As the strongest typhoon in 2015,the rapid intensification(RI)process of Typhoon Mujigae is simulated at the cloud-resolving scale by utilizing the Weather Research and Forecasting model,coupled with observed sea surf...As the strongest typhoon in 2015,the rapid intensification(RI)process of Typhoon Mujigae is simulated at the cloud-resolving scale by utilizing the Weather Research and Forecasting model,coupled with observed sea surface temperature(SST)and reduced SST as the control and sensitivity experiments,respectively.The spatiotemporal distribution characteristics of uppertropospheric potential vorticity(PV)and its response to SST changes are analyzed simultaneously.The results show a significant upper-tropospheric PV anomaly 6 h before RI,which indicates the approaching RI of Typhoon Mujigae.Deep convection overlies the strong signals of upper-tropospheric PV anomalies.More insight into the PV budget analysis verifies that the diabatic heating effect and vertical advection terms associated with deep convection dominate the upper-tropospheric PV anomaly,inferring that deep convection plays a crucial role in the upper-tropospheric PV anomaly.As SST decreases,diabatic heating and vertical advection effects are weakened due to reduced deep convection;therefore,the PV anomaly in the model run is not stronger than that in the control run,and the RI process of Mujigae disappears.Therefore,from the viewpoint of upper and lower-level interactions,how SST impacts upper-tropospheric PV anomalies and their interactions with RI are clarified.Thus,in addition to SST,the upper-tropospheric PV anomaly might be a significant factor in differentiating between RI and non-RI tropical cyclones.展开更多
For Super Typhoon Maria(2018),the multi-intensity change stages are identified and reproduced by numerical simulation.It is rather difficult to perform a perfect simulation for such a repeatedly reinforced typhoon dur...For Super Typhoon Maria(2018),the multi-intensity change stages are identified and reproduced by numerical simulation.It is rather difficult to perform a perfect simulation for such a repeatedly reinforced typhoon during its long life-cycle and remote path.In this study,the rapid intensification(RI)episode is focused on to investigate the convective burst(CB)characteristics and the relationship between the CBs and the RI of Maria.For Typhoon Maria,1)the spatial pattern of the inner-core CBs in distinct shear-relative quadrants,instead of the overall inner-core CBs frequently used in previous studies,presents cyclonic rotation from downshear to upshear quadrants during RI,producing a higher efficiency for tropical cyclone(TC)spinup,which accelerates the RI process.2)Dual meanings/relationships exist between CBs and RI for Maria,in contrast to the previous argument that CBs might be an indicator or a precursor to RI.The sudden growth of CBs prior to RI provides a precursor for the upcoming RI.Additionally,the appearance of the CB peak soon after RI indicates RI could lead to more intensive deep convections.The overlap of CBs with high inertial stability inside the radius of maximum wind plays a significant role in the RI of TCs.3)The synoptic attributions to CBs are also explored for the entire troposphere,fitting in the bottom-up thinking of convection growth.The CBs might be associated with high convective available potential energy in the boundary layer,a strengthening of the deep-layer secondary circulation,and an enhanced upper-level eddy momentum flux convergence.展开更多
The electric field integral equation (EFIE) combined with the multilevel fast multipole algorithm (MLFMA) is applied to analyze the radiation and impedance properties of wire antennas mounted on complex conducting pla...The electric field integral equation (EFIE) combined with the multilevel fast multipole algorithm (MLFMA) is applied to analyze the radiation and impedance properties of wire antennas mounted on complex conducting platforms to realize fast, accurate solutions. Wire, surface and junction basis functions are used to model the current distribution on the object. Application of MLFMA reduces memory requirement and computing time compared to conventional methods, such as method of moment (MOM), especially for the antenna on a large-sized platform. Generalized minimal residual (GMRES) solver with incomplete LU factorization preconditioner using a dual dropping strategy (ILUT) is applied to reduce the iterative number. Several typical numerical examples are presented to validate this algorithm and show the accuracy and computational efficiency.展开更多
Shear wave splitting is studied based on the digital waveforms of three seismic stations DJS, SZD and WUJ, which were set up after the Jiujiang-Ruichang MS5.7 earthquake of November 26, 2005 around the epicenter area....Shear wave splitting is studied based on the digital waveforms of three seismic stations DJS, SZD and WUJ, which were set up after the Jiujiang-Ruichang MS5.7 earthquake of November 26, 2005 around the epicenter area. The result shows that the time delays of slow shear waves of the DJS station, which is not far from the epicenter and where the distribution of faults is complex near the station, are relatively larger and the polarization directions of fast shear waves are not concentrated; the predominant polarization direction of fast shear waves of WUJ station, with single fault distributed nearby, has a difference of 35° to the strike of the fault and is inconsistent with the direction of regional principal compressive stress. The predominant polarization direction of fast shear waves of SZD station with no faults nearby is in accordance with regional principal compressive stress. There is no obvious regular relationshipship between the delay time and the focal depth.展开更多
It is still a laborious work to consult massive multidisciplinary geological maps which are scattered in different geological departments,and hard to give full play to the potential application value of geological map...It is still a laborious work to consult massive multidisciplinary geological maps which are scattered in different geological departments,and hard to give full play to the potential application value of geological map. Along with the network,the development of communication and computer technology,especially with the Web2.0 technology arisen,provides opportunities to the web for sharing of geological maps. Web fast sharing platform of massive geological maps( WSPGM) is based on the Flex technology development,using B/S architecture,with map navigation,search,display,security and other functions of the software system. Through the map pretreatment and asynchronous communication the system can display any size of geological map,and through the range limits,rights management,sharing system and watermark logo to take effective security on geological map. On the basis of this system,with the Jilin University web sharing system of geological map,the system can greatly improve the efficiency of using geological map. for research.展开更多
基金supported by the National Key Research and Development Program of China Grant Nos. 2018YFF0300102 and 2018YFC1506801the National Natural Science Foundation of China Grant Nos. 41405059,41575064,41875079,41875077,41875056,and 41630532。
文摘As the strongest typhoon in 2015,the rapid intensification(RI)process of Typhoon Mujigae is simulated at the cloud-resolving scale by utilizing the Weather Research and Forecasting model,coupled with observed sea surface temperature(SST)and reduced SST as the control and sensitivity experiments,respectively.The spatiotemporal distribution characteristics of uppertropospheric potential vorticity(PV)and its response to SST changes are analyzed simultaneously.The results show a significant upper-tropospheric PV anomaly 6 h before RI,which indicates the approaching RI of Typhoon Mujigae.Deep convection overlies the strong signals of upper-tropospheric PV anomalies.More insight into the PV budget analysis verifies that the diabatic heating effect and vertical advection terms associated with deep convection dominate the upper-tropospheric PV anomaly,inferring that deep convection plays a crucial role in the upper-tropospheric PV anomaly.As SST decreases,diabatic heating and vertical advection effects are weakened due to reduced deep convection;therefore,the PV anomaly in the model run is not stronger than that in the control run,and the RI process of Mujigae disappears.Therefore,from the viewpoint of upper and lower-level interactions,how SST impacts upper-tropospheric PV anomalies and their interactions with RI are clarified.Thus,in addition to SST,the upper-tropospheric PV anomaly might be a significant factor in differentiating between RI and non-RI tropical cyclones.
基金The authors are supported by the National Natural Science Foundation of China[grant numbers 41575064,41875079,and 41775079]the Open Research Program of the State Key Laboratory of Severe Weather,Chinese Academy of Meteorological Sciences[grant number 2019LASW-A04].
文摘For Super Typhoon Maria(2018),the multi-intensity change stages are identified and reproduced by numerical simulation.It is rather difficult to perform a perfect simulation for such a repeatedly reinforced typhoon during its long life-cycle and remote path.In this study,the rapid intensification(RI)episode is focused on to investigate the convective burst(CB)characteristics and the relationship between the CBs and the RI of Maria.For Typhoon Maria,1)the spatial pattern of the inner-core CBs in distinct shear-relative quadrants,instead of the overall inner-core CBs frequently used in previous studies,presents cyclonic rotation from downshear to upshear quadrants during RI,producing a higher efficiency for tropical cyclone(TC)spinup,which accelerates the RI process.2)Dual meanings/relationships exist between CBs and RI for Maria,in contrast to the previous argument that CBs might be an indicator or a precursor to RI.The sudden growth of CBs prior to RI provides a precursor for the upcoming RI.Additionally,the appearance of the CB peak soon after RI indicates RI could lead to more intensive deep convections.The overlap of CBs with high inertial stability inside the radius of maximum wind plays a significant role in the RI of TCs.3)The synoptic attributions to CBs are also explored for the entire troposphere,fitting in the bottom-up thinking of convection growth.The CBs might be associated with high convective available potential energy in the boundary layer,a strengthening of the deep-layer secondary circulation,and an enhanced upper-level eddy momentum flux convergence.
基金This project was supported by the National Natural Science Foundation of China (60431010).
文摘The electric field integral equation (EFIE) combined with the multilevel fast multipole algorithm (MLFMA) is applied to analyze the radiation and impedance properties of wire antennas mounted on complex conducting platforms to realize fast, accurate solutions. Wire, surface and junction basis functions are used to model the current distribution on the object. Application of MLFMA reduces memory requirement and computing time compared to conventional methods, such as method of moment (MOM), especially for the antenna on a large-sized platform. Generalized minimal residual (GMRES) solver with incomplete LU factorization preconditioner using a dual dropping strategy (ILUT) is applied to reduce the iterative number. Several typical numerical examples are presented to validate this algorithm and show the accuracy and computational efficiency.
基金sponsored by the China Spark Program of Earthquake Science and Technology(XH12027)the Three-Combination Topics of China Earthquake Administration of"Research on the Crustal Medium Anisotropy in the Jiujiang-Ruichang Earthquake Area"the Special Fund of Seismic Industry Research(201008007)
文摘Shear wave splitting is studied based on the digital waveforms of three seismic stations DJS, SZD and WUJ, which were set up after the Jiujiang-Ruichang MS5.7 earthquake of November 26, 2005 around the epicenter area. The result shows that the time delays of slow shear waves of the DJS station, which is not far from the epicenter and where the distribution of faults is complex near the station, are relatively larger and the polarization directions of fast shear waves are not concentrated; the predominant polarization direction of fast shear waves of WUJ station, with single fault distributed nearby, has a difference of 35° to the strike of the fault and is inconsistent with the direction of regional principal compressive stress. The predominant polarization direction of fast shear waves of SZD station with no faults nearby is in accordance with regional principal compressive stress. There is no obvious regular relationshipship between the delay time and the focal depth.
文摘It is still a laborious work to consult massive multidisciplinary geological maps which are scattered in different geological departments,and hard to give full play to the potential application value of geological map. Along with the network,the development of communication and computer technology,especially with the Web2.0 technology arisen,provides opportunities to the web for sharing of geological maps. Web fast sharing platform of massive geological maps( WSPGM) is based on the Flex technology development,using B/S architecture,with map navigation,search,display,security and other functions of the software system. Through the map pretreatment and asynchronous communication the system can display any size of geological map,and through the range limits,rights management,sharing system and watermark logo to take effective security on geological map. On the basis of this system,with the Jilin University web sharing system of geological map,the system can greatly improve the efficiency of using geological map. for research.
