This research was an effort to select best imputation method for missing upper air temperature data over 24 standard pressure levels. We have implemented four imputation techniques like inverse distance weighting, Bil...This research was an effort to select best imputation method for missing upper air temperature data over 24 standard pressure levels. We have implemented four imputation techniques like inverse distance weighting, Bilinear, Natural and Nearest interpolation for missing data imputations. Performance indicators for these techniques were the root mean square error (RMSE), absolute mean error (AME), correlation coefficient and coefficient of determination ( R<sup>2</sup> ) adopted in this research. We randomly make 30% of total samples (total samples was 324) predictable from 70% remaining data. Although four interpolation methods seem good (producing <1 RMSE, AME) for imputations of air temperature data, but bilinear method was the most accurate with least errors for missing data imputations. RMSE for bilinear method remains <0.01 on all pressure levels except 1000 hPa where this value was 0.6. The low value of AME (<0.1) came at all pressure levels through bilinear imputations. Very strong correlation (>0.99) found between actual and predicted air temperature data through this method. The high value of the coefficient of determination (0.99) through bilinear interpolation method, tells us best fit to the surface. We have also found similar results for imputation with natural interpolation method in this research, but after investigating scatter plots over each month, imputations with this method seem to little obtuse in certain months than bilinear method.展开更多
Day-to-day precipitation data of Juries during the 43 years of 1958-2000 from stations to the south of Yangtze River are used to divide regions and run statistical analysis of sustained torrential rainfall processes. ...Day-to-day precipitation data of Juries during the 43 years of 1958-2000 from stations to the south of Yangtze River are used to divide regions and run statistical analysis of sustained torrential rainfall processes. A preliminary analysis is then made based on it and the results show that June is the month in which torrential rains in the southern half of China take place frequently and sustained torrential rains occur at the same time in South China and the area to the south of Yangtze River. In addition, the analysis gives the basic features of sustained torrential rains of June in China and their interannual variability patterns, with the suggestion that the amount of these events increases significantly after the 1990s. Lastly, the sustained torrential rains occurring in Junes of 1994, 1998 and 2005 in the southern half of China are taken as examples in the research on the basic patterns and formation mechanisms of the evolution of double rain-bands during the rain season in South China and the area to the south of Yangtze River. The analysis shows that the large scale environment field in which sustained torrential rains occur is related to the stable sustaining of the South Asia High and upper level jet streams.展开更多
With the use of data from the National Centers for Environmental Prediction Climate Forecast System Reanalysis,the environment and structure of typhoon Toraji(2001)are investigated during the re-intensification(RI)sta...With the use of data from the National Centers for Environmental Prediction Climate Forecast System Reanalysis,the environment and structure of typhoon Toraji(2001)are investigated during the re-intensification(RI)stage of its extratropical transition(ET),a process in which a tropical cyclone transforms into an extratropical or mid-latitude cyclone.The results provide detailed insight into the ET system and identify the specific features of the system,including wind field,a cold and dry intrusion,and a frontal structure in the RI stage.The irrotational wind provides the values of upper-and lower-level jets within the transitioning tropical cyclone and the cyclone over Shandong Peninsula,accompanied with the reduced radius of maximum surface winds around the cyclone center in the lower troposphere.Simultaneously,dry air intrusion enhances the formation of fronts and leads to strong potential instability in the southwest and northeast quadrants.The distribution of frontogenesis shows that the tilting term associated with vertical motion dominates the positive frontogenesis surrounding the cyclone center,especially in the RI stage.The diagnostics of the kinetic energy budget suggest that the divergent kinetic energy generation whose time evolution corresponds well to that of cyclone center pressure is the primary factor for the development of Toraji in the lower troposphere.The ET of Toraji is a compound pattern that contains a development similar to that of a B-type extratropical cyclone within the maintaining phase and an A-type extratropical cyclone within the strengthening period,which corresponds to the distribution of the E-P fluxes with vertically downward propagation in the maintaining stage and upwards momentum in the strengthening phase.展开更多
In this study,the fifth-generation Pennsylvania State University-National Center for Atmospheric Research (PSU-NCAR) Mesoscale Model (MM5) is used to simulate Typhoon Mindulle (2004) at high resolution (3-km grid size...In this study,the fifth-generation Pennsylvania State University-National Center for Atmospheric Research (PSU-NCAR) Mesoscale Model (MM5) is used to simulate Typhoon Mindulle (2004) at high resolution (3-km grid size).The data from measurements show that in the upper atmosphere the existence of an upper jet is important to the transition cyclone.When Mindulle moved to the area of the upper jet entrance,where high-altitude divergence existed, the pumping of the high-altitude divergence would enhance the vertical motion and low-level cyclone convergence. The enhanced vertical motion was confirmed by the simulation results and indicated that the existence of upper divergence enhanced the vertical motion which was favorable for the maintenance of Typhoon Mindulle.The process of extratropical transition (ET) and re-intensification always accompanies the process of cold air invasion. This process enhances the baroclinicity of the atmosphere and the formation of front at high altitudes, which converts baroclinic potential energy into kinetic energy and strengthens the cyclone vortex.The distributions of equivalent potential temperature (θe) and temperature anomalies show that the warm-core of the typhoon at the tropopause aids the re-intensification of the system. As the typhoon reenters the ocean, latent heat flux (LHF) increases in the north and west and the strong reflectivity and vertical motion occur in the east and southeast,and the west.With the re-intensification of the typhoon the wind field evolves from an oval to a circle at the lower atmosphere, the area coverage by high winds increases, and the distribution of the tangential wind shows an asymmetric pattern.展开更多
The objective of this research was to analyze （or characterize） what motivational factors are involved in the continuity of the academic development of students in the Graduate School of Jojutla. The study is quanti...The objective of this research was to analyze （or characterize） what motivational factors are involved in the continuity of the academic development of students in the Graduate School of Jojutla. The study is quantitative, descriptive, and transversal. The population is composed of 346 students who entered college in 2014. A sample of 52 students out of this population was selected, from the majors of Business Management, Accounting, Law, Environmental Sciences, Psychology, and Computer Science. The data collection instrument was developed by Esquivel and Arjona （2003）, which measured the dimensions of security, affiliation or affection, self-fulfillment, achievement, power, recognition, and knowledge. The results showed that 72.7% of new students place a very high value on the knowledge dimension： learning new things, improve study skills, do research, better overall job training, and interest in learning. However, in other dimensions, such as affiliation or affection, the percentage given by students is 9. 1%. While the study consists of a small sample, the results provide important information on motivation as a factor that must be considered and evaluated throughout the academic record of the student in order to prevent dropouts and increase terminal efficiency.展开更多
The decay ψ（2S）→Ω-Ω＋ is analyzed using 14×106 ψ（2S） events recorded by the Beijing Spectrometer Ⅱ （BESⅡ） at the Beijing Electron Positron Collider （BEPC）. Based upon events with no missing charged...The decay ψ（2S）→Ω-Ω＋ is analyzed using 14×106 ψ（2S） events recorded by the Beijing Spectrometer Ⅱ （BESⅡ） at the Beijing Electron Positron Collider （BEPC）. Based upon events with no missing charged tracks and a satisfactory four-constraint kinematic t, we determine the upper limit for the branching fraction of ψ（2S）→Ω-Ω＋ to be 1.5×104 at a 90% confidence level. By including events with one missing charged track, we are able to report the first evidence of an Ω＋ signal with a statistical signi cance of 3.1｜σ. The branching fraction of ψ（2S）Ω＋ is determined to be （4.80±1.56（stat）±1.30（sys））105.展开更多
文摘This research was an effort to select best imputation method for missing upper air temperature data over 24 standard pressure levels. We have implemented four imputation techniques like inverse distance weighting, Bilinear, Natural and Nearest interpolation for missing data imputations. Performance indicators for these techniques were the root mean square error (RMSE), absolute mean error (AME), correlation coefficient and coefficient of determination ( R<sup>2</sup> ) adopted in this research. We randomly make 30% of total samples (total samples was 324) predictable from 70% remaining data. Although four interpolation methods seem good (producing <1 RMSE, AME) for imputations of air temperature data, but bilinear method was the most accurate with least errors for missing data imputations. RMSE for bilinear method remains <0.01 on all pressure levels except 1000 hPa where this value was 0.6. The low value of AME (<0.1) came at all pressure levels through bilinear imputations. Very strong correlation (>0.99) found between actual and predicted air temperature data through this method. The high value of the coefficient of determination (0.99) through bilinear interpolation method, tells us best fit to the surface. We have also found similar results for imputation with natural interpolation method in this research, but after investigating scatter plots over each month, imputations with this method seem to little obtuse in certain months than bilinear method.
基金National Fundamental Research Development Project for Programme "973" (2004CB418303)
文摘Day-to-day precipitation data of Juries during the 43 years of 1958-2000 from stations to the south of Yangtze River are used to divide regions and run statistical analysis of sustained torrential rainfall processes. A preliminary analysis is then made based on it and the results show that June is the month in which torrential rains in the southern half of China take place frequently and sustained torrential rains occur at the same time in South China and the area to the south of Yangtze River. In addition, the analysis gives the basic features of sustained torrential rains of June in China and their interannual variability patterns, with the suggestion that the amount of these events increases significantly after the 1990s. Lastly, the sustained torrential rains occurring in Junes of 1994, 1998 and 2005 in the southern half of China are taken as examples in the research on the basic patterns and formation mechanisms of the evolution of double rain-bands during the rain season in South China and the area to the south of Yangtze River. The analysis shows that the large scale environment field in which sustained torrential rains occur is related to the stable sustaining of the South Asia High and upper level jet streams.
基金supported by the National Natural Science Foundation of China (No. 41130859)the Science Fund for Creative Research Groups (No. 41221063)
文摘With the use of data from the National Centers for Environmental Prediction Climate Forecast System Reanalysis,the environment and structure of typhoon Toraji(2001)are investigated during the re-intensification(RI)stage of its extratropical transition(ET),a process in which a tropical cyclone transforms into an extratropical or mid-latitude cyclone.The results provide detailed insight into the ET system and identify the specific features of the system,including wind field,a cold and dry intrusion,and a frontal structure in the RI stage.The irrotational wind provides the values of upper-and lower-level jets within the transitioning tropical cyclone and the cyclone over Shandong Peninsula,accompanied with the reduced radius of maximum surface winds around the cyclone center in the lower troposphere.Simultaneously,dry air intrusion enhances the formation of fronts and leads to strong potential instability in the southwest and northeast quadrants.The distribution of frontogenesis shows that the tilting term associated with vertical motion dominates the positive frontogenesis surrounding the cyclone center,especially in the RI stage.The diagnostics of the kinetic energy budget suggest that the divergent kinetic energy generation whose time evolution corresponds well to that of cyclone center pressure is the primary factor for the development of Toraji in the lower troposphere.The ET of Toraji is a compound pattern that contains a development similar to that of a B-type extratropical cyclone within the maintaining phase and an A-type extratropical cyclone within the strengthening period,which corresponds to the distribution of the E-P fluxes with vertically downward propagation in the maintaining stage and upwards momentum in the strengthening phase.
基金supported by the National Natural Science Foundation of China(Nos.40876004,40890155 and 40675060)National 973 Project(Nos.2009CB-421500 and 2007CB411801)
文摘In this study,the fifth-generation Pennsylvania State University-National Center for Atmospheric Research (PSU-NCAR) Mesoscale Model (MM5) is used to simulate Typhoon Mindulle (2004) at high resolution (3-km grid size).The data from measurements show that in the upper atmosphere the existence of an upper jet is important to the transition cyclone.When Mindulle moved to the area of the upper jet entrance,where high-altitude divergence existed, the pumping of the high-altitude divergence would enhance the vertical motion and low-level cyclone convergence. The enhanced vertical motion was confirmed by the simulation results and indicated that the existence of upper divergence enhanced the vertical motion which was favorable for the maintenance of Typhoon Mindulle.The process of extratropical transition (ET) and re-intensification always accompanies the process of cold air invasion. This process enhances the baroclinicity of the atmosphere and the formation of front at high altitudes, which converts baroclinic potential energy into kinetic energy and strengthens the cyclone vortex.The distributions of equivalent potential temperature (θe) and temperature anomalies show that the warm-core of the typhoon at the tropopause aids the re-intensification of the system. As the typhoon reenters the ocean, latent heat flux (LHF) increases in the north and west and the strong reflectivity and vertical motion occur in the east and southeast,and the west.With the re-intensification of the typhoon the wind field evolves from an oval to a circle at the lower atmosphere, the area coverage by high winds increases, and the distribution of the tangential wind shows an asymmetric pattern.
文摘The objective of this research was to analyze （or characterize） what motivational factors are involved in the continuity of the academic development of students in the Graduate School of Jojutla. The study is quantitative, descriptive, and transversal. The population is composed of 346 students who entered college in 2014. A sample of 52 students out of this population was selected, from the majors of Business Management, Accounting, Law, Environmental Sciences, Psychology, and Computer Science. The data collection instrument was developed by Esquivel and Arjona （2003）, which measured the dimensions of security, affiliation or affection, self-fulfillment, achievement, power, recognition, and knowledge. The results showed that 72.7% of new students place a very high value on the knowledge dimension： learning new things, improve study skills, do research, better overall job training, and interest in learning. However, in other dimensions, such as affiliation or affection, the percentage given by students is 9. 1%. While the study consists of a small sample, the results provide important information on motivation as a factor that must be considered and evaluated throughout the academic record of the student in order to prevent dropouts and increase terminal efficiency.
基金Supported by National Natural Science Foundation of China （10491300, 10225524, 10225525, 10425523, 10625524, 10521003, 10821063, 10825524）, Chinese Academy of Sciences （KJ 95T-03）, 100 Talents Program of CAS （U-11, U-24, U-25）, Knowledge Innovation Project of CAS （U-602, U-34 （IHEP））, National Natural Science Foundation of China （10775077, 10225522） （Tsinghua University）, and Department of Energy （DE-FG02-04ER41291） （U. Hawaii）
文摘The decay ψ（2S）→Ω-Ω＋ is analyzed using 14×106 ψ（2S） events recorded by the Beijing Spectrometer Ⅱ （BESⅡ） at the Beijing Electron Positron Collider （BEPC）. Based upon events with no missing charged tracks and a satisfactory four-constraint kinematic t, we determine the upper limit for the branching fraction of ψ（2S）→Ω-Ω＋ to be 1.5×104 at a 90% confidence level. By including events with one missing charged track, we are able to report the first evidence of an Ω＋ signal with a statistical signi cance of 3.1｜σ. The branching fraction of ψ（2S）Ω＋ is determined to be （4.80±1.56（stat）±1.30（sys））105.
