In August 2021,a warm-sector heavy rainfall event under the control of the western Pacific subtropical high occurred over the southeastern coast of China.Induced by a linearly shaped mesoscale convective system(MCS),t...In August 2021,a warm-sector heavy rainfall event under the control of the western Pacific subtropical high occurred over the southeastern coast of China.Induced by a linearly shaped mesoscale convective system(MCS),this heavy rainfall event was characterized by localized heavy rainfall,high cumulative rainfall,and extreme rainfall intensity.Using various observational data,this study first analyzed the precipitation features and radar reflectivity evolution.It then examined the role of environmental conditions and the relationship between the ambient wind field and convective initiation(CI).Furthermore,the dynamic lifting mechanism within the organization of the MCS was revealed by em-ploying multi-Doppler radar retrieval methods.Results demonstrated that the linearly shaped MCS,developed under the influence of the subtropical high,was the primary cause of the extreme rainfall event.High temperatures and humidity,coupled with the convergence of low-level southerly winds,established the environmental conditions for MCS develop-ment.The superposition of the convergence zone generated by the southerly winds in the boundary layer(925-1000 hPa)and the divergence zone in the lower layer(700-925 hPa)supplied dynamic lifting conditions for CI.Additionally,a long-term shear line(southerly southwesterly)offered favorable conditions for the organization of the linearly shaped MCS.The combined effects of strengthening low-level southerly winds and secondary circulation in mid-upper levels were influential factors in the development and maintenance of the linearly shaped MCS.展开更多
使用常规观测资料、卫星云图、雷达回波资料、自动气象站降水量以及0.25°×0.25°的NCEP/NCAR再分析资料,对2017年8月1日发生在黑龙江南部的暖区暴雨过程的中尺度特征及成因进行了分析。结果表明:暴雨发生在副高加强西伸...使用常规观测资料、卫星云图、雷达回波资料、自动气象站降水量以及0.25°×0.25°的NCEP/NCAR再分析资料,对2017年8月1日发生在黑龙江南部的暖区暴雨过程的中尺度特征及成因进行了分析。结果表明:暴雨发生在副高加强西伸北抬及有台风活动的背景下,副高外围的水汽输送为暴雨提供了充沛的水汽条件;低层西南风的增大导致暖锋锋生,暖锋的辐合抬升作用加强,造成较大范围的暴雨天气;锋生区附近存在CSI,锋生作用及CSI的释放,加强了沿着锋面倾斜向上的斜升气流及锋面次级环流,CSI导致的斜升气流的发展进一步触发对流不稳定,导致大范围的垂直上升运动,降水显著加强;暖锋云带内部探空分析显示大气处于不稳定状态,有利于以短时强降水为主的对流发展。暴雨是由云团的后向传播造成的,强降水以暖云降水为主,降水效率高,雨强大,暖锋稳定少动,由暖锋锋生所致的对流单体在同一区域重复新生,并沿暖锋自西向东传播,形成列车效应,暴雨中心一直有最大反射率因子超过45 d Bz且降水效率高的强回波活动,持续时间超过4 h,导致强降水持续时间长,降水累积量大。展开更多
Background Most of endovascular stent-graft modifications to preserve side branch must be customized according to extensive pre-operative assessment, which may not be possible in many hospitals and emergency settings....Background Most of endovascular stent-graft modifications to preserve side branch must be customized according to extensive pre-operative assessment, which may not be possible in many hospitals and emergency settings. The study was to develop a novel stent-grafts system that would allow in situ ＂fenestration＂, with less reliance on preoperative imaging. Methods The magnitude of pressure difference （PD） between left subclavian artery （LSA） and aortic arch were measured in 12 experimental pigs. Changes of PD before and after LSA was covered were analyzed respectively. The novel stent graft was made by multi-dimensional and multiple textiles forming technology. According to the PD measurement in pigs, we evaluated the feasibility of the stent-graft in a mock circulation system. Results In pigs, the blood pressure of aortic arch was significantly higher than that of LSA after it was covered （P 〈0.001） and PD was （42.78±5.17） mmHg. After target vessel was covered and when PD between the LSA and aorta reached the magnitude measured in pigs, contrast media oozed from the cranny of graft to the LSA, which was generated by sliding and deformation of yarns of novel stent-graft. Conclusions The study proposes the design of pressure difference-induced perforation aortic stent-grafts system and verifies that the PD between LSA and aortic arch is high enough to allow in situ ＂fenestration＂ by stent graft made by multi-dimensional and multiple textiles forming technoloav.展开更多
基金National Natural Science Foundation of China(41975001)Natural Science Foundation of Fujian(2023J01186,2022J01445)+1 种基金Science Project of Fujian Meteor-ological Bureau(2021BY01,2021YJ10,3502Z20214ZD4008)Fujian Meteorological Bureau Youth Team Foundation。
文摘In August 2021,a warm-sector heavy rainfall event under the control of the western Pacific subtropical high occurred over the southeastern coast of China.Induced by a linearly shaped mesoscale convective system(MCS),this heavy rainfall event was characterized by localized heavy rainfall,high cumulative rainfall,and extreme rainfall intensity.Using various observational data,this study first analyzed the precipitation features and radar reflectivity evolution.It then examined the role of environmental conditions and the relationship between the ambient wind field and convective initiation(CI).Furthermore,the dynamic lifting mechanism within the organization of the MCS was revealed by em-ploying multi-Doppler radar retrieval methods.Results demonstrated that the linearly shaped MCS,developed under the influence of the subtropical high,was the primary cause of the extreme rainfall event.High temperatures and humidity,coupled with the convergence of low-level southerly winds,established the environmental conditions for MCS develop-ment.The superposition of the convergence zone generated by the southerly winds in the boundary layer(925-1000 hPa)and the divergence zone in the lower layer(700-925 hPa)supplied dynamic lifting conditions for CI.Additionally,a long-term shear line(southerly southwesterly)offered favorable conditions for the organization of the linearly shaped MCS.The combined effects of strengthening low-level southerly winds and secondary circulation in mid-upper levels were influential factors in the development and maintenance of the linearly shaped MCS.
文摘使用常规观测资料、卫星云图、雷达回波资料、自动气象站降水量以及0.25°×0.25°的NCEP/NCAR再分析资料,对2017年8月1日发生在黑龙江南部的暖区暴雨过程的中尺度特征及成因进行了分析。结果表明:暴雨发生在副高加强西伸北抬及有台风活动的背景下,副高外围的水汽输送为暴雨提供了充沛的水汽条件;低层西南风的增大导致暖锋锋生,暖锋的辐合抬升作用加强,造成较大范围的暴雨天气;锋生区附近存在CSI,锋生作用及CSI的释放,加强了沿着锋面倾斜向上的斜升气流及锋面次级环流,CSI导致的斜升气流的发展进一步触发对流不稳定,导致大范围的垂直上升运动,降水显著加强;暖锋云带内部探空分析显示大气处于不稳定状态,有利于以短时强降水为主的对流发展。暴雨是由云团的后向传播造成的,强降水以暖云降水为主,降水效率高,雨强大,暖锋稳定少动,由暖锋锋生所致的对流单体在同一区域重复新生,并沿暖锋自西向东传播,形成列车效应,暴雨中心一直有最大反射率因子超过45 d Bz且降水效率高的强回波活动,持续时间超过4 h,导致强降水持续时间长,降水累积量大。
基金DENG Guo-yu and ZHOU Jlan contributed equally to this work. This study was supported by the grants from National Natural Science Foundation of China （No. 30972942, No. 81273522, and No. 81270386）.
文摘Background Most of endovascular stent-graft modifications to preserve side branch must be customized according to extensive pre-operative assessment, which may not be possible in many hospitals and emergency settings. The study was to develop a novel stent-grafts system that would allow in situ ＂fenestration＂, with less reliance on preoperative imaging. Methods The magnitude of pressure difference （PD） between left subclavian artery （LSA） and aortic arch were measured in 12 experimental pigs. Changes of PD before and after LSA was covered were analyzed respectively. The novel stent graft was made by multi-dimensional and multiple textiles forming technology. According to the PD measurement in pigs, we evaluated the feasibility of the stent-graft in a mock circulation system. Results In pigs, the blood pressure of aortic arch was significantly higher than that of LSA after it was covered （P 〈0.001） and PD was （42.78±5.17） mmHg. After target vessel was covered and when PD between the LSA and aorta reached the magnitude measured in pigs, contrast media oozed from the cranny of graft to the LSA, which was generated by sliding and deformation of yarns of novel stent-graft. Conclusions The study proposes the design of pressure difference-induced perforation aortic stent-grafts system and verifies that the PD between LSA and aortic arch is high enough to allow in situ ＂fenestration＂ by stent graft made by multi-dimensional and multiple textiles forming technoloav.
