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利用2013～2016年的Aqua MODIS卫星和CloudSat卫星的二级产品资料,对发生在京津冀地区夏季的降水冰云和非降水冰云进行了统计。基于此,对比分析了两类冰云的云类型,研究了二者在云特征参数、云层数及垂直结构上的差异,并且探究了二者在不同通道下云特征参数的相对大小。结果表明:1）京津冀地区的降水冰云以深对流云和雨层云为主,分别占48.63%和34.65%,而非降水冰云以高层云和卷云为主,分别占55.62%和31.58%。2）降水冰云和非降水冰云的平均云顶温度、云顶高度、光学厚度、积分云水总量、有效粒子半径分别为230.99 K、10.90 km、53.26、937.98 g/m2、31.45
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We have analyzed the fine-structure of 131 electric field (E) waveforms that were radiated during the onset of first return strokes in cloud-to-ocean lightning. The dE/dt waveforms were recorded using an 8-bit waveform digitizer sampling at 100 MHz, and the E waveforms were sampled at 10 MHz using a 10-bit digitizer. 49 (or 37%) of the dE/dt waveforms contain one or more large pulses within ± 1 μs of the largest (or dominant) peak in dE/dt, i.e. within an interval from − 1 μs to + 1 μs, where t = 0 μs is the time of the dominant peak, and 37 (or 28%) have one or more large pulses in the interval from 4 μs before to 1 μs before the dominant peak, i.e. − 4 μs to − 1 μs, and only the dominant peak within ± 1 μs . We give statistics on the amplitude and timing of dE/dt pulses that are near the dominant peak, and we show how the presence of these pulses adds considerable fine-structure to the shape of Eint, the integrated dE/dt waveform, on a time-scale of tens to hundreds of nanoseconds. This fine-structure includes fast pulses near the beginning of the slow front, large pulses and shoulders within the slow front and during the fast-transition, and very narrow peaks in Eint. Our overall conclusion is that the electromagnetic environment near the point(s) where lightning leaders attach to the surface is often more complicated than what would be produced by a single current pulse propagating up a single channel at the time of onset. 相似文献
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Summary In this paper, we first examine the relationship of El Nino and La Nina events with the westerly wind anomalies over the
western Pacific warm pool. On this basis, the roles of the Asian and Australian winter monsoons in the formation and progress
of the westerly wind anomalies are studied. Finally, we analyze the associations of the Asian and Australian winter monsoons,
the westerly wind anomalies and the El Nino and La Nina alternations with the propagating anomalies of the Southern and Northern
Oscillation.
The results show that the westerly wind bursts are frequent over the Maritime Continent and western Pacific, only those which
can further intensify and propagate eastward are accompanied by an El Nino event. It is identified that the establishment
and eastward propagation of westerly wind bursts are related to enhanced East Asian and Australian winter monsoon, respectively.
The activities of the East Asian and Australian winter monsoon, the variation of the Pacific westerly and trade winds and
the alternate appearance of El Nino and La Nina events should be internally connected. The main agents of this relationship
are the eastward propagation of alternate positive and negative height anomalies associated with the Southern and Northern
Oscillation on a 3–5 year time scale over the south and north tropical Pacific.
Received January 4, 1998/Revised January 19, 1999 相似文献
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为了解闪电对对流层上部NOx的贡献,本文利用美国全球水资源和气候中心（GHRC）提供的1995年4月~2005年12月的闪电卫星格点资料及高层大气研究卫星 (UARS) 上的卤素掩星试验装置 (HALOE) 1991年10 月~2005 年11月的观测资料,分析了中国地区闪电与对流层上部NOx体积混合比的时空分布特征及两者的相关性.结果表明:中国地区闪电和对流层上部的NOx在季节分布、年际分布和空间分布上保持很好的一致性,闪电是对流层上部NOx的重要来源;NO极值高度在350 hPa左右,云闪直接产生的NO是极值产生的主要原因,NO2的极值高度在250 hPa左右,因为闪电产生的NO在传输过程中会被氧化成NO2并通过雷暴的垂直输送作用抬升到更高高度;强对流活动有利于NOx的传输,而人类活动产生的NOx一般较难输送到对流层上部,因此闪电多发区的NOx极值较大,所在的高度也较高. 相似文献
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厄尔尼诺和拉尼娜事件与曲江汛期旱涝和冬季冷暖的统计关系分析 总被引：1，自引：3，他引：1
本文通过制作曲江汛期旱涝指数和冬季冷指数，从强度方面简要地分析厄尔尼诺和拉尼娜事件与曲江汛期旱涝和冬季冷暖的统计关系。从而为当地的气候分析预测提供一定的参考依据。 相似文献
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Summary ?Progress in technology as well as signal processing has promoted Wind Profiler Radar (WPR) or sodar with RASS additions to become standard tools in profiling of the atmospheric boundary layer. Apart from
these instruments’ basic abilities in profiling mean winds and temperature, this paper will give an emphasis on the profiling
of ABL height as well as the turbulent fluxes of sensible heat and momentum both, with respect to methods as well as with
respect to realization. The special focus will thereby be laid on the demands for vertical profiling, which were defined within
the LITFASS-project of the German Meteorological Service. In the frame of this project, some special measuring campaigns have
been performed where remote-sensing systems were used to assess their abilities in profiling ABL parameters. On the base of
some case studies from these campaigns comparisons are shown, where results from sodar/RASS and WPR/RASS measurements are
compared to measurements from airborne sensor systems and results from numerical models. Regarding turbulent heat fluxes,
we found excellent agreement for remotely-sensed flux profiles from WPR/RASS with both, numerical models and airborne in-situ
measurements. However, as the inherent errors of the remotely-sensed fluxes are in the order of ± 20 ⋯ 30 W/m2 typically, current signal processing does not allow to interpret small-scale vertical structures in the profiles with respect
to surface inhomogeneities yet.
Received June 16, 2001; revised February 20, 2002; accepted May 30, 2002 相似文献
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桂林市汛期降水集中度和集中期与旱涝关系的研究 总被引：3，自引：0，他引：3
利用桂林13站近50a的逐日降水资料,采用近年来气象学者提出的降水集中度和集中期的定义,计算桂林汛期降水集中度和集中期,对其统计特征进行分析,结果表明：降水集中度最大值为0.59,最小值为0.12,平均值为0.33,年际变化大,有10a的变化周期;降水集中期出现在汛期第5旬到第8旬之间的年份占76%。对集中度大值年和小值年进行对比分析,得出汛期降水量偏多时,集中度偏大容易造成洪涝灾害,集中度偏小则降水较均匀,不利于洪涝的形成。多水年和少水年降水集中度的空间分布明显不同,多水年的集中期明显比少水年偏迟。 相似文献
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桂林市汛期降水集中度和集中期与旱涝关系的研究 总被引：5，自引：0，他引：5
利用桂林13站近50a的逐日降水资料,采用近年来气象学者提出的降水集中度和集中期的定义,计算桂林汛期降水集中度和集中期,对其统计特征进行分析,结果表明:降水集中度最大值为0.59,最小值为0.12,平均值为0.33,年际变化大,有10a的变化周期;降水集中期出现在汛期第5旬到第8旬之间的年份占76%。对集中度大值年和小值年进行对比分析,得出汛期降水量偏多时,集中度偏大容易造成洪涝灾害,集中度偏小则降水较均匀,不利于洪涝的形成。多水年和少水年降水集中度的空间分布明显不同,多水年的集中期明显比少水年偏迟。 相似文献
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2020/2021和2021/2022年冬季京津冀气温呈明显相反的季节内变化特征,前者前冬气温异常偏低后冬偏高,而后者前冬气温极端偏高后冬转冷。这两年前冬冷暖反相的直接原因是亚洲冬季风环流异常。2020年12月欧亚地区为典型的经向环流,西伯利亚高压偏强,乌拉尔山高压脊亦偏强,造成京津冀上空对流层中低层气温一致性偏低,而2021年12月环流形势相反。这两年冬季均处在拉尼娜背景下,但夏秋季喀拉海海冰异常有明显差异,可能是京津冀这两年前冬气温异常相反潜在的外强迫信号。统计和个例分析结果均表明,喀拉海海冰偏多易导致前冬西伯利亚高压偏弱,青藏高原地区海平面气压和亚洲大陆中纬度地区500 hPa位势高度均为正距平,不利于冷空气活动,造成2021/2022年前冬京津冀气温偏高,反之海冰偏少造成2020/2021年前冬偏冷。 相似文献
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超强厄尔尼诺事件海洋学特征分析与预测回顾 总被引：3，自引：1，他引：2
2015/2016年厄尔尼诺事件被认为是一次与1982/1983和1997/1998年相当的超强事件。基于多套再分析数据,比较了此次事件的海洋上层变量主要特征与历史上两次超强事件的异同,并利用热带太平洋混合层热收支方程对主要物理过程进行了定量分析。研究认为,2015/2016年事件前期为异常高海温东传特征,且前期形成了一次弱的中太平洋型暖事件;但后期表现为弱西传特征,在成熟位相转换成东太平洋型强厄尔尼诺。此次事件中伴随着多次西风爆发事件和开尔文波东传,但赤道开尔文波在盛期基本维持在中东太平洋而不继续东传,赤道外罗斯贝波西传特征亦不明显。相比之下,此次事件在发展-成熟期前后的赤道“热容量放电”过程更加明显些。此次事件异常暖中心位置偏西,其主要原因很可能与赤道东太平洋的强东风异常和冷海水上翻,以及纬向洋流异常和次表层温度异常分布偏西有关;东边界冷水入侵,削弱赤道东太平洋海温异常程度,可能是此次事件位置偏西的直接原因。在海洋上层热量收支中,此次事件中温跃层反馈是促进海温升高和位相转换的最关键过程,纬向平流反馈项亦发挥了重要作用,两种过程共同形成了超强的升温幅度和偏西的异常暖海温分布型。中国国家气候中心新一代ENSO预测系统（SEMAP2.0）每年两次的实际会商预测中给出了较为合理的预测,特别是考虑前期海洋变化预报因子信息的统计模型更好地预测出了海温异常的波动演变状况,成为多方法集合（MME）的重要成员。 相似文献