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热带对流活动与低频波流相互作用 总被引:4,自引:3,他引:4
利用ECMWF客观分析资料,使用Batterworth带通滤波技术,应用诊断分析的方法研究了1983/1984和1986/1987两年冬季中纬度地区低频波流间的相互作用特征,强调了热带地区对流活动的差异对于这种相互作用的重要影响。 相似文献
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Barnes权重法在进行网格点插值的同时,通过选择适当的滤波参数c、g滤去资料中短波噪音,使分析结果平稳光滑;另外可通过它构成一带通滤波器,根据实际需要分离出影响天气过程的各种尺度。本文给出Barnes权重法作滤波插值及带通滤波的详细步骤,并以1986.9.7.08时700hPa风场为例作了实例分析,可以看出客观分析结果与实况相符合,经带通滤波后次天气尺度(波长500~1500km)表现更加明显,而这种次天气尺度波动正是夏季影响我区暴雨主要天气系统。 相似文献
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近百年全球海温异常变化与长江中下游梅雨 总被引:8,自引:5,他引:8
使用Butterworth带通滤波的方法,将1885年以来全球海温和长江中下游梅雨量进行2~3年、2.5~7年、11~13年和15~20年4个时间尺度周期带的滤波,分析了二者特定周期带振荡之间的相关关系。结果表明,全球海温与长江中下游梅雨特定周期带变化之间的相关比带通滤波前的相关显著,特别是较长时间尺度的周期带的相关更显著。 相似文献
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使用带通滤波方法分析了中尺度扰动与湖北省暴雨之间的关系,得出一些有一定预报意义的暴雨中尺度扰动场概念模型。 相似文献
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利用逐日NCEP/NCAR位势高度场资料,通过Barnes带通滤波对哈尔滨地区2004年7月2日暴雨过程中高度场进行尺度分离。结果表明Barnes带通滤波方法能很好地得到常规资料不易分析出的中尺度天气系统,并分析出中尺度扰动与暴雨落区有很好的对应关系。 相似文献
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气象场中尺度带通滤波方法研究 总被引:12,自引:0,他引:12
关于带通滤波方法在气象场中尺度分析中的应用,有许多人进行过这方面的工作,并取得了一定的效果。尽管如此,在这方面仍有许多问题值得探讨和研究。例如,目前人们对带通滤波器的构造比较随意,究竟以什么为标准才能设计出比较合适和理想的滤波器呢?对这些问题的深入研究,将有助于带通滤波方法在中尺度分析研究中取得更为满意的效果。 相似文献
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本文通过对一次500hPa青藏高压前部的突发性强暴雨天气的诊断分析,揭示了暴雨产生的环境场特征。利用带通滤波方法,分析了与暴雨天气密切相关的中尺度系统及发展机理,获得了一些对业务预报有指导意义的结果。 相似文献
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东亚冬季风三维环流的低频振荡特征 总被引:1,自引:0,他引:1
利用ECMWF/WMO逐日客观分析格点资料,采用带通滤波分析了冬季风环流的低频振荡特征,结果表明冬季风水平环流和垂直环流都表现出显著的准40天振荡特征,高低层水平环流的低频变化主要受热带西太平洋和澳大利亚附近的低频涡旋系统的影响,纬向环流的低频变化表现为Walker环流的加强和减弱。经向环流则表现为局地振荡特征,它的低频振荡起着联接南北半球和高低层季风环流低频振荡的作用。 相似文献
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This paper examines the response of the bandpass filter with Gaussian weighting function to arbitrarytwo-dimensional fields and proposes a new concept of relative response function.Based on the properties of relative re-sponse function,satisfactory weighting parameters C_1 and C_2 are obtained.By studying two cases,the procedure of us-ing structure function curves to choose the maximum response wavelength is formulated.It is shown that bandpass fil-tering offers some improvements to the analysis and forecast of mesoscale weather processes. 相似文献
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A new static microwave sounding unit (MSU) channel 4 weighting function is obtained from using Coupled Model Inter-comparison Project, Phase 5 (CMIP5) historical multimodel simulations as inputs into the fast Radiative Transfer Model for TOVS (RTTOV v10). For the same CMIP5 model simulations, it is demonstrated that the computed MSU channel 4 brightness temperature (T4) trends in the lower stratosphere over both the globe and the tropics using the proposed weighting function are equivalent to those calculated by RTTOV, but show more cooling than those computed using the traditional UAH (University of Alabama at Huntsville) or RSS (Remote Sensing Systems in Santa Rosa, California) static weighting functions. The new static weighting function not only reduces the computational cost, but also reveals reasons why trends using a radiative transfer model are different from those using a traditional static weighting function. This study also shows that CMIP5 model simulated T4 trends using the traditional UAH or RSS static weighting functions show less cooling than satellite observations over the globe and the tropics. Although not completely removed, this difference can be reduced using the proposed weighting function to some extent, especially over the tropics. This work aims to explore the reasons for the trend differences and to see to what extent they are related to the inaccurate weighting functions. This would also help distinguish other sources for trend errors and thus better understand the climate change in the lower stratosphere. 相似文献
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高,低分辨率模式对典型个例的对比预报试验 总被引:3,自引:2,他引:3
利用实时观测资料T63模式预报产品资料,对1995年7-8月发生在西北地区的3次大雨、暴雨天气过程进行了高、低分痃率数值预报模式的对比预报试验。 相似文献
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Simultaneous Non-linear Retrieval of Atmospheric Temperature and Absorbing Constituent Profiles from Satellite Infrared Sounder Radiances 总被引:4,自引:3,他引:1
Based on Zeng’s theory (1974), a successive linearized form of radiative transfer equation (RTE) is derived for simultaneous retrieval of atmospheric temperature and absorbing constituent profiles from satellite infrared observa-tions. It contains the temperature component weighting function and absorbing constituent (H2O, O3, CH4 etc.) com-ponent weighting functions. All these weighting functions reach maximum at their own “optimum information levels”, and make the remote sensing equations well-conditional. Then the atmospheric profiles are derived by Newton’s non-linear iteration method. Experiments of retrieval from both TIROS-N operational High Resolution Infrared Sounder (HIRS) and the simulated Atmospheric infRared Sounder (AIRS) show an significant improvement. 相似文献
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The bandpass eddy covariance method has been used to measure the turbulent flux of scalar quantities using a slow-responsescalar sensor. The method issimilar in principle to the traditional eddy correlation method but includes the estimation of high-frequency components of the flux on the basis of cospectral similarity in the atmospheric surface layer. In order to investigate the performance of the method, measurements of the water vapour flux over a forest with the bandpass eddy covariance method and the direct eddy correlation method were compared. The flux obtained by the bandpass eddy covariance method agreed with that by the eddy correlation method within ±20% for most cases, in spite of a rather slow sensor-response of the adopted hygrometer. This result supports its relevance to a long-term continuous operation, since a stable, low-maintenance,general-purpose sensor canbe utilized for scalar quantities. Oneweak point of the method isits difficulty in principle to measure the correct flux when the magnitude of the sensible heat flux is very small, because the method uses the sensible heat flux as a standard reference for the prediction of undetectable high-frequency components of the scalar flux. An advanced method is then presented to increase its robustness. In the new method, output signals from a slow-response sensor are corrected using empirical frequency-responsefunctions for the sensor,thereby extending the width of the bandpass frequency region where components of the flux are directly measured (not predicted). The advanced method produced correct fluxes for all cases including the cases of small sensible heat flux. The advanced bandpass eddy covariance method is thus appropriate for along-term measurement of the scalar fluxes. 相似文献
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本文利用高空常规资料,格距为150km,取λ_(max)=1500km的带通滤波器对长江三角洲地区的暴雨云团所处的环境场(包括风场,高度场和温度场)进行尺度分离,讨论中尺度扰动场与暴雨云团的关系。 相似文献