This study presents a comprehensive evaluation of tropical cyclone(TC)forecast performance in the western North Pacific from 2013 to 2022,based on operational forecasts issued by the China Meteorological Administratio...This study presents a comprehensive evaluation of tropical cyclone(TC)forecast performance in the western North Pacific from 2013 to 2022,based on operational forecasts issued by the China Meteorological Administration.The analysis reveals systematic improvements in both track and intensity forecasts over the decade,with distinct error characteristics observed across various forecast parameters.Track forecast errors have steadily decreased,particularly for longer lead times,while error magnitudes have increased with longer forecast lead times.Intensity forecasts show similar progressive enhancements,with maximum sustained wind speed errors decreasing by 0.26 m/s per year for 120 h forecasts.The study also identifies several key patterns in forecast performance:typhoon-grade or stronger TCs exhibit smaller track errors than week or weaker systems;intensity forecasts systematically overestimate weaker TCs while underestimating stronger systems;and spatial error distributions show greater track inaccuracies near landmasses and regional intensity biases.These findings highlight both the significant advances in TC forecasting capability achieved through improved modeling and observational systems,and the remaining challenges in predicting TC changes and landfall behavior,providing valuable benchmarks for future forecast system development.展开更多
In this study,tropical cyclone(TC)translation speed was introduced as a new similarity factor within the generalized initial value(GIV)framework,enhancing the disaster preassessment capability of the dynamical statist...In this study,tropical cyclone(TC)translation speed was introduced as a new similarity factor within the generalized initial value(GIV)framework,enhancing the disaster preassessment capability of the dynamical statistical analog ensemble forecast model for landfalling TC disasters(DSAEF_LTD model).Three TC translation speed indicators most relevant to TC precipitation were incorporated:the maximum speed on Day 1(the first day of TC-induced precipitation and wind occurring on land)and the average and minimum speeds over All Days(all days of TC-induced precipitation and wind occurring on land),all classified using the Kmeans clustering algorithm.Simulation experiments showed that integrating TC translation speed enhanced the model's performance.The model provided a better optimal common scheme,with the TSS UM(sum of threat scores for severe and above and extremely severe and above disasters)increasing by 2.66%(from 0.5117 to 0.5253)compared with the original model.More importantly,its preassessment ability improved significantly,with the average TSS UM for independent samples increasing by 6.43%(from 0.6488 to0.6905).The modified model demonstrated greater accuracy in capturing disaster severity and distribution of TCs with significant speed characteristics or with regular tracks.This improvement stemmed from reduced false alarms due to the selection of analogs that are more similar to the target TC.The enhanced preassessment ability can be attributed to the key role of TC translation speed,which significantly influences TC precipitation patterns and improves TC precipitation forecasting.Since precipitation is one of the most crucial disaster-causing factors,better TC precipitation forecasting leads to improved disaster preassessment outcomes.These findings emphasize the promising potential of the DSAEF_LTD model for future TC disaster research and management,contributing to the achievement of the Sustainable Development Goals set by the United Nations 2030 Agenda by strengthening coastal resilience.展开更多
This study investigates the width of the secondary eyewall(SE)immediately following its formation in tropical cyclones with surface environmental winds aligned and counter-aligned with environmental vertical wind shea...This study investigates the width of the secondary eyewall(SE)immediately following its formation in tropical cyclones with surface environmental winds aligned and counter-aligned with environmental vertical wind shear(VWS),using idealized numerical experiments.Results reveal that the SE develops greater radial extent when surface winds align with VWS compared to counter-aligned conditions.In alignment configurations,shear-enhanced surface winds on the right flank amplify surface enthalpy fluxes,thereby elevating boundary-layer entropy within the downshear outer-core region.Subsequently,more vigorous outer rainbands develop,inducing marked acceleration of tangential winds in the outer core preceding SE formation.The resultant radial expansion of supergradient winds near the boundary-layer top triggers widespread convective activity immediately beyond the inner core.Progressive axisymmetrization of this convective forcing ultimately generates an expansive SE structure.展开更多
Explosive cyclones(ECs) are rapidly intensifying subtropical cyclones that can develop within a short time and pose considerable threats to coastal areas in middle and high latitudes.Gaining a comprehensive understand...Explosive cyclones(ECs) are rapidly intensifying subtropical cyclones that can develop within a short time and pose considerable threats to coastal areas in middle and high latitudes.Gaining a comprehensive understanding of their formation,evolution,and mechanisms of explosive development is essential for improving forecasts of extreme weather events and mitigating associated impacts.Potential vorticity(PV),which is closely related to cyclone dynamics,serves as a valuable diagnostic tool in the study of ECs.In this study,two wintertime ECs of differing intensity over the Northwestern Pacific Ocean are analyzed to examine how different atmospheric processes influence PV generation and the rapid development of ECs.The maximum deepening rates of the two ECs are 2.81 Bergeron(called EC1) and 1.52 Bergeron(referred to as EC2).Results indicate that different stages of EC evolution are closely associated with PV tendency changes at different atmospheric levels.Using the PV tendency equation,during the explosive development of EC1,latent heat release may trigger the downward propagation of upper-level PV.For EC2,latent heat release notably enhances low-level PV,directly contributing to its rapid intensification.To validate these findings,sensitivity tests are conducted using the Weather Research and Forecasting model,with latent heat release turned off in the microphysical scheme for both cases.The results confirm the crucial role of latent heat release in generating low-level PV,further revealing that latent heat release contributes more to the explosive development of EC2 than that of EC1.展开更多
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
At present,the identification of tropical cyclone remote precipitation(TRP)requires subjective participation,leading to inconsistent results among different researchers despite adopting the same identification standar...At present,the identification of tropical cyclone remote precipitation(TRP)requires subjective participation,leading to inconsistent results among different researchers despite adopting the same identification standard.Thus,establishing an objective identification method is greatly important.In this study,an objective synoptic analysis technique for TRP(OSAT_TRP)is proposed to identify TRP using daily precipitation datasets,historical tropical cyclone(TC)track data,and the ERA5 reanalysis data.This method includes three steps:first,independent rain belts are separated,and those that might relate to TCs'remote effects are distinguished according to their distance from the TCs.Second,the strong water vapor transport belt from the TC is identified using integrated horizontal water vapor transport(IVT).Third,TRP is distinguished by connecting the first two steps.The TRP obtained through this method can satisfy three criteria,as follows:1)the precipitation occurs outside the circulation of TCs,2)the precipitation is affected by TCs,and 3)a gap exists between the TRP and TC rain belt.Case diagnosis analysis,compared with subjective TRP results and backward trajectory analyses using HYSPLIT,indicates that OSAT_TRP can distinguish TRP even when multiple TCs in the Northwest Pacific are involved.Then,we applied the OSAT_TRP to select typical TRPs and obtained the synoptic-scale environments of the TRP through composite analysis.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
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
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
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
This study proposes a novel cyclone separator with a conical inner core to enhance particle classification efficiency in oil and gas wellhead-recovered liquids.Particle motion and force dynamics are analyzed to optimi...This study proposes a novel cyclone separator with a conical inner core to enhance particle classification efficiency in oil and gas wellhead-recovered liquids.Particle motion and force dynamics are analyzed to optimize key structural parameters,including inlet diameter(D_i),overflow pipe diameter(D_(e)),insertion depth(L_(e)),and bottom flow pipe diameter(D_(z)).Numerical simulations employ the Reynolds stress turbulence model,SIMPLEC algorithm,and discrete phase model to evaluate separation performance in a gas-liquid two-phase system.Results indicate that a smaller D_i improves fine particle separation but increases turbulence;an optimal range of D_i/D_(c)=0.35-0.4 is recommended.Larger D_(e) enhances the diversion ratio,aiding fine particle discharge(D_(e)/D_(c)=0.25-0.35).Increased Le facilitates fine particle overflow but induces vortices,whereas a smaller L_(e) stabilizes the bottom flow for larger particle separation(L_(e)/D_(c)=0.5-0.75).A reduced D_(z) enhances centrifugal force and separation efficiency but may cause turbulence;an optimal D_(z)/D_(c) of 0.6-0.65 is suggested for stability.These findings provide valuable design guidelines for improving cyclone separator performance in multiphase flow applications.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 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
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
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
This study applies Ensemble Optimal Interpolation(EnOI)to assimilate individual spectral components derived from National Data Buoy Center(NDBC)buoy directional spectra into the WAVEWATCHⅢ(WW3)wave model during tropi...This study applies Ensemble Optimal Interpolation(EnOI)to assimilate individual spectral components derived from National Data Buoy Center(NDBC)buoy directional spectra into the WAVEWATCHⅢ(WW3)wave model during tropical cyclone(TC)Isaias(2020).The analysis provides a comprehensive evaluation of the assimilation’s impact on wave parameters,frequency spectra,and directional spectra.Two series of assimilation experiments—one based on spectral components(Exp^(*)-DaSpec)and the other on significant wave height(Exp^(*)-DaSWH)—are evaluated against a non-assimilated control run(Exp-NoDa).Particular focus is placed on six key parameters:SWH,mean wave period(MWP),mean wave direction(MWD),mean wave directional spread(MWS),dominant wave period(DWP),and dominant wave direction(DWD).Sensitivity analyses suggest 400 km and 0.30 as appropriate values for the localization radius and observation error variance,respectively,though no single setting is optimal across all wave parameters.Exp4-DaSWH and Exp4-DaSpec are therefore selected as representative experiments.In non-independent validation,Exp4-DaSpec generally outperforms Exp-NoDa across MWP,MWD,MWS,DWP,and DWD,demonstrating closer agreement with observed frequency spectra and directional patterns.In independent validation,Exp4-DaSpec maintains superior overall performance,whereas Exp4-DaSWH shows only limited improvement.Exp4-DaSWH may capture the spectral peak near 0.1 Hz,although its directional characteristics remain largely similar to those of Exp-NoDa.Importantly,the assimilation experiments significantly improve SWH in both non-independent and independent validations,with Exp4-DaSWH slightly outperforming Exp4-DaSpec overall.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
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
基金supported by the National Key R&D Program of China [grant number 2023YFC3008004]。
文摘This study presents a comprehensive evaluation of tropical cyclone(TC)forecast performance in the western North Pacific from 2013 to 2022,based on operational forecasts issued by the China Meteorological Administration.The analysis reveals systematic improvements in both track and intensity forecasts over the decade,with distinct error characteristics observed across various forecast parameters.Track forecast errors have steadily decreased,particularly for longer lead times,while error magnitudes have increased with longer forecast lead times.Intensity forecasts show similar progressive enhancements,with maximum sustained wind speed errors decreasing by 0.26 m/s per year for 120 h forecasts.The study also identifies several key patterns in forecast performance:typhoon-grade or stronger TCs exhibit smaller track errors than week or weaker systems;intensity forecasts systematically overestimate weaker TCs while underestimating stronger systems;and spatial error distributions show greater track inaccuracies near landmasses and regional intensity biases.These findings highlight both the significant advances in TC forecasting capability achieved through improved modeling and observational systems,and the remaining challenges in predicting TC changes and landfall behavior,providing valuable benchmarks for future forecast system development.
基金supported by the Key Laboratory of South China Sea Meteorological Disaster Prevention and Mitigation of Hainan Province(No.SCSF202307)the Basic Research Fund of CAMS(No.2023Z016)+1 种基金the National Natural Scientific Foundation of China(No.42275037)the Jiangsu Collaborative Innovation Center for Climate Change。
文摘In this study,tropical cyclone(TC)translation speed was introduced as a new similarity factor within the generalized initial value(GIV)framework,enhancing the disaster preassessment capability of the dynamical statistical analog ensemble forecast model for landfalling TC disasters(DSAEF_LTD model).Three TC translation speed indicators most relevant to TC precipitation were incorporated:the maximum speed on Day 1(the first day of TC-induced precipitation and wind occurring on land)and the average and minimum speeds over All Days(all days of TC-induced precipitation and wind occurring on land),all classified using the Kmeans clustering algorithm.Simulation experiments showed that integrating TC translation speed enhanced the model's performance.The model provided a better optimal common scheme,with the TSS UM(sum of threat scores for severe and above and extremely severe and above disasters)increasing by 2.66%(from 0.5117 to 0.5253)compared with the original model.More importantly,its preassessment ability improved significantly,with the average TSS UM for independent samples increasing by 6.43%(from 0.6488 to0.6905).The modified model demonstrated greater accuracy in capturing disaster severity and distribution of TCs with significant speed characteristics or with regular tracks.This improvement stemmed from reduced false alarms due to the selection of analogs that are more similar to the target TC.The enhanced preassessment ability can be attributed to the key role of TC translation speed,which significantly influences TC precipitation patterns and improves TC precipitation forecasting.Since precipitation is one of the most crucial disaster-causing factors,better TC precipitation forecasting leads to improved disaster preassessment outcomes.These findings emphasize the promising potential of the DSAEF_LTD model for future TC disaster research and management,contributing to the achievement of the Sustainable Development Goals set by the United Nations 2030 Agenda by strengthening coastal resilience.
基金jointly supported by the National Natural Science Foundation of China[grant numbers U2342202,42175005,and 42175016]the Qing Lan Project[grant number R2023Q06]。
文摘This study investigates the width of the secondary eyewall(SE)immediately following its formation in tropical cyclones with surface environmental winds aligned and counter-aligned with environmental vertical wind shear(VWS),using idealized numerical experiments.Results reveal that the SE develops greater radial extent when surface winds align with VWS compared to counter-aligned conditions.In alignment configurations,shear-enhanced surface winds on the right flank amplify surface enthalpy fluxes,thereby elevating boundary-layer entropy within the downshear outer-core region.Subsequently,more vigorous outer rainbands develop,inducing marked acceleration of tangential winds in the outer core preceding SE formation.The resultant radial expansion of supergradient winds near the boundary-layer top triggers widespread convective activity immediately beyond the inner core.Progressive axisymmetrization of this convective forcing ultimately generates an expansive SE structure.
基金financially supported by the National Key R&D Program of China (No. 2022YFC3004204)the National Natural Science Foundation of China (No. 42275001)the Natural Science Foundation of Shandong Province (No. ZR2022MD038)。
文摘Explosive cyclones(ECs) are rapidly intensifying subtropical cyclones that can develop within a short time and pose considerable threats to coastal areas in middle and high latitudes.Gaining a comprehensive understanding of their formation,evolution,and mechanisms of explosive development is essential for improving forecasts of extreme weather events and mitigating associated impacts.Potential vorticity(PV),which is closely related to cyclone dynamics,serves as a valuable diagnostic tool in the study of ECs.In this study,two wintertime ECs of differing intensity over the Northwestern Pacific Ocean are analyzed to examine how different atmospheric processes influence PV generation and the rapid development of ECs.The maximum deepening rates of the two ECs are 2.81 Bergeron(called EC1) and 1.52 Bergeron(referred to as EC2).Results indicate that different stages of EC evolution are closely associated with PV tendency changes at different atmospheric levels.Using the PV tendency equation,during the explosive development of EC1,latent heat release may trigger the downward propagation of upper-level PV.For EC2,latent heat release notably enhances low-level PV,directly contributing to its rapid intensification.To validate these findings,sensitivity tests are conducted using the Weather Research and Forecasting model,with latent heat release turned off in the microphysical scheme for both cases.The results confirm the crucial role of latent heat release in generating low-level PV,further revealing that latent heat release contributes more to the explosive development of EC2 than that of EC1.
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supported by the Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.KYCX22_1136)the National Natural Scientific Foundation of China(No.42275037)+2 种基金the Basic Research Fund of CAMS(No.2023Z016)the Key Laboratory of South China Sea Meteorological Disaster Prevention and Mitigation of Hainan Province(No.SCSF202202)supported by the Jiangsu Collaborative Innovation Center for Climate Change。
文摘At present,the identification of tropical cyclone remote precipitation(TRP)requires subjective participation,leading to inconsistent results among different researchers despite adopting the same identification standard.Thus,establishing an objective identification method is greatly important.In this study,an objective synoptic analysis technique for TRP(OSAT_TRP)is proposed to identify TRP using daily precipitation datasets,historical tropical cyclone(TC)track data,and the ERA5 reanalysis data.This method includes three steps:first,independent rain belts are separated,and those that might relate to TCs'remote effects are distinguished according to their distance from the TCs.Second,the strong water vapor transport belt from the TC is identified using integrated horizontal water vapor transport(IVT).Third,TRP is distinguished by connecting the first two steps.The TRP obtained through this method can satisfy three criteria,as follows:1)the precipitation occurs outside the circulation of TCs,2)the precipitation is affected by TCs,and 3)a gap exists between the TRP and TC rain belt.Case diagnosis analysis,compared with subjective TRP results and backward trajectory analyses using HYSPLIT,indicates that OSAT_TRP can distinguish TRP even when multiple TCs in the Northwest Pacific are involved.Then,we applied the OSAT_TRP to select typical TRPs and obtained the synoptic-scale environments of the TRP through composite analysis.
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 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.
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 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supported by the National Natural Science Foundation of China(52074341)。
文摘This study proposes a novel cyclone separator with a conical inner core to enhance particle classification efficiency in oil and gas wellhead-recovered liquids.Particle motion and force dynamics are analyzed to optimize key structural parameters,including inlet diameter(D_i),overflow pipe diameter(D_(e)),insertion depth(L_(e)),and bottom flow pipe diameter(D_(z)).Numerical simulations employ the Reynolds stress turbulence model,SIMPLEC algorithm,and discrete phase model to evaluate separation performance in a gas-liquid two-phase system.Results indicate that a smaller D_i improves fine particle separation but increases turbulence;an optimal range of D_i/D_(c)=0.35-0.4 is recommended.Larger D_(e) enhances the diversion ratio,aiding fine particle discharge(D_(e)/D_(c)=0.25-0.35).Increased Le facilitates fine particle overflow but induces vortices,whereas a smaller L_(e) stabilizes the bottom flow for larger particle separation(L_(e)/D_(c)=0.5-0.75).A reduced D_(z) enhances centrifugal force and separation efficiency but may cause turbulence;an optimal D_(z)/D_(c) of 0.6-0.65 is suggested for stability.These findings provide valuable design guidelines for improving cyclone separator performance in multiphase flow applications.
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(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The Youth Talent Support Program for Doctoral Students of the China Association for Science and Technologythe Key Laboratory of Space Ocean Remote Sensing and Application at Ministry of Natural Resources under contract No.2023CFO005+1 种基金the National Natural Science Foundation of China under contract No.42176011the Fundamental Research Funds for the Central Universities under contract No.24CX03001A.
文摘This study applies Ensemble Optimal Interpolation(EnOI)to assimilate individual spectral components derived from National Data Buoy Center(NDBC)buoy directional spectra into the WAVEWATCHⅢ(WW3)wave model during tropical cyclone(TC)Isaias(2020).The analysis provides a comprehensive evaluation of the assimilation’s impact on wave parameters,frequency spectra,and directional spectra.Two series of assimilation experiments—one based on spectral components(Exp^(*)-DaSpec)and the other on significant wave height(Exp^(*)-DaSWH)—are evaluated against a non-assimilated control run(Exp-NoDa).Particular focus is placed on six key parameters:SWH,mean wave period(MWP),mean wave direction(MWD),mean wave directional spread(MWS),dominant wave period(DWP),and dominant wave direction(DWD).Sensitivity analyses suggest 400 km and 0.30 as appropriate values for the localization radius and observation error variance,respectively,though no single setting is optimal across all wave parameters.Exp4-DaSWH and Exp4-DaSpec are therefore selected as representative experiments.In non-independent validation,Exp4-DaSpec generally outperforms Exp-NoDa across MWP,MWD,MWS,DWP,and DWD,demonstrating closer agreement with observed frequency spectra and directional patterns.In independent validation,Exp4-DaSpec maintains superior overall performance,whereas Exp4-DaSWH shows only limited improvement.Exp4-DaSWH may capture the spectral peak near 0.1 Hz,although its directional characteristics remain largely similar to those of Exp-NoDa.Importantly,the assimilation experiments significantly improve SWH in both non-independent and independent validations,with Exp4-DaSWH slightly outperforming Exp4-DaSpec overall.
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.
