Based on the analysis of multiple tropical cyclone(MTC)events in the South China Sea and Northwest Pacific Ocean during 1979-2019,this study classfies periods of the tropical cyclone(TC)events into active,normal,and i...Based on the analysis of multiple tropical cyclone(MTC)events in the South China Sea and Northwest Pacific Ocean during 1979-2019,this study classfies periods of the tropical cyclone(TC)events into active,normal,and inactive phases.To analyze the spatial distribution of associated anomalous variables and indices,an anomaly-based variable model is employed.Anomalies of 850 hPa vorticity,850 hPa water vapor flux divergence,and 400 hPa vertical velocity are selected as optimal predictors with physical significance.From these predictors,a physical model for the original MTC development is established.The results show that during the period of MTC development,a stable warm-core anomaly persists at 300 hPa,with a“warm tongue”extending downward as far as 700 hPa.The upper-level high-pressure anomaly center does not completely overlap with the low-pressure anomaly center at lower levels until TC genesis approaches.In addition,the 500-1000 hPa water vapor flux initially exhibits a negative anomaly,which facilitates water vapor to accumulate.A negative vertical velocity anomaly then develops,promoting the upward motion that gradually stabilizes and expands to a wider range.Ultimately,these processes lead to the formation of a positive vorticity anomaly,signifying a TC’s formation.Among the three key factors,the water vapor flux divergence anomaly serves as the primary indicator for extended-range monitoring and forecasting of MTC events.It accounts for the highest proportion of TCs,with its anomaly values most frequently exceeding the critical thresholds at TC genesis locations.Meanwhile,the water vapor flux divergence anomaly also provides the earliest anomalous signal and demonstrates the most sustained and stable indicative effect.展开更多
41 a （1961 - 2001） seasonal Z index series of 25 representative weather stations are investigated by virtue of EOF, FFT, continuous wavelet transformation （CWT） and orthogonai wavelet transformation （OWT）. It sh...41 a （1961 - 2001） seasonal Z index series of 25 representative weather stations are investigated by virtue of EOF, FFT, continuous wavelet transformation （CWT） and orthogonai wavelet transformation （OWT）. It shows that： （1） Fujian drought/flood （DF） has a significant 2 - 3a cycle for the periods 1965 - 1975 and 1990＇s; （2） the pattern, which represents the opposite DF trend between the southern and northem parts, has la and 3 - 4a cycles since the middle of 1980＇s; （3） EOF3, which denotes the reverse change between the middle-west region and other areas, has significant 1 - 2a cycle for the period from 1985 to 1998 and 9 - 13a cycle since 1980s; （4） there is an obvious drought trend for the last 40a （especially in the 1990＇s）, which is more outstanding in the south （east） than in the north （west）; （5） the 1960＇s and 1980＇s are in relatively wet phases and the 1970＇s and 1990＇s are in drought spells.展开更多
The interannual variability of occurrence of multiple tropical cyclone （MTC） events during June-October in the western North Pacific （WNP） was examined for the period 1979-2006. The number of the MTC events ranged...The interannual variability of occurrence of multiple tropical cyclone （MTC） events during June-October in the western North Pacific （WNP） was examined for the period 1979-2006. The number of the MTC events ranged from 2 to 9 per year, exhibiting a remarkable year-to-year variation. Seven active and seven inactive MTC years were identified. Compared to the inactive years, tropical cyclone genesis locations extended farther to the east and in the meridional direction during the active MTC years. A composite analysis shows that inactive MTC years were often associated with the E1 Nifio decaying phase, as warm SST anomalies in the equatorial eastern-central Pacific in the preceding winter transitioned into cold sea surface temperature （SST） anomalies in the concurrent summer. Associated with the SST evolution were suppressed low-level cyclonic vorticity and weakened convection in the WNP monsoon region. In addition to the mean flow difference~ significant differences between active and inactive MTC years were also found in the strength of the atmospheric intraseasonal oscillation （ISO）. Compared with inactive MTC years, ISO activity was much stronger along the equator and in the WNP region during active MTC years. Both westwardand northward-propagating ISO spectrums strengthened during active MTC years compared to inactive years. The combined mean state and ISO activity changes may set up a favorable environment for the generation of MTC events.展开更多
Using the daily data of temperature from China Meteorological Administration and the NCEP/NCAR reanalysis from 1960 to 2005, we have analyzed the relationships between the summertime high/low temperature events in the...Using the daily data of temperature from China Meteorological Administration and the NCEP/NCAR reanalysis from 1960 to 2005, we have analyzed the relationships between the summertime high/low temperature events in the middle and lower reaches of the Yangtze River （MLRYR） and the related circulation anomalies in the Eastern Hemisphere. Our results have demonstrated that a significantly increasing trend is observed in daily minimum temperature in the past 50 years. And in some regions in the Northern Hemisphere, the opposite scenarios are observed in circulation anomalies in lower and upper parts of the troposphere in the years when the temperatures are higher than normal, as compared to those in the years when the temperatures are lower than normal in the middle and lower reaches of the Yangtze River （MLRYR）. Additionally, the anomalous circulation structure in vertical direction in both the high and lower temperature years are barotropic. It is found that the emergence and maintenance of the aforementioned anomalous circulations are related to three kinds of wave train teleconnection patterns. Further more, influences of the long wave surface radiation on the air temperature are stronger in the nighttime than that in the daytime. While both the maximum and minimum temperatures have negative relationships with the sensible heat flux but positive relationships with the latent heat flux. To some extent, the anomalous dynamic heating （cooling） caused by the vertical thermal advection as well as the diabatic heating （cooling） caused by diabatic processes can explain the formation of the high （low） temperature events in the middle and lower reaches of the Yangtze River （MLRYR） in boreal summer.展开更多
This is a study to compare three selected tropical cyclone datasets separately compiled by CMA Shanghai Typhoon Institute （CMA SHI）, the Joint Typhoon Warning Center （JTWC）, and the Japan Meteorological Agency （...This is a study to compare three selected tropical cyclone datasets separately compiled by CMA Shanghai Typhoon Institute （CMA SHI）, the Joint Typhoon Warning Center （JTWC）, and the Japan Meteorological Agency （JMA）. The annual fi＇equencies, observation times and destructive power index as the characteristic quantities are investigated of the tropical cyclones over the western North Pacific. The comparative study has resulted in the following findings： 1） Statistical gaps between the datasets compared are narrowing down as the intensity of tropical cyclones increases. 2） In the context of interdecadal distribution, there is for the 1950s a relatively large gap between the datasets, as compared with a narrowed gap for the period from the mid 1970s to the 1980s, and a recurring widened gap for the mid and late 1990s. Additionally, an approach is proposed in the paper to correct the wind speed data in the TC Yearbook.展开更多
Based on the meteorological monitoring data of Typhoon Nesat and Haitang in Fujian Province in 2017, the data of the typhoon disaster situation and third-party evaluation of typhoon disaster prevention and mitigation ...Based on the meteorological monitoring data of Typhoon Nesat and Haitang in Fujian Province in 2017, the data of the typhoon disaster situation and third-party evaluation of typhoon disaster prevention and mitigation benefit were investigated. By using the mean value anomaly estimation method in the similarity analysis method, it is estimated that typhoon Nesat and Haitang will cause direct economic losses of 0.8 ～ 1.8 billion yuan, and the typhoon disaster risk index evaluation model is used. The disaster risk pre-assessment of Typhoon Nesat and Haitang is carried out. The results of the study and analysis show that the pre-assessment results of Typhoon Nesat and Haitang are basically consistent with the actual disaster situation. The disaster loss was reduced to the minimum. According to the third party evaluation and investigation, it was concluded that the contribution rate of reducing economic benefits was 75% in Fujian Province for preventing and landing double typhoons Nesat and Haitang. Mainly reflected in the ship return to the port to avoid the wind, geological hazards prone to the site construction and cage culture danger removal reinforcement and other links; The contribution rate of reducing casualties is 86, mainly reflected in fishermen disembarkation and personnel transfer to safety emergency shelter and other links. The benefit of this double typhoon disaster prevention and mitigation in Fujian Province is about 0.6 billion yuan to reduce the direct economic loss. According to the investigation, the overall satisfaction of the double typhoon meteorological service is 91.0 points. Typhoon early warning information service convenience satisfaction is 91.4 points, early warning information accuracy satisfaction is 87.2 points, government departments strong anti-Taiwan disaster reduction organization, linkage departments participate in disaster prevention and mitigation high. However, there is a gap between public awareness and participation in typhoon disasters.展开更多
CTUsing the Joint Typhoon Warning Center （JTWC） optimal typhoon tracks data and the NCEP/ NCAR reanalysis, an investigation is made on the summer Asian-Pacific Oscillation （APO） in relation to synchronous air circ...CTUsing the Joint Typhoon Warning Center （JTWC） optimal typhoon tracks data and the NCEP/ NCAR reanalysis, an investigation is made on the summer Asian-Pacific Oscillation （APO） in relation to synchronous air circulation from the coastal waters of East Asia to western North Pacific （WNP）, along with a further exploration on the relationship between the APO and the tropical cyclone （TC） activities over the coastal waters of China. The results show that there exists a strong correlation between the APO inten-sity and TC activities over the WNP and coastal waters of eastern China （CWEC） during summer. When the APO is stronger （weaker）, the TC activities over the WNP are located in a more westward （eastward） and northward （southward） position and the TC number over the CWEC greatly increases （decreases）. Meanwhile, in stronger （weaker） APO years, the atmospheric circulation over the CWEC is manifested by a low-level anomalous cyclonic （anticyclonic） circulation, a decreasing （an increasing） vertical shear of zonal wind and strengthened （weakened） convection. These features are favorable （unfavorable） for the mainte-nance and development of the TC. The APO also modulates the direction of the air current that steers the movement of the TC. Corresponding to a stronger （weaker） APO, the WNP subtropical high appears more northward （southward） and eastward （westward）, with the weakening （strengthening） of the easterly wind south of the high. This feature favors the TC moving at more northern （southern） latitudes, leading to an increase （a decrease） of the number of the TCs into the CWEC. Moreover, the APO also affects the atmospheric circulation over the South China Sea and the tropical WNP where the TC is originated. Corre-sponding to a stronger （weaker） APO, the monsoon trough over these areas appears northward （southward） and westward （eastward）, which favors an increase （a decrease） of the TC number over the CWEC.展开更多
The accuracy of eight tropical cyclone(TC) intensity guidance techniques currently used in the East China Regional Meteorological Center during the 2008 and 2009 western North Pacific seasons has been evaluated within...The accuracy of eight tropical cyclone(TC) intensity guidance techniques currently used in the East China Regional Meteorological Center during the 2008 and 2009 western North Pacific seasons has been evaluated within two intensity phases:intensification and decay.In the intensification stage,the majority of the techniques indicated > 60% probabilities of the errors of forecast 12-h intensity change within ±5 ms-1 from the 12- to 60-h forecast intervals,while none had capability to predict the rapid intensification and most of them had a bias toward smaller 48-h intensity changes at the beginning of the stage.The majority of the guidance techniques showed > 70% probabilities of the errors of forecast 12-h intensity change within ±5 ms-1 through 60 h during the decay phase,and the techniques had little capability of predicting rapid decay events.It is found that the evaluated statistical models had difficulty in predicting the strongest cases of decay 36 h after peak intensity,whereas the dynamical and official forecasts were seemingly able to produce some large decay rates.展开更多
The overall statistics of the accuracy of eight statistical and dynamical tropical cyclone intensity guidance techniques used in the East China Regional Meteorological Center during the 2008 and 2009 western North Pac...The overall statistics of the accuracy of eight statistical and dynamical tropical cyclone intensity guidance techniques used in the East China Regional Meteorological Center during the 2008 and 2009 western North Pacific typhoon seasons were evaluated herein. Skill scores which were calculated based on contingency tables show that the forecast skill of the selected techniques did not persistently decline with the increasing forecast time. The probabilities of the forecast intensity inaccuracy being within 6 m s-1 and greater than 15 m s-1 were examined in the study. Additionally, the majority of the forecasts were featured by underintensity forecasts in 2008, while some guidance showed pronounced overforecasts at relatively long forecast intervals in 2009. The forecast biases and overintensity forecast errors at typhoon dissipation were verified as well.展开更多
基金Guidance Project for Industrial Technology Develop-ment and Application Plan of Fujian Province(2024Y0075)Natural Science Foundation of Fujian Province(2022J01441,2024J011139,2022J011077)+3 种基金Innovation and development Project of the China Meteorological Administration(CXFZ2024J024)National Natural Science Foundation of China(42205048)Science Foundation of the Fujian Meteorological Bureau(2023Q04)Meteorological Services Research Project of the China Meteorological Administration(JCZX202409)。
文摘Based on the analysis of multiple tropical cyclone(MTC)events in the South China Sea and Northwest Pacific Ocean during 1979-2019,this study classfies periods of the tropical cyclone(TC)events into active,normal,and inactive phases.To analyze the spatial distribution of associated anomalous variables and indices,an anomaly-based variable model is employed.Anomalies of 850 hPa vorticity,850 hPa water vapor flux divergence,and 400 hPa vertical velocity are selected as optimal predictors with physical significance.From these predictors,a physical model for the original MTC development is established.The results show that during the period of MTC development,a stable warm-core anomaly persists at 300 hPa,with a“warm tongue”extending downward as far as 700 hPa.The upper-level high-pressure anomaly center does not completely overlap with the low-pressure anomaly center at lower levels until TC genesis approaches.In addition,the 500-1000 hPa water vapor flux initially exhibits a negative anomaly,which facilitates water vapor to accumulate.A negative vertical velocity anomaly then develops,promoting the upward motion that gradually stabilizes and expands to a wider range.Ultimately,these processes lead to the formation of a positive vorticity anomaly,signifying a TC’s formation.Among the three key factors,the water vapor flux divergence anomaly serves as the primary indicator for extended-range monitoring and forecasting of MTC events.It accounts for the highest proportion of TCs,with its anomaly values most frequently exceeding the critical thresholds at TC genesis locations.Meanwhile,the water vapor flux divergence anomaly also provides the earliest anomalous signal and demonstrates the most sustained and stable indicative effect.
基金Project from the Ministry of Science and Technology of China (2001DIB20116)open projectfor KLME of Nanjing Institute of Meteorology (KJS02108)
文摘41 a （1961 - 2001） seasonal Z index series of 25 representative weather stations are investigated by virtue of EOF, FFT, continuous wavelet transformation （CWT） and orthogonai wavelet transformation （OWT）. It shows that： （1） Fujian drought/flood （DF） has a significant 2 - 3a cycle for the periods 1965 - 1975 and 1990＇s; （2） the pattern, which represents the opposite DF trend between the southern and northem parts, has la and 3 - 4a cycles since the middle of 1980＇s; （3） EOF3, which denotes the reverse change between the middle-west region and other areas, has significant 1 - 2a cycle for the period from 1985 to 1998 and 9 - 13a cycle since 1980s; （4） there is an obvious drought trend for the last 40a （especially in the 1990＇s）, which is more outstanding in the south （east） than in the north （west）; （5） the 1960＇s and 1980＇s are in relatively wet phases and the 1970＇s and 1990＇s are in drought spells.
基金GAO Jianyun was supported by National Natural Science Foundation of China(Grant Nos. 90915002 and 40775047)the Youth Project of Fujian Provincial Department of Science & Technology(Grant No. 2007F3019)+5 种基金the Science and Technology Key Project of Fujian Province(Grant No.2011Y0008)the open-end fund project of Fujian Provincial Meteorological Bureau(Grant No.2010K05)LI Tim was supported by Office of Naval Research(Grant Nos.N000140810256 and N000141010774)the International Pacific Research Center that was sponsored by the Japan Agency for Marine-Earth Science and Technology(JAMSTEC)NASA(Grant No.NNX07AG53G)NOAA(Grant No. NA17RJ1230)
文摘The interannual variability of occurrence of multiple tropical cyclone （MTC） events during June-October in the western North Pacific （WNP） was examined for the period 1979-2006. The number of the MTC events ranged from 2 to 9 per year, exhibiting a remarkable year-to-year variation. Seven active and seven inactive MTC years were identified. Compared to the inactive years, tropical cyclone genesis locations extended farther to the east and in the meridional direction during the active MTC years. A composite analysis shows that inactive MTC years were often associated with the E1 Nifio decaying phase, as warm SST anomalies in the equatorial eastern-central Pacific in the preceding winter transitioned into cold sea surface temperature （SST） anomalies in the concurrent summer. Associated with the SST evolution were suppressed low-level cyclonic vorticity and weakened convection in the WNP monsoon region. In addition to the mean flow difference~ significant differences between active and inactive MTC years were also found in the strength of the atmospheric intraseasonal oscillation （ISO）. Compared with inactive MTC years, ISO activity was much stronger along the equator and in the WNP region during active MTC years. Both westwardand northward-propagating ISO spectrums strengthened during active MTC years compared to inactive years. The combined mean state and ISO activity changes may set up a favorable environment for the generation of MTC events.
基金The key technology R&D program of China, No.2007BAC29B02Project of Jiangsu Key Laboratory of Meteorological Disaster, No.KLME060101
文摘Using the daily data of temperature from China Meteorological Administration and the NCEP/NCAR reanalysis from 1960 to 2005, we have analyzed the relationships between the summertime high/low temperature events in the middle and lower reaches of the Yangtze River （MLRYR） and the related circulation anomalies in the Eastern Hemisphere. Our results have demonstrated that a significantly increasing trend is observed in daily minimum temperature in the past 50 years. And in some regions in the Northern Hemisphere, the opposite scenarios are observed in circulation anomalies in lower and upper parts of the troposphere in the years when the temperatures are higher than normal, as compared to those in the years when the temperatures are lower than normal in the middle and lower reaches of the Yangtze River （MLRYR）. Additionally, the anomalous circulation structure in vertical direction in both the high and lower temperature years are barotropic. It is found that the emergence and maintenance of the aforementioned anomalous circulations are related to three kinds of wave train teleconnection patterns. Further more, influences of the long wave surface radiation on the air temperature are stronger in the nighttime than that in the daytime. While both the maximum and minimum temperatures have negative relationships with the sensible heat flux but positive relationships with the latent heat flux. To some extent, the anomalous dynamic heating （cooling） caused by the vertical thermal advection as well as the diabatic heating （cooling） caused by diabatic processes can explain the formation of the high （low） temperature events in the middle and lower reaches of the Yangtze River （MLRYR） in boreal summer.
基金Monitoring and Detection of Upperair Climate Change in China (GYHY200906014)
文摘This is a study to compare three selected tropical cyclone datasets separately compiled by CMA Shanghai Typhoon Institute （CMA SHI）, the Joint Typhoon Warning Center （JTWC）, and the Japan Meteorological Agency （JMA）. The annual fi＇equencies, observation times and destructive power index as the characteristic quantities are investigated of the tropical cyclones over the western North Pacific. The comparative study has resulted in the following findings： 1） Statistical gaps between the datasets compared are narrowing down as the intensity of tropical cyclones increases. 2） In the context of interdecadal distribution, there is for the 1950s a relatively large gap between the datasets, as compared with a narrowed gap for the period from the mid 1970s to the 1980s, and a recurring widened gap for the mid and late 1990s. Additionally, an approach is proposed in the paper to correct the wind speed data in the TC Yearbook.
基金2017 China Meteorological Bureau typhoon disaster prevention and mitigation benefit evaluation pilot project2018 Fujian Province disaster prevention and mitigation benefit evaluation capacity-building project to provide financial support
文摘Based on the meteorological monitoring data of Typhoon Nesat and Haitang in Fujian Province in 2017, the data of the typhoon disaster situation and third-party evaluation of typhoon disaster prevention and mitigation benefit were investigated. By using the mean value anomaly estimation method in the similarity analysis method, it is estimated that typhoon Nesat and Haitang will cause direct economic losses of 0.8 ～ 1.8 billion yuan, and the typhoon disaster risk index evaluation model is used. The disaster risk pre-assessment of Typhoon Nesat and Haitang is carried out. The results of the study and analysis show that the pre-assessment results of Typhoon Nesat and Haitang are basically consistent with the actual disaster situation. The disaster loss was reduced to the minimum. According to the third party evaluation and investigation, it was concluded that the contribution rate of reducing economic benefits was 75% in Fujian Province for preventing and landing double typhoons Nesat and Haitang. Mainly reflected in the ship return to the port to avoid the wind, geological hazards prone to the site construction and cage culture danger removal reinforcement and other links; The contribution rate of reducing casualties is 86, mainly reflected in fishermen disembarkation and personnel transfer to safety emergency shelter and other links. The benefit of this double typhoon disaster prevention and mitigation in Fujian Province is about 0.6 billion yuan to reduce the direct economic loss. According to the investigation, the overall satisfaction of the double typhoon meteorological service is 91.0 points. Typhoon early warning information service convenience satisfaction is 91.4 points, early warning information accuracy satisfaction is 87.2 points, government departments strong anti-Taiwan disaster reduction organization, linkage departments participate in disaster prevention and mitigation high. However, there is a gap between public awareness and participation in typhoon disasters.
基金Supported by the National Natural Science Foundation of China under Grant No.40921003the National Basic Research Program of China under Grant No.2009CB421404the Basic Research Project for the State Key Laboratory of Severe Weather of Chinese Academy of Meteorological Sciences under Grant No.2008LASWZI01
文摘CTUsing the Joint Typhoon Warning Center （JTWC） optimal typhoon tracks data and the NCEP/ NCAR reanalysis, an investigation is made on the summer Asian-Pacific Oscillation （APO） in relation to synchronous air circulation from the coastal waters of East Asia to western North Pacific （WNP）, along with a further exploration on the relationship between the APO and the tropical cyclone （TC） activities over the coastal waters of China. The results show that there exists a strong correlation between the APO inten-sity and TC activities over the WNP and coastal waters of eastern China （CWEC） during summer. When the APO is stronger （weaker）, the TC activities over the WNP are located in a more westward （eastward） and northward （southward） position and the TC number over the CWEC greatly increases （decreases）. Meanwhile, in stronger （weaker） APO years, the atmospheric circulation over the CWEC is manifested by a low-level anomalous cyclonic （anticyclonic） circulation, a decreasing （an increasing） vertical shear of zonal wind and strengthened （weakened） convection. These features are favorable （unfavorable） for the mainte-nance and development of the TC. The APO also modulates the direction of the air current that steers the movement of the TC. Corresponding to a stronger （weaker） APO, the WNP subtropical high appears more northward （southward） and eastward （westward）, with the weakening （strengthening） of the easterly wind south of the high. This feature favors the TC moving at more northern （southern） latitudes, leading to an increase （a decrease） of the number of the TCs into the CWEC. Moreover, the APO also affects the atmospheric circulation over the South China Sea and the tropical WNP where the TC is originated. Corre-sponding to a stronger （weaker） APO, the monsoon trough over these areas appears northward （southward） and westward （eastward）, which favors an increase （a decrease） of the TC number over the CWEC.
文摘The accuracy of eight tropical cyclone(TC) intensity guidance techniques currently used in the East China Regional Meteorological Center during the 2008 and 2009 western North Pacific seasons has been evaluated within two intensity phases:intensification and decay.In the intensification stage,the majority of the techniques indicated > 60% probabilities of the errors of forecast 12-h intensity change within ±5 ms-1 from the 12- to 60-h forecast intervals,while none had capability to predict the rapid intensification and most of them had a bias toward smaller 48-h intensity changes at the beginning of the stage.The majority of the guidance techniques showed > 70% probabilities of the errors of forecast 12-h intensity change within ±5 ms-1 through 60 h during the decay phase,and the techniques had little capability of predicting rapid decay events.It is found that the evaluated statistical models had difficulty in predicting the strongest cases of decay 36 h after peak intensity,whereas the dynamical and official forecasts were seemingly able to produce some large decay rates.
基金National Basic Research Program of China(2009CB421505)the Shanghai Typhoon Foundation(2009ST09)+1 种基金the National Natural Science Foundation of China(40775060 and 40921160381)the Program of China Meteorological Administration under Grants GYHY201006008 and GYHY200906002.
文摘The overall statistics of the accuracy of eight statistical and dynamical tropical cyclone intensity guidance techniques used in the East China Regional Meteorological Center during the 2008 and 2009 western North Pacific typhoon seasons were evaluated herein. Skill scores which were calculated based on contingency tables show that the forecast skill of the selected techniques did not persistently decline with the increasing forecast time. The probabilities of the forecast intensity inaccuracy being within 6 m s-1 and greater than 15 m s-1 were examined in the study. Additionally, the majority of the forecasts were featured by underintensity forecasts in 2008, while some guidance showed pronounced overforecasts at relatively long forecast intervals in 2009. The forecast biases and overintensity forecast errors at typhoon dissipation were verified as well.
