In situ measurements of the vertical structure of ozone were made in Changchun （43.53°N, 125.13°E）, China, by the Institute of Atmosphere Physics, in the summers of 2010-13. Analysis of the 89 validated oz...In situ measurements of the vertical structure of ozone were made in Changchun （43.53°N, 125.13°E）, China, by the Institute of Atmosphere Physics, in the summers of 2010-13. Analysis of the 89 validated ozone profiles shows the vari- ation of ozone concentration in the upper troposphere and lower stratosphere （UTLS） caused by cut-off lows （COLs） over Changchun. During the COL events, an increase of the ozone concentration and a lower height of the tropopause are observed. Backward simulations with a trajectory model show that the ozone-rich airmass brought by the COL is from Siberia. A case study proves that stratosphere-troposphere exchange （STE） occurs in the COL. The ozone-rich air mass transported from the stratosphere to the troposphere first becomes unstable, then loses its high ozone concentration. This process usually happens during the decay stage of COLs. In order to understand the influence of COLs on the ozone in the UTLS, statistical analysis of the ozone profiles within COLs, and other profiles, are employed. The results indicate that the ozone concentrations of the in-COL profiles are significantly higher than those of the other profiles between ±4 km around the tropopause. The COLs induce an increase in UTLS column ozone by 32% on average. Meanwhile, the COLs depress the lapse-rate tropopause （LRT）/dynamical tropopause height by 1.4/1.7 km and cause the atmosphere above the tropopause to be less stable. The influence of COLs is durable because the increased ozone concentration lasts at least one day after the COL has passed over Changchun. Furthermore, the relative coefficient between LRT height and lower stratosphere （LS） column ozone is -0.62, which implies a positive correlation between COL strength and LS ozone concentration.展开更多
Complimentary hexagonal-omega structures are used to design compact, low insertion loss (IL), low pass filter with sharp cut-off. It has been designed for improvement of roll-off performance based on both μ and ε ne...Complimentary hexagonal-omega structures are used to design compact, low insertion loss (IL), low pass filter with sharp cut-off. It has been designed for improvement of roll-off performance based on both μ and ε negative property of the complimentary hex-omega structure while maintaining the filter pass-band performance. By properly designing and loading the hexagonal-omega structure in the ground of microstrip line not only improve the roll-off of the low pass filter, but also reduced the filter size. The simulated results indicate that the proposed filter achieves a flat pass band with no ripples as well as selectivity of 19.68 dB/GHz, corresponding to 5-unit cells hex-omega structures. This significantly exceeds the 5.6 dB/GHz selectivity of the conventional low pass filter design, due to sub-lambda dimensions of the hex-omega structure. A prototype filter implementing area is: 0.712λg x 0.263λg, λg being the guided wavelength at 3-dB cut-off frequency (fc). The proposed filter has a size smaller by 36.2%.展开更多
利用高空、地面常规观测资料,FY-2G黑体亮度温度TBB资料和ECWMF 0. 125°×0. 125°高分辨率资料,对2018年1月3日陕西区域性暴雪进行诊断。结果表明:500 h Pa切断低压分裂低槽、700 h Pa西南急流和850 h Pa东风回流是暴雪...利用高空、地面常规观测资料,FY-2G黑体亮度温度TBB资料和ECWMF 0. 125°×0. 125°高分辨率资料,对2018年1月3日陕西区域性暴雪进行诊断。结果表明:500 h Pa切断低压分裂低槽、700 h Pa西南急流和850 h Pa东风回流是暴雪发生的主要影响系统。700 h Pa强西南急流、偏东气流分别携带来自孟加拉湾和东海的充沛水汽是产生区域性暴雪的重要原因之一;中层冷空气的侵入是本次暴雪发生的主要触发机制;高层辐散与低层辐合的有利配置导致的强上升运动和中低层深厚正涡度的发展和维持是暴雪形成的动力机制。长约1100 km、宽约200 km、TBB≤-40℃的狭长云带东移过程中发展的TBB最低为-52℃、尺度为20~100 km的中-β尺度对流云团是造成小时降雪量超过2. 0 mm、产生区域性暴雪的主要原因。本次暴雪属于冷季高架对流,对称条件不稳定导致的倾斜对流使上升运动加强,雷达回波表现为平行于0~6 km垂直风切变的平行带状结构,且雪带随气流移动。展开更多
基金jointly supported by the National Basic Research Program of China (Grant No.2010CB428602)the National Natural Science Foundation of China (Grant Nos.41275046 and 41025017)
文摘In situ measurements of the vertical structure of ozone were made in Changchun （43.53°N, 125.13°E）, China, by the Institute of Atmosphere Physics, in the summers of 2010-13. Analysis of the 89 validated ozone profiles shows the vari- ation of ozone concentration in the upper troposphere and lower stratosphere （UTLS） caused by cut-off lows （COLs） over Changchun. During the COL events, an increase of the ozone concentration and a lower height of the tropopause are observed. Backward simulations with a trajectory model show that the ozone-rich airmass brought by the COL is from Siberia. A case study proves that stratosphere-troposphere exchange （STE） occurs in the COL. The ozone-rich air mass transported from the stratosphere to the troposphere first becomes unstable, then loses its high ozone concentration. This process usually happens during the decay stage of COLs. In order to understand the influence of COLs on the ozone in the UTLS, statistical analysis of the ozone profiles within COLs, and other profiles, are employed. The results indicate that the ozone concentrations of the in-COL profiles are significantly higher than those of the other profiles between ±4 km around the tropopause. The COLs induce an increase in UTLS column ozone by 32% on average. Meanwhile, the COLs depress the lapse-rate tropopause （LRT）/dynamical tropopause height by 1.4/1.7 km and cause the atmosphere above the tropopause to be less stable. The influence of COLs is durable because the increased ozone concentration lasts at least one day after the COL has passed over Changchun. Furthermore, the relative coefficient between LRT height and lower stratosphere （LS） column ozone is -0.62, which implies a positive correlation between COL strength and LS ozone concentration.
文摘Complimentary hexagonal-omega structures are used to design compact, low insertion loss (IL), low pass filter with sharp cut-off. It has been designed for improvement of roll-off performance based on both μ and ε negative property of the complimentary hex-omega structure while maintaining the filter pass-band performance. By properly designing and loading the hexagonal-omega structure in the ground of microstrip line not only improve the roll-off of the low pass filter, but also reduced the filter size. The simulated results indicate that the proposed filter achieves a flat pass band with no ripples as well as selectivity of 19.68 dB/GHz, corresponding to 5-unit cells hex-omega structures. This significantly exceeds the 5.6 dB/GHz selectivity of the conventional low pass filter design, due to sub-lambda dimensions of the hex-omega structure. A prototype filter implementing area is: 0.712λg x 0.263λg, λg being the guided wavelength at 3-dB cut-off frequency (fc). The proposed filter has a size smaller by 36.2%.
文摘利用高空、地面常规观测资料,FY-2G黑体亮度温度TBB资料和ECWMF 0. 125°×0. 125°高分辨率资料,对2018年1月3日陕西区域性暴雪进行诊断。结果表明:500 h Pa切断低压分裂低槽、700 h Pa西南急流和850 h Pa东风回流是暴雪发生的主要影响系统。700 h Pa强西南急流、偏东气流分别携带来自孟加拉湾和东海的充沛水汽是产生区域性暴雪的重要原因之一;中层冷空气的侵入是本次暴雪发生的主要触发机制;高层辐散与低层辐合的有利配置导致的强上升运动和中低层深厚正涡度的发展和维持是暴雪形成的动力机制。长约1100 km、宽约200 km、TBB≤-40℃的狭长云带东移过程中发展的TBB最低为-52℃、尺度为20~100 km的中-β尺度对流云团是造成小时降雪量超过2. 0 mm、产生区域性暴雪的主要原因。本次暴雪属于冷季高架对流,对称条件不稳定导致的倾斜对流使上升运动加强,雷达回波表现为平行于0~6 km垂直风切变的平行带状结构,且雪带随气流移动。
