Landfalling typhoons can cause disasters over large regions.The government and emergency responders need to take measures to mitigate disasters according to the forecast of landfall position,while slight timing error ...Landfalling typhoons can cause disasters over large regions.The government and emergency responders need to take measures to mitigate disasters according to the forecast of landfall position,while slight timing error can be ignored.The reliability of operational model forecasts of typhoon landfall position needs to be evaluated beforehand,according to the forecasts and observation of historical cases.In the evaluation of landfalling typhoon track,the traditional method based on point-to-point matching methods could be influenced by the predicted typhoon translation speed.Consequently,the traditional track evaluation method may result in a large track error even if the predicted landfall position is close to observation.The purpose of this paper is to address the above issue using a simple evaluation method of landfalling typhoon track forecast based on the time neighborhood approach.In this new method,the timing error was lessened to highlight the importance of the position error during the landfall of typhoon.The properties of the time neighborhood method are compared with the traditional method based on numerical forecast results of 12 landfalling typhoon cases.Results demonstrated that the new method is not sensitive to the sampling frequency,and that the difference between the time neighborhood and traditional method will be more obvious when the moving speed of typhoon is moderate(between 15−30 km h^(−1)).The time neighborhood concept can be easily extended to a broader context when one attempts to examine the position error more than the timing error.展开更多
In order to solve the difficult problem of typhoon track prediction due to the sparsity of conventional data over the tropical ocean, in this paper, the No. 0205 typhoon Rammasun of 4-6 July 2002 is studied and an exp...In order to solve the difficult problem of typhoon track prediction due to the sparsity of conventional data over the tropical ocean, in this paper, the No. 0205 typhoon Rammasun of 4-6 July 2002 is studied and an experiment of the typhoon track prediction is made with the direct use of the Advanced TIROS-N Operational Vertical Sounder (ATOVS) microwave radiance data in three-dimensional variational data assimilation. The prediction result shows that the experiment with the ATOVS microwave radiance data can not only successfully predict the observed fact that typhoon Rammasun moves northward and turns right, but can also simulate the action of the fast movement of the typhoon, which cannot be simulated with only conventional radiosonde data. The skill of the typhoon track prediction with the ATOVS microwave radiance data is much better than that without the ATOVS data. The typhoon track prediction of the former scheme is consistent in time and in location with the observation. The direct assimilation of展开更多
It is of vital importance to reduce injuries and economic losses by accurate forecasts of typhoon tracks. A huge amount of typhoon observations have been accumulated by the meteorological department, however, they are...It is of vital importance to reduce injuries and economic losses by accurate forecasts of typhoon tracks. A huge amount of typhoon observations have been accumulated by the meteorological department, however, they are yet to be adequately utilized. It is an effective method to employ machine learning to perform forecasts. A long short term memory(LSTM) neural network is trained based on the typhoon observations during 1949–2011 in China's Mainland, combined with big data and data mining technologies, and a forecast model based on machine learning for the prediction of typhoon tracks is developed. The results show that the employed algorithm produces desirable 6–24 h nowcasting of typhoon tracks with an improved precision.展开更多
To determine the grid resolutions of the WRF model in the typhoon simulation,some sensitivity analysis of horizontal and vertical resolutions in different conditions has been carried out.Different horizontal resolutio...To determine the grid resolutions of the WRF model in the typhoon simulation,some sensitivity analysis of horizontal and vertical resolutions in different conditions has been carried out.Different horizontal resolutions(5,10,20,30 km),nesting grids(15 and 5 km),different vertical resolutions(35-layers,28-layers,20-layers)and different top maximum pressures(1 000,2 000,3 500,5 000 Pa)had been used in the mesoscale numerical model WRF to simulate the Typhoon Kai-tak.The simulation results of typhoon track,wind speed and sea level pressure at different horizontal and vertical resolutions have been compared and analyzed.The horizontal and vertical resolutions of the model have limited effect on the simulation effect of the typhoon track.Different horizontal and vertical resolutions have obvious effects on typhoon strength(defined by wind speed)and intensity(defined by sea level pressure,SLP),especially for sea level pressure.The typhoon intensity simulated by the high-resolution model is closer to the real situation and the nesting grids can improve computational accuracy and efficiency.The simulation results affected by vertical resolution using 35-layers is better than the simulation results using 20-layers and 28-layers simulations.Through comparison and analysis,the horizontal and vertical resolutions of WRF model are finally determined as follows:the two-way nesting grid of 15 and 5 km is comprehensively determined,and the vertical layers is 35-layers,the top maximum pressure is 2 000 Pa.展开更多
In this paper, we first analyzed cloud drift wind(CDW) data distribution in the vertical direction, and then reassigned the height of every CDW in the research domain in terms of background information, and finally, c...In this paper, we first analyzed cloud drift wind(CDW) data distribution in the vertical direction, and then reassigned the height of every CDW in the research domain in terms of background information, and finally, conducted contrast numerical experiments of assimilating the CDW data before and after reassignment to examine the impacts on the forecast of the track of Typhoon Chanthu(1003) from 00:00(Coordinated Universal Time) 21 July to 00:00 UTC23 July, 2010. The analysis results of the CDW data indicate that the number of CDWs is mainly distributed in the midand upper-troposphere above 500 h Pa, with the maximum number at about 300 h Pa. The height reassigning method mentioned in this work may update the height effectively, and the CDW data are distributed reasonably and no obvious contradiction occurs in the horizontal direction after height reassignment. After assimilating the height-reassigned CDW data, especially the water vapor CDW data, the initial wind field around Typhoon Chanthu(1003) became more reasonable, and then the steering current leading the typhoon to move to the correct location became stronger. As a result, the numerical track predictions are improved.展开更多
Three typhoon cases are selected to conduct a series of simulations that are initialized from sequential analyses. The results show that the forecast error in crucial area where a tropical cyclone(TC) interactes with ...Three typhoon cases are selected to conduct a series of simulations that are initialized from sequential analyses. The results show that the forecast error in crucial area where a tropical cyclone(TC) interactes with the upstream trough is highly correlated to the track forecast error after the TC recurvature. Furthermore, sensitivity experiments confirm that the developments of the midlatitude downstream circulations and then the TC track after its recurvature are highly sensitive to the TC intensity and its location relative to the upstream trough, which can give an example or one way of sensitivity of the TC track to the TC-trough interaction. If the TC interacts with the upstream trough more strongly(e.g., the TC being intensified or getting closer to the upstream trough), the downstream circulations will be more meridional, thus the TC track will be more northerly and westerly; otherwise, the downstream circulations will be more zonal, and the TC track will be more southerly and easterly.展开更多
The GRAPES-TCM is used to make ensemble prediction experiments for typhoon track.Three kinds of ensemble schemes are designed for the experiments.A total of 109 experiments are made for the nine typhoons in 2011 and t...The GRAPES-TCM is used to make ensemble prediction experiments for typhoon track.Three kinds of ensemble schemes are designed for the experiments.A total of 109 experiments are made for the nine typhoons in 2011 and the integral time is 72 h.The experiment results are shown as follows.In the three ensemble schemes,on the whole,scheme 1 has the best track prediction.Its average absolute track error and overall deviations of typhoon moving speed and moving direction are all the smallest in the three schemes.For both scheme 1 and scheme 2,they are all smaller than those of their control predictions.Both of their ensemble predictions show superiority to their deterministic predictions.Overall,compared with the observations,the typhoon moving directions of the three schemes mainly skew to the right,and in the late integration they mainly tend to be relatively slow.In the three schemes,the track dispersion of scheme 1 is the largest and that of scheme 3 the smallest.In scheme 1 it is much larger than in schemes 2 and 3.The difference of dispersion between scheme 2 and scheme 3 is small.The track dispersions of the three schemes are all much smaller than their rational dispersions.Compared with the eight domestic and overseas operational numerical weather prediction(NWP) models,scheme 1 has better predictions than the other seven operational models except ECMWF NWP model.Scheme 1 has the value of operational application.展开更多
A series of 96-h typhoon track prediction experiments were carried out using medium range forecasting system of NMC by adding BOGUS typhoon (simplified as B-TC) into the first guess field or the analysis field in orde...A series of 96-h typhoon track prediction experiments were carried out using medium range forecasting system of NMC by adding BOGUS typhoon (simplified as B-TC) into the first guess field or the analysis field in order to provide longer time typhoon track forecast. The results show that T106L19 could provide a better forecast to typhoon tracks when the B-TC was added, especially when the typhoon vortex is even weaker. The sensitive experiments on where to add the B-TC show that the results from adding the B-TC into the first guess field are better. The results also show that the initialization smoothes the B-TC a lot and this will affect the typhoon track prediction.展开更多
In this paper,by carrying out sensitivity tests of initial conditions and diagnostic analysis of physical fields,the impact factors and the physical mechanism of the unusual track of Morakot in the Taiwan Strait are d...In this paper,by carrying out sensitivity tests of initial conditions and diagnostic analysis of physical fields,the impact factors and the physical mechanism of the unusual track of Morakot in the Taiwan Strait are discussed and examined based on the potential vorticity(PV)inversion.The diagnostic results of NCEP data showed that Morakot's track was mainly steered by the subtropical high.The breaking of a high-pressure zone was the main cause for the northward turn of Morakot.A sensitivity test of initial conditions showed that the existence of upper-level trough was the leading factor for the breaking of the high-pressure zone.When the intensity was strengthened of the upper-level trough at initial time,the high-pressure zone would break ahead of time,leading to the early northward turn of Morakot.Conversely,when the intensity was weakened,the breaking of the high-pressure zone would be delayed.Especially,when the intensity was weakened to a certain extent,the high-pressure zone would not break.The typhoon,steered by the easterly flow to the south of the high-pressure zone,would keep moving westward,with no turn in the test.The diagnostic analysis of the physical fields based on the sensitivity test revealed that positive vorticity advection and cold advection associated with the upper-level trough weakened the intensity of the high-pressure zone.The upper-level trough affected typhoon's track indirectly by influencing the high-pressure zone.展开更多
This study examines the effects of cumulus parameterizations and microphysics schemes on the track forecast of typhoon Nabi using the Weather Research Forecast model. The study found that the effects of cumulus parame...This study examines the effects of cumulus parameterizations and microphysics schemes on the track forecast of typhoon Nabi using the Weather Research Forecast model. The study found that the effects of cumulus parameterizations on typhoon track forecast were comparatively strong and the typhoon track forecast of Kain-Fritsch (KF) was superior to that of Betts-Miller (BM). When KF was selected, the simulated results would be improved if microphysics schemes were selected than otherwise. The results from Ferrier, WSM6, and Lin were very close to those in the best track. KF performed well with the simulations of the western extension and eastern contraction changes of a North Pacific high as well as the distribution and strength of the typhoon wind field.展开更多
The MM5,which is the PSU/NCAR mesoscale nonhydrostatic limited-area model,and its adjoining modeling system are used in this paper.Taking T106 analysis data as background field the authors generate an optimal initial ...The MM5,which is the PSU/NCAR mesoscale nonhydrostatic limited-area model,and its adjoining modeling system are used in this paper.Taking T106 analysis data as background field the authors generate an optimal initial condition of a typhoon by using two bogus data assimilation schemes,and conduct some numerical simulating experiments.The results of No.9608 typhoon(Gloria)show that the optimal initial field have some dramatic improvements,such as inaccurate position of typhoon center,weaker typhoon circulation and incomplete inner structure of the typhoon,which are caused by shortage of data over the sea.Some improvements have been made in the track forecast.Through several comparing experiments,the initialization optimized by BDA scheme is found to be more reasonable than GFDL scheme and its typhoon track forecast is better.展开更多
This paper presents a study on the statistical forecasts of typhoon tracks. Numerical models have their own systematic errors, like a bias. In order to improve the accuracy of track forecasting, a statistical model ca...This paper presents a study on the statistical forecasts of typhoon tracks. Numerical models have their own systematic errors, like a bias. In order to improve the accuracy of track forecasting, a statistical model called DLM (dynamic linear model) is applied to remove the systematic error. In the analysis of typhoons occurring over the western North Pacific in 1997 and 2000, DLM is useful as an adaptive model for the prediction of typhoon tracks.展开更多
In this paper, a statistical interpretation composite forecast model for typhoon track is set up by us-ing numerical forecast products and several forecast schemes. Tested in 1994 typhoon season, its forecastperforman...In this paper, a statistical interpretation composite forecast model for typhoon track is set up by us-ing numerical forecast products and several forecast schemes. Tested in 1994 typhoon season, its forecastperformance is much better than that of a previous statistical forecast model. The test shows that it is aneffective method that sufficiently Anproves objective forecast of typhoon track using the numerical fore-cast output products obtained in forecast and adopting several schemes in composition.展开更多
Typhoon Maggie (1999) interacted with another tropical depression system and moved along awest-southwest track that is somewhat abnormal during its pre-landing stage. Two numerical experiments arecarried out in this p...Typhoon Maggie (1999) interacted with another tropical depression system and moved along awest-southwest track that is somewhat abnormal during its pre-landing stage. Two numerical experiments arecarried out in this paper to study the effect of the interaction on the track of typhoon Maggie using the mesoscalenumerical weather prediction model system with a tropical cyclone bogusing scheme developed by Center forCoastal and Atmospheric Research, the Hong Kong University of Science and Technology. Results show that thecyclone system interacting with Maggie is the main factor for the abnormal track of Maggie.展开更多
Obvious results have been achieved in the forecast of typhoon track that is improved with a consensus procedure Forecast experiments were conducted with the analogue model (TSF) and the Markov type model (MTSF)that ar...Obvious results have been achieved in the forecast of typhoon track that is improved with a consensus procedure Forecast experiments were conducted with the analogue model (TSF) and the Markov type model (MTSF)that are widely used and the results show that there has been significant increase in the capability of forecasting with the improvement by the consensus procedure.展开更多
A new method, BDA perturbing, is used in ensemble forecasting of typhoon track. This method isbased on the Bogus Data Assimilation scheme. It perturbs the initial position and intensity of typhoons and gets aseries of...A new method, BDA perturbing, is used in ensemble forecasting of typhoon track. This method isbased on the Bogus Data Assimilation scheme. It perturbs the initial position and intensity of typhoons and gets aseries of bogus vortex. Then each bogus vortex is used in data assimilation to obtain initial conditions. Ensembleforecast members are constructed by conducting simulation with these initial conditions. Some cases of typhoonare chosen to test the validity of this new method and the results show that: using the BDA perturbing method toperturb initial position and intensity of typhoon for track forecast can improve accuracy, compared with the directuse of the BDA assimilation scheme. And it is concluded that a perturbing amplitude of intensity of 5 hPa isprobably more appropriate than 10 hPa if the BDA perturbing method is used in combination with initialposition perturbation.展开更多
Contour dynamics (CD) method for the motions of typhoon is presented in this paper. The effect of asymmetric inner structure on the typhoon'sanomalous track has been discussed in different environmental steering. ...Contour dynamics (CD) method for the motions of typhoon is presented in this paper. The effect of asymmetric inner structure on the typhoon'sanomalous track has been discussed in different environmental steering. Todemonstrate the feasibility of the method, the track of Typhoon Yancy(9012) isconcerned with. The numerical results show that the method can describe the tendency of looping qualitatively.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.U1811464,U2142213)Guangdong Basic and Applied Basic Research Foundation(Grants Nos.2020A1515110275,2020A1515110040,2022A1515011870)the Special program for innovation and development of China Meteorological Administration(CXFZ2021Z006,CXFZ2022P026).
文摘Landfalling typhoons can cause disasters over large regions.The government and emergency responders need to take measures to mitigate disasters according to the forecast of landfall position,while slight timing error can be ignored.The reliability of operational model forecasts of typhoon landfall position needs to be evaluated beforehand,according to the forecasts and observation of historical cases.In the evaluation of landfalling typhoon track,the traditional method based on point-to-point matching methods could be influenced by the predicted typhoon translation speed.Consequently,the traditional track evaluation method may result in a large track error even if the predicted landfall position is close to observation.The purpose of this paper is to address the above issue using a simple evaluation method of landfalling typhoon track forecast based on the time neighborhood approach.In this new method,the timing error was lessened to highlight the importance of the position error during the landfall of typhoon.The properties of the time neighborhood method are compared with the traditional method based on numerical forecast results of 12 landfalling typhoon cases.Results demonstrated that the new method is not sensitive to the sampling frequency,and that the difference between the time neighborhood and traditional method will be more obvious when the moving speed of typhoon is moderate(between 15−30 km h^(−1)).The time neighborhood concept can be easily extended to a broader context when one attempts to examine the position error more than the timing error.
文摘In order to solve the difficult problem of typhoon track prediction due to the sparsity of conventional data over the tropical ocean, in this paper, the No. 0205 typhoon Rammasun of 4-6 July 2002 is studied and an experiment of the typhoon track prediction is made with the direct use of the Advanced TIROS-N Operational Vertical Sounder (ATOVS) microwave radiance data in three-dimensional variational data assimilation. The prediction result shows that the experiment with the ATOVS microwave radiance data can not only successfully predict the observed fact that typhoon Rammasun moves northward and turns right, but can also simulate the action of the fast movement of the typhoon, which cannot be simulated with only conventional radiosonde data. The skill of the typhoon track prediction with the ATOVS microwave radiance data is much better than that without the ATOVS data. The typhoon track prediction of the former scheme is consistent in time and in location with the observation. The direct assimilation of
基金The National Natural Science Foundation of China under contract Nos 61273245 and 41306028the Beijing Natural Science Foundation under contract No.4152031+2 种基金the National Special Research Fund for Non-Profit Marine Sector under contract Nos201405022-3 and 2013418026-4the Ocean Science and Technology Program of North China Sea Branch of State Oceanic Administration under contract No.2017A01the Operational Marine Forecasting Program of State Oceanic Administration
文摘It is of vital importance to reduce injuries and economic losses by accurate forecasts of typhoon tracks. A huge amount of typhoon observations have been accumulated by the meteorological department, however, they are yet to be adequately utilized. It is an effective method to employ machine learning to perform forecasts. A long short term memory(LSTM) neural network is trained based on the typhoon observations during 1949–2011 in China's Mainland, combined with big data and data mining technologies, and a forecast model based on machine learning for the prediction of typhoon tracks is developed. The results show that the employed algorithm produces desirable 6–24 h nowcasting of typhoon tracks with an improved precision.
基金The National Natural Science Foundation of China under contract Nos 51809023,51839002 and 51879015the Open Research Foundation of the Key Laboratory of the Pearl River Estuarine Dynamics and Associated Process Regulation,the Ministry of Water Resources under contract No.2018KJ03
文摘To determine the grid resolutions of the WRF model in the typhoon simulation,some sensitivity analysis of horizontal and vertical resolutions in different conditions has been carried out.Different horizontal resolutions(5,10,20,30 km),nesting grids(15 and 5 km),different vertical resolutions(35-layers,28-layers,20-layers)and different top maximum pressures(1 000,2 000,3 500,5 000 Pa)had been used in the mesoscale numerical model WRF to simulate the Typhoon Kai-tak.The simulation results of typhoon track,wind speed and sea level pressure at different horizontal and vertical resolutions have been compared and analyzed.The horizontal and vertical resolutions of the model have limited effect on the simulation effect of the typhoon track.Different horizontal and vertical resolutions have obvious effects on typhoon strength(defined by wind speed)and intensity(defined by sea level pressure,SLP),especially for sea level pressure.The typhoon intensity simulated by the high-resolution model is closer to the real situation and the nesting grids can improve computational accuracy and efficiency.The simulation results affected by vertical resolution using 35-layers is better than the simulation results using 20-layers and 28-layers simulations.Through comparison and analysis,the horizontal and vertical resolutions of WRF model are finally determined as follows:the two-way nesting grid of 15 and 5 km is comprehensively determined,and the vertical layers is 35-layers,the top maximum pressure is 2 000 Pa.
基金Specialized Science Project for Public Welfare Industries(Metrological Sector)(GYHY201206010,GYHY201406009)Science and Technology Planning Project for Guangdong Province(2012A061400012)+3 种基金Program for the 12th Five-Year Economic Development(2012BAC22B00)Natural Science Foundation of China(41075083)Program for Integration and Application of Key Meteorological Techniques from CMA(CMAGJ2012M36)Project from Guangdong Meteorological Bureau(2013A04)
文摘In this paper, we first analyzed cloud drift wind(CDW) data distribution in the vertical direction, and then reassigned the height of every CDW in the research domain in terms of background information, and finally, conducted contrast numerical experiments of assimilating the CDW data before and after reassignment to examine the impacts on the forecast of the track of Typhoon Chanthu(1003) from 00:00(Coordinated Universal Time) 21 July to 00:00 UTC23 July, 2010. The analysis results of the CDW data indicate that the number of CDWs is mainly distributed in the midand upper-troposphere above 500 h Pa, with the maximum number at about 300 h Pa. The height reassigning method mentioned in this work may update the height effectively, and the CDW data are distributed reasonably and no obvious contradiction occurs in the horizontal direction after height reassignment. After assimilating the height-reassigned CDW data, especially the water vapor CDW data, the initial wind field around Typhoon Chanthu(1003) became more reasonable, and then the steering current leading the typhoon to move to the correct location became stronger. As a result, the numerical track predictions are improved.
基金International Cooperating Program of Science and Technology(2010DFA24650)National Natural Science Foundation of China(41175061)
文摘Three typhoon cases are selected to conduct a series of simulations that are initialized from sequential analyses. The results show that the forecast error in crucial area where a tropical cyclone(TC) interactes with the upstream trough is highly correlated to the track forecast error after the TC recurvature. Furthermore, sensitivity experiments confirm that the developments of the midlatitude downstream circulations and then the TC track after its recurvature are highly sensitive to the TC intensity and its location relative to the upstream trough, which can give an example or one way of sensitivity of the TC track to the TC-trough interaction. If the TC interacts with the upstream trough more strongly(e.g., the TC being intensified or getting closer to the upstream trough), the downstream circulations will be more meridional, thus the TC track will be more northerly and westerly; otherwise, the downstream circulations will be more zonal, and the TC track will be more southerly and easterly.
基金National Natural Science Foundation of China(41575108,41275067,41475082,41475059)Special Scientific Research Fund of Meteorological Public Welfare of China(GYHY201506007)
文摘The GRAPES-TCM is used to make ensemble prediction experiments for typhoon track.Three kinds of ensemble schemes are designed for the experiments.A total of 109 experiments are made for the nine typhoons in 2011 and the integral time is 72 h.The experiment results are shown as follows.In the three ensemble schemes,on the whole,scheme 1 has the best track prediction.Its average absolute track error and overall deviations of typhoon moving speed and moving direction are all the smallest in the three schemes.For both scheme 1 and scheme 2,they are all smaller than those of their control predictions.Both of their ensemble predictions show superiority to their deterministic predictions.Overall,compared with the observations,the typhoon moving directions of the three schemes mainly skew to the right,and in the late integration they mainly tend to be relatively slow.In the three schemes,the track dispersion of scheme 1 is the largest and that of scheme 3 the smallest.In scheme 1 it is much larger than in schemes 2 and 3.The difference of dispersion between scheme 2 and scheme 3 is small.The track dispersions of the three schemes are all much smaller than their rational dispersions.Compared with the eight domestic and overseas operational numerical weather prediction(NWP) models,scheme 1 has better predictions than the other seven operational models except ECMWF NWP model.Scheme 1 has the value of operational application.
基金Key scientific research project for the State Meteorological Administration in the 9 five-year development plan (ZX95-01)
文摘A series of 96-h typhoon track prediction experiments were carried out using medium range forecasting system of NMC by adding BOGUS typhoon (simplified as B-TC) into the first guess field or the analysis field in order to provide longer time typhoon track forecast. The results show that T106L19 could provide a better forecast to typhoon tracks when the B-TC was added, especially when the typhoon vortex is even weaker. The sensitive experiments on where to add the B-TC show that the results from adding the B-TC into the first guess field are better. The results also show that the initialization smoothes the B-TC a lot and this will affect the typhoon track prediction.
基金National Public Benefit(Meteorology)Research Foundation of China(GYHY201106004)National Basic Research Program"973"of China(2009CB421502)National Nature Science Foundation of China (40730948,41005029)
文摘In this paper,by carrying out sensitivity tests of initial conditions and diagnostic analysis of physical fields,the impact factors and the physical mechanism of the unusual track of Morakot in the Taiwan Strait are discussed and examined based on the potential vorticity(PV)inversion.The diagnostic results of NCEP data showed that Morakot's track was mainly steered by the subtropical high.The breaking of a high-pressure zone was the main cause for the northward turn of Morakot.A sensitivity test of initial conditions showed that the existence of upper-level trough was the leading factor for the breaking of the high-pressure zone.When the intensity was strengthened of the upper-level trough at initial time,the high-pressure zone would break ahead of time,leading to the early northward turn of Morakot.Conversely,when the intensity was weakened,the breaking of the high-pressure zone would be delayed.Especially,when the intensity was weakened to a certain extent,the high-pressure zone would not break.The typhoon,steered by the easterly flow to the south of the high-pressure zone,would keep moving westward,with no turn in the test.The diagnostic analysis of the physical fields based on the sensitivity test revealed that positive vorticity advection and cold advection associated with the upper-level trough weakened the intensity of the high-pressure zone.The upper-level trough affected typhoon's track indirectly by influencing the high-pressure zone.
基金National Basic Research Program of China (2009CB421502)National Natural Science Foundation of China (40475018)Research and Development Program of KMA of Korea (NIMR-2010-B-6)
文摘This study examines the effects of cumulus parameterizations and microphysics schemes on the track forecast of typhoon Nabi using the Weather Research Forecast model. The study found that the effects of cumulus parameterizations on typhoon track forecast were comparatively strong and the typhoon track forecast of Kain-Fritsch (KF) was superior to that of Betts-Miller (BM). When KF was selected, the simulated results would be improved if microphysics schemes were selected than otherwise. The results from Ferrier, WSM6, and Lin were very close to those in the best track. KF performed well with the simulations of the western extension and eastern contraction changes of a North Pacific high as well as the distribution and strength of the typhoon wind field.
基金National Key Fundamental Research Project of China (40175012)
文摘The MM5,which is the PSU/NCAR mesoscale nonhydrostatic limited-area model,and its adjoining modeling system are used in this paper.Taking T106 analysis data as background field the authors generate an optimal initial condition of a typhoon by using two bogus data assimilation schemes,and conduct some numerical simulating experiments.The results of No.9608 typhoon(Gloria)show that the optimal initial field have some dramatic improvements,such as inaccurate position of typhoon center,weaker typhoon circulation and incomplete inner structure of the typhoon,which are caused by shortage of data over the sea.Some improvements have been made in the track forecast.Through several comparing experiments,the initialization optimized by BDA scheme is found to be more reasonable than GFDL scheme and its typhoon track forecast is better.
基金the project"A study on improving forecast skill using a su-percomputer"of Meteorological Research Institute,KMA,2001.
文摘This paper presents a study on the statistical forecasts of typhoon tracks. Numerical models have their own systematic errors, like a bias. In order to improve the accuracy of track forecasting, a statistical model called DLM (dynamic linear model) is applied to remove the systematic error. In the analysis of typhoons occurring over the western North Pacific in 1997 and 2000, DLM is useful as an adaptive model for the prediction of typhoon tracks.
文摘In this paper, a statistical interpretation composite forecast model for typhoon track is set up by us-ing numerical forecast products and several forecast schemes. Tested in 1994 typhoon season, its forecastperformance is much better than that of a previous statistical forecast model. The test shows that it is aneffective method that sufficiently Anproves objective forecast of typhoon track using the numerical fore-cast output products obtained in forecast and adopting several schemes in composition.
基金National Natural Science Foundation of China (60572184 40375017)
文摘Typhoon Maggie (1999) interacted with another tropical depression system and moved along awest-southwest track that is somewhat abnormal during its pre-landing stage. Two numerical experiments arecarried out in this paper to study the effect of the interaction on the track of typhoon Maggie using the mesoscalenumerical weather prediction model system with a tropical cyclone bogusing scheme developed by Center forCoastal and Atmospheric Research, the Hong Kong University of Science and Technology. Results show that thecyclone system interacting with Maggie is the main factor for the abnormal track of Maggie.
文摘Obvious results have been achieved in the forecast of typhoon track that is improved with a consensus procedure Forecast experiments were conducted with the analogue model (TSF) and the Markov type model (MTSF)that are widely used and the results show that there has been significant increase in the capability of forecasting with the improvement by the consensus procedure.
基金"The System of Ensemble Forecasting Models for Tropical Cyclones in the South China Sea",a project of the Scientific and Technological Plans for Guangdong Province(2003C32603)
文摘A new method, BDA perturbing, is used in ensemble forecasting of typhoon track. This method isbased on the Bogus Data Assimilation scheme. It perturbs the initial position and intensity of typhoons and gets aseries of bogus vortex. Then each bogus vortex is used in data assimilation to obtain initial conditions. Ensembleforecast members are constructed by conducting simulation with these initial conditions. Some cases of typhoonare chosen to test the validity of this new method and the results show that: using the BDA perturbing method toperturb initial position and intensity of typhoon for track forecast can improve accuracy, compared with the directuse of the BDA assimilation scheme. And it is concluded that a perturbing amplitude of intensity of 5 hPa isprobably more appropriate than 10 hPa if the BDA perturbing method is used in combination with initialposition perturbation.
文摘Contour dynamics (CD) method for the motions of typhoon is presented in this paper. The effect of asymmetric inner structure on the typhoon'sanomalous track has been discussed in different environmental steering. Todemonstrate the feasibility of the method, the track of Typhoon Yancy(9012) isconcerned with. The numerical results show that the method can describe the tendency of looping qualitatively.