Bomb cyclones are rapidly deepening extratropical cyclones predominantly found in midlatitude regions.These extreme events are particularly frequent over the North Pacific(NP),posing significant societal and environme...Bomb cyclones are rapidly deepening extratropical cyclones predominantly found in midlatitude regions.These extreme events are particularly frequent over the North Pacific(NP),posing significant societal and environmental risks.Currently,our understanding of the variability of bomb cyclones over the NP remains limited.This study analyzes the variations in multiple NP bomb cyclone characteristics from 1980 onward using four major reanalysis datasets.The results show a weakening trend of bomb cyclones since the beginning of the 21st century,which is characterized by significant reductions in maximum near-surface wind speeds,increases in minimum sea level pressure,and slower deepening rates.Further analysis reveals that the observed weakening trend of bomb cyclones is closely linked to a reduction in maximum 850 hPa Eady growth rate,driven primarily by reduced vertical wind shear within the 30°-45°N latitudinal band.Furthermore,our findings indicate that the Aleutian Low acts to modulate the meridional air temperature gradient over the midlatitude NP,which is corroborated by climate model outputs.This modulation provides a pathway for the Aleutian Low to affect low-level baroclinicity and thus bomb cyclone characteristics.These results have important implications for future projections of bomb cyclone activity over the NP,aiding in risk assessment and mitigating the impacts of these extreme events.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
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
The purpose of this study is to analyze the impact of upper ocean dynamics on velocity bunching,represented by az-imuthal cutoff wavelength(i.e.,sea surface wind,wave,and current).In this study,over 1400 dual-polarize...The purpose of this study is to analyze the impact of upper ocean dynamics on velocity bunching,represented by az-imuthal cutoff wavelength(i.e.,sea surface wind,wave,and current).In this study,over 1400 dual-polarized(vertical-vertical(VV)and vertical-horizontal(VH))Sentinel-1(S-1)synthetic aperture radar(SAR)images collected in tropical cyclones(TC)are utilized.These images are combined with wind and rain observations from the stepped-frequency microwave radiometer(SFMR),wave simu-lations conducted using a third-generation numerical wave model,WAVEWATCH-III(WW3),and SAR-derived wind information collected from CyclObs winds.The WW3-simulated significant wave height(SWH)is validated against measurements from HY-2B altimeter taken in August and September 2021,yielding a root mean square error(RMSE)of 0.48 m and a correlation coefficient(COR)of 0.88.The SAR-based azimuthal cutoff wavelengths in VV polarization,which quantitatively represent the effect of velocity bunching,are compared with theoretical values calculated using WW3-simulated SWH.A notable relationship is observed between the difference in azimuthal cutoff wavelength and SAR-derived wind speed and WW3-simulated SWH.Analysis results show that the correlation between SAR-based azimuthal cutoff wavelength and SWH is stronger than that with wind and current.Finally,a machine learning algorithm is used to develop an algorithm aimed at simulating the azimuthal cutoff wavelength in TCs,including wind,wave,and incidence angle.This method yields an RMSE of 8.90 m,a COR of 0.91,and a scatter index of 0.04 for VV-polar-ization SAR.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
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
Landfalling tropical cyclones(TCs)pose tremendous hazards to East Asian coastal areas,particularly in East China,a densely populated and economically vital center.This underscores the critical need for a more in-depth...Landfalling tropical cyclones(TCs)pose tremendous hazards to East Asian coastal areas,particularly in East China,a densely populated and economically vital center.This underscores the critical need for a more in-depth investigation into the evolving characteristics and influences of these landfalling TCs.In this study,we explored changes in landfalling TC activity during 1965–2022 and estimated their influences in East China.Our findings demonstrate that the annual frequency of landfalling TCs has exhibited a slight increase since the mid-1990s,while their overall influences have significantly intensified.This intensification is closely associated with the prolonged duration of TCs over land after landfall.The results also reveal that longer overland sustainment is attributed to the descending vertical wind shear(VWS)and ascending low-layer moisture supply over the corresponding areas.In addition,the annual mean genesis location of these landfalling TCs has shown a significant westward migration,which may be advantageous to the increase in TC influences.展开更多
This study investigates the characteristics of secondary eyewall formation(SEF)in idealized tropical cyclones embedded in vertical wind shear(VWS)at different heights.The results show that upper-layer VWS at a relativ...This study investigates the characteristics of secondary eyewall formation(SEF)in idealized tropical cyclones embedded in vertical wind shear(VWS)at different heights.The results show that upper-layer VWS at a relatively low shear height is more favorable for SEF than upper-layer VWS at a relatively high shear height and lowerlayer VWS.In the experiments with upper-layer VWS at a relatively low shear height,better-organized stratiform clouds are located in the downwind sector of outer rainbands.The low-level descending inflow associated with the stratiform sector is stronger in these experiments than in the experiments with upper-layer VWS at a relatively high shear height and lower-layer VWS.The enhanced descending inflow can trigger supergradient winds and convergence near the top of the boundary layer,close to three times the radius of the maximum wind,where convection is locally forced.The subsequent convection axisymmetrization leads to SEF.展开更多
An extraordinary tropical cyclone-remote rainstorm with a 24-hour precipitation amount of 624.1 mm occurred in Zhengzhou,China,on 20 July 2021,during which a severe hourly precipitation amount of 201.9 mm at 1700 LST(...An extraordinary tropical cyclone-remote rainstorm with a 24-hour precipitation amount of 624.1 mm occurred in Zhengzhou,China,on 20 July 2021,during which a severe hourly precipitation amount of 201.9 mm at 1700 LST(LST=UTC+8)caused significant economic losses and casualties.Observational analysis and backward trajectory modeling showed that low-level water vapor for this extraordinary rainstorm was transported by the southeasterly jet below 900 hPa from the intensifying Typhoon In-Fa(2021)in the western North Pacific(low-level southeasterly channel).Although the southerly flow between 900 and 800 hPa brought water vapor from the developing Typhoon Cempaka in the South China Sea(low-level southerly channel),it did not converge over Zhengzhou.展开更多
Extratropical transition(ET)is one of the last phases of tropical cyclones(TCs)and corresponds to the structural change from a tropical system to an extratropical system characterized by pronounced asymmetric distribu...Extratropical transition(ET)is one of the last phases of tropical cyclones(TCs)and corresponds to the structural change from a tropical system to an extratropical system characterized by pronounced asymmetric distributions of heavy rainfall and strong wind.This study analyzes the statistical characteristics of ET events involving TCs over the western North Pacific(WNP)during 1981–2022.The analysis employs the Cyclone Phase Space(CPS)method to evaluate the accuracy of the fifth-generation reanalysis from the European Centre for Medium-Range Weather Forecasts(ERA5)in identifying ET based on different TC center definitions.Results show that defining the TC center by the minimum sea level pressure yields the most accurate ET identification.Subsequently,the study investigates several characteristics of ET events in the WNP.It is found that TCs undergoing ET(ETTCs)primarily form in the region of 125°–155°E,10°–25°N,with ET typically initiating between 30°–40°N and completing between 35°–50°N.These ETTCs predominantly occur from April to December,with peak activity observed from August to October.Additionally,the average duration of the ET process is 18.5 h,with longer durations observed from August to October,displaying a roughly 6-year cycle.Spatially,ET events with longer durations tend to occur at lower latitudes.Correspondingly,TCs initiating their ET phase at lower latitudes are typically stronger and larger,and they also experience longer ET durations.展开更多
The present study employs statistical analysis to investigate the relationship between the geopotential height anomalies induced by tropical cyclones(TCs)and the meridional movement of the western Pacific subtropical ...The present study employs statistical analysis to investigate the relationship between the geopotential height anomalies induced by tropical cyclones(TCs)and the meridional movement of the western Pacific subtropical high(WPSH),as well as the mechanisms through which TCs can induce such geopotential height anomalies.Results show that TCs can cause the WPSH to move northward,and the meridional motion of the WPSH ridgeline is related with the geopotential height anomalies,which is better indicated by the relative geopotential height anomalies.In the process of TCs causing the WPSH to move northward,the TCs cause abnormal horizonal warm(cold)advection and abnormal ascending(descending)motion in the region south(north)of 40°N.Since the influence of the abnormal vertical motion is weaker,the abnormal temperature tendency eventually shows a more consistent phase distribution with the abnormal horizonal temperature advection,which is favorable for the temperature to abnormally increase near 40°N.Such an abnormal increase in temperature causes the geopotential height to abnormally increase under the static equilibrium constraint,which further changes the location of the centroid of the WPSH geopotential height,and hence the location of the WPSH ridgeline changes as well.展开更多
This study investigates the size characteristics and related temporal variations of tropical cyclones(TCs)over the Western North Pacific(WNP)and those affecting East China(EC)using Joint Typhoon Warning Center(JTWC)da...This study investigates the size characteristics and related temporal variations of tropical cyclones(TCs)over the Western North Pacific(WNP)and those affecting East China(EC)using Joint Typhoon Warning Center(JTWC)data during 2001-20.The average size of EC TCs is found to be similar to that over the WNP.Furthermore,the annual maximum lifetime maximum size(LMS)of EC TCs shows a statistically significant increasing trend,implying a more severe impact on the EC region.Composite analyses of intensity and size variation over the entire lifetime of TCs,before and after re-curvature,and before and after rapid intensification(RI),show that there are significant differences between them in some key areas:(1)The intensity begins to rapidly decrease after the TC has reached its highest intensity,but the size remains quasi-constant;(2)When a TC recurves south of 15°N or north of 30°N,the variation trend for both intensity and size are broadly similar before and after curvature,but their variation trends are opposite when the recurvature occurs between 15°-30°N;(3)After RI,the intensity reaches its peak value within 24 h,whereas the size reaches its LMS after30-48 h.A significant correlation is also found between the rate of change in intensity and that of size during the development stage,with a correlation coefficient of 0.67 and 0.73 for TCs in the WNP and EC,respectively.However,no significant correlation exists during the weakening stage.展开更多
Upper ocean responses to the passage of sequential tropical cyclones over the northwestern South China Sea(SCS)in 2011 were investigated using satellite remote sensing data,Argo reanalysis data,and an array of mooring...Upper ocean responses to the passage of sequential tropical cyclones over the northwestern South China Sea(SCS)in 2011 were investigated using satellite remote sensing data,Argo reanalysis data,and an array of mooring data.We found that the sea surface low temperature region lasted for more than 38 days and two phytoplankton blooms occurred after the passage of sequential tropical cyclones.The upper ocean cooling reached 2–5°C with a right-side bias was observed along the typhoon track to about 200 km.The maintenance of low temperature region and the two phytoplankton blooms were mainly driven by upwelling and near-inertial turbulence mixing induced by the sequential tropical cyclones.The fi rst phytoplankton bloom appeared on the 7 th day after the passage of the three tropical cyclones,and the chlorophyll-a(chl-a)concentration increased by 226%,which may be mainly driven by typhoons induced upwelling.The second phytoplankton bloom occurred on the 30 th day,the chl-a concentration increased by 290%.Further analysis suggested that only the typhoons with similar characteristics as Nesat and Nalgae can induce strong near-inertial oscillation(NIO).Strong turbulent mixing associated with the near-inertial baroclinic shear instability lasted for 26 days.The measured mean eddy diff usivity in the upper ocean was above 10-4 m 2/s after typhoon Nesat.Enhancement of the turbulent mixing in the upper ocean helped to transport nutrient-rich cold waters from the deep layer to the euphotic layer,and is a major mechanism for the long-term maintenance of low temperature region as well as the second phytoplankton bloom.展开更多
The ability to forecast heavy rainfall associated with landfalling tropical cyclones （LTCs） can be improved with a better understanding of the mechanism of rainfall rates and distributions of LTCs. Research in the a...The ability to forecast heavy rainfall associated with landfalling tropical cyclones （LTCs） can be improved with a better understanding of the mechanism of rainfall rates and distributions of LTCs. Research in the area of LTCs has shown that associated heavy rainfall is related closely to mechanisms such as moisture transport, extratropical transition （ET）, interaction with monsoon surge, land surface processes or topographic effects, mesoscale convective system activities within the LTC, and boundary layer energy transfer etc.. LTCs interacting with environmental weather systems, especially the westerly trough and mei-yu front, could change the rainfall rate and distribution associated with these mid-latitude weather systems. Recently improved technologies have contributed to advancements within the areas of quantitative precipitation estimation （QPE） and quantitative precipitation forecasting （QPF）. More specifically, progress has been due primarily to remote sensing observations and mesoscale numerical models which incorporate advanced assimilation techniques. Such progress may provide the tools necessary to improve rainfall forecasting techniques associated with LTCs in the future.展开更多
A 28-year best track dataset containing size parameters that include the radii of the 15.4 m s^-1 winds （R15） and the 25.7 m s^-1 winds （R26） of tropical cyclones （TCs） in the Northwestern Pacific, the NCEP/ NCA...A 28-year best track dataset containing size parameters that include the radii of the 15.4 m s^-1 winds （R15） and the 25.7 m s^-1 winds （R26） of tropical cyclones （TCs） in the Northwestern Pacific, the NCEP/ NCAR reanalysis dataset and the Extended Reconstructed Sea Surface Temperature （ERSST） dataset are employed in this study. The climatology of size parameters for the tropical cyclones in the Northwestern Pacific from 1977 to 2004 is investigated in terms of the spatial and temporal distributions. The results show that the major activity of TCs in the Northwestern Pacific is from July to October. A majority of TCs lie over the ocean west of 150°E, and a few TCs can intensify to the Saffir-Simpson （S-S） categories 4, 5. Both R15 and R26 tend to increase as the tropical cyclones intensify. The values of R15 and R26 are larger for intense TCs in the Northwestern Pacific than in the North Atlantic generally. Both R15 and R26 peak in October, and before and after October, R15 and R26 decrease, which is different from the case in the North Atlantic. The smaller R15s and R26s occur in a large range over the Northwestern Pacific, while the larger R15s and R26s mainly lie in the eastern ocean from Taiwan Island to the Philippine Islands where many tropical cyclones develop in intense systems. The tropical cyclones with size parameters of R15 or R26 on average take a longer time to intensify than to weaken, and the weak tropical cyclones have faster weakening rates than intensification rates. From 1977 to 2004, the annual mean values of R15 increase basically with year; during the 28-year period, the value of R15 increases by 52.7 kin, but R26 does not change with year obviously.展开更多
The tropical cyclone that lands or passes through Guangxi coast is a serious natural disaster, which brings about strong winds, heavy rains, storm surges and other disasters causing severe damage of property or casual...The tropical cyclone that lands or passes through Guangxi coast is a serious natural disaster, which brings about strong winds, heavy rains, storm surges and other disasters causing severe damage of property or casualties in the coastal region every year. By counting and analyzing the tropical cyclones affecting Guangxi coast from 1950 to 2012, we find that the annual number of tropical cyclones changes significantly, and the maximum value can be up to 9, whereas the minimum value is 0 in some year. The regularity of seasonal distribution of tropical cyclones is obvious, and the peak period is in July, August and September every year, followed by June and October. Most of tropical cyclones come from the east of Philippines. After entering the South China Sea and passing through Hainan province and Leizhou Peninsula, they landed on Guangxi coast once again and caused the mean of peak surge reaching 111.2 cm, which is 2.6 times of non-landing typhoon. The formation of storm surge disaster is directly related to the severe typhoon weather systems, diurnal spring tide and discharge of river flood. Severe typhoons generate huge waves and rainfall, which lead to the rise of water level at the estuary, and would result in significant increasing water when stacking up with the storm surge, and cause huge tidal disaster.展开更多
Valuable dropsonde data were obtained from multiple field campaigns targeting tropical cyclones,namely Higos,Nangka,Saudel,and Atsani,over the western North Pacific by the Hong Kong Observatory and Taiwan Central Weat...Valuable dropsonde data were obtained from multiple field campaigns targeting tropical cyclones,namely Higos,Nangka,Saudel,and Atsani,over the western North Pacific by the Hong Kong Observatory and Taiwan Central Weather Bureau in 2020.The conditional nonlinear optimal perturbation(CNOP)method has been utilized in real-time to identify the sensitive regions for targeting observations adhering to the procedure of real-time field campaigns for the first time.The observing system experiments were conducted to evaluate the effect of dropsonde data and CNOP sensitivity on TC forecasts in terms of track and intensity,using the Weather Research and Forecasting model.It is shown that the impact of assimilating all dropsonde data on both track and intensity forecasts is case-dependent.However,assimilation using only the dropsonde data inside the sensitive regions displays unanimously positive effects on both the track and intensity forecast,either of which obtains comparable benefits to or greatly reduces deterioration of the skill when assimilating all dropsonde data.Therefore,these results encourage us to further carry out targeting observations for the forecast of tropical cyclones according to CNOP sensitivity.展开更多
A new tangential wind profile for simulating strong tropical cyclones is put forward and planted into the NCAR- AFWA tropical cyclone bogussing scheme in MM5. The scheme for the new profile can make full use of the in...A new tangential wind profile for simulating strong tropical cyclones is put forward and planted into the NCAR- AFWA tropical cyclone bogussing scheme in MM5. The scheme for the new profile can make full use of the information from routine typhoon reports, including not only the maximum wind, but also the additional information of the wind speeds of 25.7 and 15.4 ms-1 and their corresponding radii, which are usually provided for strong cyclones. Thus, the new profile can be used to describe the outer structure of cyclones more accurately than by using the earlier scheme of MM5 in which on- ly the maximum wind speed is considered. Numerical experimental forecasts of two strong tropical cyclones are performed to examine the new profile. Results show that by using the new profile the prediction of both cyclones’ intensity can be obvi- ously improved, but the effects on the track prediction of the two cyclones are different. It seems that the new profile might be more suitable for strong cyclones with shifted tracks. However, the conclusion is drawn from only two typhoon cases, so more cases are needed to evaluate the new profile.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.42030410)the Laoshan Laboratory(Grant Nos.LSKJ202202404 and LSKJ202202403)+1 种基金the Startup Foundation for Introducing Tal-ent of NUIST,Jiangsu Innovation Research Group(Grant No.JSS-CTD202346)the Jiangsu Funding Program for Excellent Post-doctoral Talent(Grant No.2023ZB690).
文摘Bomb cyclones are rapidly deepening extratropical cyclones predominantly found in midlatitude regions.These extreme events are particularly frequent over the North Pacific(NP),posing significant societal and environmental risks.Currently,our understanding of the variability of bomb cyclones over the NP remains limited.This study analyzes the variations in multiple NP bomb cyclone characteristics from 1980 onward using four major reanalysis datasets.The results show a weakening trend of bomb cyclones since the beginning of the 21st century,which is characterized by significant reductions in maximum near-surface wind speeds,increases in minimum sea level pressure,and slower deepening rates.Further analysis reveals that the observed weakening trend of bomb cyclones is closely linked to a reduction in maximum 850 hPa Eady growth rate,driven primarily by reduced vertical wind shear within the 30°-45°N latitudinal band.Furthermore,our findings indicate that the Aleutian Low acts to modulate the meridional air temperature gradient over the midlatitude NP,which is corroborated by climate model outputs.This modulation provides a pathway for the Aleutian Low to affect low-level baroclinicity and thus bomb cyclone characteristics.These results have important implications for future projections of bomb cyclone activity over the NP,aiding in risk assessment and mitigating the impacts of these extreme events.
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.
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(Nos.42076238,42376174)the Natural Science Foundation of Shanghai(No.23ZR1426900).
文摘The purpose of this study is to analyze the impact of upper ocean dynamics on velocity bunching,represented by az-imuthal cutoff wavelength(i.e.,sea surface wind,wave,and current).In this study,over 1400 dual-polarized(vertical-vertical(VV)and vertical-horizontal(VH))Sentinel-1(S-1)synthetic aperture radar(SAR)images collected in tropical cyclones(TC)are utilized.These images are combined with wind and rain observations from the stepped-frequency microwave radiometer(SFMR),wave simu-lations conducted using a third-generation numerical wave model,WAVEWATCH-III(WW3),and SAR-derived wind information collected from CyclObs winds.The WW3-simulated significant wave height(SWH)is validated against measurements from HY-2B altimeter taken in August and September 2021,yielding a root mean square error(RMSE)of 0.48 m and a correlation coefficient(COR)of 0.88.The SAR-based azimuthal cutoff wavelengths in VV polarization,which quantitatively represent the effect of velocity bunching,are compared with theoretical values calculated using WW3-simulated SWH.A notable relationship is observed between the difference in azimuthal cutoff wavelength and SAR-derived wind speed and WW3-simulated SWH.Analysis results show that the correlation between SAR-based azimuthal cutoff wavelength and SWH is stronger than that with wind and current.Finally,a machine learning algorithm is used to develop an algorithm aimed at simulating the azimuthal cutoff wavelength in TCs,including wind,wave,and incidence angle.This method yields an RMSE of 8.90 m,a COR of 0.91,and a scatter index of 0.04 for VV-polar-ization SAR.
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General Scientific Research Projects of Jiangsu Provincial Meteorological Service(KM202401)Young Scientists Found of the National Natural Science Foundation of China(42205197)+2 种基金Beijige Fund of Nanjing Joint Institute for Atmospheric Sciences(BJG202501)Joint Research Project for Meteorological Capacity Improvement(22NLTSY009)Key Scientific Research Projects of Jiangsu Provincial Meteorological Bureau(KZ202203)。
文摘Landfalling tropical cyclones(TCs)pose tremendous hazards to East Asian coastal areas,particularly in East China,a densely populated and economically vital center.This underscores the critical need for a more in-depth investigation into the evolving characteristics and influences of these landfalling TCs.In this study,we explored changes in landfalling TC activity during 1965–2022 and estimated their influences in East China.Our findings demonstrate that the annual frequency of landfalling TCs has exhibited a slight increase since the mid-1990s,while their overall influences have significantly intensified.This intensification is closely associated with the prolonged duration of TCs over land after landfall.The results also reveal that longer overland sustainment is attributed to the descending vertical wind shear(VWS)and ascending low-layer moisture supply over the corresponding areas.In addition,the annual mean genesis location of these landfalling TCs has shown a significant westward migration,which may be advantageous to the increase in TC influences.
基金jointly supported by the National Natural Science Foundation of China[Grant Nos.U2342202 and 42175005]the Qing Lan Project[Grant No.R2023Q06]。
文摘This study investigates the characteristics of secondary eyewall formation(SEF)in idealized tropical cyclones embedded in vertical wind shear(VWS)at different heights.The results show that upper-layer VWS at a relatively low shear height is more favorable for SEF than upper-layer VWS at a relatively high shear height and lowerlayer VWS.In the experiments with upper-layer VWS at a relatively low shear height,better-organized stratiform clouds are located in the downwind sector of outer rainbands.The low-level descending inflow associated with the stratiform sector is stronger in these experiments than in the experiments with upper-layer VWS at a relatively high shear height and lower-layer VWS.The enhanced descending inflow can trigger supergradient winds and convergence near the top of the boundary layer,close to three times the radius of the maximum wind,where convection is locally forced.The subsequent convection axisymmetrization leads to SEF.
基金supported by the National Natural Science Foundation of China(Grant No.42305007).
文摘An extraordinary tropical cyclone-remote rainstorm with a 24-hour precipitation amount of 624.1 mm occurred in Zhengzhou,China,on 20 July 2021,during which a severe hourly precipitation amount of 201.9 mm at 1700 LST(LST=UTC+8)caused significant economic losses and casualties.Observational analysis and backward trajectory modeling showed that low-level water vapor for this extraordinary rainstorm was transported by the southeasterly jet below 900 hPa from the intensifying Typhoon In-Fa(2021)in the western North Pacific(low-level southeasterly channel).Although the southerly flow between 900 and 800 hPa brought water vapor from the developing Typhoon Cempaka in the South China Sea(low-level southerly channel),it did not converge over Zhengzhou.
基金Science and Technology Commission of Shanghai Municipality,China(23DZ1204703)。
文摘Extratropical transition(ET)is one of the last phases of tropical cyclones(TCs)and corresponds to the structural change from a tropical system to an extratropical system characterized by pronounced asymmetric distributions of heavy rainfall and strong wind.This study analyzes the statistical characteristics of ET events involving TCs over the western North Pacific(WNP)during 1981–2022.The analysis employs the Cyclone Phase Space(CPS)method to evaluate the accuracy of the fifth-generation reanalysis from the European Centre for Medium-Range Weather Forecasts(ERA5)in identifying ET based on different TC center definitions.Results show that defining the TC center by the minimum sea level pressure yields the most accurate ET identification.Subsequently,the study investigates several characteristics of ET events in the WNP.It is found that TCs undergoing ET(ETTCs)primarily form in the region of 125°–155°E,10°–25°N,with ET typically initiating between 30°–40°N and completing between 35°–50°N.These ETTCs predominantly occur from April to December,with peak activity observed from August to October.Additionally,the average duration of the ET process is 18.5 h,with longer durations observed from August to October,displaying a roughly 6-year cycle.Spatially,ET events with longer durations tend to occur at lower latitudes.Correspondingly,TCs initiating their ET phase at lower latitudes are typically stronger and larger,and they also experience longer ET durations.
基金sponsored by the National Natural Science Foundation of China[grant number 42305011]。
文摘The present study employs statistical analysis to investigate the relationship between the geopotential height anomalies induced by tropical cyclones(TCs)and the meridional movement of the western Pacific subtropical high(WPSH),as well as the mechanisms through which TCs can induce such geopotential height anomalies.Results show that TCs can cause the WPSH to move northward,and the meridional motion of the WPSH ridgeline is related with the geopotential height anomalies,which is better indicated by the relative geopotential height anomalies.In the process of TCs causing the WPSH to move northward,the TCs cause abnormal horizonal warm(cold)advection and abnormal ascending(descending)motion in the region south(north)of 40°N.Since the influence of the abnormal vertical motion is weaker,the abnormal temperature tendency eventually shows a more consistent phase distribution with the abnormal horizonal temperature advection,which is favorable for the temperature to abnormally increase near 40°N.Such an abnormal increase in temperature causes the geopotential height to abnormally increase under the static equilibrium constraint,which further changes the location of the centroid of the WPSH geopotential height,and hence the location of the WPSH ridgeline changes as well.
基金supported by National Natural Science Foundation of China under(Grant No.U2142206)the Shanghai Natural Science Foundation(21ZR1477300)+1 种基金Shanghai Science and Technology Commission Project(23DZ1204701)National Natural Science Foundation of China(Grant No.42075056)。
文摘This study investigates the size characteristics and related temporal variations of tropical cyclones(TCs)over the Western North Pacific(WNP)and those affecting East China(EC)using Joint Typhoon Warning Center(JTWC)data during 2001-20.The average size of EC TCs is found to be similar to that over the WNP.Furthermore,the annual maximum lifetime maximum size(LMS)of EC TCs shows a statistically significant increasing trend,implying a more severe impact on the EC region.Composite analyses of intensity and size variation over the entire lifetime of TCs,before and after re-curvature,and before and after rapid intensification(RI),show that there are significant differences between them in some key areas:(1)The intensity begins to rapidly decrease after the TC has reached its highest intensity,but the size remains quasi-constant;(2)When a TC recurves south of 15°N or north of 30°N,the variation trend for both intensity and size are broadly similar before and after curvature,but their variation trends are opposite when the recurvature occurs between 15°-30°N;(3)After RI,the intensity reaches its peak value within 24 h,whereas the size reaches its LMS after30-48 h.A significant correlation is also found between the rate of change in intensity and that of size during the development stage,with a correlation coefficient of 0.67 and 0.73 for TCs in the WNP and EC,respectively.However,no significant correlation exists during the weakening stage.
基金Supported by the Basic Project of the Ministry of Science and Technology(No.2016YFC14001403)the National Program on Global Change and Air-Sea Interaction(No.GASI-IPOVAI-04)+1 种基金the National Science Foundation of China(Nos.41676008,40876005,U1901213)the Scientifi c Research Start-Up Foundation of Shantou University(No.NTF20006)。
文摘Upper ocean responses to the passage of sequential tropical cyclones over the northwestern South China Sea(SCS)in 2011 were investigated using satellite remote sensing data,Argo reanalysis data,and an array of mooring data.We found that the sea surface low temperature region lasted for more than 38 days and two phytoplankton blooms occurred after the passage of sequential tropical cyclones.The upper ocean cooling reached 2–5°C with a right-side bias was observed along the typhoon track to about 200 km.The maintenance of low temperature region and the two phytoplankton blooms were mainly driven by upwelling and near-inertial turbulence mixing induced by the sequential tropical cyclones.The fi rst phytoplankton bloom appeared on the 7 th day after the passage of the three tropical cyclones,and the chlorophyll-a(chl-a)concentration increased by 226%,which may be mainly driven by typhoons induced upwelling.The second phytoplankton bloom occurred on the 30 th day,the chl-a concentration increased by 290%.Further analysis suggested that only the typhoons with similar characteristics as Nesat and Nalgae can induce strong near-inertial oscillation(NIO).Strong turbulent mixing associated with the near-inertial baroclinic shear instability lasted for 26 days.The measured mean eddy diff usivity in the upper ocean was above 10-4 m 2/s after typhoon Nesat.Enhancement of the turbulent mixing in the upper ocean helped to transport nutrient-rich cold waters from the deep layer to the euphotic layer,and is a major mechanism for the long-term maintenance of low temperature region as well as the second phytoplankton bloom.
基金financed by the National Grand Fundamental Research 973 Program of China (Grant Nos. 2009CB421504 and 2004CB418301)the Key Program of the National Natural Science Foun-dation of China (NSFC) (Grant No. 40730948)the NSFC (Grant Nos. 40575018, 40675033 and 40975032)
文摘The ability to forecast heavy rainfall associated with landfalling tropical cyclones （LTCs） can be improved with a better understanding of the mechanism of rainfall rates and distributions of LTCs. Research in the area of LTCs has shown that associated heavy rainfall is related closely to mechanisms such as moisture transport, extratropical transition （ET）, interaction with monsoon surge, land surface processes or topographic effects, mesoscale convective system activities within the LTC, and boundary layer energy transfer etc.. LTCs interacting with environmental weather systems, especially the westerly trough and mei-yu front, could change the rainfall rate and distribution associated with these mid-latitude weather systems. Recently improved technologies have contributed to advancements within the areas of quantitative precipitation estimation （QPE） and quantitative precipitation forecasting （QPF）. More specifically, progress has been due primarily to remote sensing observations and mesoscale numerical models which incorporate advanced assimilation techniques. Such progress may provide the tools necessary to improve rainfall forecasting techniques associated with LTCs in the future.
文摘A 28-year best track dataset containing size parameters that include the radii of the 15.4 m s^-1 winds （R15） and the 25.7 m s^-1 winds （R26） of tropical cyclones （TCs） in the Northwestern Pacific, the NCEP/ NCAR reanalysis dataset and the Extended Reconstructed Sea Surface Temperature （ERSST） dataset are employed in this study. The climatology of size parameters for the tropical cyclones in the Northwestern Pacific from 1977 to 2004 is investigated in terms of the spatial and temporal distributions. The results show that the major activity of TCs in the Northwestern Pacific is from July to October. A majority of TCs lie over the ocean west of 150°E, and a few TCs can intensify to the Saffir-Simpson （S-S） categories 4, 5. Both R15 and R26 tend to increase as the tropical cyclones intensify. The values of R15 and R26 are larger for intense TCs in the Northwestern Pacific than in the North Atlantic generally. Both R15 and R26 peak in October, and before and after October, R15 and R26 decrease, which is different from the case in the North Atlantic. The smaller R15s and R26s occur in a large range over the Northwestern Pacific, while the larger R15s and R26s mainly lie in the eastern ocean from Taiwan Island to the Philippine Islands where many tropical cyclones develop in intense systems. The tropical cyclones with size parameters of R15 or R26 on average take a longer time to intensify than to weaken, and the weak tropical cyclones have faster weakening rates than intensification rates. From 1977 to 2004, the annual mean values of R15 increase basically with year; during the 28-year period, the value of R15 increases by 52.7 kin, but R26 does not change with year obviously.
基金supported by National Nature Science (Grant No. 41266002)
文摘The tropical cyclone that lands or passes through Guangxi coast is a serious natural disaster, which brings about strong winds, heavy rains, storm surges and other disasters causing severe damage of property or casualties in the coastal region every year. By counting and analyzing the tropical cyclones affecting Guangxi coast from 1950 to 2012, we find that the annual number of tropical cyclones changes significantly, and the maximum value can be up to 9, whereas the minimum value is 0 in some year. The regularity of seasonal distribution of tropical cyclones is obvious, and the peak period is in July, August and September every year, followed by June and October. Most of tropical cyclones come from the east of Philippines. After entering the South China Sea and passing through Hainan province and Leizhou Peninsula, they landed on Guangxi coast once again and caused the mean of peak surge reaching 111.2 cm, which is 2.6 times of non-landing typhoon. The formation of storm surge disaster is directly related to the severe typhoon weather systems, diurnal spring tide and discharge of river flood. Severe typhoons generate huge waves and rainfall, which lead to the rise of water level at the estuary, and would result in significant increasing water when stacking up with the storm surge, and cause huge tidal disaster.
基金jointly sponsored by the National Nature Scientific Foundation of China(Grant.Nos.41930971 and 41775061)the National Key Research and Development Program of China(Grant No.2018YFC1506402)。
文摘Valuable dropsonde data were obtained from multiple field campaigns targeting tropical cyclones,namely Higos,Nangka,Saudel,and Atsani,over the western North Pacific by the Hong Kong Observatory and Taiwan Central Weather Bureau in 2020.The conditional nonlinear optimal perturbation(CNOP)method has been utilized in real-time to identify the sensitive regions for targeting observations adhering to the procedure of real-time field campaigns for the first time.The observing system experiments were conducted to evaluate the effect of dropsonde data and CNOP sensitivity on TC forecasts in terms of track and intensity,using the Weather Research and Forecasting model.It is shown that the impact of assimilating all dropsonde data on both track and intensity forecasts is case-dependent.However,assimilation using only the dropsonde data inside the sensitive regions displays unanimously positive effects on both the track and intensity forecast,either of which obtains comparable benefits to or greatly reduces deterioration of the skill when assimilating all dropsonde data.Therefore,these results encourage us to further carry out targeting observations for the forecast of tropical cyclones according to CNOP sensitivity.
文摘A new tangential wind profile for simulating strong tropical cyclones is put forward and planted into the NCAR- AFWA tropical cyclone bogussing scheme in MM5. The scheme for the new profile can make full use of the information from routine typhoon reports, including not only the maximum wind, but also the additional information of the wind speeds of 25.7 and 15.4 ms-1 and their corresponding radii, which are usually provided for strong cyclones. Thus, the new profile can be used to describe the outer structure of cyclones more accurately than by using the earlier scheme of MM5 in which on- ly the maximum wind speed is considered. Numerical experimental forecasts of two strong tropical cyclones are performed to examine the new profile. Results show that by using the new profile the prediction of both cyclones’ intensity can be obvi- ously improved, but the effects on the track prediction of the two cyclones are different. It seems that the new profile might be more suitable for strong cyclones with shifted tracks. However, the conclusion is drawn from only two typhoon cases, so more cases are needed to evaluate the new profile.
