_(2)from the perovskite surface through strong coordination with TBP molecules.Additionally,by carefully adjusting the concentration of the TBP solution,we achieved enhanced film crystallinity without disrupting the perovskite structure.The TBP-treated perovskite films exhibit a low defect density,improved crystallinity,and improved carrier lifetime.As a result,the PSCs manufactured with TBP treatment achieve power conversion efficiency(PCE)exceeding 24%.Moreover,we obtained the PCE of 21.39%for the 12.25 cm^(2)module.
文摘Natural organic matters(NOM)affect water environmental security and have posed a potential threat to human health,and thus they have long been considered as a key index to evaluate water treatment performance.Dissolved organic nitrogen is one of the NOM,which produces some disinfection byproducts having more toxic than those carbon-based materials.Coagulation is a key unit of drinking water purification and has received wide attention.However,conventional flocculation technology on removal of DON is so poor that we have to seek more effective technologies[1,2].Compared with activated carbon,biological aerated filter and sand filtration,the coagulation efficiency of removing DON is relatively low[3].
基金funded by the 2021 Nantong Science and Technology Plan Project“Research on the digital design of popularization of scientiflc knowledge”(Grant No.JCZ21074)。
文摘AI-driven interior design generation offers promising applications.However,current AI-based diffusion models struggle to generate indoor layouts in pixel-level alignment with the indoor structure.This study proposes a new stable diffusion-based interior design workflow with an Interior Design Control Network(IDCN).IDCN ensures that the batchgenerated creative interior designs based on an input image of an unfurnished room match the indoor structure.Generating innovative designs and rendering images directly with the proposed method eliminates the tedious creative design and drawing work in traditional design practices.The results indicate that the proposed method with the new design approach achieves nearly real-time design generation and modiflcation and signiflcantly enhances design creativity and efflciency.Moreover,the proposed method can be generalized to other design generation tasks,thereby promoting the transformation toward intelligent design.
基金jointly supported by the National Natural Science Foundation of China (91437218, 91637312)the Strategic Priority Research Program of Chinese Academy of Sciences (XDA20100300)the Third Tibetan Plateau Atmospheric Scientific Experiment (GYHY201406001)
文摘Because the Tibetan Plateau (TP)has the highest elevation in the world and is a key area affecting the Asian extreme weather and climate events,studies on the Tibetan Plateau meteorology have been highly concerned by the international scientific community.In the late 1970s.Ye and Gao [1]reveled the climatic characteristics of the TP heating and its connection with global and regional atmospheric circulations.With the seasonal evolution from winter to summer,strong surface sensible heat regulates the timing of the establishment of the Asian summer monsoon [2].However,Boos and Kuang [3]addressed that the large-scale South Asian summer monsoon is unaffected by removal of the plateau,provided that the narrow orography of the Himalayas and adjacent mountain ranges is preserved,and revealed the domi- nance of the uplift of the Himalayas in the formation of the present South Asian summer monsoon.Then,does this indicate a weak effect of the summer TP thermal forcing on the variability of the present South Asian monsoon and larger-scale climates?Some dis- cussions have been also stimulated in Science [4].
基金Supported by the China Meteorological Administration Special Public Welfare Research Fund for The Third Tibetan Plateau Atmospheric Science Experiment(TIPEX-Ⅲ)—Boundary Layer and Tropospheric Observations(GYHY201406001)
文摘The Tibetan Plateau(TP) is a key area affecting forecasts of weather and climate in China and occurrences of extreme weather and climate events over the world. The China Meteorological Administration, the National Natural Science Foundation of China, and the Chinese Academy of Sciences jointly initiated the Third Tibetan Plateau Atmospheric Science Experiment(TIPEX-Ⅲ) in 2013, with an 8–10-yr implementation plan. Since its preliminary field measurements conducted in 2013, routine automatic sounding systems have been deployed at Shiquanhe, Gaize, and Shenzha stations in western TP, where no routine sounding observations were available previously. The observational networks for soil temperature and soil moisture in the central and western TP have also been established. Meanwhile, the plateau-scale and regional-scale boundary layer observations, cloud–precipitation microphysical observations with multiple radars and aircraft campaigns, and tropospheric–stratospheric air composition observations at multiple sites, were performed. The results so far show that the turbulent heat exchange coefficient and sensible heat flux are remarkably lower than the earlier estimations at grassland, meadow, and bare soil surfaces of the central and western TP. Climatologically, cumulus clouds over the main body of the TP might develop locally instead of originating from the cumulus clouds that propagate northward from South Asia. The TIPEX-Ⅲ observations up to now also reveal diurnal variations, macro-and microphysical characteristics, and water-phase transition mechanisms, of cumulus clouds at Naqu station. Moreover, TIPEX-Ⅲ related studies have proposed a maintenance mechanism responsible for the Asian "atmospheric water tower" and demonstrated the effects of the TP heating anomalies on African, Asian, and North American climates. Additionally, numerical modeling studies show that the Γ distribution of raindrop size is more suitable for depicting the TP raindrop characteristics compared to the M–P distribution, the overestimation of sensible heat flux can be reduced via modifying the heat transfer parameterization over the TP, and considering climatic signals in some key areas of the TP can improve the skill for rainfall forecast in the central and eastern parts of China. Furthermore, the TIPEX-Ⅲ has been promoting the technology in processing surface observations, soundings, and radar observations, improving the quality of satellite retrieved soil moisture and atmospheric water vapor content products as well as high-resolution gauge–radar–satellite merged rainfall products, and facilitating the meteorological monitoring, forecasting, and data sharing operations.
基金Supported by the Strategic Priority Research Program of Chinese Academy of Sciences(XDA20100300)National Key Research and Development Program of China(2019YFC1509101 and 2021YFC2802504)+2 种基金Basic Research Fund of Chinese Academy of Meteorological Sciences(2021Z007)National Natural Science Foundation of China(41375091 and 41205056)Jiangsu Collaborative Innovation Center for Climate Change。
文摘In summer,the Yangtze River valley(YRV)in central–eastern China frequently suffers consecutive extreme rainfall(CER)events,causing floods and huge damages.On the daily timescale,our previous study has shown that the Pacific–Japan(PJ)teleconnection is related to the CER events over the YRV,and is a source for long-term(lead time of about 10 days)forecasts of CER events.To facilitate extended-range(lead time of about 20 days)prediction of CER,in the present study,we use the band-pass filter for the PJ teleconnection to keep only the prolonged atmospheric circulation information at the intraseasonal timescale and try to identify more advanced precursors for the CER events over the YRV.Power spectrum analysis was implemented on 9-day sliding mean of the precipitation anomalies.It is found that summer precipitation in YRV has significant 10–40-day oscillations,and the CER events over the YRV are affected by the intraseasonal oscillation(ISO)of the PJ teleconnection.When the ISO of the PJ teleconnection enters its positive phase,it is favorable for CER events to occur.Dynamic diagnoses and model experiments demonstrate that the ISO of the PJ teleconnection is attributed to the intraseasonal convective activities and diabatic heating around the Philippines,which generate significant northward energy dispersion and propagation of Rossby waves up to 16 days prior to occurrences of the CER events in the YRV.The ISO of the PJ teleconnection and the convective activities in the tropical South Asia provide significant and earlier precursors for extended-range forecasts of the CER events along the YRV.
基金supported by S & T Development Program (Grant No. CAMS 2018KJ026)
文摘This paper establishes the kinetic equations in atmospheric chemistry that describe the macroscopic mechanisms of secondary fine particle pollution generated by precursors during atmospheric self-purification.The dynamic and static solutions of these equations can be applied to calculate quantitative relationships between the concentration ratio of precursors and secondary fine particles as well as the physical clearance power of the atmosphere,chemical reaction rate,and the scale of a contaminated area.The dynamic solution presented here therefore corresponds with a theoretical formula for calculating the overall rate constant for the oxidation reaction of reducing pollutants in the actual atmosphere based on their local concentrations and meteorological monitoring data.In addition,the static solution presented in this paper reveals the functional relationship between the concentration of secondary fine particles and precursor emission rate as well as atmospheric self-purification capacity.This result can be applied to determine the atmospheric environmental capacity of a precursor.Hourly records collected over the last 40 years from 378 weather stations in China's Mainland as well as the spatiotemporal distribution sequence of overall oxidation reaction rates from precursors show that when the reference concentration limit of secondary fine particles is100μmol m-3,the atmospheric environmental capacity of total precursors canbe calculated as 24890×1010 mol yr-1.Thus,when the annual average concentration limit of given fine particles is 35μg m-3 and the ratio of sulfate and nitrate to 30%and 20%of the total amount of fine particles,the capacities of SO2,NOx and NH3 are 1255,1344,and 832(1010g yr-1),respectively.The clearance density of precursors for different return periods across China's Mainland under above conditions are also provided in this study.
