Ocean waves and Stokes drift are generated by typhoons.This study investigated the characteristics of ocean waves and wave-induced Stokes drift and their effects during Typhoon Mangkhut using European Centre for Mediu...Ocean waves and Stokes drift are generated by typhoons.This study investigated the characteristics of ocean waves and wave-induced Stokes drift and their effects during Typhoon Mangkhut using European Centre for MediumRange Weather Forecasts(ECMWF)ERA5 datasets and observational data.The results revealed that the typhoon generated intense cyclones and huge typhoon waves with a maximum wind speed of 45 m/s,a minimum pressure of955 h Pa,and a maximum significant wave height of 12 m.The Stokes drift caused by typhoon waves exceeded 0.6m/s,the Stokes depth scale exceeded 18 m,and the maximum Stokes transport reached 6 m^(2)/s.The spatial distribution of 10-m wind speed,typhoon wave height,Stokes drift,Stokes depth,and Stokes transport during the typhoon was highly correlated with the typhoon track.The distribution along the typhoon track showed significant zonal asymmetry,with greater intensity on the right side of the typhoon track than on the left side.These findings provide important insights into the impact of typhoons on ocean waves and Stokes drift,thus improving our understanding of the interactions between typhoons and the ocean environment.This study also investigated the contribution of Stokes transport to the total net transport during typhoons using Ekman-Stokes Numbers as a comparative measure.The results indicated that the ratio of Stokes transport to the total net transport reached up to 50%within the typhoon radius,while it was approximately 30%outside the radius.Strong Stokes transport induced by typhoon waves led to divergence in the transport direction,which resulted in upwelling of the lower ocean as a compensation current.Thus,Stokes transport played a crucial role in the vertical mixing of the ocean during typhoons.The findings suggested that Stokes transport should be paid more attention to,particularly in high latitude ocean regions,where strong winds can amplify its effects.展开更多
This study investigates the impact of the salinity barrier layer(BL)on the upper ocean response to Super Typhoon Mangkhut(2018)in the western North Pacific.After the passage of Mangkhut,a noticeable increase(~0.6 psu)...This study investigates the impact of the salinity barrier layer(BL)on the upper ocean response to Super Typhoon Mangkhut(2018)in the western North Pacific.After the passage of Mangkhut,a noticeable increase(~0.6 psu)in sea surface salinity and a weak decrease(<1℃)in sea surface temperature(SST)were observed on the right side of the typhoon track.Mangkhut-induced SST change can be divided into the three stages,corresponding to the variations in BL thickness and SST before,during,and after the passage of Mangkhut.During the pre-typhoon stage,SST slightly warmed due to the entrainment of BL warm water,which suppressed the cooling induced by surface heat fluxes and horizontal advection.During the forced stage,SST cooling was controlled by entrainment,and the preexisting BL reduced the total cooling by 0.89℃ d-1,thus significantly weakening the overall SST cooling induced by Mangkhut.During the relaxation stage,the SST cooling was primarily caused by the entrainment.Our results indicate that a preexisting BL can limit typhoon-induced SST cooling by suppressing the entrainment of cold thermocline water,which contributed to Mangkhut becoming the strongest typhoon in 2018.展开更多
The aim of this study is to investigate the sea surface temperature(SST) cooling as typhoons pass the Kuroshio Current.A numerical circulation model,denoted as the Stony Brook Parallel Ocean Model(sbPOM),was used to s...The aim of this study is to investigate the sea surface temperature(SST) cooling as typhoons pass the Kuroshio Current.A numerical circulation model,denoted as the Stony Brook Parallel Ocean Model(sbPOM),was used to simulate the SST,which includes four wave-induced effect terms(i.e.,radiation stress,nonbreaking waves,Stokes drift,and breaking waves) simulated using the third-generation wave model,called WAVEWATCH-Ⅲ(WW3).The significant wave height(SWH) measurements from the Jason-2 altimeter were used to validate the WW3-simulated results,yielding a root mean square error(RMSE) of less than 0.50 m and a correlation coefficient(COR) of approximately 0.93.The water temperature measured from the Advanced Research and Global Observation Satellite was applied to validate the model simulation.Accordingly,the RMSE of the SST is 0.92℃ with a COR of approximately 0.99.As revealed in the sbPOM-simulated SST fields,a reduction in the SST at the Kuroshio Current region was observed as a typhoon passed,although the water temperature of the Kuroshio Current is relatively high.The variation of the SST is consistent with that of the current,whereas the maximum SST lagged behind the occurrence of the peak SWH.Moreover,the Stokes drift plays an important role in the SST cooling after analyzing four wave-induced terms in the background of the Kuroshio Current.The sensitivity experiment also showed that the accuracy of the water temperature was significantly reduced when including breaking waves,which play a negative role in the inside part of the ocean.The variation in the mean mixing layer depth(MLD) showed that a typhoon could enhance the mean MLD in the Kuroshio Current area in September and October,whereas a typhoon has little influence on the mean MLD in the Kuroshio Current area in May.Moreover,the mean MLD rapidly decreased with the weakening of the strong wind force and wave-induced effects when a typhoon crossed the Kuroshio Current.展开更多
In recent years, the coastal region of Southeast China has witnessed a significant increase in the frequency and intensity of extreme rainfall events associated with landfalling typhoons. The hilly and mountainous ter...In recent years, the coastal region of Southeast China has witnessed a significant increase in the frequency and intensity of extreme rainfall events associated with landfalling typhoons. The hilly and mountainous terrain of this area, combined with rapid rainfall accumulation, has led to a surge in flash floods and severe geological hazards. On August 10, 2019, Typhoon Lekima made landfall in Zhejiang Province, China, and its torrential rainfall triggered extensive landslides, resulting in substantial damage and economic losses. Utilizing high-resolution satellite images, we compiled a landslide inventory of the affected area, which comprises a total of 2,774 rainfallinduced landslides over an area of 2965 km2. The majority of these landslides were small to mediumsized and exhibited elongated, clustered patterns. Some landslides displayed characteristics of high-level initiation, obstructing or partially blocking rivers, leading to the formation of debris dams. We used the inventory to analyze the distribution pattern of the landslides and their relationship with topographical, geological, and hydrological factors. The results showed that landslide abundance was closely related to elevation, slope angle, faults, and road density. The landslides were predominantly located in hilly and low mountainous areas, with elevations ranging from 150 to 300 m, slopes of 20 to 30 degrees, and a NE-SE aspect. Notably, we observed the highest Landslide Number Density(LND) and Landslide Area Percentage(LAP) in the rhyolite region. Landslides were concentrated within approximately 4 km on either side of fault zones, with their size and frequency negatively correlated with distances to faults, roads, and river systems. Furthermore, under the influence of typhoons, regions with denser vegetation cover exhibited higher landslide density, reaching maximum values in shrubland areas. In areas experiencing significantly increased concentrated rainfall, landslide density also showed a corresponding rise. In terms of spatial distribution, the rainfall-triggered landslides primarily occurred in the northeastern part of the study area, particularly in regions characterized by complex topography such as Shanzao Village in Yantan Town, Xixia Township, and Shangzhang Township. The research findings offer crucial data on the rainfallinduced landslides triggered by Typhoon Lekima, shedding light on their spatial distribution patterns. These findings provide valuable references for mitigating risks and planning reconstruction in typhoon-affected area.展开更多
The effect of Stokes drift production(SDP),which includes Coriolis-Stokes forcing,Langmuir circulation,and Craik-Lei-bovich vortexes,on the upper ocean during typhoon passage in the Bohai Sea(BS),China,is investigated...The effect of Stokes drift production(SDP),which includes Coriolis-Stokes forcing,Langmuir circulation,and Craik-Lei-bovich vortexes,on the upper ocean during typhoon passage in the Bohai Sea(BS),China,is investigated by using a coupled wave-current model.The role of SDP in turbulent mixing and the further dynamics during the entire typhoon period are comprehensively stud-ied.Experimental results show that SDP greatly increases turbulent mixing at all depths under typhoon conditions by up to seven times that under normal weather conditions.SDP generally strengthens sea surface cooling by more than 0.4℃,with the maximum reduction in sea surface temperature(SST)at the during-typhoon stage exceeding 2℃,which is approximately seven times larger than that under normal weather conditions.The SDP-induced decrease in current speed can exceed 0.2ms^(-1),and the change in current direction is generally opposite the wind direction.These results suggest that Stokes drift depresses the effect of strong winds on currents by intensifying turbulent mixing.Mixed layer depth(MLD)is distinctly increased by O(1)during typhoons due to SDP and can deepen by more than 5m.In addition,the continuous effects of SDP on SST,current,and MLD at the after-typhoon stage indi-cate a hysteretic response between SDP and typhoon actions.展开更多
The generation and propagation mechanism of strong nonlinear waves in the South China Sea is an essential research area. In this study, the third-generation wave model WAVEWATCH Ⅲ is employed to simulate wave fields ...The generation and propagation mechanism of strong nonlinear waves in the South China Sea is an essential research area. In this study, the third-generation wave model WAVEWATCH Ⅲ is employed to simulate wave fields under extreme sea states. The model, integrating the ST6 source term, is validated against observed data, demonstrating its credibility. The spatial distribution of the occurrence probability of strong nonlinear waves during typhoons is shown, and the waves in the straits and the northeastern part of the South China Sea show strong nonlinear characteristics. The high-order spectral model HOS-ocean is employed to simulate the random wave surface series beneath five different platform areas. The waves during the typhoon exhibit strong nonlinear characteristics, and freak waves exist. The space-varying probability model is established to describe the short-term probability distribution of nonlinear wave series. The exceedance probability distributions of the wave surface beneath different platform areas are compared and analyzed. The results show that with an increase in the platform area, the probability of a strong nonlinear wave beneath the platform increases.展开更多
The potential of monitoring the movement of typhoons using the precipitable water vapor(PWV) has been confirmed. However, monitoring the movement of typhoon is focused on PWV, making it difficult to describe the movem...The potential of monitoring the movement of typhoons using the precipitable water vapor(PWV) has been confirmed. However, monitoring the movement of typhoon is focused on PWV, making it difficult to describe the movement of a typhoon in detail minutely and resulting in insufficient accuracy. Hence,based on PWV and meteorological data, we propose an improved typhoon monitoring mode. First, the European Centre for Medium-Range Weather Forecasts Reanalysis 5-derived PWV(ERA5-PWV) and the Global Navigation Satellite System-derived PWV(GNSS-PWV) were compared with the reference radiosonde PWV(RS-PWV). Then, using the PWV and atmospheric parameters derived from ERA5, we discussed the anomalous variations of PWV, pressure(P), precipitation, and wind speed during different typhoons. Finally, we compiled a list of critical factors related to typhoon movement, PWV and P. We developed an improved multi-factor typhoon monitoring mode(IMTM) with different models(i.e.,IMTM-I and IMTM-II) in different cases with a higher density of GNSS observation or only Numerical Weather Prediction(NWP) data. The IMTM was evaluated through the reference movement speeds of HATO and Mangkhut from the China Meteorological Observatory Typhoon Network(CMOTN). The results show that the root mean square(RMS) of the IMTM-I is 1.26 km/h based on ERA5-P and ERA5-PWV,and the absolute bias values are mostly within 2 km/h. Compared with the models considering the single factor ERA5-P/ERA5-PWV, the RMS of the IMTM-I is improved by 26.3% and 38.5%, respectively. The IMTM-II model manifests a residual of only 0.35 km/h. Compared with the single-factor model based on GNSS-PWV/P, the residual of the IMTM-II model is reduced by 90.8% and 84.1%, respectively. These results propose that the typhoon movement monitoring approach combining PWV and P has evident advantages over the single-factor model and is expected to supplement traditional typhoon monitoring.展开更多
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
There was an evident increase in the number of earthquakes in the Xinfengjiang Reservoir from June to July 2014 after the landing of Typhoon Hagibis.To understand the spatial and temporal evolution of this microseismi...There was an evident increase in the number of earthquakes in the Xinfengjiang Reservoir from June to July 2014 after the landing of Typhoon Hagibis.To understand the spatial and temporal evolution of this microseismicity,we built a high-precision earthquake catalog for 2014 and relocated 2275 events using recently developed methods for event picking and catalog construction.Seismicity occurred in the southeastern part of the reservoir,with the preferred fault plane orientation aligned along the Heyuan Fault.The total seismic energy peaked when the typhoon passed through the reservoir,and seismicity correlated with typhoon energy.In contrast,a limited seismic response was observed during the later Typhoon Rammasun.Combining data regarding the water level in the Xinfengjiang Reservoir and seismicity frequency changes in the Taiwan region during these two typhoon events,we suggest that typhoon activity may increase microseism energy by impacting fault stability around the Xinfengjiang Reservoir.Whether a fault can be activated also depends on how close the stress accumulation is to its failure point.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 movement speed of Typhoon In-Fa(2021)was notably slow,at 10 km h-1or less,for over 20 hours following its landfall in Zhejiang,China,in contrast to other typhoons that have made landfall.This study examines the fa...The movement speed of Typhoon In-Fa(2021)was notably slow,at 10 km h-1or less,for over 20 hours following its landfall in Zhejiang,China,in contrast to other typhoons that have made landfall.This study examines the factors contributing to the slow movement of Typhoon In-Fa,including the steering flow,diabatic heating,vertical wind shear(VWS),and surface synoptic situation,by comparing it with Typhoons Yagi(2018)and Rumbia(2018)which followed similar tracks.The findings reveal that the movement speed of Typhoons Yagi and Rumbia is most closely associated with their respective 500 h Pa environmental winds,with a steering flow of 10^(-12)m s^(-1).In contrast,Typhoon InFa’s movement speed is most strongly correlated with the 850 h Pa environmental wind field,with a steering flow speed of only 2 m s^(-1).Furthermore,as Typhoon In-Fa moves northwest after landfall,its intensity is slightly greater than that of Typhoons Yagi and Rumbia,and the pressure gradient in front of Typhoon In-Fa is notably smaller,leading to its slow movement.Additionally,the precipitation distribution of Typhoon In-Fa differs from that of the other two typhoons,resulting in a weak asymmetry of wavenumber-1 diabatic heating,which indirectly affects its movement speed.Further analysis indicates that VWS can alter the typhoon’s structure,weaken its intensity,and ultimately impact its movement.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
Natural events have had a significant impact on overall flight activity,and the aviation industry plays a vital role in helping society cope with the impact of these events.As one of the most impactful weather typhoon...Natural events have had a significant impact on overall flight activity,and the aviation industry plays a vital role in helping society cope with the impact of these events.As one of the most impactful weather typhoon seasons appears and continues,airlines operating in threatened areas and passengers having travel plans during this time period will pay close attention to the development of tropical storms.This paper proposes a deep multimodal fusion and multitasking trajectory prediction model that can improve the reliability of typhoon trajectory prediction and reduce the quantity of flight scheduling cancellation.The deep multimodal fusion module is formed by deep fusion of the feature output by multiple submodal fusion modules,and the multitask generation module uses longitude and latitude as two related tasks for simultaneous prediction.With more dependable data accuracy,problems can be analysed rapidly and more efficiently,enabling better decision-making with a proactive versus reactive posture.When multiple modalities coexist,features can be extracted from them simultaneously to supplement each other’s information.An actual case study,the typhoon Lichma that swept China in 2019,has demonstrated that the algorithm can effectively reduce the number of unnecessary flight cancellations compared to existing flight scheduling and assist the new generation of flight scheduling systems under extreme weather.展开更多
To investigate the stratosphere-troposphere exchange(STE)process induced by the gravity waves(GWs)caused by Typhoon Molave(2020)in the upper troposphere and lower stratosphere,we analyzed the ERA5 reanalysis data prov...To investigate the stratosphere-troposphere exchange(STE)process induced by the gravity waves(GWs)caused by Typhoon Molave(2020)in the upper troposphere and lower stratosphere,we analyzed the ERA5 reanalysis data provided by the European Centre for Medium-Range Weather Forecasts and the CMA Tropical Cyclone Best Track Dataset.We also adopted the mesoscale forecast model Weather Research and Forecasting model V4.3 for numerical simulation.Most of the previous studies were about typhoon-induced STE and typhoon-induced GWs,while our research focused on the STE caused by typhoon-induced gravity waves.Our analysis shows that most of the time,the gravity wave signal of Typhoon Molave appeared below the tropopause.It was stronger on the east side of the typhoon center(10°-20°N,110°-120°E)than on the west side,suggesting an eastward tilted structure with height increase.When the GWs in the upper troposphere and lower stratosphere region on the west side of the typhoon center broke up,it produced strong turbulence,resulting in stratosphere-troposphere exchange.At this time,the average potential vorticity vertical flux increased with the average ozone mass mixing ratio.The gravity wave events and STE process simulated by the WRF model were basically consistent with the results of ERA5 reanalysis data,but the time of gravity wave breaking was different.This study indicates that after the breaking of the GWs induced by typhoons,turbulent mixing will also be generated,and thus the STE.展开更多
Typhoon Meranti originated over the western North Pacific off the south tip of the Taiwan Island in 2010.It moved westward entering the South China Sea,then abruptly turned north into the Taiwan Strait,got intensified...Typhoon Meranti originated over the western North Pacific off the south tip of the Taiwan Island in 2010.It moved westward entering the South China Sea,then abruptly turned north into the Taiwan Strait,got intensified on its way northward,and eventually made landfall on Fujian province.In its evolution,there was a northwest-moving cold vortex in upper troposphere to the south of the Subtropical High over the western North Pacific(hereafter referred to as the Subtropical High).In this paper,the possible impacts of this cold vortex on Meranti in terms of its track and intensity variation is investigated using typhoon best track data from China Meteorological Administration,analyses data of 0.5×0.5 degree provided by the global forecasting system of National Centers for Environmental Prediction,GMS satellite imagery and Taiwan radar data.Results show as follows:(1)The upper-level cold vortex was revolving around the typhoon anticlockwise from its east to its north.In the early stage,due to the blocking of the cold vortex,the role of the Subtropical High to steer Meranti was weakened,which results in the looping of the west-moving typhoon.However,when Meranti was coupled with the cold vortex in meridional direction,the northerly wind changed to the southerly at the upper level of the typhoon;at the same time the Subtropical High protruded westward and its southbound steering flow gained strength,and eventually created an environment in which the southerly winds in both upper and lower troposphere suddenly steered Meranti to the north;(2)The change of airflow direction above the typhoon led to a weak vertical wind shear,which in return facilitated the development of Meranti.Meanwhile,to the east of typhoon Meranti,the overlapped southwesterly jets in upper and lower atmosphere accelerated its tangential wind and contributed to its cyclonic development;(3)The cold vortex not only supplied positive vorticity to the typhoon,but also transported cold advection to its outer bands.In conjunction with the warm and moist air masses at the lower levels,the cold vortex increased the vertical instability in the atmosphere,which was favorable for convection development within the typhoon circulation,and its warmer center was enhanced through latent heat release;(4)Vertical vorticity budget averaged over the typhoon area further shows that the intensification of a typhoon vorticity column mainly depends on horizontal advection of its high-level vorticity,low-level convergence,uneven wind field distribution and its convective activities.展开更多
Typhoon ' Meranti'(1010) is one of the rare offshore strengthened mini-typhoons,featured by heavy impacts,meandering moving route,small coverage,strong intensity and large difficulty in prediction and preventi...Typhoon ' Meranti'(1010) is one of the rare offshore strengthened mini-typhoons,featured by heavy impacts,meandering moving route,small coverage,strong intensity and large difficulty in prediction and prevention.Therefore,the partial characteristics of such typhoon are analyzed in this paper and the discussions of location of the typhoon in offshore area by Doppler radar are the focus of this paper.展开更多
The present work describes the basic features of super typhoon Meranti(2016)by multiple data sources.We mainly focus on the upper ocean response to Meranti using multiplatform satellites,in situ surface drifter and Ar...The present work describes the basic features of super typhoon Meranti(2016)by multiple data sources.We mainly focus on the upper ocean response to Meranti using multiplatform satellites,in situ surface drifter and Argo floats,and compare the results with the widely used idealized wind vortex model and reanalysis datasets.The pre-existing meso-scale eddy provided a favor underlying surface boundary condition and also modulated the upper ocean response to Meranti.Results show that the maximum sea surface cooling was 2.0℃after Meranti.The satellite surface wind failed to capture the core structure of Meranti as the idealized wind vortex model deduced.According to the observation of sea surface drifters,the near-inertial currents were significantly enhanced during the passage of Meranti.The temperature and salinity profiles from Argo floats revealed both the mixed-layer extension and subsurface upwelling induced by Meranti.The comparison results show that the sea surface temperature and surface wind in the reanalysis datasets differs from those in remote sensing system.Sea surface cooling is similar in both satellite and in situ observation,and sea surface salinity response has a lower correlation with the precipitation rate.展开更多
This study is the fi rst to depict typhoon-induced continental shelf wave(CSW)propagation in the eastern Taiwan Strait(TWS)during the passage of Typhoon Meranti in 2016 using tidal gauge data and along-track satellite...This study is the fi rst to depict typhoon-induced continental shelf wave(CSW)propagation in the eastern Taiwan Strait(TWS)during the passage of Typhoon Meranti in 2016 using tidal gauge data and along-track satellite altimeter data.The strong amplitude response of sea level oscillations(within the range of 0.30–0.54 m)as a free,barotropic CSW after Meranti,which impacted the TWS,was clearly detected in time and frequency(in bands of 64–81 h)using wavelet and cross-wavelet analyses.The measured group and phase speeds were consistent with the dispersion curves for CSW with the fi rst-mode derived from the cross-shelf sections of the eastern TWS,with the mean speeds reaching 3 and 5.6±0.7 m/s,respectively.Coincidentally,the typhoon-induced sea level anomaly(SLA)was also captured by the satellite altimeter before this CSW entered into the TWS.Using the theoretical cross-shore CSW modes to fi t the SLA data,the results indicated that the fi rst three wave modes can interpret this CSW event appeared in the southern TWS very well,with the fi rst mode being the dominant one.展开更多
Based on the flood area hydrodynamic model, this paper backs the analysis of the risk warning point of the Mayang Stream in the typical flood process, to determine the disaster-caused critical precipitation and the co...Based on the flood area hydrodynamic model, this paper backs the analysis of the risk warning point of the Mayang Stream in the typical flood process, to determine the disaster-caused critical precipitation and the corresponding flood risk map at different depths of submergence. The result is used as the mountain torrent disaster monitoring and warning indicators and risk assessment of the Mayang Stream. Then based on the flood risk warning service system of small and middle rivers of Fujian Province, the risk warning service of mountain torrent disaster is developed during the impact time of Meranti in 2016. After the process of typhoon, the mountain torrent caused by Meranti was back analyzed by using the decided flood area model, then compared with the results of filed investigation to verify the accuracy of the disaster-caused critical precipitation forecast and the effect of monitoring and early warning services. The result shows that the cause of Mayang Stream’s mountain torrent disaster of the typhoon Meranti is the heavy rainfall and the strong wind. The highest mountain torrent disaster was forecasted by the refine precipitation based on the disaster-caused critical rainfall of the Mayang Stream. The simulated flood scenarios and the field trip’s results were basically matched in upstream and not matched in the downstream. The post-mountain simulation assessment also showed that the flood inundation range basically matched with reality, but the flood process was biased. The reason was that in addition to the differences between the surface rainfall forecast and the real situation, many actual situations cannot be ignored. For example, Meranti caused serious damage to trees, increased river blockages, resulting in changes in flood inundation time and depth, affecting the flood process. It showed the tourism development would cause the river way blocking and increase the risk of flood. In order to prevent and reduce the flood disasters accurately and effectively, the flood risk forecast and the disaster-caused facts should be considered at the same time.展开更多
This paper uses the Coupled Ocean-Atmosphere-Wave-Sediment Transport(COAWST)model to analyze the impact of typhoon‘Hongxia’on the velocity and position movement of the Kuroshio axis,the impact of typhoons on the Kur...This paper uses the Coupled Ocean-Atmosphere-Wave-Sediment Transport(COAWST)model to analyze the impact of typhoon‘Hongxia’on the velocity and position movement of the Kuroshio axis,the impact of typhoons on the Kuroshio intrusion into South China Sea(SCS),the corresponding water,heat,and salt fluxes,and the impact of Kuroshio water in the northeastern SCS.When typhoon‘Hongxia’passed,the Kuroshio intrusion into the SCS was the most significant at 21?N latitude.In the vertical direction,the Kuroshio intrusion was strongest in the subsurface layer,leading to the most significant changes in temperature and salinity in the northeastern part of the SCS in the subsurface layer.Under the influence of the southeastern monsoon in summer,a large amount of low-salinity water accumulates at the surface of the northeastern part of the SCS,and Kuroshio intrusive water remains in the bottom and middle portions of the subsurface layer.The westward deviation of the Kuroshio axis caused by the typhoon displays a certain lag compared with the hot and salty water intrusion into the SCS approximately 7 d later.The impact of the typhoon on the Kuroshio intrusion into the SCS lasts for 20 d.The typhoon caused increases in the water,heat,and salt fluxes associated with the Kuroshio intrusion into the SCS,and the contribution of the typhoon to these fluxes was as high as 40%.Under typhoon conditions,the maximum Kuroshio intrusion flux reached more than twice that before the typhoon.展开更多
基金financially supported by the National Key Research and Development Program of China(Grant No.2021YFB2601100)the National Natural Science Foundation of China(Grant No.52171246)+4 种基金The Belt and Road Special Foundation of the State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering(Grant No.2019491911)the Open Research Foundation of the State Key Laboratory of Coastal and Offshore Engineering,Dalian University of Technology(Grant No.LP2005)the Science and Technology Innovation Program of Hunan Province(Grant No.2023RC3136)the Natural Science Foundation of Hunan Province(Grant No.2022JJ20041)Educational Science Foundation of Hunan Province(Grant No.23A0265)。
文摘Ocean waves and Stokes drift are generated by typhoons.This study investigated the characteristics of ocean waves and wave-induced Stokes drift and their effects during Typhoon Mangkhut using European Centre for MediumRange Weather Forecasts(ECMWF)ERA5 datasets and observational data.The results revealed that the typhoon generated intense cyclones and huge typhoon waves with a maximum wind speed of 45 m/s,a minimum pressure of955 h Pa,and a maximum significant wave height of 12 m.The Stokes drift caused by typhoon waves exceeded 0.6m/s,the Stokes depth scale exceeded 18 m,and the maximum Stokes transport reached 6 m^(2)/s.The spatial distribution of 10-m wind speed,typhoon wave height,Stokes drift,Stokes depth,and Stokes transport during the typhoon was highly correlated with the typhoon track.The distribution along the typhoon track showed significant zonal asymmetry,with greater intensity on the right side of the typhoon track than on the left side.These findings provide important insights into the impact of typhoons on ocean waves and Stokes drift,thus improving our understanding of the interactions between typhoons and the ocean environment.This study also investigated the contribution of Stokes transport to the total net transport during typhoons using Ekman-Stokes Numbers as a comparative measure.The results indicated that the ratio of Stokes transport to the total net transport reached up to 50%within the typhoon radius,while it was approximately 30%outside the radius.Strong Stokes transport induced by typhoon waves led to divergence in the transport direction,which resulted in upwelling of the lower ocean as a compensation current.Thus,Stokes transport played a crucial role in the vertical mixing of the ocean during typhoons.The findings suggested that Stokes transport should be paid more attention to,particularly in high latitude ocean regions,where strong winds can amplify its effects.
基金supported by the National Natural Science Foundation of China(Grant No.42176015)the National Natural Science Foundation of China(Grant No.41605070)+3 种基金the National Key Research and Development Program(Grant No.2021YFC3101500)the Hunan Provincial Natural Science Outstanding Youth Fund(Grant No.2023JJ10053)the Innovation Group Project of the Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)(Grant No.311022001)a project of the Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)(Grant No.SML2021SP207)。
文摘This study investigates the impact of the salinity barrier layer(BL)on the upper ocean response to Super Typhoon Mangkhut(2018)in the western North Pacific.After the passage of Mangkhut,a noticeable increase(~0.6 psu)in sea surface salinity and a weak decrease(<1℃)in sea surface temperature(SST)were observed on the right side of the typhoon track.Mangkhut-induced SST change can be divided into the three stages,corresponding to the variations in BL thickness and SST before,during,and after the passage of Mangkhut.During the pre-typhoon stage,SST slightly warmed due to the entrainment of BL warm water,which suppressed the cooling induced by surface heat fluxes and horizontal advection.During the forced stage,SST cooling was controlled by entrainment,and the preexisting BL reduced the total cooling by 0.89℃ d-1,thus significantly weakening the overall SST cooling induced by Mangkhut.During the relaxation stage,the SST cooling was primarily caused by the entrainment.Our results indicate that a preexisting BL can limit typhoon-induced SST cooling by suppressing the entrainment of cold thermocline water,which contributed to Mangkhut becoming the strongest typhoon in 2018.
基金supported by the National Natural Science Foundation of China(Nos.42076238,42176012,and 42130402)the National Key Research and Development Program of China(No.2021YFC3101702)the Shanghai Frontiers Research Center of the Hadal Biosphere.
文摘The aim of this study is to investigate the sea surface temperature(SST) cooling as typhoons pass the Kuroshio Current.A numerical circulation model,denoted as the Stony Brook Parallel Ocean Model(sbPOM),was used to simulate the SST,which includes four wave-induced effect terms(i.e.,radiation stress,nonbreaking waves,Stokes drift,and breaking waves) simulated using the third-generation wave model,called WAVEWATCH-Ⅲ(WW3).The significant wave height(SWH) measurements from the Jason-2 altimeter were used to validate the WW3-simulated results,yielding a root mean square error(RMSE) of less than 0.50 m and a correlation coefficient(COR) of approximately 0.93.The water temperature measured from the Advanced Research and Global Observation Satellite was applied to validate the model simulation.Accordingly,the RMSE of the SST is 0.92℃ with a COR of approximately 0.99.As revealed in the sbPOM-simulated SST fields,a reduction in the SST at the Kuroshio Current region was observed as a typhoon passed,although the water temperature of the Kuroshio Current is relatively high.The variation of the SST is consistent with that of the current,whereas the maximum SST lagged behind the occurrence of the peak SWH.Moreover,the Stokes drift plays an important role in the SST cooling after analyzing four wave-induced terms in the background of the Kuroshio Current.The sensitivity experiment also showed that the accuracy of the water temperature was significantly reduced when including breaking waves,which play a negative role in the inside part of the ocean.The variation in the mean mixing layer depth(MLD) showed that a typhoon could enhance the mean MLD in the Kuroshio Current area in September and October,whereas a typhoon has little influence on the mean MLD in the Kuroshio Current area in May.Moreover,the mean MLD rapidly decreased with the weakening of the strong wind force and wave-induced effects when a typhoon crossed the Kuroshio Current.
基金supported by National Natural Science Foundation of China (42277136)Natural Science Research Project of Anhui Educational Committee (2023AH030041)National Key Research and Development Program of China (2021YFB3901205)。
文摘In recent years, the coastal region of Southeast China has witnessed a significant increase in the frequency and intensity of extreme rainfall events associated with landfalling typhoons. The hilly and mountainous terrain of this area, combined with rapid rainfall accumulation, has led to a surge in flash floods and severe geological hazards. On August 10, 2019, Typhoon Lekima made landfall in Zhejiang Province, China, and its torrential rainfall triggered extensive landslides, resulting in substantial damage and economic losses. Utilizing high-resolution satellite images, we compiled a landslide inventory of the affected area, which comprises a total of 2,774 rainfallinduced landslides over an area of 2965 km2. The majority of these landslides were small to mediumsized and exhibited elongated, clustered patterns. Some landslides displayed characteristics of high-level initiation, obstructing or partially blocking rivers, leading to the formation of debris dams. We used the inventory to analyze the distribution pattern of the landslides and their relationship with topographical, geological, and hydrological factors. The results showed that landslide abundance was closely related to elevation, slope angle, faults, and road density. The landslides were predominantly located in hilly and low mountainous areas, with elevations ranging from 150 to 300 m, slopes of 20 to 30 degrees, and a NE-SE aspect. Notably, we observed the highest Landslide Number Density(LND) and Landslide Area Percentage(LAP) in the rhyolite region. Landslides were concentrated within approximately 4 km on either side of fault zones, with their size and frequency negatively correlated with distances to faults, roads, and river systems. Furthermore, under the influence of typhoons, regions with denser vegetation cover exhibited higher landslide density, reaching maximum values in shrubland areas. In areas experiencing significantly increased concentrated rainfall, landslide density also showed a corresponding rise. In terms of spatial distribution, the rainfall-triggered landslides primarily occurred in the northeastern part of the study area, particularly in regions characterized by complex topography such as Shanzao Village in Yantan Town, Xixia Township, and Shangzhang Township. The research findings offer crucial data on the rainfallinduced landslides triggered by Typhoon Lekima, shedding light on their spatial distribution patterns. These findings provide valuable references for mitigating risks and planning reconstruction in typhoon-affected area.
基金supported by the National Natural Science Foundation of China(No.42176020)the National Key Research and Development Program(No.2022 YFC3105002).
文摘The effect of Stokes drift production(SDP),which includes Coriolis-Stokes forcing,Langmuir circulation,and Craik-Lei-bovich vortexes,on the upper ocean during typhoon passage in the Bohai Sea(BS),China,is investigated by using a coupled wave-current model.The role of SDP in turbulent mixing and the further dynamics during the entire typhoon period are comprehensively stud-ied.Experimental results show that SDP greatly increases turbulent mixing at all depths under typhoon conditions by up to seven times that under normal weather conditions.SDP generally strengthens sea surface cooling by more than 0.4℃,with the maximum reduction in sea surface temperature(SST)at the during-typhoon stage exceeding 2℃,which is approximately seven times larger than that under normal weather conditions.The SDP-induced decrease in current speed can exceed 0.2ms^(-1),and the change in current direction is generally opposite the wind direction.These results suggest that Stokes drift depresses the effect of strong winds on currents by intensifying turbulent mixing.Mixed layer depth(MLD)is distinctly increased by O(1)during typhoons due to SDP and can deepen by more than 5m.In addition,the continuous effects of SDP on SST,current,and MLD at the after-typhoon stage indi-cate a hysteretic response between SDP and typhoon actions.
基金financially supported by the National Key R&D Program of China(No.2022YFC3104205)the National Natural Science Foundation of China(No.42377457).
文摘The generation and propagation mechanism of strong nonlinear waves in the South China Sea is an essential research area. In this study, the third-generation wave model WAVEWATCH Ⅲ is employed to simulate wave fields under extreme sea states. The model, integrating the ST6 source term, is validated against observed data, demonstrating its credibility. The spatial distribution of the occurrence probability of strong nonlinear waves during typhoons is shown, and the waves in the straits and the northeastern part of the South China Sea show strong nonlinear characteristics. The high-order spectral model HOS-ocean is employed to simulate the random wave surface series beneath five different platform areas. The waves during the typhoon exhibit strong nonlinear characteristics, and freak waves exist. The space-varying probability model is established to describe the short-term probability distribution of nonlinear wave series. The exceedance probability distributions of the wave surface beneath different platform areas are compared and analyzed. The results show that with an increase in the platform area, the probability of a strong nonlinear wave beneath the platform increases.
基金supported by the Guangxi Natural Science Foundation of China (2020GXNSFBA297145,Guike AD23026177)the Foundation of Guilin University of Technology(GUTQDJJ6616032)+3 种基金Guangxi Key Laboratory of Spatial Information and Geomatics (21-238-21-05)the National Natural Science Foundation of China (42064002,42004025,42074035,42204006)the Innovative Training Program Foundation (202210596015,202210596402)the Open Fund of Hubei Luojia Laboratory(gran 230100020,230100019)。
文摘The potential of monitoring the movement of typhoons using the precipitable water vapor(PWV) has been confirmed. However, monitoring the movement of typhoon is focused on PWV, making it difficult to describe the movement of a typhoon in detail minutely and resulting in insufficient accuracy. Hence,based on PWV and meteorological data, we propose an improved typhoon monitoring mode. First, the European Centre for Medium-Range Weather Forecasts Reanalysis 5-derived PWV(ERA5-PWV) and the Global Navigation Satellite System-derived PWV(GNSS-PWV) were compared with the reference radiosonde PWV(RS-PWV). Then, using the PWV and atmospheric parameters derived from ERA5, we discussed the anomalous variations of PWV, pressure(P), precipitation, and wind speed during different typhoons. Finally, we compiled a list of critical factors related to typhoon movement, PWV and P. We developed an improved multi-factor typhoon monitoring mode(IMTM) with different models(i.e.,IMTM-I and IMTM-II) in different cases with a higher density of GNSS observation or only Numerical Weather Prediction(NWP) data. The IMTM was evaluated through the reference movement speeds of HATO and Mangkhut from the China Meteorological Observatory Typhoon Network(CMOTN). The results show that the root mean square(RMS) of the IMTM-I is 1.26 km/h based on ERA5-P and ERA5-PWV,and the absolute bias values are mostly within 2 km/h. Compared with the models considering the single factor ERA5-P/ERA5-PWV, the RMS of the IMTM-I is improved by 26.3% and 38.5%, respectively. The IMTM-II model manifests a residual of only 0.35 km/h. Compared with the single-factor model based on GNSS-PWV/P, the residual of the IMTM-II model is reduced by 90.8% and 84.1%, respectively. These results propose that the typhoon movement monitoring approach combining PWV and P has evident advantages over the single-factor model and is expected to supplement traditional typhoon monitoring.
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Strategic Priority Research Program(B)of the Chinese Academy of Sciences(No.XDB42020304)National Natural Science Foundation of China(No.42074059).
文摘There was an evident increase in the number of earthquakes in the Xinfengjiang Reservoir from June to July 2014 after the landing of Typhoon Hagibis.To understand the spatial and temporal evolution of this microseismicity,we built a high-precision earthquake catalog for 2014 and relocated 2275 events using recently developed methods for event picking and catalog construction.Seismicity occurred in the southeastern part of the reservoir,with the preferred fault plane orientation aligned along the Heyuan Fault.The total seismic energy peaked when the typhoon passed through the reservoir,and seismicity correlated with typhoon energy.In contrast,a limited seismic response was observed during the later Typhoon Rammasun.Combining data regarding the water level in the Xinfengjiang Reservoir and seismicity frequency changes in the Taiwan region during these two typhoon events,we suggest that typhoon activity may increase microseism energy by impacting fault stability around the Xinfengjiang Reservoir.Whether a fault can be activated also depends on how close the stress accumulation is to its failure point.
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Natural Science Foundation of Shandong Province(ZR2021MD012)CMA Special Fund for Innovation and Development(CXFZ2023J015)。
文摘The movement speed of Typhoon In-Fa(2021)was notably slow,at 10 km h-1or less,for over 20 hours following its landfall in Zhejiang,China,in contrast to other typhoons that have made landfall.This study examines the factors contributing to the slow movement of Typhoon In-Fa,including the steering flow,diabatic heating,vertical wind shear(VWS),and surface synoptic situation,by comparing it with Typhoons Yagi(2018)and Rumbia(2018)which followed similar tracks.The findings reveal that the movement speed of Typhoons Yagi and Rumbia is most closely associated with their respective 500 h Pa environmental winds,with a steering flow of 10^(-12)m s^(-1).In contrast,Typhoon InFa’s movement speed is most strongly correlated with the 850 h Pa environmental wind field,with a steering flow speed of only 2 m s^(-1).Furthermore,as Typhoon In-Fa moves northwest after landfall,its intensity is slightly greater than that of Typhoons Yagi and Rumbia,and the pressure gradient in front of Typhoon In-Fa is notably smaller,leading to its slow movement.Additionally,the precipitation distribution of Typhoon In-Fa differs from that of the other two typhoons,resulting in a weak asymmetry of wavenumber-1 diabatic heating,which indirectly affects its movement speed.Further analysis indicates that VWS can alter the typhoon’s structure,weaken its intensity,and ultimately impact its movement.
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supported by the National Natural Science Foundation of China(62073330)。
文摘Natural events have had a significant impact on overall flight activity,and the aviation industry plays a vital role in helping society cope with the impact of these events.As one of the most impactful weather typhoon seasons appears and continues,airlines operating in threatened areas and passengers having travel plans during this time period will pay close attention to the development of tropical storms.This paper proposes a deep multimodal fusion and multitasking trajectory prediction model that can improve the reliability of typhoon trajectory prediction and reduce the quantity of flight scheduling cancellation.The deep multimodal fusion module is formed by deep fusion of the feature output by multiple submodal fusion modules,and the multitask generation module uses longitude and latitude as two related tasks for simultaneous prediction.With more dependable data accuracy,problems can be analysed rapidly and more efficiently,enabling better decision-making with a proactive versus reactive posture.When multiple modalities coexist,features can be extracted from them simultaneously to supplement each other’s information.An actual case study,the typhoon Lichma that swept China in 2019,has demonstrated that the algorithm can effectively reduce the number of unnecessary flight cancellations compared to existing flight scheduling and assist the new generation of flight scheduling systems under extreme weather.
基金Guangdong Basic and Applied Basic Research Foundation(2023A1515011323)National Natural Science Foun-dation of China(42130604,42130605,72293604)+4 种基金Guangdong Provincial Observation and Research Station for Tropical Ocean Environment in Western Coastal Waters(GSTOEW)First-Class Discipline Plan of Guangdong Province(080503032101,231420003)Fundamental Research Funds for the Central Universities(202362001,202072010)China Scholarship Council(202208440223)Natural Science Foundation of Shanghai(23ZR1473800)。
文摘To investigate the stratosphere-troposphere exchange(STE)process induced by the gravity waves(GWs)caused by Typhoon Molave(2020)in the upper troposphere and lower stratosphere,we analyzed the ERA5 reanalysis data provided by the European Centre for Medium-Range Weather Forecasts and the CMA Tropical Cyclone Best Track Dataset.We also adopted the mesoscale forecast model Weather Research and Forecasting model V4.3 for numerical simulation.Most of the previous studies were about typhoon-induced STE and typhoon-induced GWs,while our research focused on the STE caused by typhoon-induced gravity waves.Our analysis shows that most of the time,the gravity wave signal of Typhoon Molave appeared below the tropopause.It was stronger on the east side of the typhoon center(10°-20°N,110°-120°E)than on the west side,suggesting an eastward tilted structure with height increase.When the GWs in the upper troposphere and lower stratosphere region on the west side of the typhoon center broke up,it produced strong turbulence,resulting in stratosphere-troposphere exchange.At this time,the average potential vorticity vertical flux increased with the average ozone mass mixing ratio.The gravity wave events and STE process simulated by the WRF model were basically consistent with the results of ERA5 reanalysis data,but the time of gravity wave breaking was different.This study indicates that after the breaking of the GWs induced by typhoons,turbulent mixing will also be generated,and thus the STE.
基金Natural Fundamental Research and Development Project"973"Program(2009CB421504)Natural Science Foundation of China(40975032+2 种基金4073094841075037)Special Project of Chinese Academy of Meteorological Sciences(2007Y006)
文摘Typhoon Meranti originated over the western North Pacific off the south tip of the Taiwan Island in 2010.It moved westward entering the South China Sea,then abruptly turned north into the Taiwan Strait,got intensified on its way northward,and eventually made landfall on Fujian province.In its evolution,there was a northwest-moving cold vortex in upper troposphere to the south of the Subtropical High over the western North Pacific(hereafter referred to as the Subtropical High).In this paper,the possible impacts of this cold vortex on Meranti in terms of its track and intensity variation is investigated using typhoon best track data from China Meteorological Administration,analyses data of 0.5×0.5 degree provided by the global forecasting system of National Centers for Environmental Prediction,GMS satellite imagery and Taiwan radar data.Results show as follows:(1)The upper-level cold vortex was revolving around the typhoon anticlockwise from its east to its north.In the early stage,due to the blocking of the cold vortex,the role of the Subtropical High to steer Meranti was weakened,which results in the looping of the west-moving typhoon.However,when Meranti was coupled with the cold vortex in meridional direction,the northerly wind changed to the southerly at the upper level of the typhoon;at the same time the Subtropical High protruded westward and its southbound steering flow gained strength,and eventually created an environment in which the southerly winds in both upper and lower troposphere suddenly steered Meranti to the north;(2)The change of airflow direction above the typhoon led to a weak vertical wind shear,which in return facilitated the development of Meranti.Meanwhile,to the east of typhoon Meranti,the overlapped southwesterly jets in upper and lower atmosphere accelerated its tangential wind and contributed to its cyclonic development;(3)The cold vortex not only supplied positive vorticity to the typhoon,but also transported cold advection to its outer bands.In conjunction with the warm and moist air masses at the lower levels,the cold vortex increased the vertical instability in the atmosphere,which was favorable for convection development within the typhoon circulation,and its warmer center was enhanced through latent heat release;(4)Vertical vorticity budget averaged over the typhoon area further shows that the intensification of a typhoon vorticity column mainly depends on horizontal advection of its high-level vorticity,low-level convergence,uneven wind field distribution and its convective activities.
文摘Typhoon ' Meranti'(1010) is one of the rare offshore strengthened mini-typhoons,featured by heavy impacts,meandering moving route,small coverage,strong intensity and large difficulty in prediction and prevention.Therefore,the partial characteristics of such typhoon are analyzed in this paper and the discussions of location of the typhoon in offshore area by Doppler radar are the focus of this paper.
基金The National Program on Global Change and Air-Sea Interaction under contract No.GASI-IPOVAI-04the National Natural Science Foundation of China under contract Nos 41830533,41876003 and 41621064the China-Sweden(NSFC-STINT)Cooperation and Exchange Project under contract No.41911530149
文摘The present work describes the basic features of super typhoon Meranti(2016)by multiple data sources.We mainly focus on the upper ocean response to Meranti using multiplatform satellites,in situ surface drifter and Argo floats,and compare the results with the widely used idealized wind vortex model and reanalysis datasets.The pre-existing meso-scale eddy provided a favor underlying surface boundary condition and also modulated the upper ocean response to Meranti.Results show that the maximum sea surface cooling was 2.0℃after Meranti.The satellite surface wind failed to capture the core structure of Meranti as the idealized wind vortex model deduced.According to the observation of sea surface drifters,the near-inertial currents were significantly enhanced during the passage of Meranti.The temperature and salinity profiles from Argo floats revealed both the mixed-layer extension and subsurface upwelling induced by Meranti.The comparison results show that the sea surface temperature and surface wind in the reanalysis datasets differs from those in remote sensing system.Sea surface cooling is similar in both satellite and in situ observation,and sea surface salinity response has a lower correlation with the precipitation rate.
基金Supported by the Science Foundation of Fujian Province(No.2019J01119)the Scientifi c Research Foundation of Third Institute of Oceanography,MNR(Nos.2017011,2019018)+1 种基金the National Natural Science Foundation of China(No.41506014)the National Key Research and Development Program of China(No.2016YFC1402607)。
文摘This study is the fi rst to depict typhoon-induced continental shelf wave(CSW)propagation in the eastern Taiwan Strait(TWS)during the passage of Typhoon Meranti in 2016 using tidal gauge data and along-track satellite altimeter data.The strong amplitude response of sea level oscillations(within the range of 0.30–0.54 m)as a free,barotropic CSW after Meranti,which impacted the TWS,was clearly detected in time and frequency(in bands of 64–81 h)using wavelet and cross-wavelet analyses.The measured group and phase speeds were consistent with the dispersion curves for CSW with the fi rst-mode derived from the cross-shelf sections of the eastern TWS,with the mean speeds reaching 3 and 5.6±0.7 m/s,respectively.Coincidentally,the typhoon-induced sea level anomaly(SLA)was also captured by the satellite altimeter before this CSW entered into the TWS.Using the theoretical cross-shore CSW modes to fi t the SLA data,the results indicated that the fi rst three wave modes can interpret this CSW event appeared in the southern TWS very well,with the fi rst mode being the dominant one.
文摘Based on the flood area hydrodynamic model, this paper backs the analysis of the risk warning point of the Mayang Stream in the typical flood process, to determine the disaster-caused critical precipitation and the corresponding flood risk map at different depths of submergence. The result is used as the mountain torrent disaster monitoring and warning indicators and risk assessment of the Mayang Stream. Then based on the flood risk warning service system of small and middle rivers of Fujian Province, the risk warning service of mountain torrent disaster is developed during the impact time of Meranti in 2016. After the process of typhoon, the mountain torrent caused by Meranti was back analyzed by using the decided flood area model, then compared with the results of filed investigation to verify the accuracy of the disaster-caused critical precipitation forecast and the effect of monitoring and early warning services. The result shows that the cause of Mayang Stream’s mountain torrent disaster of the typhoon Meranti is the heavy rainfall and the strong wind. The highest mountain torrent disaster was forecasted by the refine precipitation based on the disaster-caused critical rainfall of the Mayang Stream. The simulated flood scenarios and the field trip’s results were basically matched in upstream and not matched in the downstream. The post-mountain simulation assessment also showed that the flood inundation range basically matched with reality, but the flood process was biased. The reason was that in addition to the differences between the surface rainfall forecast and the real situation, many actual situations cannot be ignored. For example, Meranti caused serious damage to trees, increased river blockages, resulting in changes in flood inundation time and depth, affecting the flood process. It showed the tourism development would cause the river way blocking and increase the risk of flood. In order to prevent and reduce the flood disasters accurately and effectively, the flood risk forecast and the disaster-caused facts should be considered at the same time.
基金Tianjin Key Laboratory for Oceanic Meteorology for its support via the 2020 Open Fund Project(No.2020TKLOMZD01).
文摘This paper uses the Coupled Ocean-Atmosphere-Wave-Sediment Transport(COAWST)model to analyze the impact of typhoon‘Hongxia’on the velocity and position movement of the Kuroshio axis,the impact of typhoons on the Kuroshio intrusion into South China Sea(SCS),the corresponding water,heat,and salt fluxes,and the impact of Kuroshio water in the northeastern SCS.When typhoon‘Hongxia’passed,the Kuroshio intrusion into the SCS was the most significant at 21?N latitude.In the vertical direction,the Kuroshio intrusion was strongest in the subsurface layer,leading to the most significant changes in temperature and salinity in the northeastern part of the SCS in the subsurface layer.Under the influence of the southeastern monsoon in summer,a large amount of low-salinity water accumulates at the surface of the northeastern part of the SCS,and Kuroshio intrusive water remains in the bottom and middle portions of the subsurface layer.The westward deviation of the Kuroshio axis caused by the typhoon displays a certain lag compared with the hot and salty water intrusion into the SCS approximately 7 d later.The impact of the typhoon on the Kuroshio intrusion into the SCS lasts for 20 d.The typhoon caused increases in the water,heat,and salt fluxes associated with the Kuroshio intrusion into the SCS,and the contribution of the typhoon to these fluxes was as high as 40%.Under typhoon conditions,the maximum Kuroshio intrusion flux reached more than twice that before the typhoon.
