利用中国地面加密自动站观测资料、北京地区雷达探测资料、NCEP(1°×1°)FNL资料、ECMWF ERA Interim(0.125°×0.125°)逐日再分析资料等,对造成2016年7月19—20日华北极端暴雨中的低涡系统发展演变的结构特...利用中国地面加密自动站观测资料、北京地区雷达探测资料、NCEP(1°×1°)FNL资料、ECMWF ERA Interim(0.125°×0.125°)逐日再分析资料等,对造成2016年7月19—20日华北极端暴雨中的低涡系统发展演变的结构特征和加强机制进行了研究。华北地区这次特大暴雨过程出现了3个阶段降水,其中与低涡系统强烈发展对应的第2阶段降水是本次华北暴雨过程的主要降水阶段。针对该低涡的分析表明:(1)850 hPa以西南低涡为中心的低压带中,在河南西北部新生低涡系统,并且其在向华北地区移动过程中显著加强,该低涡系统在空间结构上,从倾斜涡柱逐渐发展成近乎直立的、贯穿整个对流层的深厚低涡系统;(2)中低层低涡系统快速发展过程与高低空系统构成耦合作用有关:低层低涡系统显著加强之前,对流层上层(300—200 hPa)首先出现高空槽异常加深并向南发展,该高空槽发展的开始阶段与其本身冷暖平流造成的斜压发展过程对应;而后,随着高纬度平流层高位涡沿等熵面向南运动,造成华北地区对流层上层涡度增强,形成正位涡异常区;当这一正位涡异常区叠加在对流层中低层锋区上空时,造成对流层中低层气旋快速发展并向下伸展,诱发河南西北部的新生气旋;低涡系统的发展进一步强化了低空暖平流,促使低空气旋向东北方向发展"移动"(本质上是暖平流前端造成的气旋发展),这一动力学过程反过来使高层的涡度增强;这一正反馈过程形成的耦合环流不仅造成了整个涡度柱强度增强,而且垂直结构上逐渐由倾斜涡柱演变为近乎于直立的涡柱;(3)随着低涡系统增强,极大地加强了垂直上升运动并触发了对流,形成大范围的强降水,大量的凝结潜热释放,造成了低层低涡系统在强降水开始阶段的快速发展和增强;20日00时(世界时)以后,虽然对流活动显著减弱,但低涡系统的加深维持了大范围强降�展开更多
Observations of a quasi-90-day oscillation in the mesosphere and lower thermosphere(MLT) region from April 2011 to December 2014 are presented in this study. There is clear evidence of a quasi-90-day oscillation in te...Observations of a quasi-90-day oscillation in the mesosphere and lower thermosphere(MLT) region from April 2011 to December 2014 are presented in this study. There is clear evidence of a quasi-90-day oscillation in temperatures obtained from the Kunming meteor radar(25.6°N, 103.8°E) and Sounding of the Atmosphere using Broadband Emission Radiometry(SABER), as well as in wind observed by the Kunming meteor radar. The quasi-90-day oscillation appears to be a prominent feature in the temperatures and meridional wind tides and presents quite regular cycles that occur approximately twice per year. The amplitudes and phases of the quasi-90-day oscillation in the SABER temperature show a feature similar to that of upward-propagated diurnal tides, which have a vertical wavelength of ～20 km above 70 km. In the lower atmosphere, a similar 90-day variability is presented in the surface latent heat flux and correlates with the temperature in the MLT region. Similar to the quasi-90-day oscillation in temperature, a 90-day variability of ozone(O3) is also present in the MLT region and is considered to be driven by a similar variability in the upwardly-propagated diurnal tides generated in the lower atmosphere. Moreover, the 90-day variability in the absorption of ultraviolet(UV) radiation by daytime O3 in the MLT region is an in situ source of the quasi-90-day oscillation in the MLT temperature.展开更多
利用中尺度WRF模式对2008年6月30日—7月1日生成于川东南地区的一个西南低涡的发生发展过程进行了数值模拟研究。模拟结果显示低涡首先出现在850 h Pa上,几个小时后700h Pa上才有低涡生成,850 h Pa低涡的形成与西南低空急流有着密切的...利用中尺度WRF模式对2008年6月30日—7月1日生成于川东南地区的一个西南低涡的发生发展过程进行了数值模拟研究。模拟结果显示低涡首先出现在850 h Pa上,几个小时后700h Pa上才有低涡生成,850 h Pa低涡的形成与西南低空急流有着密切的联系。通过ω方程的诊断分析表明,涡度的水平平流项和辐散项对850 h Pa低涡的形成起主要作用,而潜热释放对850 h Pa低涡的形成作用不大;潜热加热是700 h Pa气流不断辐合从而形成低涡的主要因子。干敏感性试验研究进一步证实了潜热释放对850 h Pa低涡的影响不明显,但是会导致700 h Pa上气旋性的切变加强辐合从而形成低涡。展开更多
In this paper, the potential vorticity structure and inversion of the cyclogenesis over the Yangtze River and Huaihe River valleys during 21 23 June 2003 are investigated with a potential vorticity （PV） framework. T...In this paper, the potential vorticity structure and inversion of the cyclogenesis over the Yangtze River and Huaihe River valleys during 21 23 June 2003 are investigated with a potential vorticity （PV） framework. The cyclogenesis is manifested by a lower-tropospheric PV anomaly over the Yangtze River and Huaihe River valleys at early stages mainly due to latent heat release, which greatly affects the evolution of the associated lower-tropospheric geopotential height and wind fields as demonstrated by piecewise PV inversion. At later stages, an upper-tropospheric PV anomaly develops, resulting in the growth of ridges over the cyclone in both the upstream and downstream, which provide a favorable background field for the low-level cyclone development. But the effect of a surface thermal anomaly always impedes the development of the cyclone to different extents during this cyclogenesis. It is further demonstrated that the position and the strength of the PV anomaly are closely related to the low-level cyclone development, and the lower-tropospheric PV anomaly seems to constitute the most significant feature, for instance, contributing about 60% to the low-level jet （LLJ）.展开更多
The mesoscale orographic effects on typhoon Aere＇s precipitation are simulated using an Advanced Regional Eta-coordinate Model （AREM） version 3.0. In particular, the effects of the latent heat release are studied b...The mesoscale orographic effects on typhoon Aere＇s precipitation are simulated using an Advanced Regional Eta-coordinate Model （AREM） version 3.0. In particular, the effects of the latent heat release are studied by two comparable experiments： with and without condensational heating. The results show that the typhoon rainfall is tripled by the southeastern China mesoscale terrain, and the condensational heating is responsible for at least half of the increase. One role of the latent heat release is to warm the atmosphere, leading to a depression of the surface pressure, which then causes a larger pressure difference in the zonal direction. This pressure gradient guides the water vapour to flow into the foothills, which in turn amplifies the water vapour flux divergence amplified, causing the typhoon rainfall to increase eventually. The other role of the latent heat release is to make the convection more organized, resulting in a relatively smaller rain area and stronger precipitation.展开更多
本文利用欧洲中期天气预报中心(European Centre for Medium-Range Weather Forecasts,ECMWF)提供的0.125(°)×0.125(°)的ERA-Interim再分析资料、美国国家航空航天局(National Aeronautics and Space Administration,NA...本文利用欧洲中期天气预报中心(European Centre for Medium-Range Weather Forecasts,ECMWF)提供的0.125(°)×0.125(°)的ERA-Interim再分析资料、美国国家航空航天局(National Aeronautics and Space Administration,NASA)提供的MODIS(Moderate Resolution Imaging Spectroradiometer)可见光云图、气象卫星合作研究所(Cooperative Institute for Meteorological Satellite Studies,CIMSS)提供的GOES-EAST红外卫星云图等资料以及WRF(Weather Research and Forecasting)数值模式的模拟结果,对2003年3月北大西洋上一个爆发性气旋B“吞并”另一个气旋A后快速发展机制进行了分析。气旋A和B均生成于美国东部,气旋A于2003年3月5日06 UTC生成,气旋B于6日00 UTC生成,且比气旋A向东北方向移动得更快,7日18 UTC达到最大加深率3.27 hPa·h^(-1)。在北大西洋中部地区,从8日00 UTC开始,气旋B吞并气旋A后形成气旋C,8日12 UTC气旋C中心气压达到最低值938.3 hPa。高空急流、低空水汽输送和潜热释放为气旋A和气旋B的快速发展提供了有利的环流背景场。气旋B吞并气旋A的过程经历三个阶段:前期阶段、吞并阶段、完成阶段。利用WRF模式模拟结果的分析表明,气旋A和B之间建立水汽输运通道,水汽从气旋A向气旋B输送。气旋B吞并气旋A后形成气旋C快速发展的主要原因是暖平流的作用。展开更多
利用NCEP(National Centers for Environmental Prediction)提供的FNL(Final Analyses)资料和WRF模式(Weather Research Forecast Model)对2009年0920号超强台风LUPIT变性后再次爆发性发展的现象进行了研究,详细分析了潜热加热在热带气...利用NCEP(National Centers for Environmental Prediction)提供的FNL(Final Analyses)资料和WRF模式(Weather Research Forecast Model)对2009年0920号超强台风LUPIT变性后再次爆发性发展的现象进行了研究,详细分析了潜热加热在热带气旋变性为温带爆发性气旋过程中的作用。研究发现:潜热释放是气旋快速发展阶段的重要影响因素,潜热通过影响环流促使气旋的爆发性发展,较为深厚的对流系统使潜热释放的位置发生在对流层的中高层。热量释放之后,地面气旋上空高空槽前的西南气流向槽前高压脊内输送热量,造成高层等压面坡度增大,涡度平流随高度增加,涡度平流的增加又进一步促进了上升运动加强,有利于更多水汽凝结,释放潜热,使得气旋海平面中心气压快速降低。天气尺度低压系统与对流活动相伴随的潜热释放之间的相互促进的正反馈过程类似于热带气旋的CISK机制,这可能是热带气旋变性后爆发性发展的一种重要机制。展开更多
文摘利用中国地面加密自动站观测资料、北京地区雷达探测资料、NCEP(1°×1°)FNL资料、ECMWF ERA Interim(0.125°×0.125°)逐日再分析资料等,对造成2016年7月19—20日华北极端暴雨中的低涡系统发展演变的结构特征和加强机制进行了研究。华北地区这次特大暴雨过程出现了3个阶段降水,其中与低涡系统强烈发展对应的第2阶段降水是本次华北暴雨过程的主要降水阶段。针对该低涡的分析表明:(1)850 hPa以西南低涡为中心的低压带中,在河南西北部新生低涡系统,并且其在向华北地区移动过程中显著加强,该低涡系统在空间结构上,从倾斜涡柱逐渐发展成近乎直立的、贯穿整个对流层的深厚低涡系统;(2)中低层低涡系统快速发展过程与高低空系统构成耦合作用有关:低层低涡系统显著加强之前,对流层上层(300—200 hPa)首先出现高空槽异常加深并向南发展,该高空槽发展的开始阶段与其本身冷暖平流造成的斜压发展过程对应;而后,随着高纬度平流层高位涡沿等熵面向南运动,造成华北地区对流层上层涡度增强,形成正位涡异常区;当这一正位涡异常区叠加在对流层中低层锋区上空时,造成对流层中低层气旋快速发展并向下伸展,诱发河南西北部的新生气旋;低涡系统的发展进一步强化了低空暖平流,促使低空气旋向东北方向发展"移动"(本质上是暖平流前端造成的气旋发展),这一动力学过程反过来使高层的涡度增强;这一正反馈过程形成的耦合环流不仅造成了整个涡度柱强度增强,而且垂直结构上逐渐由倾斜涡柱演变为近乎于直立的涡柱;(3)随着低涡系统增强,极大地加强了垂直上升运动并触发了对流,形成大范围的强降水,大量的凝结潜热释放,造成了低层低涡系统在强降水开始阶段的快速发展和增强;20日00时(世界时)以后,虽然对流活动显著减弱,但低涡系统的加深维持了大范围强降�
基金supported by Project(KJCX2-EW-J01,KZZD-EW-0101)of the Chinese Academy of Sciencesthe National Natural Science Foundation of China(41322029,41474129,41421063 and41804147)+5 种基金the National Basic Research Program of China(2012CB825605)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(2011324)the Fundamental Research Funds for the Central Universitiesthe open research project of Chinese Academy of Sciences Large Research Infrastructuresthe Chinese Meridian Projectthe Open Research Program of National Key Laboratory of Electromagnetic Environment of the China Research Institute of Radiowave Propagation
文摘Observations of a quasi-90-day oscillation in the mesosphere and lower thermosphere(MLT) region from April 2011 to December 2014 are presented in this study. There is clear evidence of a quasi-90-day oscillation in temperatures obtained from the Kunming meteor radar(25.6°N, 103.8°E) and Sounding of the Atmosphere using Broadband Emission Radiometry(SABER), as well as in wind observed by the Kunming meteor radar. The quasi-90-day oscillation appears to be a prominent feature in the temperatures and meridional wind tides and presents quite regular cycles that occur approximately twice per year. The amplitudes and phases of the quasi-90-day oscillation in the SABER temperature show a feature similar to that of upward-propagated diurnal tides, which have a vertical wavelength of ～20 km above 70 km. In the lower atmosphere, a similar 90-day variability is presented in the surface latent heat flux and correlates with the temperature in the MLT region. Similar to the quasi-90-day oscillation in temperature, a 90-day variability of ozone(O3) is also present in the MLT region and is considered to be driven by a similar variability in the upwardly-propagated diurnal tides generated in the lower atmosphere. Moreover, the 90-day variability in the absorption of ultraviolet(UV) radiation by daytime O3 in the MLT region is an in situ source of the quasi-90-day oscillation in the MLT temperature.
文摘利用中尺度WRF模式对2008年6月30日—7月1日生成于川东南地区的一个西南低涡的发生发展过程进行了数值模拟研究。模拟结果显示低涡首先出现在850 h Pa上,几个小时后700h Pa上才有低涡生成,850 h Pa低涡的形成与西南低空急流有着密切的联系。通过ω方程的诊断分析表明,涡度的水平平流项和辐散项对850 h Pa低涡的形成起主要作用,而潜热释放对850 h Pa低涡的形成作用不大;潜热加热是700 h Pa气流不断辐合从而形成低涡的主要因子。干敏感性试验研究进一步证实了潜热释放对850 h Pa低涡的影响不明显,但是会导致700 h Pa上气旋性的切变加强辐合从而形成低涡。
文摘In this paper, the potential vorticity structure and inversion of the cyclogenesis over the Yangtze River and Huaihe River valleys during 21 23 June 2003 are investigated with a potential vorticity （PV） framework. The cyclogenesis is manifested by a lower-tropospheric PV anomaly over the Yangtze River and Huaihe River valleys at early stages mainly due to latent heat release, which greatly affects the evolution of the associated lower-tropospheric geopotential height and wind fields as demonstrated by piecewise PV inversion. At later stages, an upper-tropospheric PV anomaly develops, resulting in the growth of ridges over the cyclone in both the upstream and downstream, which provide a favorable background field for the low-level cyclone development. But the effect of a surface thermal anomaly always impedes the development of the cyclone to different extents during this cyclogenesis. It is further demonstrated that the position and the strength of the PV anomaly are closely related to the low-level cyclone development, and the lower-tropospheric PV anomaly seems to constitute the most significant feature, for instance, contributing about 60% to the low-level jet （LLJ）.
基金This work was jointly supported by the National Key Basic Research and Development Project of China under Grant No.2004CB418304the National Natural Science Foundation of China under Grant Nos.40505016,40575030 and 40233031.
文摘The mesoscale orographic effects on typhoon Aere＇s precipitation are simulated using an Advanced Regional Eta-coordinate Model （AREM） version 3.0. In particular, the effects of the latent heat release are studied by two comparable experiments： with and without condensational heating. The results show that the typhoon rainfall is tripled by the southeastern China mesoscale terrain, and the condensational heating is responsible for at least half of the increase. One role of the latent heat release is to warm the atmosphere, leading to a depression of the surface pressure, which then causes a larger pressure difference in the zonal direction. This pressure gradient guides the water vapour to flow into the foothills, which in turn amplifies the water vapour flux divergence amplified, causing the typhoon rainfall to increase eventually. The other role of the latent heat release is to make the convection more organized, resulting in a relatively smaller rain area and stronger precipitation.
文摘本文利用欧洲中期天气预报中心(European Centre for Medium-Range Weather Forecasts,ECMWF)提供的0.125(°)×0.125(°)的ERA-Interim再分析资料、美国国家航空航天局(National Aeronautics and Space Administration,NASA)提供的MODIS(Moderate Resolution Imaging Spectroradiometer)可见光云图、气象卫星合作研究所(Cooperative Institute for Meteorological Satellite Studies,CIMSS)提供的GOES-EAST红外卫星云图等资料以及WRF(Weather Research and Forecasting)数值模式的模拟结果,对2003年3月北大西洋上一个爆发性气旋B“吞并”另一个气旋A后快速发展机制进行了分析。气旋A和B均生成于美国东部,气旋A于2003年3月5日06 UTC生成,气旋B于6日00 UTC生成,且比气旋A向东北方向移动得更快,7日18 UTC达到最大加深率3.27 hPa·h^(-1)。在北大西洋中部地区,从8日00 UTC开始,气旋B吞并气旋A后形成气旋C,8日12 UTC气旋C中心气压达到最低值938.3 hPa。高空急流、低空水汽输送和潜热释放为气旋A和气旋B的快速发展提供了有利的环流背景场。气旋B吞并气旋A的过程经历三个阶段:前期阶段、吞并阶段、完成阶段。利用WRF模式模拟结果的分析表明,气旋A和B之间建立水汽输运通道,水汽从气旋A向气旋B输送。气旋B吞并气旋A后形成气旋C快速发展的主要原因是暖平流的作用。
文摘利用NCEP(National Centers for Environmental Prediction)提供的FNL(Final Analyses)资料和WRF模式(Weather Research Forecast Model)对2009年0920号超强台风LUPIT变性后再次爆发性发展的现象进行了研究,详细分析了潜热加热在热带气旋变性为温带爆发性气旋过程中的作用。研究发现:潜热释放是气旋快速发展阶段的重要影响因素,潜热通过影响环流促使气旋的爆发性发展,较为深厚的对流系统使潜热释放的位置发生在对流层的中高层。热量释放之后,地面气旋上空高空槽前的西南气流向槽前高压脊内输送热量,造成高层等压面坡度增大,涡度平流随高度增加,涡度平流的增加又进一步促进了上升运动加强,有利于更多水汽凝结,释放潜热,使得气旋海平面中心气压快速降低。天气尺度低压系统与对流活动相伴随的潜热释放之间的相互促进的正反馈过程类似于热带气旋的CISK机制,这可能是热带气旋变性后爆发性发展的一种重要机制。
