A modified three-dimensional turbulence parameterization scheme,implemented by replacing the conventional eddydiffusivity formulation with the H-gradient model,has shown good performance in representing the subgrid-sc...A modified three-dimensional turbulence parameterization scheme,implemented by replacing the conventional eddydiffusivity formulation with the H-gradient model,has shown good performance in representing the subgrid-scale(SGS)turbulent fluxes associated with convective clouds in idealized tropical cyclone(TC)simulations.To evaluate the capability of the modified scheme in simulating real TCs,two sets of simulations of TC Soudelor(2015),one with the modified scheme and the other with the original scheme,are conducted.Comparisons with observations and coarse-grained results from large eddy simulation benchmarks demonstrate that the modified scheme improves the forecasting of the intensity and structure,as well as the SGS turbulent fluxes of Soudelor.Using the modified turbulence scheme,a TC with stronger intensity,smaller size,a shallower but stronger inflow layer,and a more intense but less inclined convective updraft is simulated.The rapid intensification process and secondary eyewall features can also be captured better by the modified scheme.By analyzing the mechanism by which turbulent transport impacts the intensity and structure of TCs,it is shown that accurately representing the turbulent transport associated with convective clouds above the planetary boundary layer helps to initiate the TC spin-up process.展开更多
In this study,numerical experiments with different initial radius of maximum wind(RMW)are performed to study the effects of tropical cyclone(TC)size combined with land-sea contrast on TC motion and low-level wind stru...In this study,numerical experiments with different initial radius of maximum wind(RMW)are performed to study the effects of tropical cyclone(TC)size combined with land-sea contrast on TC motion and low-level wind structure before landfall.By idealized numerical simulations,we found that larger TC arrived coastline earlier than smaller TC,when they started moving from the same position.This is because that the larger TCs not only accelerate earlier but also have greater movement speed than smaller TCs when they approach the coastline.The mechanism responsible for this is that the edge of large TCs reach coastline earlier,thus their movement speed accelerated earlier than small TCs,due to the asymmetries in diabatic heating and radial flow generated by the land-sea contrast.Moreover,when TCs in three experiments all affected by the land-sea contrast,the stronger asymmetries generated in larger TC,thus resulting in faster movement in larger TC.The stronger inflow in western quadrant and weaker inflow(even outflow)in eastern quadrant of larger TC deduced apparently difference in vertical motion and diabatic heating between western and eastern quadrant of TC before landfall.An analysis of potential vorticity tendency proved that the diabatic heating terms were important and considered in determining the TC landward drift because asymmetries in vertical motion and relative vorticity developed due to asymmetric flow.展开更多
Tropical cyclones(TCs)are one of the most serious types of natural disasters,and accurate TC activity predictions are key to disaster prevention and mitigation.Recently,TC track predictions have made significant progr...Tropical cyclones(TCs)are one of the most serious types of natural disasters,and accurate TC activity predictions are key to disaster prevention and mitigation.Recently,TC track predictions have made significant progress,but the ability to predict their intensity is obviously lagging behind.At present,research on TC intensity prediction takes atmospheric reanalysis data as the research object and mines the relationship between TC-related environmental factors and intensity through deep learning.However,reanalysis data are non-real-time in nature,which does not meet the requirements for operational forecasting applications.Therefore,a TC intensity prediction model named TC-Rolling is proposed,which can simultaneously extract the degree of symmetry for strong TC convective cloud and convection intensity,and fuse the deviation-angle variance with satellite images to construct the correlation between TC convection structure and intensity.For TCs'complex dynamic processes,a convolutional neural network(CNN)is used to learn their temporal and spatial features.For real-time intensity estimation,multi-task learning acts as an implicit time-series enhancement.The model is designed with a rolling strategy that aims to moderate the long-term dependent decay problem and improve accuracy for short-term intensity predictions.Since multiple tasks are correlated,the loss function of 12 h and 24 h are corrected.After testing on a sample of TCs in the Northwest Pacific,with a 4.48 kt root-mean-square error(RMSE)of 6 h intensity prediction,5.78 kt for 12 h,and 13.94 kt for 24 h,TC records from official agencies are used to assess the validity of TC-Rolling.展开更多
This paper investigates the impact of the model top and damping layer on the numerical simulation of tropical cyclones(TCs)and reveals the significant role of stratospheric gravity waves(SGWs).TCs can generate SGWs,wh...This paper investigates the impact of the model top and damping layer on the numerical simulation of tropical cyclones(TCs)and reveals the significant role of stratospheric gravity waves(SGWs).TCs can generate SGWs,which propagate upward and outward into the stratosphere.These SGWs can reach the damping layer,which is a consequence of the numerical scheme employed,where they can affect the tangential circulation through the dragging and forcing processes.In models with a higher top boundary,this tangential circulation develops far from the TC and has minimal direct impact on TC intensity.By comparison,in models with a lower top(e.g.,20 km),the damping layer is located just above the top of the TC.The SGW dragging in the damping layer and the consequent tangential force can thus induce ascent outside the eyewall,promote latent heat release,tilt the eyewall,and enlarge the inner-core radius.This process will reduce inner-core vorticity advection within the boundary layer,and eventually inhibits the intensification of the TC.This suggests that when the thickness of the damping layer is 5 km,the TC numerical model top height should be at least higher than 20 km to generate more accurate simulations.展开更多
Forecasting tropical cyclone(TC)activities has been a topic of great interest and research.Taiwan Island(TW)is one of the key regions that is highly exposed to TCs originated from the western North Pacific.Here,the au...Forecasting tropical cyclone(TC)activities has been a topic of great interest and research.Taiwan Island(TW)is one of the key regions that is highly exposed to TCs originated from the western North Pacific.Here,the authors utilize two mainstream reanalysis datasets for the period 1979-2013 and propose an effective statistical seasonal forecasting model-namely,the Sun Yat-sen University(SYSU)Model-for predicting the number of TC landfalls on TW based on the environmental factors in the preseason.The comprehensive predictor sampling and multiple linear regression show that the 850-hPa meridional wind over the west of the Antarctic Peninsula in January,the 300-hPa specific humidity over the open ocean southwest of Australia in January,the 300-hPa relative vorticity over the west of the Sea of Okhotsk in March,and the sea surface temperature in the South Indian Ocean in April,are the most significant predictors.The correlation coefficient between the modeled results and observations reaches 0.87.The model is validated by the leave-one-out and nine-fold cross-validation methods,and recent 9-yr observations(2014-2022).The Antarctic Oscillation,variabilities of the western Pacific subtropical high,Asian summer monsoon,and oceanic tunnel are the possible physical linkages or mechanisms behind the model result.The SYSU Model exhibits a 98%hit rate in 1979-2022(43 out of 44),suggesting an operational potential in the seasonal forecasting of TC landfalls on TW.展开更多
This study employs the self-organizing map method to investigate the upper-tropospheric outflow patterns of tropical cyclones(TCs)over the western North Pacific from 1979 to 2019,using the 200 hPa horizontal wind fiel...This study employs the self-organizing map method to investigate the upper-tropospheric outflow patterns of tropical cyclones(TCs)over the western North Pacific from 1979 to 2019,using the 200 hPa horizontal wind fields from the ERA5 reanalysis datasets.According to the number and orientation of TC outflow channels,as well as the wind speed,the outflow patterns are classified into five categories:southwestward single-channel pattern S1(26.1%);northwestward single-channel pattern S2(23.6%);northeastward single-channel pattern S3(23.6%);double-channel outflow pattern D(20.8%);and high latitude outflow pattern H(6.0%).Composite analysis shows that the orientations of the TC outflow channels are aligned with the direction of the environmental vertical wind shear and closely related to the distribution of the environmental inertial instability,upper-level divergence,and inner-core convective activities.TC intensity and intensity changes for different outflow patterns are also significantly different.Patterns S1 and S2 usually appear in the development phase and are thus prone to TC intensification,while patterns S3 and H usually occur in the weakening phase and are thus prone to TC weakening.The double-channel pattern(D)has the largest mean intensity and accounts for more than 60%of super-typhoon samples.展开更多
Traditional pyrometallurgical and hydrometallurgical methods to extract bismuth from sulfide ores face problems such as high cost,low-concentration SO_(2)generation,and long process time.In this study,the cyclone tech...Traditional pyrometallurgical and hydrometallurgical methods to extract bismuth from sulfide ores face problems such as high cost,low-concentration SO_(2)generation,and long process time.In this study,the cyclone technology and slurry electrolysis method were combined.The bismuth sulfide ore was dissolved directly at the anode,while the high purity bismuth was deposited efficiently at the cathode under the advantages of the two methods.The short process and high-efficiency extraction of bismuth sulfide ore were realized,and the pollution of low-concentration SO_(2)was avoided.Then,the effects of several crucial experimental conditions(current density,reaction time,temperature,pH,liquid-solid ratio,and circulation flow rate)on the leaching efficiency and recovery efficiency of bismuth were investigated.The leaching and electrowinning mechanisms during the recovery process were also analyzed according to the research results of this paper to better understand the cyclone slurry electrolysis process.The experimental results showed that 95.19%bismuth was leached into the acid solution in the anode area under optimal conditions,and the recovery efficiency and purity of bismuth on the cathode reached 91.13%and 99.26%,respectively,which were better than those by the traditional hydrometallurgy recovery process.展开更多
Spaceborne microwave instruments possess the capability of day-and-night and all-weather measurements that can penetrate clouds and fog,and directly measure tropical cyclone(TC)ocean surface winds.In this study,we est...Spaceborne microwave instruments possess the capability of day-and-night and all-weather measurements that can penetrate clouds and fog,and directly measure tropical cyclone(TC)ocean surface winds.In this study,we establish an effective methodology to estimate TC dynamic characteristic parameters(DCP),including the storm center location,intensity,radius of maximum wind(RMW)and wind structure,purely from TC ocean winds measured by multi-platform spaceborne microwave instruments.Combining measurements from active and passive sensors can provide long time series data for monitoring changes in storm DCP.Here,the evolution of the DCP for TC Freddy(2023),from its genesis to its landfall,is evaluated using data from synthetic aperture radars(SARs),as well as radiometer(RAD)and scatterometer(SCA)observations.Comparing the results to the best-track datasets for the longitudes and latitudes of the storm centers,we show that the root-mean-square errors(RMSEs)are 0.22°and 0.31°,respectively,both with a correlation of 0.99.For the detected intensity,the RMSEs are 6.8 m s^(−1) for SARs and 7.3 m s^(−1) for RADs.However,TC intensities measured by C-band SCAs are significantly underestimated,especially for wind speeds less than 50 m s^(−1).In terms of RMW and wind radii,the SARs,RADs and SCAs demonstrate good accuracy and applicability.Our investigation emphasizes the crucial role played by spaceborne microwave instruments in the study of TCs.This is helpful in monitoring,and in the future,will help improve the forecasting of TC intensities and their characteristic structures.展开更多
The disasters caused by tropical cyclones(TCs),including gale-force winds,heavy rainfall,and storm surges,have profound social and economic impacts,which are closely associated with the track,intensity,and structure o...The disasters caused by tropical cyclones(TCs),including gale-force winds,heavy rainfall,and storm surges,have profound social and economic impacts,which are closely associated with the track,intensity,and structure of TCs.Over the past few decades,significant progress has been made in developing theories and understanding the mechanisms of TC genesis and development,as well as advancing the monitoring and forecasting of TCs.展开更多
Tropical cyclone-induced heavy precipitation(TCP)can have a detrimental impact on human productivity,causing significant economic losses and even human casualties in coastal countries every year.In this review article...Tropical cyclone-induced heavy precipitation(TCP)can have a detrimental impact on human productivity,causing significant economic losses and even human casualties in coastal countries every year.In this review article,the authors highlight the latest research developments in terms of ocean-atmosphere interactions and TCP,and identify the gaps where further research is required to enhance our understanding.The paper revolves around the following topics:(1)the characteristics of TCP over the ocean;(2)how air-sea interface processes,including sea surface temperature,sea-salt aerosols,and sea spray,influence TCP development;(3)the effects of TCP on the ocean;and(4)TCP changes in the context of global warming.In addition,directions and suggestions for future research toward a more comprehensive understanding of TCP-ocean interactions are discussed.Overall,this review summarizes the recent research progress and challenges in TCP-ocean interactions,and could serve as a guide for improvements in convective parameterization schemes and climate models toward predicting TCP distribution and intensity more accurately.展开更多
The dynamic processes responsible for the movement of tropical cyclone Khanun(2017)were studied by analyzing data from the mesoscale WRF model simulation.The simulated motion was induced by the ventilation flow of bot...The dynamic processes responsible for the movement of tropical cyclone Khanun(2017)were studied by analyzing data from the mesoscale WRF model simulation.The simulated motion was induced by the ventilation flow of both the environmentaland asymmetric rotational wind averaged over an area within a radius of 200 km from Khanun's center.The results revealed that during Khanun's intensification period,environmental wind barely changed,whereas the speed and direction of asymmetric rotational wind exhibited significant changes as Khanun's southwestward movement switched to a northwestward movement.The streamfunction analysis revealed that the change in the direction of movement was consistent with the ventilation flow of asymmetric rotational wind across Khanun's center associated with the asymmetric circulation rotation.The cyclonic circulation center rotated counterclockwise,moving from the northeast to the north before and during the rapid intensification period,and exhibited wandering behavior during this period.The rotational rate of asymmetric circulation was quantitatively estimated using the formulation based on the budget of asymmetric rotational kinetic energy.This calculation revealed that the rapid counterclockwise rotation resulted from the conversion of environmental to asymmetric rotational kinetic energy and was related to the horizontal advection of environmental tangential flow.The rotation of the asymmetric circulation displayed a wandering behavior when the dissipation term became significant.The dissipation term plus the conversion from symmetric to asymmetric rotational kinetic energy associated with the advection of symmetric tangential wind by the environmental radial wind led to a slow clockwise rotation of the asymmetric cyclonic center to the north.展开更多
Tropical cyclone activity has undergone significant changes under the impact of global warming since the 20th century.However,the characteristic and trend changes of landfalling tropical cyclones over China still need...Tropical cyclone activity has undergone significant changes under the impact of global warming since the 20th century.However,the characteristic and trend changes of landfalling tropical cyclones over China still need to be further clarified.The study conducted an analysis of the spatiotemporal characteristics and trends of landfalling tropical cyclones over China from 1949 to 2022 using the dataset of the best tracks of tropical cyclones from the China Meteorological Administration.Additionally,we explored the influences of ENSO and the Pacific Decadal Oscillation(PDO)on landfalling tropical cyclone activities.The results indicate that:(1)The annual average number of landfalling tropical cyclones over China is approximately 8.85,showing a significant decreasing trend,and the decreasing range becomes larger with lower latitude overall.However,both the proportion of landfalling tropical cyclones to the total number and the percentage of higher intensity tropical cyclones increase.(2)The landfall locations of tropical cyclones in China are mainly concentrated between 18°N and 26°N,accounting for approximately 88.2%of the total,and the landfall frequency shows a sharp decline in the regions north of 30°N.The central landfall location of tropical cyclones has shifted significantly northwestward,moving closer to China.Compared to 1949–1969,the central genesis location from 2010 to 2022 shifted 4.5°westward and 2.0°northward.(3)There is a correlation between ENSO and the genesis frequency variation of tropical cyclones in the Northwest Pacific and landfalling over China.El Ni?o promotes the genesis of strong tropical cyclones and leads to a more southeastern bias in the genesis location of landfalling tropical cyclones,while La Ni?a has an opposite effect.The PDO also affects the tropical cyclones to a certain extent.During the PDO warm phase,the genesis position of tropical cyclones is westward and the number is smaller than that in the cold phase.This study further clarifies the changing trends and characteristics of landfalling tropical cyclones over China since 1949.It also highlights the impacts of ENSO and the PDO on tropical cyclone activities.The findings can serve as a scientific basis for conducting simulations and assessments of tropical cyclones and for disaster prevention and mitigation efforts.展开更多
In this study, a variety of high-resolution satellite data were used to analyze the similarities and differences in horizontal and vertical cloud microphysical characteristics of 11 tropical cyclones(TCs) in three dif...In this study, a variety of high-resolution satellite data were used to analyze the similarities and differences in horizontal and vertical cloud microphysical characteristics of 11 tropical cyclones(TCs) in three different ocean basins.The results show that for the 11 TCs in different ocean basins, no matter in what season the TCs were generated when they reached or approached Category 4, their melting layers were all distributed in the vertical direction at the height of about 5 km. The high value of ice water contents in the vertical direction of 11 TCs all reach or approach about 2000 g cm^(–3).The total attenuated scattering coefficient at 532 nm, TAB-532, can successfully characterize the distribution of areas with high ice water content when the vertical distribution was concentrated near 0.1 km^(–1)sr^(–1), possibly because the diameter distribution of the corresponding range of aerosol particles had a more favorable effect on the formation of ice nuclei,indicating that aerosols had a significant impact on the ice-phase processes and characteristics. Moreover, by analyzing the horizontal cloud water content, the distribution analysis of cloud water path(CWP) and ice water path(IWP) shows that when the sea surface temperature was at a relatively high value, and the vertical wind shear was relatively small, the CWP and the IWP can reach a relatively high value, which also proves the importance of environmental field factors on the influence of TC cloud microphysical characteristics.展开更多
In recent years,torrential rain events caused by extratropical cyclones(ETCs)during the boreal midsummer(July-August)in Central and Eastern China have shown an increasing trend.For instence,in August 2024,two ETCs bro...In recent years,torrential rain events caused by extratropical cyclones(ETCs)during the boreal midsummer(July-August)in Central and Eastern China have shown an increasing trend.For instence,in August 2024,two ETCs brought large-scale heavy rainfall to North China,with daily precipitation exceeding 100 mm.Using reanalysis datasets and gridded precipitation data,the ETCs that affected Central and Eastern China during the boreal midsummer from 1981 to 2020 were objectively identified and tracked.ETCs causing precipitation were classified based on maximum daily precipitation,resulting in datasets for ETCs with torrential rain(daily precipitation exceeding 100 mm,referred to as ETC_R100)and heavy rain(daily precipitation exceeding 25 mm,referred to as ETC_R25).Comparative analysis can help highlight the characteristics of ETC_R100.This study compares the spatial distribution,movement paths,weather impacts,large-scale atmospheric circulation,and environmental conditions of these two types of precipitation-related ETCs.The following findings emerged:(1)ETC_R100 is driven by the combined forcing of upper-level troughs and warm-moist airflows at lower levels,exhibiting stronger thermal forcing than ETC_R25.(2)The moisture source for ETC_R100 are the Bay of Bengal and the Northwest Pacific,with moisture transported via the South China Sea.Compared to ETCs with nonextreme rainfall,ETC_R100 is characterized by greater atmospheric instability and better moisture conditions,resulting in higher precipitation intensity.(3)Regardless of the precipitation level,ETCs affected different regions but contributed significantly to precipitation in northern China,accounting for approximately 50%of the total precipitation.The results indicate that ETC_R100 differs significantly from ETCs with varying levels of precipitation in terms of statistical characteristics,weather impact,environmental conditions,and cyclogenesis conditions.展开更多
Tropical cyclone(TC)intensity estimation is a fundamental aspect of TC monitoring and forecasting.Deep learning models have recently been employed to estimate TC intensity from satellite images and yield precise resul...Tropical cyclone(TC)intensity estimation is a fundamental aspect of TC monitoring and forecasting.Deep learning models have recently been employed to estimate TC intensity from satellite images and yield precise results.This work proposes the ViT-TC model based on the Vision Transformer(ViT)architecture.Satellite images of TCs,including infrared(IR),water vapor(WV),and passive microwave(PMW),are used as inputs for intensity estimation.Experiments indicate that combining IR,WV,and PMW as inputs yields more accurate estimations than other channel combinations.The ensemble mean technique is applied to enhance the model's estimations,reducing the root-mean-square error to 9.32 kt(knots,1 kt≈0.51 m s^(-1))and the mean absolute error to 6.49 kt,which outperforms traditional methods and is comparable to existing deep learning models.The model assigns high attention weights to areas with high PMW,indicating that PMW magnitude is essential information for the model's estimation.The model also allocates significance to the cloud-cover region,suggesting that the model utilizes the whole TC cloud structure and TC eye to determine TC intensity.展开更多
EC-Earth3P-HR reproduces well the observed Boreal Summer Intraseasonal Oscillation(BSISO)and its impacts on tropical cyclone genesis(TCG)in the western North Pacific(WNP).Hence,the historical simulation(1950-1979)and ...EC-Earth3P-HR reproduces well the observed Boreal Summer Intraseasonal Oscillation(BSISO)and its impacts on tropical cyclone genesis(TCG)in the western North Pacific(WNP).Hence,the historical simulation(1950-1979)and future projection under the SSP5-8.5 scenario(2020-2049)in EC-Earth3P-HR are adopted to explore possible changes in the BSISO’s modification of WNP TCG under global warming to enhance the understanding of TC activities in the WNP.Results show that the BSISO circulation in the WNP shifts northeastward under global warming.This leads to enhanced convection in a northwest-southeast-oriented band crossing the WNP.Along the band,the BSISO-related TCG anomalies are enhanced.Analyses of genesis potential index show that changes in the BSISO-related mid-tropospheric relative humidity play the dominant role in modifying the BSISO’s impacts on WNP TCG under global warming.The enhanced BSISO convection in the band moistens the middle troposphere,which helps reduce the entrainment of generally dry mid-tropospheric air in the updrafts and the modification of the boundary layer by the downdraft of generally dry mid-tropospheric air,leading to enhanced TCG.展开更多
The rapid intensification(RI)magnitude of tropical cyclones(TCs)over the western North Pacific(WNP)exhibits significant interannual variability and is influenced by multiple factors across various scales.These factors...The rapid intensification(RI)magnitude of tropical cyclones(TCs)over the western North Pacific(WNP)exhibits significant interannual variability and is influenced by multiple factors across various scales.These factors primarily include:interannual factors—sea surface temperature(SST)in key regions of the WNP,eastern Indian Ocean SST,El Niño-Southern Oscillation(ENSO),South Pacific Subtropical Dipole(SPSD),and western Pacific teleconnection;decadal factors—Atlantic Multidecadal Oscillation(AMO)and Pacific Decadal Oscillation(PDO);and longer-term factor—global warming.This study systematically analyzes these factors and their potential impacts,quantitatively assessing their relative importance.A statistical prediction model for the WNP TC-RI magnitude is developed based on ridge regression methods.The results indicate that the influence of these factors on the RI magnitude is closely related to the large-scale thermodynamic and dynamic conditions.Among them,the SPSD plays the most critical role in the interannual variability of the RI magnitude,followed by global warming and the AMO.Further analysis reveals that the statistical prediction model based on multiple factors demonstrates good predictive skill for the interannual variability of the TC RI magnitude.展开更多
In the novel fully dry converter gas recovery process,a novel circumfluent cyclone separator with an evaporation heating surface can simultaneously realize the dust removal and sensible heat recovery of converter gas....In the novel fully dry converter gas recovery process,a novel circumfluent cyclone separator with an evaporation heating surface can simultaneously realize the dust removal and sensible heat recovery of converter gas.For this equipment,the distributions of internal flow and wall heat transfer affect the efficiency of dust removal and sensible heat recovery.In this study,based on on-site operation tests,the distributions of internal flow and wall heat transfer in the circumfluent cyclone separator are studied by numerical simulation.The results indicate that the flow rate proportions in different regions of the circumfluent cyclone separator remain constant during the steelmaking process,approximately 80.1%of the converter gas flows through the cone chamber,and 15.4%of the converter gas flows through the annular chamber.The heat transfer rate proportions on the walls of different regions of the circumfluent cyclone separator remain constant during the steelmaking process,and the heat transfer rate proportions on the walls of the cone chamber,straight shell,shell head and outlet pipe are 40.2%,27.0%,17.6%and 15.2%,respectively.展开更多
Against the backdrop of climate change,the activity of tropical cyclones(TCs)has captured widespread attention.Observational datasets indicate a declining trend in the genesis longitude of western North Pacific(WNP)TC...Against the backdrop of climate change,the activity of tropical cyclones(TCs)has captured widespread attention.Observational datasets indicate a declining trend in the genesis longitude of western North Pacific(WNP)TCs.This study investigates the zonal changes of WNP TCs with CMIP6-HighResMIP models.These models capture the genesis density of WNP TCs fairly well.The results reveal a westward shift in TC genesis longitude.This trend is associated with the significant reduction in the TC frequency over the southeastern WNP.The study also discusses changes in large-scale circulation patterns and the impact of the strengthening Pacific Walker circulation.展开更多
基金supported by the National Key Research and Development Program of China(Grant No.2021YFC3000803)the National Natural Science Foundation of China(Grant Nos.42375149,41975133 and 42205070)the Shanghai Pujiang Program(Grant No.22PJ1415900)。
文摘A modified three-dimensional turbulence parameterization scheme,implemented by replacing the conventional eddydiffusivity formulation with the H-gradient model,has shown good performance in representing the subgrid-scale(SGS)turbulent fluxes associated with convective clouds in idealized tropical cyclone(TC)simulations.To evaluate the capability of the modified scheme in simulating real TCs,two sets of simulations of TC Soudelor(2015),one with the modified scheme and the other with the original scheme,are conducted.Comparisons with observations and coarse-grained results from large eddy simulation benchmarks demonstrate that the modified scheme improves the forecasting of the intensity and structure,as well as the SGS turbulent fluxes of Soudelor.Using the modified turbulence scheme,a TC with stronger intensity,smaller size,a shallower but stronger inflow layer,and a more intense but less inclined convective updraft is simulated.The rapid intensification process and secondary eyewall features can also be captured better by the modified scheme.By analyzing the mechanism by which turbulent transport impacts the intensity and structure of TCs,it is shown that accurately representing the turbulent transport associated with convective clouds above the planetary boundary layer helps to initiate the TC spin-up process.
基金The National Natural Science Foundation of China under contract Nos 42175011,42192554,and 42305007.
文摘In this study,numerical experiments with different initial radius of maximum wind(RMW)are performed to study the effects of tropical cyclone(TC)size combined with land-sea contrast on TC motion and low-level wind structure before landfall.By idealized numerical simulations,we found that larger TC arrived coastline earlier than smaller TC,when they started moving from the same position.This is because that the larger TCs not only accelerate earlier but also have greater movement speed than smaller TCs when they approach the coastline.The mechanism responsible for this is that the edge of large TCs reach coastline earlier,thus their movement speed accelerated earlier than small TCs,due to the asymmetries in diabatic heating and radial flow generated by the land-sea contrast.Moreover,when TCs in three experiments all affected by the land-sea contrast,the stronger asymmetries generated in larger TC,thus resulting in faster movement in larger TC.The stronger inflow in western quadrant and weaker inflow(even outflow)in eastern quadrant of larger TC deduced apparently difference in vertical motion and diabatic heating between western and eastern quadrant of TC before landfall.An analysis of potential vorticity tendency proved that the diabatic heating terms were important and considered in determining the TC landward drift because asymmetries in vertical motion and relative vorticity developed due to asymmetric flow.
基金jointly supported by the National Natural Science Foundation of China(Grant Nos.42075138 and 42375147)the Program on Key Basic Research Project of Jiangsu(Grant No.BE2023829)。
文摘Tropical cyclones(TCs)are one of the most serious types of natural disasters,and accurate TC activity predictions are key to disaster prevention and mitigation.Recently,TC track predictions have made significant progress,but the ability to predict their intensity is obviously lagging behind.At present,research on TC intensity prediction takes atmospheric reanalysis data as the research object and mines the relationship between TC-related environmental factors and intensity through deep learning.However,reanalysis data are non-real-time in nature,which does not meet the requirements for operational forecasting applications.Therefore,a TC intensity prediction model named TC-Rolling is proposed,which can simultaneously extract the degree of symmetry for strong TC convective cloud and convection intensity,and fuse the deviation-angle variance with satellite images to construct the correlation between TC convection structure and intensity.For TCs'complex dynamic processes,a convolutional neural network(CNN)is used to learn their temporal and spatial features.For real-time intensity estimation,multi-task learning acts as an implicit time-series enhancement.The model is designed with a rolling strategy that aims to moderate the long-term dependent decay problem and improve accuracy for short-term intensity predictions.Since multiple tasks are correlated,the loss function of 12 h and 24 h are corrected.After testing on a sample of TCs in the Northwest Pacific,with a 4.48 kt root-mean-square error(RMSE)of 6 h intensity prediction,5.78 kt for 12 h,and 13.94 kt for 24 h,TC records from official agencies are used to assess the validity of TC-Rolling.
基金supported by the National Natural Science Foundation of China(Grant Nos.42475016,42192555 and 42305085)the China Postdoctoral Science Foundation(Grant No.2023M741615)the 2023 Graduate Research Innovation Project of Hunan Province(Grant No.CX20230011)。
文摘This paper investigates the impact of the model top and damping layer on the numerical simulation of tropical cyclones(TCs)and reveals the significant role of stratospheric gravity waves(SGWs).TCs can generate SGWs,which propagate upward and outward into the stratosphere.These SGWs can reach the damping layer,which is a consequence of the numerical scheme employed,where they can affect the tangential circulation through the dragging and forcing processes.In models with a higher top boundary,this tangential circulation develops far from the TC and has minimal direct impact on TC intensity.By comparison,in models with a lower top(e.g.,20 km),the damping layer is located just above the top of the TC.The SGW dragging in the damping layer and the consequent tangential force can thus induce ascent outside the eyewall,promote latent heat release,tilt the eyewall,and enlarge the inner-core radius.This process will reduce inner-core vorticity advection within the boundary layer,and eventually inhibits the intensification of the TC.This suggests that when the thickness of the damping layer is 5 km,the TC numerical model top height should be at least higher than 20 km to generate more accurate simulations.
基金jointly supported by the Innovation Group Project of the Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)[grant number 316323005]the Guangdong Basic and Applied Basic Research Foundation[grant numbers 2023A1515010741 and 2024B1515020035]the Science and Technology Planning Project of Guangdong Province[grant number 2023B1212060019]。
文摘Forecasting tropical cyclone(TC)activities has been a topic of great interest and research.Taiwan Island(TW)is one of the key regions that is highly exposed to TCs originated from the western North Pacific.Here,the authors utilize two mainstream reanalysis datasets for the period 1979-2013 and propose an effective statistical seasonal forecasting model-namely,the Sun Yat-sen University(SYSU)Model-for predicting the number of TC landfalls on TW based on the environmental factors in the preseason.The comprehensive predictor sampling and multiple linear regression show that the 850-hPa meridional wind over the west of the Antarctic Peninsula in January,the 300-hPa specific humidity over the open ocean southwest of Australia in January,the 300-hPa relative vorticity over the west of the Sea of Okhotsk in March,and the sea surface temperature in the South Indian Ocean in April,are the most significant predictors.The correlation coefficient between the modeled results and observations reaches 0.87.The model is validated by the leave-one-out and nine-fold cross-validation methods,and recent 9-yr observations(2014-2022).The Antarctic Oscillation,variabilities of the western Pacific subtropical high,Asian summer monsoon,and oceanic tunnel are the possible physical linkages or mechanisms behind the model result.The SYSU Model exhibits a 98%hit rate in 1979-2022(43 out of 44),suggesting an operational potential in the seasonal forecasting of TC landfalls on TW.
基金supported by the National Natural Science Foundation of China[grant numbers 42192553 and 61827091]。
文摘This study employs the self-organizing map method to investigate the upper-tropospheric outflow patterns of tropical cyclones(TCs)over the western North Pacific from 1979 to 2019,using the 200 hPa horizontal wind fields from the ERA5 reanalysis datasets.According to the number and orientation of TC outflow channels,as well as the wind speed,the outflow patterns are classified into five categories:southwestward single-channel pattern S1(26.1%);northwestward single-channel pattern S2(23.6%);northeastward single-channel pattern S3(23.6%);double-channel outflow pattern D(20.8%);and high latitude outflow pattern H(6.0%).Composite analysis shows that the orientations of the TC outflow channels are aligned with the direction of the environmental vertical wind shear and closely related to the distribution of the environmental inertial instability,upper-level divergence,and inner-core convective activities.TC intensity and intensity changes for different outflow patterns are also significantly different.Patterns S1 and S2 usually appear in the development phase and are thus prone to TC intensification,while patterns S3 and H usually occur in the weakening phase and are thus prone to TC weakening.The double-channel pattern(D)has the largest mean intensity and accounts for more than 60%of super-typhoon samples.
基金Projects(52104355,52074363,52374364)supported by the National Natural Science Foundation of ChinaProject(2023YFC2907904)supported by the National Key R&D Program of China。
文摘Traditional pyrometallurgical and hydrometallurgical methods to extract bismuth from sulfide ores face problems such as high cost,low-concentration SO_(2)generation,and long process time.In this study,the cyclone technology and slurry electrolysis method were combined.The bismuth sulfide ore was dissolved directly at the anode,while the high purity bismuth was deposited efficiently at the cathode under the advantages of the two methods.The short process and high-efficiency extraction of bismuth sulfide ore were realized,and the pollution of low-concentration SO_(2)was avoided.Then,the effects of several crucial experimental conditions(current density,reaction time,temperature,pH,liquid-solid ratio,and circulation flow rate)on the leaching efficiency and recovery efficiency of bismuth were investigated.The leaching and electrowinning mechanisms during the recovery process were also analyzed according to the research results of this paper to better understand the cyclone slurry electrolysis process.The experimental results showed that 95.19%bismuth was leached into the acid solution in the anode area under optimal conditions,and the recovery efficiency and purity of bismuth on the cathode reached 91.13%and 99.26%,respectively,which were better than those by the traditional hydrometallurgy recovery process.
基金supported by the Zhejiang Provincial Natural Science Foundation of China (Grant Nos. LZJMZ25D050008 and LQ21D060001)the National Natural Science Foundation of China (Grant No. 42305153)+4 种基金the East China Meteorological Science and Technology Collaborative Innovation Foundation Cooperation Project (Grant No. QYHZ202307)the Zhejiang Meteorological Science and Technology Plan Project (Grant Nos. 2021YB07, 2022ZD06 and 2023YB06)the Youth Innovation Team Fund of the China Meteorological Administration (Grant No.CMA2023QN12)support of the Canadian program “Transforming Climate Action” led by Dalhousie University in Canadathe Canadian Space Agency (CSA) projects “Ocean surface features related to aggregation of North Atlantic Right Whales (NARWs)” and “Fine resolution classification of sea ice from the RADARSAT Constellation Mission (RCM)”
文摘Spaceborne microwave instruments possess the capability of day-and-night and all-weather measurements that can penetrate clouds and fog,and directly measure tropical cyclone(TC)ocean surface winds.In this study,we establish an effective methodology to estimate TC dynamic characteristic parameters(DCP),including the storm center location,intensity,radius of maximum wind(RMW)and wind structure,purely from TC ocean winds measured by multi-platform spaceborne microwave instruments.Combining measurements from active and passive sensors can provide long time series data for monitoring changes in storm DCP.Here,the evolution of the DCP for TC Freddy(2023),from its genesis to its landfall,is evaluated using data from synthetic aperture radars(SARs),as well as radiometer(RAD)and scatterometer(SCA)observations.Comparing the results to the best-track datasets for the longitudes and latitudes of the storm centers,we show that the root-mean-square errors(RMSEs)are 0.22°and 0.31°,respectively,both with a correlation of 0.99.For the detected intensity,the RMSEs are 6.8 m s^(−1) for SARs and 7.3 m s^(−1) for RADs.However,TC intensities measured by C-band SCAs are significantly underestimated,especially for wind speeds less than 50 m s^(−1).In terms of RMW and wind radii,the SARs,RADs and SCAs demonstrate good accuracy and applicability.Our investigation emphasizes the crucial role played by spaceborne microwave instruments in the study of TCs.This is helpful in monitoring,and in the future,will help improve the forecasting of TC intensities and their characteristic structures.
文摘The disasters caused by tropical cyclones(TCs),including gale-force winds,heavy rainfall,and storm surges,have profound social and economic impacts,which are closely associated with the track,intensity,and structure of TCs.Over the past few decades,significant progress has been made in developing theories and understanding the mechanisms of TC genesis and development,as well as advancing the monitoring and forecasting of TCs.
基金supported by the National Natural Science Foundation of China [grant numbers 42192552 and 42475011]。
文摘Tropical cyclone-induced heavy precipitation(TCP)can have a detrimental impact on human productivity,causing significant economic losses and even human casualties in coastal countries every year.In this review article,the authors highlight the latest research developments in terms of ocean-atmosphere interactions and TCP,and identify the gaps where further research is required to enhance our understanding.The paper revolves around the following topics:(1)the characteristics of TCP over the ocean;(2)how air-sea interface processes,including sea surface temperature,sea-salt aerosols,and sea spray,influence TCP development;(3)the effects of TCP on the ocean;and(4)TCP changes in the context of global warming.In addition,directions and suggestions for future research toward a more comprehensive understanding of TCP-ocean interactions are discussed.Overall,this review summarizes the recent research progress and challenges in TCP-ocean interactions,and could serve as a guide for improvements in convective parameterization schemes and climate models toward predicting TCP distribution and intensity more accurately.
基金supported by the National Natural Science Foundation of China(Grant No.41930967)。
文摘The dynamic processes responsible for the movement of tropical cyclone Khanun(2017)were studied by analyzing data from the mesoscale WRF model simulation.The simulated motion was induced by the ventilation flow of both the environmentaland asymmetric rotational wind averaged over an area within a radius of 200 km from Khanun's center.The results revealed that during Khanun's intensification period,environmental wind barely changed,whereas the speed and direction of asymmetric rotational wind exhibited significant changes as Khanun's southwestward movement switched to a northwestward movement.The streamfunction analysis revealed that the change in the direction of movement was consistent with the ventilation flow of asymmetric rotational wind across Khanun's center associated with the asymmetric circulation rotation.The cyclonic circulation center rotated counterclockwise,moving from the northeast to the north before and during the rapid intensification period,and exhibited wandering behavior during this period.The rotational rate of asymmetric circulation was quantitatively estimated using the formulation based on the budget of asymmetric rotational kinetic energy.This calculation revealed that the rapid counterclockwise rotation resulted from the conversion of environmental to asymmetric rotational kinetic energy and was related to the horizontal advection of environmental tangential flow.The rotation of the asymmetric circulation displayed a wandering behavior when the dissipation term became significant.The dissipation term plus the conversion from symmetric to asymmetric rotational kinetic energy associated with the advection of symmetric tangential wind by the environmental radial wind led to a slow clockwise rotation of the asymmetric cyclonic center to the north.
基金Young Taishan Scholars Program of Shandong Province,No.tsqn202103065National Natural Science Foundation of China,No.42371084。
文摘Tropical cyclone activity has undergone significant changes under the impact of global warming since the 20th century.However,the characteristic and trend changes of landfalling tropical cyclones over China still need to be further clarified.The study conducted an analysis of the spatiotemporal characteristics and trends of landfalling tropical cyclones over China from 1949 to 2022 using the dataset of the best tracks of tropical cyclones from the China Meteorological Administration.Additionally,we explored the influences of ENSO and the Pacific Decadal Oscillation(PDO)on landfalling tropical cyclone activities.The results indicate that:(1)The annual average number of landfalling tropical cyclones over China is approximately 8.85,showing a significant decreasing trend,and the decreasing range becomes larger with lower latitude overall.However,both the proportion of landfalling tropical cyclones to the total number and the percentage of higher intensity tropical cyclones increase.(2)The landfall locations of tropical cyclones in China are mainly concentrated between 18°N and 26°N,accounting for approximately 88.2%of the total,and the landfall frequency shows a sharp decline in the regions north of 30°N.The central landfall location of tropical cyclones has shifted significantly northwestward,moving closer to China.Compared to 1949–1969,the central genesis location from 2010 to 2022 shifted 4.5°westward and 2.0°northward.(3)There is a correlation between ENSO and the genesis frequency variation of tropical cyclones in the Northwest Pacific and landfalling over China.El Ni?o promotes the genesis of strong tropical cyclones and leads to a more southeastern bias in the genesis location of landfalling tropical cyclones,while La Ni?a has an opposite effect.The PDO also affects the tropical cyclones to a certain extent.During the PDO warm phase,the genesis position of tropical cyclones is westward and the number is smaller than that in the cold phase.This study further clarifies the changing trends and characteristics of landfalling tropical cyclones over China since 1949.It also highlights the impacts of ENSO and the PDO on tropical cyclone activities.The findings can serve as a scientific basis for conducting simulations and assessments of tropical cyclones and for disaster prevention and mitigation efforts.
基金National Natural Science Foundation of China(42192554, 42175008)Shanghai Typhoon Research Foundation(TFJJ202201)+1 种基金S&T Development Fund of CAMS (2022KJ012)Basic Research Fund of CAMS (2022Y006)。
文摘In this study, a variety of high-resolution satellite data were used to analyze the similarities and differences in horizontal and vertical cloud microphysical characteristics of 11 tropical cyclones(TCs) in three different ocean basins.The results show that for the 11 TCs in different ocean basins, no matter in what season the TCs were generated when they reached or approached Category 4, their melting layers were all distributed in the vertical direction at the height of about 5 km. The high value of ice water contents in the vertical direction of 11 TCs all reach or approach about 2000 g cm^(–3).The total attenuated scattering coefficient at 532 nm, TAB-532, can successfully characterize the distribution of areas with high ice water content when the vertical distribution was concentrated near 0.1 km^(–1)sr^(–1), possibly because the diameter distribution of the corresponding range of aerosol particles had a more favorable effect on the formation of ice nuclei,indicating that aerosols had a significant impact on the ice-phase processes and characteristics. Moreover, by analyzing the horizontal cloud water content, the distribution analysis of cloud water path(CWP) and ice water path(IWP) shows that when the sea surface temperature was at a relatively high value, and the vertical wind shear was relatively small, the CWP and the IWP can reach a relatively high value, which also proves the importance of environmental field factors on the influence of TC cloud microphysical characteristics.
基金National Natural Science Foundation of China(42375014,42088101,42030605)Joint Research Project for Meteorological Capacity Improvement(24NLTSZ010)Young Elite Scientists Sponsorship Program by BAST(BYESS2023205)。
文摘In recent years,torrential rain events caused by extratropical cyclones(ETCs)during the boreal midsummer(July-August)in Central and Eastern China have shown an increasing trend.For instence,in August 2024,two ETCs brought large-scale heavy rainfall to North China,with daily precipitation exceeding 100 mm.Using reanalysis datasets and gridded precipitation data,the ETCs that affected Central and Eastern China during the boreal midsummer from 1981 to 2020 were objectively identified and tracked.ETCs causing precipitation were classified based on maximum daily precipitation,resulting in datasets for ETCs with torrential rain(daily precipitation exceeding 100 mm,referred to as ETC_R100)and heavy rain(daily precipitation exceeding 25 mm,referred to as ETC_R25).Comparative analysis can help highlight the characteristics of ETC_R100.This study compares the spatial distribution,movement paths,weather impacts,large-scale atmospheric circulation,and environmental conditions of these two types of precipitation-related ETCs.The following findings emerged:(1)ETC_R100 is driven by the combined forcing of upper-level troughs and warm-moist airflows at lower levels,exhibiting stronger thermal forcing than ETC_R25.(2)The moisture source for ETC_R100 are the Bay of Bengal and the Northwest Pacific,with moisture transported via the South China Sea.Compared to ETCs with nonextreme rainfall,ETC_R100 is characterized by greater atmospheric instability and better moisture conditions,resulting in higher precipitation intensity.(3)Regardless of the precipitation level,ETCs affected different regions but contributed significantly to precipitation in northern China,accounting for approximately 50%of the total precipitation.The results indicate that ETC_R100 differs significantly from ETCs with varying levels of precipitation in terms of statistical characteristics,weather impact,environmental conditions,and cyclogenesis conditions.
基金Research funding for this project was provided by the National Natural Science Foundation of China(Grant Nos.42192563 and 42120104001)the Hong Kong RGC General Research Fund(Grant No.11300920)+1 种基金Anhui Provincial Natural Science Foundation(Grant Nos.2208085UQ12,2308085US01)Anhui&Huaihe River Institute of Hydraulic Research(Grant Nos.KJGG202201,KY202306)。
文摘Tropical cyclone(TC)intensity estimation is a fundamental aspect of TC monitoring and forecasting.Deep learning models have recently been employed to estimate TC intensity from satellite images and yield precise results.This work proposes the ViT-TC model based on the Vision Transformer(ViT)architecture.Satellite images of TCs,including infrared(IR),water vapor(WV),and passive microwave(PMW),are used as inputs for intensity estimation.Experiments indicate that combining IR,WV,and PMW as inputs yields more accurate estimations than other channel combinations.The ensemble mean technique is applied to enhance the model's estimations,reducing the root-mean-square error to 9.32 kt(knots,1 kt≈0.51 m s^(-1))and the mean absolute error to 6.49 kt,which outperforms traditional methods and is comparable to existing deep learning models.The model assigns high attention weights to areas with high PMW,indicating that PMW magnitude is essential information for the model's estimation.The model also allocates significance to the cloud-cover region,suggesting that the model utilizes the whole TC cloud structure and TC eye to determine TC intensity.
基金financially supported by the National Natural Science Foundation of China[grant number 42088101]。
文摘EC-Earth3P-HR reproduces well the observed Boreal Summer Intraseasonal Oscillation(BSISO)and its impacts on tropical cyclone genesis(TCG)in the western North Pacific(WNP).Hence,the historical simulation(1950-1979)and future projection under the SSP5-8.5 scenario(2020-2049)in EC-Earth3P-HR are adopted to explore possible changes in the BSISO’s modification of WNP TCG under global warming to enhance the understanding of TC activities in the WNP.Results show that the BSISO circulation in the WNP shifts northeastward under global warming.This leads to enhanced convection in a northwest-southeast-oriented band crossing the WNP.Along the band,the BSISO-related TCG anomalies are enhanced.Analyses of genesis potential index show that changes in the BSISO-related mid-tropospheric relative humidity play the dominant role in modifying the BSISO’s impacts on WNP TCG under global warming.The enhanced BSISO convection in the band moistens the middle troposphere,which helps reduce the entrainment of generally dry mid-tropospheric air in the updrafts and the modification of the boundary layer by the downdraft of generally dry mid-tropospheric air,leading to enhanced TCG.
基金Guangdong Major Project of Basic and Applied Basic Research(2020B0301030004)National Natural Science Foundation of China(41875114)Science and Technology Commission of Shanghai Municipality,China(23DZ1204703)。
文摘The rapid intensification(RI)magnitude of tropical cyclones(TCs)over the western North Pacific(WNP)exhibits significant interannual variability and is influenced by multiple factors across various scales.These factors primarily include:interannual factors—sea surface temperature(SST)in key regions of the WNP,eastern Indian Ocean SST,El Niño-Southern Oscillation(ENSO),South Pacific Subtropical Dipole(SPSD),and western Pacific teleconnection;decadal factors—Atlantic Multidecadal Oscillation(AMO)and Pacific Decadal Oscillation(PDO);and longer-term factor—global warming.This study systematically analyzes these factors and their potential impacts,quantitatively assessing their relative importance.A statistical prediction model for the WNP TC-RI magnitude is developed based on ridge regression methods.The results indicate that the influence of these factors on the RI magnitude is closely related to the large-scale thermodynamic and dynamic conditions.Among them,the SPSD plays the most critical role in the interannual variability of the RI magnitude,followed by global warming and the AMO.Further analysis reveals that the statistical prediction model based on multiple factors demonstrates good predictive skill for the interannual variability of the TC RI magnitude.
基金funded by the Strategic Priority Research Program of the Chinese Academy of Sciences,Grant Number XDA29020503.
文摘In the novel fully dry converter gas recovery process,a novel circumfluent cyclone separator with an evaporation heating surface can simultaneously realize the dust removal and sensible heat recovery of converter gas.For this equipment,the distributions of internal flow and wall heat transfer affect the efficiency of dust removal and sensible heat recovery.In this study,based on on-site operation tests,the distributions of internal flow and wall heat transfer in the circumfluent cyclone separator are studied by numerical simulation.The results indicate that the flow rate proportions in different regions of the circumfluent cyclone separator remain constant during the steelmaking process,approximately 80.1%of the converter gas flows through the cone chamber,and 15.4%of the converter gas flows through the annular chamber.The heat transfer rate proportions on the walls of different regions of the circumfluent cyclone separator remain constant during the steelmaking process,and the heat transfer rate proportions on the walls of the cone chamber,straight shell,shell head and outlet pipe are 40.2%,27.0%,17.6%and 15.2%,respectively.
基金supported by a key project of the National Natural Science Foundation of China[grant number 42192563]。
文摘Against the backdrop of climate change,the activity of tropical cyclones(TCs)has captured widespread attention.Observational datasets indicate a declining trend in the genesis longitude of western North Pacific(WNP)TCs.This study investigates the zonal changes of WNP TCs with CMIP6-HighResMIP models.These models capture the genesis density of WNP TCs fairly well.The results reveal a westward shift in TC genesis longitude.This trend is associated with the significant reduction in the TC frequency over the southeastern WNP.The study also discusses changes in large-scale circulation patterns and the impact of the strengthening Pacific Walker circulation.
