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1.
梅雨期一次黄淮气旋发展的干侵入特征分析 总被引：8，自引：0，他引：8
利用水汽图像、等熵气流、θse等物理量，对2003年梅雨期的一次黄淮气旋发展过程进行了分析，试图揭示干侵入在黄淮气旋发展中的作用。分析结果表明：与干侵入相联系的水汽图像暗区的移动、发展变化与黄淮气旋的发展、加强、减弱对应关系较好。水汽图像暗区前部依气旋的发展加强、维持、减弱而主要出现在黄淮气旋西侧、南侧和东侧。分析垂直环流表明，干侵入来自对流层中上层，与水汽图像暗区有较好的对应关系，在气旋发展强盛期下沉气流区自西向东、自南向北推进。高空动量下传促使地面气旋发展，从而使中、低层大气变得非常干燥。335K等熵面上的流场特征、等熵面陡峭处与水汽图像暗区的对应关系较好。θse的垂直剖面能反映干侵入特征。等熵面在垂直方向的折叠可使对流层中下层出现潜在对流不稳定区。θse=335K位温舌能较好地反映天气系统的三维结构和干侵入特征。自高层向下传递、加强的位涡变化能反映干侵入的动力特征。 相似文献
2.
强烈发展的中尺度涡旋影响下持续性暴雨的位涡诊断 总被引：3，自引：0，他引：3
利用高分辨率的模式输出资料,对2008年6月广西致洪暴雨及其中尺度低涡(简称广西涡)进行了等熵位涡(IPV)和湿位涡(MPV)的诊断分析。结果表明,低值等熵面上正IPV带的位置和强度可以反映暴雨的落区和强度,等熵面上的西风气流可分别将高纬度干冷和低纬度暖湿的高值IPV向广西涡处输送,使得广西涡维持高IPV。高值等熵面上南部的IPV存在下传现象,有利于其下游的广西涡IPV的增长,从而使得广西涡强烈发展、降水增强。利用MPV守恒原理的分析表明,持续性暴雨出现在高值等熵湿位涡前方的对流不稳定区中;暴雨区南北两侧对流层中高层的冷空气下沉时对流稳定性减小,对应的气旋性涡度增大;而暖湿气流沿着干冷空气爬升,它与具有强涡度的沿等熵面下滑的干冷空气发生强烈的辐合,使得涡度急剧增强,再加上地形的强迫抬升作用,形成强烈的垂直上升运动,导致涡旋强烈发展。等压面上的MPV及其分量分布显示,对流层中低层MPV负值带对雨带有指示作用,强降水时段对应着对流不稳定和条件性对称不稳定。 相似文献
3.
以2009年7月17—18日一次山东特大暴雨为研究对象,利用NCEP/NCAR再分析资料、FY-2C卫星水汽资料及常规气象观测资料,通过数字化卫星水汽图像与大气动力场相结合的方式,揭示干侵入在本次暴雨过程中的特征及其对暴雨发生、发展的作用机制。结果表明,此次强降水过程是在高空槽和低层低涡切变的有利形势下产生的。暴雨过程与干侵入密切相关,干侵入在对流层中高层随高度向东倾斜,强降水出现在干侵入前沿湿度梯度最大值处的湿区一侧。卫星水汽图像干侵入暗区与对应着350hPa位涡高值区、干冷区。与干侵入相伴随的高位涡下传,使低层气旋性涡度加强,气旋发展。高层干冷空气下传有利于干层的形成和维持,干层的存在加强了暴雨过程的对流不稳定,对暴雨的加强和发展起重要作用。 相似文献
4.
一个干侵入参数及其应用 总被引：7，自引：0，他引：7
鉴于干侵入在气旋的爆发性发展、冷锋的演变等方面起着重要的促进作用,因此,文章详细分析了一次北方暴雨中的干侵入特征.分析发现,干侵入在此次降水事件中一直维持,而且降水随干侵入的增强而加强,干侵入推动了降水区的东南向移动.在McNulty早期工作的基础上,借鉴Doswell以及Schultz等发展的IM(ingredients-based methodology)方法,将其应用于干侵入的研究.文章将过去对干侵入(无论在等压面还足等熵面上)的研究中,用低相对湿度、冷平流、高位涡来表征干侵入气流的这些单个物理量综合起来,用一个简单、使用方便的物理参数来表征干侵入.这是以往暴雨研究巾的IM理论方法在干侵入研究领域的新尝试.文章朋新的干侵人参数,在等熵面上分析了实际降水过程中干侵入的演变.分析表明,干侵入参数能够较好地量化干侵入强度,指示卫星云图和水汽图像上干区的演变.通过等熵面与相应气压层的对比分析,发现等熵和等压面上的分析比较一致,等熵面上的干侵入在高层比低层强度大.由垂直剖面图的分析可见,干侵入气流位于低层暖湿气流上方,这就使得垂直方向上出现位势不稳定,有利于降水发生.这样,我们就可以通过干侵入参数来找干侵入区,关注干侵入区附近的不稳定区.来对降水做出预测,从而提高降水预报的准确率. 相似文献
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《湖北气象》2016,(1)
利用FY-2E卫星水汽图像、常规观测资料和NCEP/NCAR 1°×1°再分析资料,针对山东半岛一次与台风相关的大暴雨事件中干冷空气的侵入特征进行分析。结果表明:台风北上与极地大陆气团交汇,是导致此次大暴雨发生的重要因素。干冷空气从西侧侵入台风环流,台风变性,斜压锋生,位能向动能转换,导致上升运动加强,有利于产生强降水。冷空气具有高位涡和低湿度的特点,水汽图像上的暗区、高层等熵面上的干区和高位涡区有良好的对应关系。水汽图像直观地反映了此次大暴雨过程的系统演变过程。台风云系与斜压叶状云结合,先形成新的涡旋云系,后演变成逗点云型。暗区指示的干冷空气不断发展,先形成干舌,后以干缝的形式卷入涡旋中心。在实际预报中,除了流型识别外,通过水汽图像还可以追踪干湿区及其边界等变化特征。通过连续时次的对比分析,可监测高空动力强迫,判断灾害性天气系统的发展演变。 相似文献
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综合考虑干侵入的特征、机制和效应,定义了干侵入强度指数(DII)以表征干侵入的强度,并从一个个例进一步揭示干侵入强度指数的物理意义.结果表明,DII是干侵入强度较好的定量描述指标,它与水平温度平流、位涡、假相当位温相关,正的DII表明存在干侵入过程,随着DII的增大,干侵入效应增强,此时可能高位涡异常越强、湿球位温越低、冷平流效应越强;345K等熵面上DII>1PVU/s的正值区与水汽图像暗区较为一致,DII在=三维结构上表现为高层波状下传的特征,在任一特定的等熵面上,低涡西北方向的中高纬度地区是DII正值区的源地;DII体现了水平温度平流效应,低涡降水区西侧为冷平流,东侧为暖平流,冷暖平流一直贯穿于对流层整层,冷平流在西北气流引导下沿等熵面下滑,在冷暖平流交汇处出现降水,随着水平温度平流梯度的增大,对应的降水增强.在实际天气预报业务工作中,DII可用以界定干侵入区域、过程以及强度,具有一定实际业务应用价值. 相似文献
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利用NCEP/NCAR1°×1°再分析资料、FY-2C卫星资料及常规气象观测资料,对一次典型东北冷涡暴雨过程中干侵入特征及其对东北冷涡暴雨发生发展的作用机制进行分析。结果表明,干侵入在卫星水汽图像上明显,为暗区,该暗区与大气动力场有较好的配置,与350hPa位涡高值区分布一致;干侵入区是高位涡和低湿的重叠区,干侵入前沿为降水落区,表明了干侵入与强降水落区存在密切联系;对流层高层低湿、高位涡的冷空气下传有利于冷涡暴雨的发生发展,暴雨强度随着干侵入强度增强而增大。同时冷平流效应非常重要,其对干侵入强度指数的变化起到主要作用。 相似文献
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针对2009年2月7～8日持续干旱近百天的黄河中游地区出现的转折性雨雪天气,利用实况资料计算了等熵温度梯度、可降水量、水汽通量及其散度、相对湿度、垂直速度等,分析了熵分布及演变、干侵入、水汽场特征等,结果表明:(1)这次降水出现在500hPa环流形势平直,极地冷空气活动较弱,在地面回流高压呈东西向带状分布的背景下,系统浅薄,降水量级难以把握。(2)熵诊断揭示,500hPa等熵梯度大值区的出现对未来12～24h强降水有先兆指示意义,强降水中心出现在500hPa等熵梯度大值区与700hPa温度露点差3℃的叠加区。(3)水汽诊断表明,强降水出现前,黄河中游及其上游西南地区的可降水量显著增加,为强降水的出现提供了水汽的积聚,而降水开始后,低空超低空东南急流则是水汽的主要补充来源;强降水并不是出现在水汽通量大值区内,而是在水汽通量大值区西北侧、等值线密集带附近,同时又有风辐合的区域。(4)这次雨雪过程中,干冷空气主要来自对流层高层,在雨雪区上空的垂直分布呈"漏斗"状,该过程中从贝加尔湖地区南下的西北和东北气流沿漏斗壁下滑向低层传播;而中低层湿区呈倒扣的"碗状"向上伸展,中低层西南和东南两支暖湿气流沿"碗壁"爬升,在对流层中层耦合加强,与干冷空气交汇,产生强降水。(5)对流层高层持续的干侵入,使得中低层切变线稳定维持,有利于其前方西南急流的稳定加强和对流性不稳定的持续发展,是导致强降雪持续、增幅的重要原因。(6)强降水出现在地面中尺度辐合稳定加强期间,降水落区在辐合区及其东南侧;辐合区内强烈的上升运动是触发不稳定能量释放,使熵由不平衡达到平衡的重要机制。 相似文献
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干侵入在黄河气旋爆发性发展中的作用 总被引：7，自引：0，他引：7
利用数字化的6.7,um卫星水汽图像资料、NCEP/NCAR逐6小时1°×1°再分析等资料和干侵入、位涡理论,对2007年3月3—5日引发渤海强风暴潮的黄河气旋发展过程进行了天气动力学分析,揭示干侵人在爆发性黄河气旋中的特征和作用。结果表明：本次渤海强风暴潮是发生在泰米尔半岛附近不稳定小槽东移发展,东亚大槽重建的过程中,是对流层高层干侵入下沉引起黄河气旋爆发性发展产生强东北大风所致。干侵入具有高位势涡度特征,高位涡区和水汽图像上的暗区形态及强度变化特征对气旋生命史不同阶段有预报指示意义。干冷和暖湿气流沿着等熵面Ω型皱折带南北流动,使得等熵面陡峭程度加大,大气的斜压性增强;尽管高层干侵入在下沉过程中会产生增温效应,但在下沉运动和强冷平流效应的共同作用下,地面气旋的上空出现水平方向温度比临近地区低的现象,大气静力稳定度减小,绝对涡度（ζ_p＋f）增大,促使中低层气旋性涡度发展,垂直上升运动迅速加强,导致地面气旋强烈发展。 相似文献
10.
2005年初夏云南严重干旱的诊断分析 总被引：6，自引：2，他引：6
利用MM5V3.6模式对2005年4月25日一次典型的西南涡影响下的广西强降水过程进行了数值模拟与诊断分析,结果表明,在500hPa低槽、700hPa西南涡东南移的过程中,在西南涡的南端,由于对流层高层高值干位涡下传引起低层气旋性涡度增加,低涡向南伸出一低槽,使西南涡发展成“北涡南槽”形式,广西强降水出现在西南涡的南伸低槽附近。西南涡的南伸低槽附近垂直剖面上为等θe线陡立密集区,700hPa上MPV1<0,MPV2>0,低层有强烈辐合,高层有强烈辐散,从低层到高层都有上升运动。螺旋度对强降水的落区以及造成强降水的中尺度系统的发展有较好的指示性,它反映了大气的动力场特征,运用螺旋度作强降水预报还要结合水汽和不稳定条件。 相似文献
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The spatial and temporal variations of daily maximum temperature(Tmax), daily minimum temperature(Tmin), daily maximum precipitation(Pmax) and daily maximum wind speed(WSmax) were examined in China using Mann-Kendall test and linear regression method. The results indicated that for China as a whole, Tmax, Tmin and Pmax had significant increasing trends at rates of 0.15℃ per decade, 0.45℃ per decade and 0.58 mm per decade,respectively, while WSmax had decreased significantly at 1.18 m·s~(-1) per decade during 1959—2014. In all regions of China, Tmin increased and WSmax decreased significantly. Spatially, Tmax increased significantly at most of the stations in South China(SC), northwestern North China(NC), northeastern Northeast China(NEC), eastern Northwest China(NWC) and eastern Southwest China(SWC), and the increasing trends were significant in NC, SC, NWC and SWC on the regional average. Tmin increased significantly at most of the stations in China, with notable increase in NEC, northern and southeastern NC and northwestern and eastern NWC. Pmax showed no significant trend at most of the stations in China, and on the regional average it decreased significantly in NC but increased in SC, NWC and the mid-lower Yangtze River valley(YR). WSmax decreased significantly at the vast majority of stations in China, with remarkable decrease in northern NC, northern and central YR, central and southern SC and in parts of central NEC and western NWC. With global climate change and rapidly economic development, China has become more vulnerable to climatic extremes and meteorological disasters, so more strategies of mitigation and/or adaptation of climatic extremes,such as environmentally-friendly and low-cost energy production systems and the enhancement of engineering defense measures are necessary for government and social publics. 相似文献
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Observed daily precipitation data from the National Meteorological Observatory in Hainan province and daily data from the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis-2 dataset from 1981 to 2014 are used to analyze the relationship between Hainan extreme heavy rainfall processes in autumn (referred to as EHRPs) and 10–30 d low-frequency circulation. Based on the key low-frequency signals and the NCEP Climate Forecast System Version 2 (CFSv2) model forecasting products, a dynamical-statistical method is established for the extended-range forecast of EHRPs. The results suggest that EHRPs have a close relationship with the 10–30 d low-frequency oscillation of 850 hPa zonal wind over Hainan Island and to its north, and that they basically occur during the trough phase of the low-frequency oscillation of zonal wind. The latitudinal propagation of the low-frequency wave train in the middle-high latitudes and the meridional propagation of the low-frequency wave train along the coast of East Asia contribute to the ‘north high (cold), south low (warm)’ pattern near Hainan Island, which results in the zonal wind over Hainan Island and to its north reaching its trough, consequently leading to EHRPs. Considering the link between low-frequency circulation and EHRPs, a low-frequency wave train index (LWTI) is defined and adopted to forecast EHRPs by using NCEP CFSv2 forecasting products. EHRPs are predicted to occur during peak phases of LWTI with value larger than 1 for three or more consecutive forecast days. Hindcast experiments for EHRPs in 2015–2016 indicate that EHRPs can be predicted 8–24 d in advance, with an average period of validity of 16.7 d. 相似文献
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Based on the measurements obtained at 64 national meteorological stations in the Beijing–Tianjin–Hebei (BTH) region between 1970 and 2013, the potential evapotranspiration (ET0) in this region was estimated using the Penman–Monteith equation and its sensitivity to maximum temperature (Tmax), minimum temperature (Tmin), wind speed (Vw), net radiation (Rn) and water vapor pressure (Pwv) was analyzed, respectively. The results are shown as follows. (1) The climatic elements in the BTH region underwent significant changes in the study period. Vw and Rn decreased significantly, whereas Tmin, Tmax and Pwv increased considerably. (2) In the BTH region, ET0 also exhibited a significant decreasing trend, and the sensitivity of ET0 to the climatic elements exhibited seasonal characteristics. Of all the climatic elements, ET0 was most sensitive to Pwv in the fall and winter and Rn in the spring and summer. On the annual scale, ET0 was most sensitive to Pwv, followed by Rn, Vw, Tmax and Tmin. In addition, the sensitivity coefficient of ET0 with respect to Pwv had a negative value for all the areas, indicating that increases in Pwv can prevent ET0 from increasing. (3) The sensitivity of ET0 to Tmin and Tmax was significantly lower than its sensitivity to other climatic elements. However, increases in temperature can lead to changes in Pwv and Rn. The temperature should be considered the key intrinsic climatic element that has caused the "evaporation paradox" phenomenon in the BTH region. 相似文献
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Storms that occur at the Bay of Bengal (BoB) are of a bimodal pattern, which is different from that of the other sea areas. By using the NCEP, SST and JTWC data, the causes of the bimodal pattern storm activity of the BoB are diagnosed and analyzed in this paper. The result shows that the seasonal variation of general atmosphere circulation in East Asia has a regulating and controlling impact on the BoB storm activity, and the “bimodal period” of the storm activity corresponds exactly to the seasonal conversion period of atmospheric circulation. The minor wind speed of shear spring and autumn contributed to the storm, which was a crucial factor for the generation and occurrence of the “bimodal pattern” storm activity in the BoB. The analysis on sea surface temperature (SST) shows that the SSTs of all the year around in the BoB area meet the conditions required for the generation of tropical cyclones (TCs). However, the SSTs in the central area of the bay are higher than that of the surrounding areas in spring and autumn, which facilitates the occurrence of a “two-peak” storm activity pattern. The genesis potential index (GPI) quantifies and reflects the environmental conditions for the generation of the BoB storms. For GPI, the intense low-level vortex disturbance in the troposphere and high-humidity atmosphere are the sufficient conditions for storms, while large maximum wind velocity of the ground vortex radius and small vertical wind shear are the necessary conditions of storms. 相似文献
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Yuepeng PAN Mengna GU Yuexin HE Dianming WU Chunyan LIU Linlin SONG Shili TIAN Xuemei Lü Yang SUN Tao SONG Wendell W. WALTERS Xuejun LIU Nicholas A. MARTIN Qianqian ZHANG Yunting FANG Valerio FERRACCI Yuesi WANG 《大气科学进展》2020,37(9):933-938
正While China’s Air Pollution Prevention and Control Action Plan on particulate matter since 2013 has reduced sulfate significantly, aerosol ammonium nitrate remains high in East China. As the high nitrate abundances are strongly linked with ammonia, reducing ammonia emissions is becoming increasingly important to improve the air quality of China. Although satellite data provide evidence of substantial increases in atmospheric ammonia concentrations over major agricultural regions, long-term surface observation of ammonia concentrations are sparse. In addition, there is still no consensus on 相似文献
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《大气和海洋科学快报》2013,(1):67
正AIMS AND SCOPE Atmospheric and Oceanic Science Letters (AOSL) publishes short research letters on all disciplines of the atmosphere sciences and physical oceanography. Contributions from all over the world are welcome.SUBMISSIONAll submitted 相似文献
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《大气和海洋科学快报》2012,(3):273
正AIMS AND SCOPE Atmospheric and Oceanic Science Letters (AOSL) publishes short research letters on all disciplines of the atmosphere sciences 相似文献
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《大气科学进展》2014,(6)
正Aims Scope Advances in Atmospheric Sciences(AAS)is an international journal on the dynamics,physics,and chemistry of the atmosphere and ocean with papers across the full range of the atmospheric sciences,co-published bimonthly by Science Press and Springer.The journal includes Articles,Note and Correspondence,and Letters.Contributions from all over the world are welcome. 相似文献