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Energy budgets on the interactions between the mean and eddy flows during a persistent heavy rainfall event over the Yangtze River valley in summer 2010 总被引：1，自引：1，他引：0 
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下载免费PDF全文 In this study,a persistent heavy rainfall event(PHRE) that lasted for around 9 days(from 0000 UTC 17 to0000 UTC 26 June 2010) and caused accumulated precipitation above 600 mm over the Yangtze River valley,was reasonably reproduced by the advanced research WRF model.Based on the simulation,a set of energy budget equations that divided the real meteorological field into the mean and eddy flows were calculated so as to understand the interactions between the precipitation-related eddy flows and their background circulations(BCs).The results indicated that the precipitation-related eddy flows interacted with their BCs intensely during the PHRE.At different layers,the energy cycles showed distinct characteristics.In the upper troposphere,downscaled energy cascade processes appeared,which favored the maintenance of upper-level eddy flows;whereas,a baroclinic energy conversion,which reduced the upper-level jet,also occurred.In the middle troposphere,significant upscaled energy cascade processes,which reflect the eddy flows’ reactionary effects on their BCs,appeared.These effects cannot be ignored with respect to the BCs’ evolution,and the reactionary effects were stronger in the dynamical field than in the thermodynamical field.In the lower troposphere,a long-lived quasi-stationary lower-level shear line was the direct trigger for the PHRE.The corresponding eddy flows were sustained mainly through the baroclinic energy conversion associated with convection activities.Alongside this,the downscaled energy cascade processes of kinetic energy,which reflect the direct influences of BCs on the precipitation-related eddy flows,were also favorable.A downscaled energy cascade of exergy also appeared in the lower troposphere,which favored the precipitation-related eddy flow indirectly via the baroclinic energy conversion. 相似文献
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The Puguang (普光) gas field is the largest gas field found in marine carbonate in China.The Puguang gas field experienced complicated evolution history from paleo-oil pool to gas pool.The purpose of this article is to reveal the evolution history of Puguang gas field through systematic study on the relationship between paleo-oil-water contact (POWC) and present-day gas-water contact (PGWC).POWC was recognized by observing the change of relative content of residual solid bitumen in the cores,and PGWC was observed using log and drilling stem test data.Two types of relationship between POWC and PGWC were observed in the Puguang gas field:POWC is above PGWC,and POWC is below PGWC.The former is normal as oil cracking may cause gas-water contact to move downward.The latter can be interpreted by lateral gas re-migration and re-accumulation caused by changes in structural configuration.The relationship between POWC and PGWC suggests that during oil charge,the southwestern and northwestern parts of the Puguang gas field were structurally lower than the northeastern and southeastern parts.Thrusting from Xuefengshan (雪峰山) since Yanshanian movement and from Dabashan (大巴山) since Himalayan movement resulted in the relative uplift of the southwestern and northwestern parts of the Puguang structure,which significantly changed the structural configuration.Based on the paleo-structure discussed in this article,the most probable migration directions of paleo-oil were from the northwest to the southeast and from the southwest to the northeast.Consequently,the evolution history of the Puguang gas field can be divided into three stages,namely,oil charging (200-170 Ma),cracking oil to gas (155-120 Ma),and gas pool adjustment (1200-0Ma). 相似文献
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Current oil saturation in the Moxizhuang (莫西庄) Oil Field in central Janggar (准噶尔) basin was evaluated by logging interpretation and measured on core samples, and the paleo-oil saturation in both the pay zones and water zones was investigated by graln-containing-oil inclusion (GOI) analysis.The pay zones in this field have low oil saturation and display low resistivity and small contrast between pay zones and water zones, and are classified as low-porosity, low oil saturation, and low resistivity reservoirs. Both the current low oil-saturation pay zones and the water zones above 4 365 m have high GOI values (up to 38%), suggesting high paleo-oil saturation. The significant difference between current oil saturation from both logging interpretation and core sample measurement and paleo-oil saturation indicated by GOI analysis suggests that this low oil-saturation field evolved from a high oil-saturation pool. Lateral re-migration and spill of formally trapped oil owing to changes in structural configuration since Neogene was the most plausible mechanism for oil loss in the Moxizhuang Oil Field.The combined effects of differential accumulation in the charge phase and the differential re-migration and spill of accumulated oil in Neogene are responsible for the complicated correlation between residual oil saturation and porosity/permeability of the reservoir sandstones and the distribution of low oil-saturation pay zones and paleo-oil zones (current water zones). 相似文献
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通过对四川盆地西部一次持续性暴雨过程的半理想数值模拟,研究了青藏高原热力作用对四川盆地持续性暴雨过程的影响。研究表明,高原的热力作用对于下游地区有着显著的影响,主要表现为:（1）关闭高原地面感热和潜热后,高原地区和四川盆地西部的降水明显减弱,而盆地中东部降水却有所加强,且四川盆地降水的日变化特征稍有减弱;（2）500 hPa青藏高原上的短波槽减弱,位于四川盆地中西部的背风槽强度、范围有所减弱,但低层盆地东部的气旋性涡旋加强;（3）涡度收支的定量分析发现,关闭高原热力作用后,盆地东部对流层低层垂直风切变的增强使得夜间倾斜项的正贡献增强,从而使该区域涡旋发展加强,盆地东部降水增强。 相似文献
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本文对江淮流域持续性暴雨事件（PHREs）的多尺度物理模型和能量转换特征以及青藏高原东部对流系统东移影响下游地区降水的研究成果进行了总结。从欧亚大陆Rossby波列能量频散的角度揭示了江淮流域PHREs中纬度系统槽脊稳定的机制,定量分析了冷暖空气的源地和输送路径,提出了江南型和江北型PHREs的多尺度物理模型。从天气尺度和次天气尺度之间的能量转换角度呈现了不同尺度系统相互作用的物理图像,指出背景场的能量供给是直接触发暴雨的次天气尺度系统维持的最重要因子,尤其是在对流层的低层,动能的降尺度级串（即能量由背景场传递给次天气尺度系统）最强。研究表明青藏高原东部对流系统东移影响江淮流域的降水是一系列天气系统配合和活跃的结果,主要由青藏高原和四川盆地、二级地形和东部平原之间的热力环流、西南涡、二级地形以东中尺度涡旋和对流系统的共同影响。除了本文总结的内容,还有一些影响PHREs的因子值得深入研究,多尺度相互作用中的Rossby波源及其波列如何影响天气系统,中尺度系统对其背景场的能量反馈等。 相似文献
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冬季一次引发华北暴雪的低涡涡度分析 总被引：5，自引：0，他引：5
利用NCEP FNL 1°×1°再分析资料和WRF模式,模拟了2010年1月2～3日我国华北地区的一次由涡旋造成的冬季降雪过程,并采用位涡和涡度方程对引发暴雪的涡旋发展机制进行了诊断分析。结果表明,这次降雪过程中,对流层中层高空浅槽东移、加深及发展,并引导低空和地面系统自西向东移动,高空位涡的下传强迫加强了对流层中低层涡旋的发展。平均通量和涡旋区域的辐合、辐散作用对涡旋涡度的增长贡献最大,扰动通量和类倾斜项的作用较小。在中层涡旋成熟期,环境场的风速小于中层涡旋的移动速度时,环境场相对于涡旋区域为辐散,涡旋涡度减小;当环境场风速大于涡旋的移动速度时,环境场相对于涡旋区域为辐合,涡旋涡度增加。在涡旋衰减期,向涡旋外输送的绝对涡度通量使得涡旋涡度逐渐减弱。这次过程中,高空位涡强迫、低空辐合和涡旋边界平均气流对扰动涡度的输送是涡旋发展的主要机制。 相似文献
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夏季长江流域两类中尺度涡旋的统计与合成研究 总被引：4，自引：0，他引：4
利用2000~2013年夏季6 h一次、水平分辨率为0.5°(纬度)×0.5°(经度)的CFSR(Climate Forecast System Reanalysis)再分析资料,对产生于四川盆地的西南涡和产生于大别山地区的大别山低涡进行了识别,统计出西南涡和大别山低涡的发生频数、初生时段、移动路径、三维结构等气候特征;在此基础上根据涡旋生成前的地面气压场和降水特征,对西南涡和大别山低涡分别进行了分类与合成研究,并细致对比了两类涡旋的异同点,主要结论如下:(1)西南涡在7月上旬最活跃,而大别山低涡则在6月上旬发生频数最高。凌晨时段是两类涡旋的高发期;西南涡日间的生成数目多于夜间,而大别山低涡则与之相反。(2)绝大多数西南涡和大别山低涡维持时间少于12 h;绝大多数西南涡维持准静止,而大别山低涡则主要向东北方向和偏东方向移动。(3)两类涡旋均为对流层中低层的低压系统,其中大别山低涡的垂直伸展层次较西南涡更低。相比于西南涡,由于水汽条件更优,大别山低涡所引发的降水更强,强降水的凝结潜热释放使得大别山低涡的平均生命史比西南涡更长。(4)产生前有降水的西南涡/大别山低涡相比于产生前无降水的西南涡/大别山低涡而言,对流层高层南亚高压的强度更强、辐散更显著;对流层中层与500 h Pa西风带短波槽的配置条件更好;对流层低层涡旋中心附近的辐合更显著、切变更强;并且对流层中低层的上升运动更强。这些都是有利于降水发生与维持的有利条件,而与降水凝结潜热密切相关的热力强迫使得产生前有降水的西南涡/大别山低涡相比于产生前无降水的西南涡/大别山低涡拥有更长的生命史长度,更大的水平半径和更大的涡旋生命史内降水量。 相似文献
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准噶尔盆地中部侏罗系油气成藏经历了多源、多期充注和晚期的调整改造.综合运用地质、测井和油藏地球化学等资料, 分析了油气藏经历晚期调整改造后的地质、地球化学响应特征.结果表明: 位于车-莫古隆起北翼的莫西庄、沙窝地地区, 经历反向调整后, 油气藏呈分散和小规模分布, 油气藏类型由以构造-岩性油气藏为主变成以地层/岩性油气藏为主, 且油气水层关系复杂; 油层低孔、低渗, 且低含油饱和度、低电阻率, 原油密度和粘度大; 今油水界面高于古油水界面, 部分水层中含有较高的"非烃+沥青质"; 而位于车-莫古隆起北翼的永进地区, 经历同向调整后, 今油柱高于古油柱, 油气藏规模变大. 相似文献
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基于加密自动站降水、葵花8卫星和ECMWF ERA5再分析等多种资料,本文对2018年6月17日08时至18日22时（协调世界时,下同）一次青藏高原（简称高原）中尺度对流系统（Mesoscale Convective System,简称MCS）东移与下游西南低涡作用并引起四川盆地强降水的典型事件进行了研究（四川盆地附近最大6小时降水量高达88.5 mm）。研究表明,本次事件四川盆地的强降水主要由高原东移MCS与西南低涡作用引起,高原MCS与西南低涡的耦合期是本次降水的强盛时段,暴雨区主要集中在高原东移MCS的冷云区。高原东移MCS整个生命史长达33 h,在其生命史中,它经历了强度起伏变化的数个阶段,总体而言,移出高原前后,高原MCS对流的重心显著降低,但对流强度大大增强。在高原MCS的演变过程中,四川盆地有西南低涡发展,该涡旋生命史约为21h,所在层次比较浅薄,主要位于对流层低层。西南低涡与高原MCS存在显著的作用,在高原MCS与西南低涡耦合阶段,两者的上升运动区相叠加直接造成了强降水。此后,由于高原MCS系统东移而西南低涡维持准静止,高原MCS与西南低涡解耦,西南低涡由此减弱消亡,东移高原MCS所伴随的降水也随之减弱。涡度收支表明,散度项是西南低涡发展和维持的最主导因子,此外,倾斜项是800 hPa以下正涡度制造的第二贡献项,而垂直输送项则是西南低涡800hPa以上正涡度增长的另一个主导项,这两项分别有利于西南低涡向下和向上的伸展。相关分析表明,在西南低涡发展期间,高原MCS中冷云面积（相当黑体亮度温度TBB≤?52°C）可以有效地指示西南低涡强度（涡度）的变化,超前两小时的相关最显著,相关系数可达0.83。 相似文献