共查询到20条相似文献，搜索用时 265 毫秒
1.
《中国气象科学研究院年报》1999,(1)
Withtheadventofthe21stcentury,thedevelopmentofthehumansocietyfacilitatestheprogressandprosperity,inthemeanwhile,italsoproducessuchmomentousproblemsasexplodingpopulation,resourcesshortage,environmentdegradationandincreasingnaturaldisasters,whichseriouslysu… 相似文献
2.
张人禾 《中国气象科学研究院年报》2001,(1)
刚刚走过的2001年,是新世纪的开局之年,也是我们祖国大事连连、喜事频频的一年,北京的申办奥运成功、中国的成功入世、中国足球的如愿出线、APEC会议的成功举办……,在给全国人民带来无比喜悦的同时,也给正处于科技体制改革的中国气象科 相似文献
3.
4.
5.
在物理学研究中,尺度特征是一个必须要处理好的问题,大气科学也不例外,在不同的时空尺度条件下,运动所遵循的规律会表现出很大差异,或者说运动的特征会因尺度的变化而完全不同。在以往的多尺度研究领域,尺度分离问题相对比较成熟,可通过有效的方法、技术来实现。相对而言,对不同尺度系统间的相互作用,尽管也从不同角度开展过大量工作,但仍显薄弱。如果不能清晰、合理地分析尺度间相互作用问题,就难以解释大气运动如何在较为平稳的状态下产生变异,并有新尺度系统产生。多尺度相互作用一般用尺度间的能量传输来衡量,但这种传输属流体的内部过程,要靠动力学理论来推断。然而流体力学中较长时间延用的能量传输经验公式有着重大缺陷——能量不守恒,导致我们用此所作的动力学诊断不能如实反映大气内部的物理过程。针对这个问题,过去20年来气象学家从最基本的物理概念出发,通过构造物理意义上自洽的数学工具,在严格意义上导出了流体内部多尺度之间的能量传输公式。 相似文献
6.
7.
The first 1,000 year long Carpathian tree-ring width chronology was established based on living and subfossil stone pine (Pinus cembra L.) samples from an upper timberline forest located in Calimani Mts. (Romania). Tree-ring data were standardized using the regional curve standardization method in order to preserve the low and medium frequency climate signals. The de-trended index strongly correlates with summer mean temperature both at annual and decadal scales. The Calimani summer mean temperature anomalies were reconstructed for the period ad 1163-2005 applying the rescaling method. This new climate proxy from the Carpathians shows similar fluctuations to other North Hemispheric temperature reconstructions, but with periods of distinct differences. The fingerprint of Little Ice Age in the Calimani area is visible between ad 1370 and 1630 followed by lagged cold decades in ad 1820 and 1840. The recent warming is evident only after the 1980s in our reconstruction. 相似文献
8.
Climatic inferences from the ventilated thermocline 总被引：1，自引：0，他引：1
Several computed cases of a model of the subtropical gyre with a partially ventilated thermocline (Luytenet al., 1982) are presented to illustrate the sensitivity of the field of density stratification, mean flow and location of unventilated
regions to slight changes in surface boundary conditions. The structure of the low latitude thermocline is less sensitive
to climatic change in amount of water forced down by convergence of wind-driven surface layers at higher latitudes than might
be expected, even allowing for the well-known localness of vertically integrated meridional transport. On the other hand changes
in structure at low latitudes do arise from changes in boundary conditions on the surface density at higher latitudes.
The main climatic inference for transient tracers injected into a thermocline in steady state is that there are two time-scales
in the subtropical thermocline: an advective time scale associated with distance from regions of direct ventilation of a density
layer at the surface, and a subsurface diffusive time scale from ventilated to unventilated region. 相似文献
9.
10.
The mechanism of the Q-burst is investigated in the time and frequency domains. Electric fields in the ELF (extremely low frequency) to VLF (very low frequency) range have been observed with a ball antenna since 2003 in Kochi City, Japan (latitude 33.3°north, longitude 133.4°east). Source-to-observer distances (SODs) of Q-bursts are estimated by analyzing the waveforms. It is found as a result that the Q-burst is produced by combination of direct and antipodal pulses from a source lightning stroke occurring all over the world. 相似文献
11.
D. Robbins J. Waters P. Zimmermann R. Jarnot J. Hardy H. Pickett S. Pollitt W. Traub K. Chance N. Louisnard W. Evans J. Kerr 《Journal of Atmospheric Chemistry》1990,10(2):181-218
Measurements of the Balloon Intercomparison Campaign (BIC), conducted during fall, 1982 (BIC-1) and summer, 1983 (BIC-2), are reported. Results of five remote and two in situ techniques agree (with a few exceptions) within 95% confidence level uncertainties and generally within 15% above 20 km. Weighted mean profiles, which best represent conditions during the capaign, are used as a comparison standard. Accuracies of experiments indicated by BIC generally confirm estimated uncertainites for ECC sondes, UV photometry, and microwave emission experiments, are somewhat better for far IR emission and IR absorption experiments, and are somewhat worse for IR emission and solar UV absorption experiments. The large collection of BIC measurements confirms a problem reported earlier with current theoretical modeling of ozone near 40 km where transport is negligible and the chemistry is believed to be simpler. 相似文献
12.
中国南方地基雨量计观测与星载测雨雷达探测降水的比较分析 总被引：7，自引：2，他引：5
利用热带测雨卫星(TRMM)上搭载的测雨雷达(PR)探测结果和中国40°N以南地区约430个台站雨量计观测结果,分析研究了1998-2005年中国南方地区这两种降水资料气候分布的异同.研究结果表明两种降水资料在2.5°空间水平分辨率上,所描述的中国南方降水率气候分布在多年年平均和季平均上具有较好的一致性,但在降水率极值和极值区范围大小等细节上两者还存在一定的差异,主要是地面雨量计结果相对PR结果偏高,其中中同南方50%以上地区两者相差在1 mm/d以内、30%的地区两者相差在1-2 mm/d,夏季差异可超过2 mm/d.对两种降水资料差异的原因分析表明,地面雨量计空间分布密度是影响两者差异的决定性因素,当格子内雨量计超过6个时,两者的相关系数大于0.7;夏季两种降水资料的相关性都比其他季节差,不论格子内的雨量计数量多与少;对流降水多发地区,两种降水资料之间的差异大于层云降水多发地.利用PR探测结果对夏季青藏高原多年月平均降水率分布及高原东、西部的降水特点的分析表明,6月高原东部出现2 mm/d左右的降水区,而在7和8月1 mm/d的降水区域基本覆盖了除高原西部以外的整个高原,其中高原中部地区出现降水率近3mm/d的大值区.月降水距平的时间演变表明,高原降水偏少月份要多于偏多月份. 相似文献
13.
S. Hastenrath 《Meteorology and Atmospheric Physics》2003,83(1-2):51-65
Summary ?The upper-air circulation characteristics of the Southern Oscillation (SO) are studied from the 1958–97 NCEP-NCAR Reanalysis.
The low/high phase of the SO is defined by anomalously small/large values of the Tahiti minus Darwin surface pressure difference.
For the fields of 200 mb topography, divergence and divergent flow, 500 mb vertical motion, and 1000 mb topography, during
January, April, July and October, differences are computed between ensembles of years of extremely low versus high SO phase,
and tested for statistical significance. The 1000 mb topography bears out SO characteristics consistent with earlier work
on surface pressure, such as the seesaw between the western and eastern Pacific in all seasons, and in the low SO phase in
the boreal winter a northward displaced near-equatorial trough over the Atlantic. In addition, the new dataset afforded documentation
of functional upper-air processes. Thus, overall positive/negative 1000 mb topography anomalies tend to be associated with
enhanced/reduced subsidence or reduced/enhanced ascending motion. Ensemble differences in mid-tropospheric vertical motion
are coherent with those in upper-tropospheric divergence and divergent flow. Characteristic of the low SO phase are significant
positive anomalies of upper-tropospheric topographies especially in the tropics and most prominently over the eastern Pacific,
reflecting the anomalously warm atmospheric column, and during the boreal winter a train of centers with alternatingly positive
and negative topography differences extending from the tropical Pacific across North America to the Atlantic.
Received October 10, 2001; revised May 8, 2002; accepted May 31, 2002 相似文献
14.
本文采用数值试验对比分析的方法,利用一维半地形积层混合云模式,分别进行引入与不引入极端水汽源的模拟试验.研究表明,一旦引入极端水汽源,地形积层混合云系统即成为一个极为有效的造雨系统.极端水汽源的引入提供了更加饱和的环境,维持更久的辐合场,还增大了冰相粒子对云水的碰并.这些初步认为是暴雨产生的主要物理原因. 相似文献
15.
16.
Detecting Aerosols over Land from Satellites by Measuring Far IR Radiation from the Earth-Atmospheric System 
下载免费PDF全文
下载免费PDF全文 In this study, a special method is proposed for detecting aerosols over land by analyzing satellite-measured far IR radiation at three channels, 8.7, 11.5, and 12.5 um. Sensitivity tests revealed that the behavioral features of radiative brightness temperatures (BTs) at these three channels with increasing optical depth are different among different types of aerosols. Analyzing how BTs and their differences, xBT (BT11.5-BT12.5) and yBT (BT8.7-BT11.5), behave with varying optical depth can help to qualitatively distinguish among aerosols and semi-quantitatively estimate their optical thicknesses. In addition, the authors found that the vertical density profile of aerosols has little impact on this method. 相似文献
17.
随着物联网、云计算技术的飞速发展,大数据及其相关科学成为学术界和工业界关注的热点.本文从范式理论的角度对大数据科学进行剖析,阐述大数据研究与传统研究的联系与区别;从机器学习的视角出发,分析了大数据带来的三大主要挑战及其背后的科学问题.此外,本文介绍了第四范式视角下进行大数据科学研究的洞察力,以及其所具有的积极意义;最后总结并展望未来大数据科学面临的挑战. 相似文献
18.
地形积层混合云模式数值试验研究 总被引：1，自引：0，他引：1
本文采用数值试验对比分析的方法,利用一维半地形积层混合云模式,分别进行引入与不引入极端水汽源的模拟试验。研究表明,一旦引入极端水汽源,地形积层混合云系统即成为一个极为有效的造雨系统。极端水汽源的引入提供了更加饱和的环境,维持更久的辐合场,还增大了冰相粒子对云水的碰并。这些初步认为是暴雨产生的主要物理原因。 相似文献
19.
V. Hisdal 《Theoretical and Applied Climatology》1959,10(1):59-68
Summary Spectral intensities of the scattered radiation from the zenith sky were measured using a filter monochromator. The monochromator was calibrated by means of a tungsten-filament lamp with known spectral energy distribution. The intensities of the individual wave-bands were referred to the total radiation intensity in the wave range considered, i. e. all spectral distributions were adjusted so as to give a constant total radiation. The relative intensity distributions obtained in this way are discussed. The results indicate that the relative intensity in a wave-band around 460 m is to a large extent independent of the atmospheric scattering conditions.
With 4 Figures 相似文献
Zusammenfassung Die spektrale Intensität der gestreuten Himmelsstrahlung des Zenithimmels wurde mit einem Filtermonochromator gemessen; der Monochromator wurde mittels einer Wolframbandlampe mit bekannter Energieverteilung geeicht. Die Intensität der einzelnen Wellenlängenbereiche ist auf die totale Strahlungsintensität des untersuchten Bereichs bezogen, d. h. alle spektralen Verteilungen wurden so umgerechnet, daß sie eine konstante Gesamtstrahlung ergaben; die in dieser Weise erhaltenen relativen Intensitätsverteilungen werden diskutiert. Die Resultate lassen erkennen, daß die relative Intensität in einem Wellenbereich um 460 m in hohem Maße von den Verhältnissen der atmosphärischen Streuung unabhängig ist.
Résumé On mesure l'intensité spectrale de la lumière diffuse du ciel provenant du zénith à l'aide d'un monochromateur à filtre étalonné au moyen d'une lampe au wolfram à spectre énergétique connu. L'intensité des diverses régions spectrales est rapportée à l'intensité totale du domaine étudié, c'està-dire que toutes les distributions spectrales ont été calculées de façon à donner un rayonnement total constant. Les distributions relatives ainsi obtenues front l'objet d'une discussion qui montre que, dans un domaine centré sur 460 m, l'intensité relative est dans une large mesure indépendante des conditions de la dispersion atmosphérique.
With 4 Figures 相似文献
20.