Climate change affects the activity of global and regional tropical cyclones(TCs).Among all TCs,typical super typhoons(STYs)are particularly devastating because they maintain their intensity when landing on the coast ...Climate change affects the activity of global and regional tropical cyclones(TCs).Among all TCs,typical super typhoons(STYs)are particularly devastating because they maintain their intensity when landing on the coast and thus cause casualties,economic losses,and environmental damage.Using a 3D tidal model,we reconstructed the typhoon(TY)wind field to simulate the storm surge induced by typical STYs.The TY activity was then analyzed using historical data.Results showed a downtrend of varying degrees in the annual frequency of STYs and TCs in the Western North Pacific(WNP)Basin,with a significant trend change observed for TCs from 1949 to 2021.A large difference in the interannual change in frequency was found between STYs and TCs in the WNP and Eastern China Sea(ECS).Along the coast of EC,the frequency of landfall TCs showed a weak downtrend,and the typical STYs showed reverse micro growth with peak activity in August.Zhejiang,Fujian,and Taiwan were highly vulnerable to the frontal hits of typical STYs.Affected by climate change,the average lifetime maximum intensity(LMI)locations and landfall locations of typical STYs in the ECS basin showed a significant poleward migration trend.In addition,the annual average LMI and accumulated cyclone energy showed an uptrend,indicating the increasing severity of the disaster risk.Affected by the typical STY activity in the ECS,the maximum storm surge area also showed poleward migration,and the coast of North China faced potential growth in high storm surge risks.展开更多
This paper presents an attempt at assimilating clear-sky FY-4A Advanced Geosynchronous Radiation Imager(AGRI)radiances from two water vapor channels for the prediction of three landfalling typhoon events over the West...This paper presents an attempt at assimilating clear-sky FY-4A Advanced Geosynchronous Radiation Imager(AGRI)radiances from two water vapor channels for the prediction of three landfalling typhoon events over the West Pacific Ocean using the 3DVar data assimilation(DA)method along with the WRF model.A channel-sensitive cloud detection scheme based on the particle filter(PF)algorithm is developed and examined against a cloud detection scheme using the multivariate and minimum residual(MMR)algorithm and another traditional cloud mask–dependent cloud detection scheme.Results show that both channel-sensitive cloud detection schemes are effective,while the PF scheme is able to reserve more pixels than the MMR scheme for the same channel.In general,the added value of AGRI radiances is confirmed when comparing with the control experiment without AGRI radiances.Moreover,it is found that the analysis fields of the PF experiment are mostly improved in terms of better depicting the typhoon,including the temperature,moisture,and dynamical conditions.The typhoon track forecast skill is improved with AGRI radiance DA,which could be explained by better simulating the upper trough.The impact of assimilating AGRI radiances on typhoon intensity forecasts is small.On the other hand,improved rainfall forecasts from AGRI DA experiments are found along with reduced errors for both the thermodynamic and moisture fields,albeit the improvements are limited.展开更多
Highly productive estuaries facilitate intense decomposition of dissolved organic matter(DOM) as a carbon source.However,the specific impacts of typhoons on DOM decomposition in eutrophic bays remain unclear.To addres...Highly productive estuaries facilitate intense decomposition of dissolved organic matter(DOM) as a carbon source.However,the specific impacts of typhoons on DOM decomposition in eutrophic bays remain unclear.To address this issue,we investigated the spectral characteristics of DOM before and after Typhoon Ewiniar in Zhanjiang B ay,a eutrophic semi-enclosed bay in the northwestern South China Sea.The results revealed that intense microbial decomposition of DOM occurred during the pre-typhoon period because high nutrient inputs facilitated the mobilization of DOM in the bay.However,the intrusion of external seawater induced by the typhoon diluted the nutrient levels in Zhanjiang B ay,reducing the impact of microbial decomposition on DOM during the post-typhoon perio d.Nevertheless,the net addition of DOM occurred in Zhanjiang Bay during the post-typhoon period,possibly because of the decomposition of particulate organic matter(POM) and desorption of particulate matter.In addition,an increase in apparent oxygen utilization,a decrease in DO saturation and the reduced level of Chl a indicated that organic matter(OM) decomposition was enhanced and OM decomposition shifted to POM decomposition in Zhanjiang Bay after the typhoon.Overall,our study highlighted the shift in the intense OM decomposition from DOM to POM decomposition before and after typhoons in eutrophic bays,providing new insights into the response of typhoons to biogeo chemistry.展开更多
The influences of the three types of reanalysis wind fields on the simulation of three typhoon waves occurred in2015 in offshore China were numerically investigated.The typhoon wave model was based on the simulating w...The influences of the three types of reanalysis wind fields on the simulation of three typhoon waves occurred in2015 in offshore China were numerically investigated.The typhoon wave model was based on the simulating waves nearshore model(SWAN),in which the wind fields for driving waves were derived from the European Centre for Medium-Range Weather Forecasts(ECMWF)Re-Analysis-Interim(ERA-interim),the National Centers for Environmental Prediction climate forecast system version 2(CFSv2)and cross-calibrated multi-platform(CCMP)datasets.Firstly,the typhoon waves generated during the occurrence of typhoons Chan-hom(1509),Linfa(1510)and Nangka(1511)in 2015 were simulated by using the wave model driven by ERA-interim,CFSv2 and CCMP datasets.The numerical results were validated using buoy data and satellite observation data,and the simulation results under the three types of wind fields were in good agreement with the observed data.The numerical results showed that the CCMP wind data was the best in simulating waves overall,and the wind speeds pertaining to ERA-Interim and CCMP were notably smaller than those observed near the typhoon centre.To correct the accuracy of the wind fields,the Holland theoretical wind model was used to revise and optimize the wind speed pertaining to the CCMP near the typhoon centre.The results indicated that the CCMP wind-driven SWAN model could appropriately simulate the typhoon waves generated by three typhoons in offshore China,and the use of the CCMP/Holland blended wind field could effectively improve the accuracy of typhoon wave simulations.展开更多
Climatic characteristics of China-influencing typhoons (CIT) were analyzed in this paper. Main characteristics include:(1) CIT season is May-November, especially from July to September. (2) Frequency of the CIT shows ...Climatic characteristics of China-influencing typhoons (CIT) were analyzed in this paper. Main characteristics include:(1) CIT season is May-November, especially from July to September. (2) Frequency of the CIT shows a decreasing trend during 1951-2004, especially after the late period of the 1960s. (3) Strong CIT also shows an obvious decreasing trend. Meanwhile, there exist obvious interdecadal variations in the CIT genesis, being more southward and eastward than normal in 1960s-1970s, and more northward and westward than normal in the 1980s. In addition, the interrelations between CIT and its environmental factors show that CIT has close relationships with sea surface temperature and East Asian summer monsoon;the structure of the circulations in frequent CIT years is much different from that in infrequent CIT years.展开更多
We present a typhoon-generated noise model with which the noise intensity during typhoons can be estimated accurately. The model is verified through experimental study, and the simulation results agree reasonably with...We present a typhoon-generated noise model with which the noise intensity during typhoons can be estimated accurately. The model is verified through experimental study, and the simulation results agree reasonably with the experimental data. The measured noise intensity is approximately proportional to the cube of the local wind speed.展开更多
Based on the Tropical Region Atmospheric Modeling System for South China Sea(TRAMS),Typhoon Roke(1115) and Sonca(1116) in 2011 which have large forecast errors in numerical operation prediction,have been selected for ...Based on the Tropical Region Atmospheric Modeling System for South China Sea(TRAMS),Typhoon Roke(1115) and Sonca(1116) in 2011 which have large forecast errors in numerical operation prediction,have been selected for research focusing on the initial scheme and its influence on forecast.The purpose is to find a clue for model improvement and enhance the performance of the typhoon model.Several initialization schemes have been designed and the corresponding experiments have been done for Typhoon Roke and Sonca.The results show that the forecast error of both typhoons' track and intensity are less using the initial scheme of relocation and bogus just for the weak Typhoon Sonca,compared with using the scheme for both typhoons.By analysis the influence of the scheme on weak typhoon vortex circulation may be the reason that leads to the improvement.All weak typhoons in 2011 to 2012 are selected for tests.It comes to the conclusion that the initial scheme of relocation and bogus can reduce the error of track and intensity forecast.Besides,the height of cloud top in typhoon vortex constructed by bogus is too high according to weak typhoon.It is feasible to develop a bogus which is suitable for weak typhoon.展开更多
A moored acoustic Doppler current profiler(ADCP) data,satellite-derived sea surface wind data,and the chlorophyll-a concentration were used to examine the influence of typhoon events on the upper ocean in the central ...A moored acoustic Doppler current profiler(ADCP) data,satellite-derived sea surface wind data,and the chlorophyll-a concentration were used to examine the influence of typhoon events on the upper ocean in the central Luzon Strait. The data were collected between August 27 and October 6,2011. Large changes in ocean dynamics and marine life were recorded in the upper layers over the short term during the transit of each of the three violent typhoons that passed over the region during the study period. The geostrophic flow during the period of ADCP monitoring was comparable to the Ekman flow,recently shown to be prominent in the upper layer. Based on the influence of the three typhoon events that swept the Luzon Strait or traversed Luzon Island on their way to the South China Sea,we postulated a typhoon-induced upwelling around the ADCP and found that upward isothermal displacements reached 11.8–39.0 m,which was confirmed by the sea-level anomaly data recorded at the same time. This variability in the upper ocean may play an important role in biological activity,especially in offshore deep-sea regions.展开更多
In this paper, time and space distribution regularity of meso-scale heavy rains in five selected typhoons which landed at Fujian from 1996 to 1998 has been analyzed. Besides, with hourly digitized satellite infrared i...In this paper, time and space distribution regularity of meso-scale heavy rains in five selected typhoons which landed at Fujian from 1996 to 1998 has been analyzed. Besides, with hourly digitized satellite infrared imagery, the features of the mesoscale are revealed for the genesis and evolution of mesoscale convective systems in typhoons. It indicates that the intensity of mesoscale storms is closely connected with the temperature and the area of the coldest cloud cluster. The heavy rainfall usually emerges on the eastern side of the mesoscale convective cloud clusters, where the cloud mass is developing and with a dense gradient and big curvature of isoline of the cloud top temperature.展开更多
In 1998, the annual frequency of typhoon (including tropical storms) genesis created a minimum value — 14, far lower than the minimum of 20 in 1950 over North-West Pacific, while in the Atlantic Ocean, the annual fre...In 1998, the annual frequency of typhoon (including tropical storms) genesis created a minimum value — 14, far lower than the minimum of 20 in 1950 over North-West Pacific, while in the Atlantic Ocean, the annual frequency of hurricanes (including the tropical storm) created a maximum value — 14, far higher than the average number — 9.2. In this paper, an analysis on the relationship between the generation of Typhoon, Hurricane and the Cross-Equatorial Flow was done by using the NCEP/NCAR reanalysis data for 1979 – 1995. It is pointed out that the anomalies of the CEF over the Pacific and Atlantic Ocean is the main cause for the 1998 annual frequency anomalies of Typhoon and Hurricane, respectively.展开更多
X-ray fluorescence scanning with synchrotron radiation was performed to study sediment core records of floods in Amur Bay,Sea of Japan.Interlayers of 3–8 mm with abnormally low bromine content were formed by the Razd...X-ray fluorescence scanning with synchrotron radiation was performed to study sediment core records of floods in Amur Bay,Sea of Japan.Interlayers of 3–8 mm with abnormally low bromine content were formed by the Razdolnaya River discharge to the central part of the bay during extreme floods,accompanied by severe storms at sea.Such conditions in the region are typical for periods of deep tropical cyclones(typhoons),to which the distinguished interlayers were compared on the timescale.This approach was made possible thanks to the high rate of sedimentation in the bay(3–5 mm/a) and low bioturbation of sediments under anoxic conditions.展开更多
The interaction between the typhoons Fengshen and Fung-wong over the Western Pacific in 2002 is studied with the Conditional Nonlinear Optimal Perturbation(CNOP) method.The study discovered that the CNOP method reveal...The interaction between the typhoons Fengshen and Fung-wong over the Western Pacific in 2002 is studied with the Conditional Nonlinear Optimal Perturbation(CNOP) method.The study discovered that the CNOP method reveals the process of one-way interaction between Fengshen and Fung-wong.Moreover,if the region of Fung-wong was selected for verification,the sensitivity area was mainly located in the region of Fengshen and presented a half-ring structure;if the region of Fengshen was selected for verification,most of the sensitivity areas were located in the region between the Fengshen and the subtropical high,far away from Fung-wong.This indicated that Fung-wong is mainly steered by Fengshen,but Fengshen is mainly affected by the subtropical high.The sensitivity experiment showed that the initial errors in the CNOP-identified sensitive areas have larger impacts on the verification-area prediction than those near the typhoon center and their developments take a large proportion in the whole domain.This suggests that the CNOP-identified sensitive areas do have large influence on the verification-area prediction.展开更多
The conventional observations data,NCAR/NCEP-2 reanalysis data,and NOAA outgoing longwave radiation data are used to investigate different characteristics of Leo and Neoguri,two April typhoons that ever made landfall ...The conventional observations data,NCAR/NCEP-2 reanalysis data,and NOAA outgoing longwave radiation data are used to investigate different characteristics of Leo and Neoguri,two April typhoons that ever made landfall on the continent of China over the past 60 years.The results showed that both Leo and Neoguri occurred during the La Nina events.Strong convective activity,weak vertical wind shear and upper-level divergence were in favor of the formation of these April typhoons.Leo originated from a monsoon depression and Neoguri evolved from an easterly wave.The meandering moving track of Leo attributed to strong northeast monsoon and a weak and changeable subtropical high;the steady moving track of Neoguri was governed by a strong and stable subtropical high.Leo and Neoguri had similar terrain conditions and intensities during landfall but were different in precipitation as water vapor transport and duration of kinetic uplifting resulted in apparent discrepancies between them.展开更多
Hurricanes,typhoons and cyclones are the most destructive weather systems.In order to mitigate the disasters caused by these storms,it is necessary to clarify the cause and activity rule of these storms.However,the fo...Hurricanes,typhoons and cyclones are the most destructive weather systems.In order to mitigate the disasters caused by these storms,it is necessary to clarify the cause and activity rule of these storms.However,the formation of hurricanes,typhoons and cyclones as well as the cause of their path and strength changes still remains the major unsolved problems in today’s world.Fortunately,the author has recently studied the formation and activity of polar vortices,therefore can reveal the formation and current driving warm core structure of hurricanes,typhoons and cyclones,which plays an important guiding role in preventing major disasters caused by them.The author finds that all hurricanes,typhoons and cyclones are formed by polar vortices pulled by the moon.In order to prevent hurricanes from raging along the east coast of the United States or cyclones from setting wildfires in western United States,the potentially dangerous vortex genesises near Baffin Island and those over northeastern Siberia should be monitored and weakened in the month before they prevail;in order to prevent typhoons from ravaging the Northwest Pacific or South China Sea,the potentially dangerous vortex genesises over northeastern Siberia should be monitored and weakened in the month before they prevail;in order to prevent cyclones from raging over the South Indian Ocean or the Bay of Bengal,the potentially dangerous vortex genesises in Antarctic should be monitored and weakened in the month before they prevail;in order to avoid abnormal cold in late winter or early spring in the Northern Hemisphere,the potentially dangerous Arctic cold vortex genesises near Baffin Island and those over northeastern Siberia should be monitored and weakened in the month before they prevail.展开更多
Based on typhoon data in Hainan Island from 1957 to 2006,the basic changing characteristics of typhoons' landing on the east of Hainan Island were analyzed.Based on 48 typhoons cases and their disaster conditions,...Based on typhoon data in Hainan Island from 1957 to 2006,the basic changing characteristics of typhoons' landing on the east of Hainan Island were analyzed.Based on 48 typhoons cases and their disaster conditions,objective quantitative grades of typhoon disaster were separated with disaster indicator of typhoon(G) and disaster losses ratio(S).Besides,the disaster assessment was statistically analyzed.The results showed that in the past 50 years,the frequency of typhoons' landing on Hainan Island presented significant annual and monthly changes.The landing locations of typhoons were distributed unevenly.It showed fluctuant changes in disaster indexes of disastrous typhoons,and disaster indexes had increased in the recent 50 years.Typhoon disasters in Hainan Island were catastrophic and a vast majority of those typhoons were of disastrous scales.展开更多
ABSTRACT Data from the World Wide Lightning Location Network (WWLLN) were used to analyze the lightning activity and the relationship between maximum sustained wind and lightning rate in 69 tropical cyclones over t...ABSTRACT Data from the World Wide Lightning Location Network (WWLLN) were used to analyze the lightning activity and the relationship between maximum sustained wind and lightning rate in 69 tropical cyclones over the Northwest Pacific Ocean from 2005 to 2009. The minimum lightning density was observed in the category 2 typhoon Kong-Rey (2007), with a value of only 1.15 d-1 (100 kin)-2. The maximum lightning density occurred in the category 2 typhoon Mitag (2007), with a value of 510.42 d-1 (100 km)-2. The average lightning density decreased with radius from the typhoon center in both weak (categories 1-3) and super (categories 4-5) typhoons. The average lightning density in the inner core of super typhoons was more than twice as large as that for weak typhoons. Both groups of typhoons showed a near-monotonic decrease in lightning density with radius. Results also showed that lightning activity was more active in typhoons that made landfall than in those that did not. The mean correlation coefficient between the accumulated flashes within a 600-kin radius and the maximum wind speed in the weak typhoons and super typhoons was 0.81 and 0.74, respectively. For more than 78% (56%) of the super (weak) typhoons, the lightning activity peaked before the maximum sustained wind speed, with the most common leading time being 30 (60) h. The results suggest that, for the Northwest Pacific Ocean, lightning activity might be used as a measurement of the intensification of typhoons.展开更多
We deployed two ADCP mooring systems west of the Luzon Strait in August 2008,and measured the upper ocean currents at high frequency.Two typhoons passed over the moorings during approximately one-month observation per...We deployed two ADCP mooring systems west of the Luzon Strait in August 2008,and measured the upper ocean currents at high frequency.Two typhoons passed over the moorings during approximately one-month observation period.Using ADCP observations,satellite wind and heat flux measurements,and high-resolution model assimilation products,we studied the response of the upper ocean to typhoons.The first typhoon,Nuri,passed over one of the moorings,resulting in strong Ekman divergence and significant surface cooling.The cooling of surface water lagged the typhoon wind forcing about one day and lasted about five days.The second typhoon,Sinlaku,moved northward east of the Luzon Strait,and did not directly impact currents near the observation regions.Sinlaku increased anomalous surface water transport exchange across the Luzon Strait,which modulated the surface layer current of the Kuroshio.展开更多
In this study,typhoon waves generated during three typhoons(Damrey(1210),Fung-wong(1416),and Chan-hom(1509))in the Yellow Sea and East China Sea were simulated in a simulating waves nearshore(SWAN)model,and the wind f...In this study,typhoon waves generated during three typhoons(Damrey(1210),Fung-wong(1416),and Chan-hom(1509))in the Yellow Sea and East China Sea were simulated in a simulating waves nearshore(SWAN)model,and the wind forcing was constructed by combining reanalyzed wind data with a Holland typhoon wind model.Various parameters,such as the Holland fitting parameter(B)and the maximum wind radius?,were investigated in sensitivity experiments in the Holland model that affect the wind field construction.Six different formulations were considered and the parameters determined by comparing the simulated wind results with in-situ wind measurements.The key factors affecting wave growth and dissipation processes from deep to shallow waters were studied,including wind input,whitecapping,and bottom friction.Comparison with in-situ wave measurements suggested that the KOMEN scheme(wind input exponential growth and whitecapping energy dissipation)and the JONSWAP scheme(dissipation of bottom friction)resulted in good reproduction of the significant wave height of typhoon waves.A preliminary analysis of the wave characteristics in terms of wind-sea and swell wave revealed that swell waves dominated with the distance of R to the eye of the typhoon,while wind-sea prevailed in the outer region up to six to eight times the R values despite a clear misalignment between wind and waves.The results support the hypothesis that nonlinear wave-wave interactions may play a key role in the formation of wave characteristics.展开更多
Five numerical experiments have been performed in this paper by using a quasigtostrophic barotropical model to investigate the interaction of different scale vortiCes on the structure and motion of typhoons.Results sh...Five numerical experiments have been performed in this paper by using a quasigtostrophic barotropical model to investigate the interaction of different scale vortiCes on the structure and motion of typhoons.Results show that this interaction may arouse the irregular changes of the asymmetric structure of typhoons,thus leading to anomalous Phenomena such as meandering tracks and sudden changes in the motion speed of typhoons;the  ̄t Of this interaction on the strucure and motion may be quite different when the smaller vortex is situated in different Posihons of the typhoon circulation.展开更多
This study aims to estimate and predict the impact of climate change on typhoons and wave overtopping during typhoon progresses in Qingdao, China. The SWAN wave model is used to simulate wave elements. The scale coeff...This study aims to estimate and predict the impact of climate change on typhoons and wave overtopping during typhoon progresses in Qingdao, China. The SWAN wave model is used to simulate wave elements. The scale coefficients of wave overtopping are estimated using an empirical prediction formula. A total of 75 tropical cyclones affected Qingdao from 1949 to 2019. These tropical cyclones can be grouped into eight categories according to typhoon tracks. Typhoon wind speed during Track G is projected to decrease, and those of the other seven typhoon progresses will increase by 0.35% – 0.75% in 2025, 0.69% – 1.5% in 2035, and 1.38% – 3.0% in 2055. The significant wave height and wave overtopping outside the bay are greater than those inside the bay. Among the 506 typical points selected, the maximum values of the significant wave height and wave overtopping inside the bay are mainly distributed in the range of 0 – 2 m and 0 – 60 m^3 km^(-1) s^(-1), respectively. The increments of the significant wave height and wave overtopping of Track F are most obvious. The significant wave height of Track F will increase by 50.5% in 2025, 51.8% in 2035, and 53.4% in 2055. In the 2℃ scenario, the maximum value of wave overtopping of Track F will increase by 21.9% in 2025, 24.3% in 2035, and 29.5% in 2055. In the 4℃ scenario, the maximum value of wave overtopping of Track F will increase by 21.9% in 2025, 24.3% in 2035, and 29.5% in 2055.展开更多
基金supported by four funds,including the National Key Research and Development Program of China(No.2022YFC3106102)the Marine Science and Technology Innovation Project of Jiangsu Province(Nos.JSZRH YKJ202105,JSZRHYKI202303)+1 种基金the Nantong Social and Livelihood Science and Technology Project(Nos.MS12022009,MS22022082,MS22022083)the Project on Excellent Post-Graduate Dissertation of Hohai University(No.422003470).
文摘Climate change affects the activity of global and regional tropical cyclones(TCs).Among all TCs,typical super typhoons(STYs)are particularly devastating because they maintain their intensity when landing on the coast and thus cause casualties,economic losses,and environmental damage.Using a 3D tidal model,we reconstructed the typhoon(TY)wind field to simulate the storm surge induced by typical STYs.The TY activity was then analyzed using historical data.Results showed a downtrend of varying degrees in the annual frequency of STYs and TCs in the Western North Pacific(WNP)Basin,with a significant trend change observed for TCs from 1949 to 2021.A large difference in the interannual change in frequency was found between STYs and TCs in the WNP and Eastern China Sea(ECS).Along the coast of EC,the frequency of landfall TCs showed a weak downtrend,and the typical STYs showed reverse micro growth with peak activity in August.Zhejiang,Fujian,and Taiwan were highly vulnerable to the frontal hits of typical STYs.Affected by climate change,the average lifetime maximum intensity(LMI)locations and landfall locations of typical STYs in the ECS basin showed a significant poleward migration trend.In addition,the annual average LMI and accumulated cyclone energy showed an uptrend,indicating the increasing severity of the disaster risk.Affected by the typical STY activity in the ECS,the maximum storm surge area also showed poleward migration,and the coast of North China faced potential growth in high storm surge risks.
基金primarily supported by the Chinese National Natural Science Foundation of China(Grant No. G42192553)Open Fund of Fujian Key Laboratory ofSevere Weather and Key Laboratory of Straits Severe Weather(Grant No. 2023KFKT03)+6 种基金the Open Project Fund of China Meteorological Administration Basin Heavy Rainfall Key Laboratory(Grant No. 2023BHR-Y20)the Open Fund of the State Key Laboratory of Remote Sensing Science (Grant No. OFSLRSS202321)the Program of Shanghai Academic/Technology Research Leader(Grant No. 21XD1404500)the Shanghai Typhoon Research Foundation (Grant No. TFJJ202107)the Chinese National Natural Science Foundation of China (Grant No. G41805016)the National Meteorological Center Foundation (Grant No. FY-APP-2021.0207)the High Performance Computing Center of Nanjing University of Information Science&Technology for their support of this work
文摘This paper presents an attempt at assimilating clear-sky FY-4A Advanced Geosynchronous Radiation Imager(AGRI)radiances from two water vapor channels for the prediction of three landfalling typhoon events over the West Pacific Ocean using the 3DVar data assimilation(DA)method along with the WRF model.A channel-sensitive cloud detection scheme based on the particle filter(PF)algorithm is developed and examined against a cloud detection scheme using the multivariate and minimum residual(MMR)algorithm and another traditional cloud mask–dependent cloud detection scheme.Results show that both channel-sensitive cloud detection schemes are effective,while the PF scheme is able to reserve more pixels than the MMR scheme for the same channel.In general,the added value of AGRI radiances is confirmed when comparing with the control experiment without AGRI radiances.Moreover,it is found that the analysis fields of the PF experiment are mostly improved in terms of better depicting the typhoon,including the temperature,moisture,and dynamical conditions.The typhoon track forecast skill is improved with AGRI radiance DA,which could be explained by better simulating the upper trough.The impact of assimilating AGRI radiances on typhoon intensity forecasts is small.On the other hand,improved rainfall forecasts from AGRI DA experiments are found along with reduced errors for both the thermodynamic and moisture fields,albeit the improvements are limited.
基金The National Natural Science Foundation of China under contract Nos 42276047, 92158201 and U1901213the Entrepreneurship Project of Shantou under contract No.2021112176541391the Scientific Research Start-Up Foundation of Shantou University under contract No.NTF20006。
文摘Highly productive estuaries facilitate intense decomposition of dissolved organic matter(DOM) as a carbon source.However,the specific impacts of typhoons on DOM decomposition in eutrophic bays remain unclear.To address this issue,we investigated the spectral characteristics of DOM before and after Typhoon Ewiniar in Zhanjiang B ay,a eutrophic semi-enclosed bay in the northwestern South China Sea.The results revealed that intense microbial decomposition of DOM occurred during the pre-typhoon period because high nutrient inputs facilitated the mobilization of DOM in the bay.However,the intrusion of external seawater induced by the typhoon diluted the nutrient levels in Zhanjiang B ay,reducing the impact of microbial decomposition on DOM during the post-typhoon perio d.Nevertheless,the net addition of DOM occurred in Zhanjiang Bay during the post-typhoon period,possibly because of the decomposition of particulate organic matter(POM) and desorption of particulate matter.In addition,an increase in apparent oxygen utilization,a decrease in DO saturation and the reduced level of Chl a indicated that organic matter(OM) decomposition was enhanced and OM decomposition shifted to POM decomposition in Zhanjiang Bay after the typhoon.Overall,our study highlighted the shift in the intense OM decomposition from DOM to POM decomposition before and after typhoons in eutrophic bays,providing new insights into the response of typhoons to biogeo chemistry.
基金The Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)under contract No.GML2019ZD0403the Program for Guangdong Introducing Innovative and Enterpreneurial Teams under contract No.2019ZT08L213the Guangdong Provincial Key Laboratory Project under contract No.2019B121203011
文摘The influences of the three types of reanalysis wind fields on the simulation of three typhoon waves occurred in2015 in offshore China were numerically investigated.The typhoon wave model was based on the simulating waves nearshore model(SWAN),in which the wind fields for driving waves were derived from the European Centre for Medium-Range Weather Forecasts(ECMWF)Re-Analysis-Interim(ERA-interim),the National Centers for Environmental Prediction climate forecast system version 2(CFSv2)and cross-calibrated multi-platform(CCMP)datasets.Firstly,the typhoon waves generated during the occurrence of typhoons Chan-hom(1509),Linfa(1510)and Nangka(1511)in 2015 were simulated by using the wave model driven by ERA-interim,CFSv2 and CCMP datasets.The numerical results were validated using buoy data and satellite observation data,and the simulation results under the three types of wind fields were in good agreement with the observed data.The numerical results showed that the CCMP wind data was the best in simulating waves overall,and the wind speeds pertaining to ERA-Interim and CCMP were notably smaller than those observed near the typhoon centre.To correct the accuracy of the wind fields,the Holland theoretical wind model was used to revise and optimize the wind speed pertaining to the CCMP near the typhoon centre.The results indicated that the CCMP wind-driven SWAN model could appropriately simulate the typhoon waves generated by three typhoons in offshore China,and the use of the CCMP/Holland blended wind field could effectively improve the accuracy of typhoon wave simulations.
基金Natural Science Foundation of China (4037502540775046)+1 种基金Project 973 (2006CB403601)Typhoon Research Foundation of Shanghai
文摘Climatic characteristics of China-influencing typhoons (CIT) were analyzed in this paper. Main characteristics include:(1) CIT season is May-November, especially from July to September. (2) Frequency of the CIT shows a decreasing trend during 1951-2004, especially after the late period of the 1960s. (3) Strong CIT also shows an obvious decreasing trend. Meanwhile, there exist obvious interdecadal variations in the CIT genesis, being more southward and eastward than normal in 1960s-1970s, and more northward and westward than normal in the 1980s. In addition, the interrelations between CIT and its environmental factors show that CIT has close relationships with sea surface temperature and East Asian summer monsoon;the structure of the circulations in frequent CIT years is much different from that in infrequent CIT years.
基金Supported by the National Natural Science Foundation of China under Grant No 11125420
文摘We present a typhoon-generated noise model with which the noise intensity during typhoons can be estimated accurately. The model is verified through experimental study, and the simulation results agree reasonably with the experimental data. The measured noise intensity is approximately proportional to the cube of the local wind speed.
基金Guangdong Science and Technology Planning Project(2012A061400012)China Meteorological Administration Special Public Welfare Research Fund(GYHY201406009)+1 种基金Science and Technology Research Project of Guangdong Meteorological Bureau(2013A04)that of Shenzhen(ZDSYS2014071515395703)
文摘Based on the Tropical Region Atmospheric Modeling System for South China Sea(TRAMS),Typhoon Roke(1115) and Sonca(1116) in 2011 which have large forecast errors in numerical operation prediction,have been selected for research focusing on the initial scheme and its influence on forecast.The purpose is to find a clue for model improvement and enhance the performance of the typhoon model.Several initialization schemes have been designed and the corresponding experiments have been done for Typhoon Roke and Sonca.The results show that the forecast error of both typhoons' track and intensity are less using the initial scheme of relocation and bogus just for the weak Typhoon Sonca,compared with using the scheme for both typhoons.By analysis the influence of the scheme on weak typhoon vortex circulation may be the reason that leads to the improvement.All weak typhoons in 2011 to 2012 are selected for tests.It comes to the conclusion that the initial scheme of relocation and bogus can reduce the error of track and intensity forecast.Besides,the height of cloud top in typhoon vortex constructed by bogus is too high according to weak typhoon.It is feasible to develop a bogus which is suitable for weak typhoon.
基金Supported by the National Natural Science Foundation of China(Nos.41306019,U1133001)the Open Grant of LTO SCSIO/CAS(No.LTO201305)+5 种基金the Sanya and CAS Cooperation Project(No.2013YD77)the NSFC Innovative Group(No.41421005)the NSFC-Shandong Joint Fund for Marine Science Research Centers(No.U1406401)the Pilot Strategic Project of CAS(No.XDA11020101)the Knowledge Innovation Engineering Frontier Project of SIDSSE(No.SIDSSE-201205)the Public Science and Technology Research Funds Projects of Ocean(No.201205010)
文摘A moored acoustic Doppler current profiler(ADCP) data,satellite-derived sea surface wind data,and the chlorophyll-a concentration were used to examine the influence of typhoon events on the upper ocean in the central Luzon Strait. The data were collected between August 27 and October 6,2011. Large changes in ocean dynamics and marine life were recorded in the upper layers over the short term during the transit of each of the three violent typhoons that passed over the region during the study period. The geostrophic flow during the period of ADCP monitoring was comparable to the Ekman flow,recently shown to be prominent in the upper layer. Based on the influence of the three typhoon events that swept the Luzon Strait or traversed Luzon Island on their way to the South China Sea,we postulated a typhoon-induced upwelling around the ADCP and found that upward isothermal displacements reached 11.8–39.0 m,which was confirmed by the sea-level anomaly data recorded at the same time. This variability in the upper ocean may play an important role in biological activity,especially in offshore deep-sea regions.
文摘In this paper, time and space distribution regularity of meso-scale heavy rains in five selected typhoons which landed at Fujian from 1996 to 1998 has been analyzed. Besides, with hourly digitized satellite infrared imagery, the features of the mesoscale are revealed for the genesis and evolution of mesoscale convective systems in typhoons. It indicates that the intensity of mesoscale storms is closely connected with the temperature and the area of the coldest cloud cluster. The heavy rainfall usually emerges on the eastern side of the mesoscale convective cloud clusters, where the cloud mass is developing and with a dense gradient and big curvature of isoline of the cloud top temperature.
基金Research on Short-term Climatic Prediction Systems in China - a core scientific project inthe 9th five-year economic development plan Century-bridging Youth Academic Research Backbones from theChinese Academy of Meteorological Sciences
文摘In 1998, the annual frequency of typhoon (including tropical storms) genesis created a minimum value — 14, far lower than the minimum of 20 in 1950 over North-West Pacific, while in the Atlantic Ocean, the annual frequency of hurricanes (including the tropical storm) created a maximum value — 14, far higher than the average number — 9.2. In this paper, an analysis on the relationship between the generation of Typhoon, Hurricane and the Cross-Equatorial Flow was done by using the NCEP/NCAR reanalysis data for 1979 – 1995. It is pointed out that the anomalies of the CEF over the Pacific and Atlantic Ocean is the main cause for the 1998 annual frequency anomalies of Typhoon and Hurricane, respectively.
文摘X-ray fluorescence scanning with synchrotron radiation was performed to study sediment core records of floods in Amur Bay,Sea of Japan.Interlayers of 3–8 mm with abnormally low bromine content were formed by the Razdolnaya River discharge to the central part of the bay during extreme floods,accompanied by severe storms at sea.Such conditions in the region are typical for periods of deep tropical cyclones(typhoons),to which the distinguished interlayers were compared on the timescale.This approach was made possible thanks to the high rate of sedimentation in the bay(3–5 mm/a) and low bioturbation of sediments under anoxic conditions.
基金National Natural Science Foundation of China(41105038)National Science and Technology Support Program(2012BAC22B03)
文摘The interaction between the typhoons Fengshen and Fung-wong over the Western Pacific in 2002 is studied with the Conditional Nonlinear Optimal Perturbation(CNOP) method.The study discovered that the CNOP method reveals the process of one-way interaction between Fengshen and Fung-wong.Moreover,if the region of Fung-wong was selected for verification,the sensitivity area was mainly located in the region of Fengshen and presented a half-ring structure;if the region of Fengshen was selected for verification,most of the sensitivity areas were located in the region between the Fengshen and the subtropical high,far away from Fung-wong.This indicated that Fung-wong is mainly steered by Fengshen,but Fengshen is mainly affected by the subtropical high.The sensitivity experiment showed that the initial errors in the CNOP-identified sensitive areas have larger impacts on the verification-area prediction than those near the typhoon center and their developments take a large proportion in the whole domain.This suggests that the CNOP-identified sensitive areas do have large influence on the verification-area prediction.
基金Research on Techniques of Forecasting and Pre-warning Typhoons Landing on or Seriously Affecting Guangdong,a Project of Guangdong Science and Technology Bureau (2007B060401016)Natural Science Foundation of China (40730951)
文摘The conventional observations data,NCAR/NCEP-2 reanalysis data,and NOAA outgoing longwave radiation data are used to investigate different characteristics of Leo and Neoguri,two April typhoons that ever made landfall on the continent of China over the past 60 years.The results showed that both Leo and Neoguri occurred during the La Nina events.Strong convective activity,weak vertical wind shear and upper-level divergence were in favor of the formation of these April typhoons.Leo originated from a monsoon depression and Neoguri evolved from an easterly wave.The meandering moving track of Leo attributed to strong northeast monsoon and a weak and changeable subtropical high;the steady moving track of Neoguri was governed by a strong and stable subtropical high.Leo and Neoguri had similar terrain conditions and intensities during landfall but were different in precipitation as water vapor transport and duration of kinetic uplifting resulted in apparent discrepancies between them.
文摘Hurricanes,typhoons and cyclones are the most destructive weather systems.In order to mitigate the disasters caused by these storms,it is necessary to clarify the cause and activity rule of these storms.However,the formation of hurricanes,typhoons and cyclones as well as the cause of their path and strength changes still remains the major unsolved problems in today’s world.Fortunately,the author has recently studied the formation and activity of polar vortices,therefore can reveal the formation and current driving warm core structure of hurricanes,typhoons and cyclones,which plays an important guiding role in preventing major disasters caused by them.The author finds that all hurricanes,typhoons and cyclones are formed by polar vortices pulled by the moon.In order to prevent hurricanes from raging along the east coast of the United States or cyclones from setting wildfires in western United States,the potentially dangerous vortex genesises near Baffin Island and those over northeastern Siberia should be monitored and weakened in the month before they prevail;in order to prevent typhoons from ravaging the Northwest Pacific or South China Sea,the potentially dangerous vortex genesises over northeastern Siberia should be monitored and weakened in the month before they prevail;in order to prevent cyclones from raging over the South Indian Ocean or the Bay of Bengal,the potentially dangerous vortex genesises in Antarctic should be monitored and weakened in the month before they prevail;in order to avoid abnormal cold in late winter or early spring in the Northern Hemisphere,the potentially dangerous Arctic cold vortex genesises near Baffin Island and those over northeastern Siberia should be monitored and weakened in the month before they prevail.
文摘Based on typhoon data in Hainan Island from 1957 to 2006,the basic changing characteristics of typhoons' landing on the east of Hainan Island were analyzed.Based on 48 typhoons cases and their disaster conditions,objective quantitative grades of typhoon disaster were separated with disaster indicator of typhoon(G) and disaster losses ratio(S).Besides,the disaster assessment was statistically analyzed.The results showed that in the past 50 years,the frequency of typhoons' landing on Hainan Island presented significant annual and monthly changes.The landing locations of typhoons were distributed unevenly.It showed fluctuant changes in disaster indexes of disastrous typhoons,and disaster indexes had increased in the recent 50 years.Typhoon disasters in Hainan Island were catastrophic and a vast majority of those typhoons were of disastrous scales.
基金supported by the National Natural Science Foundation of China (Grant Nos.41005004 and 40930949)the "One-Hundred Talents Project" of the Chinese Academy of Sciences
文摘ABSTRACT Data from the World Wide Lightning Location Network (WWLLN) were used to analyze the lightning activity and the relationship between maximum sustained wind and lightning rate in 69 tropical cyclones over the Northwest Pacific Ocean from 2005 to 2009. The minimum lightning density was observed in the category 2 typhoon Kong-Rey (2007), with a value of only 1.15 d-1 (100 kin)-2. The maximum lightning density occurred in the category 2 typhoon Mitag (2007), with a value of 510.42 d-1 (100 km)-2. The average lightning density decreased with radius from the typhoon center in both weak (categories 1-3) and super (categories 4-5) typhoons. The average lightning density in the inner core of super typhoons was more than twice as large as that for weak typhoons. Both groups of typhoons showed a near-monotonic decrease in lightning density with radius. Results also showed that lightning activity was more active in typhoons that made landfall than in those that did not. The mean correlation coefficient between the accumulated flashes within a 600-kin radius and the maximum wind speed in the weak typhoons and super typhoons was 0.81 and 0.74, respectively. For more than 78% (56%) of the super (weak) typhoons, the lightning activity peaked before the maximum sustained wind speed, with the most common leading time being 30 (60) h. The results suggest that, for the Northwest Pacific Ocean, lightning activity might be used as a measurement of the intensification of typhoons.
基金Supported by the Knowledge Innovation Program of the Chinese Academy of Sciences (Nos.KZCX1-YW-12-01KZCX2-YW-BR-04)+1 种基金the National Natural Science Foundation of China (Nos.40876007,40806006)the National High Technology Research and Development Program of China (863 Program) (No.2008AA09A402)
文摘We deployed two ADCP mooring systems west of the Luzon Strait in August 2008,and measured the upper ocean currents at high frequency.Two typhoons passed over the moorings during approximately one-month observation period.Using ADCP observations,satellite wind and heat flux measurements,and high-resolution model assimilation products,we studied the response of the upper ocean to typhoons.The first typhoon,Nuri,passed over one of the moorings,resulting in strong Ekman divergence and significant surface cooling.The cooling of surface water lagged the typhoon wind forcing about one day and lasted about five days.The second typhoon,Sinlaku,moved northward east of the Luzon Strait,and did not directly impact currents near the observation regions.Sinlaku increased anomalous surface water transport exchange across the Luzon Strait,which modulated the surface layer current of the Kuroshio.
基金Supported by the National Natural Science Foundation of China(Nos.U1706216,41606024,41506023)the National Key Research and Development Program of China(Nos.2016YFC1402000,2018YFC1407003)+2 种基金the CAS Strategic Priority Project(No.XDA19060202)the NSFC Innovative Group Grant Project(No.41421005)the NSFC-Shandong Joint Fund for Marine Science Research Centers Grant(No.U1406402)
文摘In this study,typhoon waves generated during three typhoons(Damrey(1210),Fung-wong(1416),and Chan-hom(1509))in the Yellow Sea and East China Sea were simulated in a simulating waves nearshore(SWAN)model,and the wind forcing was constructed by combining reanalyzed wind data with a Holland typhoon wind model.Various parameters,such as the Holland fitting parameter(B)and the maximum wind radius?,were investigated in sensitivity experiments in the Holland model that affect the wind field construction.Six different formulations were considered and the parameters determined by comparing the simulated wind results with in-situ wind measurements.The key factors affecting wave growth and dissipation processes from deep to shallow waters were studied,including wind input,whitecapping,and bottom friction.Comparison with in-situ wave measurements suggested that the KOMEN scheme(wind input exponential growth and whitecapping energy dissipation)and the JONSWAP scheme(dissipation of bottom friction)resulted in good reproduction of the significant wave height of typhoon waves.A preliminary analysis of the wave characteristics in terms of wind-sea and swell wave revealed that swell waves dominated with the distance of R to the eye of the typhoon,while wind-sea prevailed in the outer region up to six to eight times the R values despite a clear misalignment between wind and waves.The results support the hypothesis that nonlinear wave-wave interactions may play a key role in the formation of wave characteristics.
文摘Five numerical experiments have been performed in this paper by using a quasigtostrophic barotropical model to investigate the interaction of different scale vortiCes on the structure and motion of typhoons.Results show that this interaction may arouse the irregular changes of the asymmetric structure of typhoons,thus leading to anomalous Phenomena such as meandering tracks and sudden changes in the motion speed of typhoons;the  ̄t Of this interaction on the strucure and motion may be quite different when the smaller vortex is situated in different Posihons of the typhoon circulation.
基金supported by the National Key Research and Development Program of China (No. 2016YFC1401103)the National Natural Science Foundation of China (No. 51779236)+1 种基金the International Cooperation Projects (No. INTASAVE ACCC-045)the Open Fund of Shandong Province Key Laboratory of Ocean Engineering。
文摘This study aims to estimate and predict the impact of climate change on typhoons and wave overtopping during typhoon progresses in Qingdao, China. The SWAN wave model is used to simulate wave elements. The scale coefficients of wave overtopping are estimated using an empirical prediction formula. A total of 75 tropical cyclones affected Qingdao from 1949 to 2019. These tropical cyclones can be grouped into eight categories according to typhoon tracks. Typhoon wind speed during Track G is projected to decrease, and those of the other seven typhoon progresses will increase by 0.35% – 0.75% in 2025, 0.69% – 1.5% in 2035, and 1.38% – 3.0% in 2055. The significant wave height and wave overtopping outside the bay are greater than those inside the bay. Among the 506 typical points selected, the maximum values of the significant wave height and wave overtopping inside the bay are mainly distributed in the range of 0 – 2 m and 0 – 60 m^3 km^(-1) s^(-1), respectively. The increments of the significant wave height and wave overtopping of Track F are most obvious. The significant wave height of Track F will increase by 50.5% in 2025, 51.8% in 2035, and 53.4% in 2055. In the 2℃ scenario, the maximum value of wave overtopping of Track F will increase by 21.9% in 2025, 24.3% in 2035, and 29.5% in 2055. In the 4℃ scenario, the maximum value of wave overtopping of Track F will increase by 21.9% in 2025, 24.3% in 2035, and 29.5% in 2055.