This study investigates the activity of tropical cyclones(TCs)in the Bay of Bengal(BOB)from 1979 to 2018 to discover the mechanism affecting the contribution rate to the meridional moisture budget anomaly(MMBA)over th...This study investigates the activity of tropical cyclones(TCs)in the Bay of Bengal(BOB)from 1979 to 2018 to discover the mechanism affecting the contribution rate to the meridional moisture budget anomaly(MMBA)over the southern boundary of the Tibetan Plateau(SBTP).May and October–December are the bimodal phases of BOB TC frequency,which decreases month by month from October to December and is relatively low in May.However,the contribution rate to the MMBA is the highest in May.The seasonal variation in the meridional position of the westerlies is the key factor affecting the contribution rate.The relatively southern(northern)position of the westerlies in November and December(May)results in a lower(higher)contribution rate to the MMBA.This mechanism is confirmed by the momentum equation.When water vapor enters the westerlies near the trough line,the resultant meridional acceleration is directed north.It follows that the farther north the trough is,and the farther north the water vapor can be transported.When water vapor enters the westerlies from the area near the ridge line,for Type-T(Type-R)TCs,water vapor enters the westerlies downstream of the trough(ridge).Consequently,the direction of the resultant meridional acceleration is directed south and the resultant zonal acceleration is directed east(west),which is not conducive to the northward transport of water vapor.This is especially the case if the trough or ridge is relatively south,as the water vapor may not cross the SBTP.展开更多
In the past decade,there has been tremendous progress in integrating chalcogenide phase-change materials(PCMs)on the silicon photonic platform for non-volatile memory to neuromorphic in-memory computing applications.I...In the past decade,there has been tremendous progress in integrating chalcogenide phase-change materials(PCMs)on the silicon photonic platform for non-volatile memory to neuromorphic in-memory computing applications.In particular,these non von Neumann computational elements and systems benefit from mass manufacturing of silicon photonic integrated circuits(PICs)on 8-inch wafers using a 130 nm complementary metal-oxide semiconductor line.Chip manufacturing based on deep-ultraviolet lithography and electron-beam lithography enables rapid prototyping of PICs,which can be integrated with high-quality PCMs based on the wafer-scale sputtering technique as a back-end-of-line process.In this article,we present an overview of recent advances in waveguide integrated PCM memory cells,functional devices,and neuromorphic systems,with an emphasis on fabrication and integration processes to attain state-of-the-art device performance.After a short overview of PCM based photonic devices,we discuss the materials properties of the functional layer as well as the progress on the light guiding layer,namely,the silicon and germanium waveguide platforms.Next,we discuss the cleanroom fabrication flow of waveguide devices integrated with thin films and nanowires,silicon waveguides and plasmonic microheaters for the electrothermal switching of PCMs and mixed-mode operation.Finally,the fabrication of photonic and photonic–electronic neuromorphic computing systems is reviewed.These systems consist of arrays of PCM memory elements for associative learning,matrix-vector multiplication,and pattern recognition.With large-scale integration,the neuromorphic photonic computing paradigm holds the promise to outperform digital electronic accelerators by taking the advantages of ultra-high bandwidth,high speed,and energy-efficient operation in running machine learning algorithms.展开更多
Under global warming,understanding the long-term variation in different types of heatwaves is vital for China’s preparedness against escalating heat stress.This study investigates dry and wet heatwave shifts in easte...Under global warming,understanding the long-term variation in different types of heatwaves is vital for China’s preparedness against escalating heat stress.This study investigates dry and wet heatwave shifts in eastern China over recent decades.Spatial trend analysis displays pronounced warming in inland midlatitudes and the Yangtze River Valley,with increased humidity in coastal regions.EOF results indicate intensifying dry heatwaves in northern China,while the Yangtze River Valley sees more frequent dry heatwaves.On the other hand,Indochina and regions north of 25°N also experience intensified wet heatwaves,corresponding to regional humidity increases.Composite analysis is conducted based on different situations:strong,frequent dry or wet heatwaves.Strong dry heatwaves are influenced by anticyclonic circulations over northern China,accompanied by warming SST anomalies around the coastal midlatitudes of the western North Pacific(WNP).Frequent dry heatwaves are related to strong subsidence along with a strengthened subtropical high over the WNP.Strong and frequent wet heatwaves show an intensified Okhotsk high at higher latitudes in the lower troposphere,and a negative circumglobal teleconnection wave train pattern in the upper troposphere.Decaying El Niño SST patterns are observed in two kinds of wet heatwave and frequent dry heatwave years.Risk analysis indicates that El Niño events heighten the likelihood of these heatwaves in regions most at risk.As global warming continues,adapting and implementing mitigation strategies toward extreme heatwaves becomes crucial,especially for the aforementioned regions under significant heat stress.展开更多
Centrifugal pumps are widely used in the metallurgy,coal,and building sectors.In order to study the hydraulic characteristics of a closed impeller centrifugal pump during its shutdown in the so-called power frequency ...Centrifugal pumps are widely used in the metallurgy,coal,and building sectors.In order to study the hydraulic characteristics of a closed impeller centrifugal pump during its shutdown in the so-called power frequency and frequency conversion modes,experiments were carried to determine the characteristic evolution of parameters such as speed,inlet and outlet pressure,head,flow rate and shaft power.A quasi-steady-state method was also used to further investigate these transient behaviors.The results show that,compared to the power frequency input,the performance parameter curves for the frequency conversion input are less volatile and smoother.The characteristic time is longer and the response to shutdown is slower.The quasi-steady-state theoretical head-flow curves match the experimental head-flow curves more closely at low flow rates when the frequency conversion input is considered.Moreover,in this case,the similarity law predicts the hydraulic performance more accurately.展开更多
Knowledge graph technology has distinct advantages in terms of fault diagnosis.In this study,the control rod drive mechanism(CRDM)of the liquid fuel thorium molten salt reactor(TMSR-LF1)was taken as the research objec...Knowledge graph technology has distinct advantages in terms of fault diagnosis.In this study,the control rod drive mechanism(CRDM)of the liquid fuel thorium molten salt reactor(TMSR-LF1)was taken as the research object,and a fault diagnosis system was proposed based on knowledge graph.The subject–relation–object triples are defined based on CRDM unstructured data,including design specification,operation and maintenance manual,alarm list,and other forms of expert experience.In this study,we constructed a fault event ontology model to label the entity and relationship involved in the corpus of CRDM fault events.A three-layer robustly optimized bidirectional encoder representation from transformers(RBT3)pre-training approach combined with a text convolutional neural network(TextCNN)was introduced to facilitate the application of the constructed CRDM fault diagnosis graph database for fault query.The RBT3-TextCNN model along with the Jieba tool is proposed for extracting entities and recognizing the fault query intent simultaneously.Experiments on the dataset collected from TMSR-LF1 CRDM fault diagnosis unstructured data demonstrate that this model has the potential to improve the effect of intent recognition and entity extraction.Additionally,a fault alarm monitoring module was developed based on WebSocket protocol to deliver detailed information about the appeared fault to the operator automatically.Furthermore,the Bayesian inference method combined with the variable elimination algorithm was proposed to enable the development of a relatively intelligent and reliable fault diagnosis system.Finally,a CRDM fault diagnosis Web interface integrated with graph data visualization was constructed,making the CRDM fault diagnosis process intuitive and effective.展开更多
We successfully demonstrate 32-Gbaud Probabilistically Shaped 4096-ary Quadrature Amplitude Modulation(PS-4096QAM)TeraHertz(THz)signal wired transmission at 325 GHz over the 1-m Hollow-Core Fiber(HCF)in a photon-assis...We successfully demonstrate 32-Gbaud Probabilistically Shaped 4096-ary Quadrature Amplitude Modulation(PS-4096QAM)TeraHertz(THz)signal wired transmission at 325 GHz over the 1-m Hollow-Core Fiber(HCF)in a photon-assisted THz-wave communication system.By employing advanced Digital Signal Processing(DSP)and the PS technique,the 352-Gbit/s line rate(288-Gbit/s net rate)delivery with a net Spectral Efficiency(SE)of 9 bit/s/Hz is realized in the experiment,satisfying the 0.86-Normalized Generalized Mutual Information(NGMI)Low-Density Parity-Check(LDPC)threshold.展开更多
BACKGROUND Restoration of immune homeostasis by targeting the balance between memory T helper(mTh)cells and memory follicular T helper(mTfh)cells is a potential therapeutic strategy against ulcerative colitis(UC).Beca...BACKGROUND Restoration of immune homeostasis by targeting the balance between memory T helper(mTh)cells and memory follicular T helper(mTfh)cells is a potential therapeutic strategy against ulcerative colitis(UC).Because of its anti-inflammatory and immunomodulatory properties,curcumin(Cur)is a promising drug for UC treatment.However,fewer studies have demonstrated whether Cur can modulate the mTh/mTfh subset balance in mice with colitis.AIM To explore the potential mechanism underlying Cur-mediated alleviation of colitis induced by dextran sulfate sodium(DSS)in mice by regulating the mTh and mTfh immune homeostasis.METHODS Balb/c mice were administered 3%and 2%DSS to establish the UC model and treated with Cur(200 mg/kg/d)by gavage on days 11-17.On the 18th d,all mice were anesthetized and euthanized,and the colonic length,colonic weight,and colonic weight index were evaluated.Histomorphological changes in the mouse colon were observed through hematoxylin-eosin staining.Levels of Th/mTh and Tfh/mTfh cell subsets in the spleen were detected through flow cytometry.Western blotting was performed to detect SOCS-1,SOCS-3,STAT3,p-STAT3,JAK1,p-JAK1,and NF-κB p65 protein expression levels in colon tissues.RESULTS Cur effectively mitigates DSS-induced colitis,facilitates the restoration of mouse weight and colonic length,and diminishes the colonic weight and colonic weight index.Simultaneously,it hinders ulcer development and inflammatory cell infiltration in the colonic mucous membrane.While the percentage of Th1,mTh1,Th7,mTh7,Th17,mTh17,Tfh1,mTfh1,Tfh7,mTfh7,Tfh17,and mTfh17 cells decreased after Cur treatment of the mice for 7 d,and the frequency of mTh10,Th10,mTfh10,and Tfh10 cells in the mouse spleen increased.Further studies revealed that Cur administration prominently decreased the SOCS-1,SOCS-3,STAT3,p-STAT3,JAK1,p-JAK1,and NF-κB p65 protein expression levels in the colon tissue.CONCLUSION Cur regulated the mTh/mTfh cell homeostasis to reduce DSS-induced colonic pathological damage,potentially by suppressing the JAK1/STAT3/SOCS signaling pathway.展开更多
Here,we analyze the characteristics and the formation mechanisms of low-level jets(LLJs)in the middle reaches of the Yangtze River during the 2010 mei-yu season using Wuhan station radiosonde data and the fifth genera...Here,we analyze the characteristics and the formation mechanisms of low-level jets(LLJs)in the middle reaches of the Yangtze River during the 2010 mei-yu season using Wuhan station radiosonde data and the fifth generation of the European Centre for Medium-Range Weather Forecasts(ERA5)reanalysis dataset.Our results show that the vertical structure of LLJs is characterized by a predominance of boundary layer jets(BLJs)concentrated at heights of 900-1200 m.The BLJs occur most frequently at 2300 LST(LST=UTC+8 hours)but are strongest at 0200 LST,with composite wind velocities>14 m s^(-1).Synoptic-system-related LLJs(SLLJs)occur most frequently at 0800 LST but are strongest at 1100LST,with composite wind velocities>12 m s^(-1).Both BLJs and SLLJs are characterized by a southwesterly wind direction,although the wind direction of SLLJs is more westerly,and northeasterly SLLJs occur more frequently than northeasterly BLJs.When Wuhan is south of the mei-yu front,the westward extension of the northwest Pacific subtropical high intensifies,and the low-pressure system in the eastern Tibetan Plateau strengthens,favoring the formation of LLJs,which are closely related to precipitation.The wind speeds on rainstorm days are greater than those on LLJ days.Our analysis of four typical heavy precipitation events shows the presence of LLJs at the center of the precipitation and on its southern side before the onset of heavy precipitation.BLJs were shown to develop earlier than SLLJs.展开更多
During boreal winter,the invasion of cold air can lead to remarkable temperature drops in East Asia which can result in serious socioeconomic impacts.Here,we find that the intensity of strong synoptic cold days in the...During boreal winter,the invasion of cold air can lead to remarkable temperature drops in East Asia which can result in serious socioeconomic impacts.Here,we find that the intensity of strong synoptic cold days in the East China Sea and Indochina Peninsula are increasing.The enhanced synoptic cold days in these two regions are attributed to surface warming over the South China Sea and Philippine Sea(SCSPS).The oceanic forcing of the SCSPS on the synoptic cold days in the two regions is verified by numerical simulation.The warming of the SCSPS enhances the baroclinicity,which intensifies meridional wind and cold advection on synoptic timescales.This leads to a more extended region that is subject to the influence of cold invasion.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.42288101)the Second Tibetan Plateau Scientific Expedition and Research(STEP)program(2019QZKK010201-02)+4 种基金GuangDong Basic and Applied Basic Research Foundation(2022A1515010945)the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDA20060503)National Natural Science Foundation of China(Grant Nos.92158204,42176026,42005035,41906181)Lei YANG is also supported by Science and Technology Program of Guangdong Province(2022B1212050003)Special fund of South China Sea Institute of Oceanology of the Chinese Academy of Sciences(SCSIO2023QY01).
文摘This study investigates the activity of tropical cyclones(TCs)in the Bay of Bengal(BOB)from 1979 to 2018 to discover the mechanism affecting the contribution rate to the meridional moisture budget anomaly(MMBA)over the southern boundary of the Tibetan Plateau(SBTP).May and October–December are the bimodal phases of BOB TC frequency,which decreases month by month from October to December and is relatively low in May.However,the contribution rate to the MMBA is the highest in May.The seasonal variation in the meridional position of the westerlies is the key factor affecting the contribution rate.The relatively southern(northern)position of the westerlies in November and December(May)results in a lower(higher)contribution rate to the MMBA.This mechanism is confirmed by the momentum equation.When water vapor enters the westerlies near the trough line,the resultant meridional acceleration is directed north.It follows that the farther north the trough is,and the farther north the water vapor can be transported.When water vapor enters the westerlies from the area near the ridge line,for Type-T(Type-R)TCs,water vapor enters the westerlies downstream of the trough(ridge).Consequently,the direction of the resultant meridional acceleration is directed south and the resultant zonal acceleration is directed east(west),which is not conducive to the northward transport of water vapor.This is especially the case if the trough or ridge is relatively south,as the water vapor may not cross the SBTP.
基金the support of the National Natural Science Foundation of China(Grant No.62204201)。
文摘In the past decade,there has been tremendous progress in integrating chalcogenide phase-change materials(PCMs)on the silicon photonic platform for non-volatile memory to neuromorphic in-memory computing applications.In particular,these non von Neumann computational elements and systems benefit from mass manufacturing of silicon photonic integrated circuits(PICs)on 8-inch wafers using a 130 nm complementary metal-oxide semiconductor line.Chip manufacturing based on deep-ultraviolet lithography and electron-beam lithography enables rapid prototyping of PICs,which can be integrated with high-quality PCMs based on the wafer-scale sputtering technique as a back-end-of-line process.In this article,we present an overview of recent advances in waveguide integrated PCM memory cells,functional devices,and neuromorphic systems,with an emphasis on fabrication and integration processes to attain state-of-the-art device performance.After a short overview of PCM based photonic devices,we discuss the materials properties of the functional layer as well as the progress on the light guiding layer,namely,the silicon and germanium waveguide platforms.Next,we discuss the cleanroom fabrication flow of waveguide devices integrated with thin films and nanowires,silicon waveguides and plasmonic microheaters for the electrothermal switching of PCMs and mixed-mode operation.Finally,the fabrication of photonic and photonic–electronic neuromorphic computing systems is reviewed.These systems consist of arrays of PCM memory elements for associative learning,matrix-vector multiplication,and pattern recognition.With large-scale integration,the neuromorphic photonic computing paradigm holds the promise to outperform digital electronic accelerators by taking the advantages of ultra-high bandwidth,high speed,and energy-efficient operation in running machine learning algorithms.
基金supported by the National Natural Science Foundation of China(Grant Nos.42120104001,42192563 and 42005010)the Hong Kong RGC General Research Fund 11300920.
文摘Under global warming,understanding the long-term variation in different types of heatwaves is vital for China’s preparedness against escalating heat stress.This study investigates dry and wet heatwave shifts in eastern China over recent decades.Spatial trend analysis displays pronounced warming in inland midlatitudes and the Yangtze River Valley,with increased humidity in coastal regions.EOF results indicate intensifying dry heatwaves in northern China,while the Yangtze River Valley sees more frequent dry heatwaves.On the other hand,Indochina and regions north of 25°N also experience intensified wet heatwaves,corresponding to regional humidity increases.Composite analysis is conducted based on different situations:strong,frequent dry or wet heatwaves.Strong dry heatwaves are influenced by anticyclonic circulations over northern China,accompanied by warming SST anomalies around the coastal midlatitudes of the western North Pacific(WNP).Frequent dry heatwaves are related to strong subsidence along with a strengthened subtropical high over the WNP.Strong and frequent wet heatwaves show an intensified Okhotsk high at higher latitudes in the lower troposphere,and a negative circumglobal teleconnection wave train pattern in the upper troposphere.Decaying El Niño SST patterns are observed in two kinds of wet heatwave and frequent dry heatwave years.Risk analysis indicates that El Niño events heighten the likelihood of these heatwaves in regions most at risk.As global warming continues,adapting and implementing mitigation strategies toward extreme heatwaves becomes crucial,especially for the aforementioned regions under significant heat stress.
基金supported by the“Pioneer”and“Leading Goose”R&D Program of Zhejiang(Grant No.2022C03170)Science and Technology Project of Quzhou(Grant No.2022K98)Hunan Province Key Field R&D Plan Project(Grant No.2022GK2068).
文摘Centrifugal pumps are widely used in the metallurgy,coal,and building sectors.In order to study the hydraulic characteristics of a closed impeller centrifugal pump during its shutdown in the so-called power frequency and frequency conversion modes,experiments were carried to determine the characteristic evolution of parameters such as speed,inlet and outlet pressure,head,flow rate and shaft power.A quasi-steady-state method was also used to further investigate these transient behaviors.The results show that,compared to the power frequency input,the performance parameter curves for the frequency conversion input are less volatile and smoother.The characteristic time is longer and the response to shutdown is slower.The quasi-steady-state theoretical head-flow curves match the experimental head-flow curves more closely at low flow rates when the frequency conversion input is considered.Moreover,in this case,the similarity law predicts the hydraulic performance more accurately.
基金supported by the National Key R&D Program of China[grant number 2022YFC3002801]a key project of the National Natural Science Foundation of China[grant numbers 42120104001 and 42192563]+1 种基金a project of the Center for Ocean Research in Hong Kong and Macao(CORE)the National Natural Science Foundation of China for Youth[grant number 42205191].
基金the Young Potential Program of Shanghai Institute of Applied Physics,Chinese Academy of Sciences(No.E0553101).
文摘Knowledge graph technology has distinct advantages in terms of fault diagnosis.In this study,the control rod drive mechanism(CRDM)of the liquid fuel thorium molten salt reactor(TMSR-LF1)was taken as the research object,and a fault diagnosis system was proposed based on knowledge graph.The subject–relation–object triples are defined based on CRDM unstructured data,including design specification,operation and maintenance manual,alarm list,and other forms of expert experience.In this study,we constructed a fault event ontology model to label the entity and relationship involved in the corpus of CRDM fault events.A three-layer robustly optimized bidirectional encoder representation from transformers(RBT3)pre-training approach combined with a text convolutional neural network(TextCNN)was introduced to facilitate the application of the constructed CRDM fault diagnosis graph database for fault query.The RBT3-TextCNN model along with the Jieba tool is proposed for extracting entities and recognizing the fault query intent simultaneously.Experiments on the dataset collected from TMSR-LF1 CRDM fault diagnosis unstructured data demonstrate that this model has the potential to improve the effect of intent recognition and entity extraction.Additionally,a fault alarm monitoring module was developed based on WebSocket protocol to deliver detailed information about the appeared fault to the operator automatically.Furthermore,the Bayesian inference method combined with the variable elimination algorithm was proposed to enable the development of a relatively intelligent and reliable fault diagnosis system.Finally,a CRDM fault diagnosis Web interface integrated with graph data visualization was constructed,making the CRDM fault diagnosis process intuitive and effective.
基金supported by National Key R&D Program of China(2018YFB1800900)National Natural Science Foundation of China(61935005,91938202,61720106015,61835002,61805043,62127802).
文摘We successfully demonstrate 32-Gbaud Probabilistically Shaped 4096-ary Quadrature Amplitude Modulation(PS-4096QAM)TeraHertz(THz)signal wired transmission at 325 GHz over the 1-m Hollow-Core Fiber(HCF)in a photon-assisted THz-wave communication system.By employing advanced Digital Signal Processing(DSP)and the PS technique,the 352-Gbit/s line rate(288-Gbit/s net rate)delivery with a net Spectral Efficiency(SE)of 9 bit/s/Hz is realized in the experiment,satisfying the 0.86-Normalized Generalized Mutual Information(NGMI)Low-Density Parity-Check(LDPC)threshold.
基金Supported by the National Natural Science Foundation of China,No.81760808 and No.82260863Scientific and Technological Project of Education Department of Jiangxi Province,No.GJJ181582+1 种基金Jiangxi University of Chinese Medicine Science and Technology Innovation Team Development Program,No.CXTD22008Key Laboratory of Pharmacodynamics and Quality Evaluation on anti-Inflammatory Chinese Herbs,Jiangxi Administration of Traditional Chinese Medicine,No.202208.
文摘BACKGROUND Restoration of immune homeostasis by targeting the balance between memory T helper(mTh)cells and memory follicular T helper(mTfh)cells is a potential therapeutic strategy against ulcerative colitis(UC).Because of its anti-inflammatory and immunomodulatory properties,curcumin(Cur)is a promising drug for UC treatment.However,fewer studies have demonstrated whether Cur can modulate the mTh/mTfh subset balance in mice with colitis.AIM To explore the potential mechanism underlying Cur-mediated alleviation of colitis induced by dextran sulfate sodium(DSS)in mice by regulating the mTh and mTfh immune homeostasis.METHODS Balb/c mice were administered 3%and 2%DSS to establish the UC model and treated with Cur(200 mg/kg/d)by gavage on days 11-17.On the 18th d,all mice were anesthetized and euthanized,and the colonic length,colonic weight,and colonic weight index were evaluated.Histomorphological changes in the mouse colon were observed through hematoxylin-eosin staining.Levels of Th/mTh and Tfh/mTfh cell subsets in the spleen were detected through flow cytometry.Western blotting was performed to detect SOCS-1,SOCS-3,STAT3,p-STAT3,JAK1,p-JAK1,and NF-κB p65 protein expression levels in colon tissues.RESULTS Cur effectively mitigates DSS-induced colitis,facilitates the restoration of mouse weight and colonic length,and diminishes the colonic weight and colonic weight index.Simultaneously,it hinders ulcer development and inflammatory cell infiltration in the colonic mucous membrane.While the percentage of Th1,mTh1,Th7,mTh7,Th17,mTh17,Tfh1,mTfh1,Tfh7,mTfh7,Tfh17,and mTfh17 cells decreased after Cur treatment of the mice for 7 d,and the frequency of mTh10,Th10,mTfh10,and Tfh10 cells in the mouse spleen increased.Further studies revealed that Cur administration prominently decreased the SOCS-1,SOCS-3,STAT3,p-STAT3,JAK1,p-JAK1,and NF-κB p65 protein expression levels in the colon tissue.CONCLUSION Cur regulated the mTh/mTfh cell homeostasis to reduce DSS-induced colonic pathological damage,potentially by suppressing the JAK1/STAT3/SOCS signaling pathway.
基金supported by the National Natural Science Foundation of China(Grant Nos.42230612,41620104009,41705019,42075186,and 41975058)the Projects of the S&T Development Foundation of the Hubei Meteorological Bureau(Grants No.2021Q04 and 2020Y04)。
文摘Here,we analyze the characteristics and the formation mechanisms of low-level jets(LLJs)in the middle reaches of the Yangtze River during the 2010 mei-yu season using Wuhan station radiosonde data and the fifth generation of the European Centre for Medium-Range Weather Forecasts(ERA5)reanalysis dataset.Our results show that the vertical structure of LLJs is characterized by a predominance of boundary layer jets(BLJs)concentrated at heights of 900-1200 m.The BLJs occur most frequently at 2300 LST(LST=UTC+8 hours)but are strongest at 0200 LST,with composite wind velocities>14 m s^(-1).Synoptic-system-related LLJs(SLLJs)occur most frequently at 0800 LST but are strongest at 1100LST,with composite wind velocities>12 m s^(-1).Both BLJs and SLLJs are characterized by a southwesterly wind direction,although the wind direction of SLLJs is more westerly,and northeasterly SLLJs occur more frequently than northeasterly BLJs.When Wuhan is south of the mei-yu front,the westward extension of the northwest Pacific subtropical high intensifies,and the low-pressure system in the eastern Tibetan Plateau strengthens,favoring the formation of LLJs,which are closely related to precipitation.The wind speeds on rainstorm days are greater than those on LLJ days.Our analysis of four typical heavy precipitation events shows the presence of LLJs at the center of the precipitation and on its southern side before the onset of heavy precipitation.BLJs were shown to develop earlier than SLLJs.
基金supported by the Key Project of the National Natural Science Foundation of China[grant number 42192563]the International Cooperation and Exchange Program of the National Natural Science Foundation of China[grant number 42120104001].
基金jointly supported by the National Natural Science Foundation of China (Grant Nos. 42120104001, 41805042)the Science and Technology Program of Guangzhou, China (Grant No. 202102020939)+1 种基金the Fundamental Research Funds for the Central University, Sun Yat-Sen University (Grant No. 22qntd2202)a project of the Center for Ocean Research in Hong Kong and Macao (CORE)
文摘During boreal winter,the invasion of cold air can lead to remarkable temperature drops in East Asia which can result in serious socioeconomic impacts.Here,we find that the intensity of strong synoptic cold days in the East China Sea and Indochina Peninsula are increasing.The enhanced synoptic cold days in these two regions are attributed to surface warming over the South China Sea and Philippine Sea(SCSPS).The oceanic forcing of the SCSPS on the synoptic cold days in the two regions is verified by numerical simulation.The warming of the SCSPS enhances the baroclinicity,which intensifies meridional wind and cold advection on synoptic timescales.This leads to a more extended region that is subject to the influence of cold invasion.
基金Yuanhong Guan is supported by the National Natural Science Foundation of China[grant numbers 41975087,U2242212,41975085]Wen Zhou is supported by the International Cooperation and Exchange Programme of the National Natural Science Foundation of China[grant number 42120104001]the Hong Kong RGC General Fund[grant number 11300920]。
