CONDITIONAL SAMPLING AND SCALE ANALYSIS OF THE MARINE ATMOSPHERIC MIXED LAYER -- SOFIA EXPERIMENT     

ANNE RéCHOU  PIERRE DURAND 《Boundary-Layer Meteorology》1997,82(1):81-104

During the SOFIA experiment, performed in the Azores region in June1992, airborne missions were conducted in the atmospheric boundary layerwith two aircraft instrumented for turbulence measurements. We show howthe conditional sampling technique, applied to the velocity, temperatureand moisture fluctuations, is able to describe the various parcels whichconstitute the turbulent field. Each parcel, so identified, is characterized byits fractional area and by its contribution to the transfers of sensible heat andlatent heat. On the other hand, a scale analysis is conducted by filteringthe turbulent signals in five non-overlapping frequency bands, definedaccording to the characteristic turbulent scales. The contribution of eachband to the turbulent energy and to the transfers is thus presented. Theimportance of the lowest frequencies, which are generally removed fromthe signals by high-pass filtering before computing turbulent fluxes, isshown. In the final section, the conditional sampling technique is applied tothe signals filtered in the various bands. Despite a slight deformation of theeddies due to the filtering technique, the contribution of each parcel can beestimated at the various scales analysed.  相似文献   

Theoretical Basis and Application of an Analogue- Dynamical Model in the Lorenz System   总被引：2，自引：0，他引：2  

REN Hongli  CHOU Jifan  HUANG Jianping  ZHANG Peiqun 《大气科学进展》2009,26(1):67-77

The theoretical basis and application of an analogue-dynamical model (ADM) in the Lorenz system is studied. The ADM can effectively combine statistical and dynamical methods in which the small disturbance of the current initial value superimposed on the historical analogue reference state can be regarded as a prediction objective. Primary analyses show that under the condition of appending disturbances in model parameters, the model errors of ADM are much smaller than those of the pure dynamical model (PDM). The characteristics of predictability on the ADM in the Lorenz system are analyzed in phase space by conducting case studies and global experiments. The results show that the ADM can quite effectively reduce prediction errors and prolong the valid time of the prediction in most situations in contrast to the PDM, but when model errors are considerably small, the latter will be superior to the former. To overcome such a problem, the multi-reference-state updating can be applied to introduce the information of multi-analogue and update analogue and can exhibit exciting performance in the ADM.  相似文献   

用地震反射波全部时間值求有效速度          下载免费PDF全文

周焕然 《地球物理学报》1965,14(3):204-208

本文讨论了用地震反射波的全部时间值求有效速度的方法,得出了四种计算有效速度的公式。经过实际运用,认为有一定的效果,同时可用来计算断层面引起的绕射波的有效速度,对识别绕射波提供了一些线索。本文仅作为地震勘探工作交流实际经验而提出。  相似文献   

积云发展问题的数值试验   总被引：1，自引：0，他引：1  

周晓平  李兴生  张耀科  龚增锦 《气象学报》1964,34(4):475-485

本文给出了一个三维轴对称的积云发展模式,考虑了凝结对流场的反馈影响,并假定环境的温度递减率和相对湿度随高度减小。在电子计算机上求得的数值解表明:当大气中有1℃左右的温度扰动时,则在二十分钟以内就可以发展成一块5—6公里厚的积云。在积云下部形成一个变化不大的湿绝热不稳定区,流场和温度场在积云发展后期变化也不大。而在积云上部的稳定层结中,流场和温度场随时间变化则比较大,从云中下部上升的对流泡到顶部形成波动。这与观测结果是相象的。  相似文献   

电离层的直接探測研究          下载免费PDF全文

周炜 《地球物理学报》1963,12(1):100-117

本文叙述了利用地球物理火箭和人造地球卫星研究电离层和无綫电波传播的各种实驗方法,对各方法之間的关系及其所能解决的問题作了說明,并綜述了在这方面已經得到的重要研究成果。最后扼要地指出了今后研究的主要趋向。  相似文献   

新疆柯坪断裂带地震活动的特征及趋势分析          下载免费PDF全文

刘一鸣  姚虹  周海南 《地球物理学报》1975,18(1):39-51

本文通过对1972年1月16日新疆西部柯坪地区6.2级的地震进行重点分析和总结,进一步扩大了研究地区,并从地震活动特征、发震的物理机制、波速变化以及当前的地壳运动等方面进行对比分析,对该地区地震趋势进行了初步探讨。  相似文献   

燕山某地新型富钾岩石物质组成及其成因          下载免费PDF全文

周中毅  王东安 《地质科学》1966,7(1):79-88

1960年在燕山地区发现了一种新型富钾岩石,其 K₂O 含量可高达16.68%,分布颇广,层位稳定,厚度大,矿物成分简单,据了解它们不但可成为陶瓷、玻璃、耐火和化工等工业原料,而且经过初步试验证明有可能成为制取钾肥的新的原料来源。由于此种岩石有很大的特殊性,可能是一种新的沉积岩类型,因而进行深入的研究不但有其实际意义,而且对于了解钾的化学地史、燕山震且系沉积特点、后生作用（包括变生作用）对钾等有用元素富集的意义及讨论成矿元素物质来源等都有很大意义。1962年笔者曾与陈开惠同志一道去野外进行调查,回室后在叶连俊教授的关切和指导下,对共物质组成进行了研究。整个工作中曾多次得到范德廉、陈志明、杨培基、戴永定和李继亮等同志热情的帮助。  相似文献   

TELECONNECTION BETWEEN INDIAN MONSOON AND EAST ASIAN CIRCULATION^*          下载免费PDF全文

DAI Xingang  WANG Ping  WU Guoxiong  CHOU Jifan 《Acta Meteorologica Sinica》2004,18(4):397-410

Correlation analysis identified that Indian summer rainfall and East Asian 500 hPa geopotential height field are significantly correlated.A teleconnection pattern between Indian monsoon and East Asian summer circulation (IEA pattern) was proposed.We suggested that the Pacific-Japan teleconnection pattern (PJ pattern) primarily influences the meridional position of the northwestern Pacific subtropical high (NPSH) in summer,while IEA pattern partly affects its zonal stretch or the anomaly of geopotential height field over China mainland.The numerical experiments imply that the IEA pattern has important impact on East Asian circulation and it can be stimulated by the SST anomaly of the Indian Ocean.We summarized that there are two ways,a directive way and a selective way,by which ENSO exerts impacts on East Asian summer monsoon.  相似文献   

煤中黄铁矿的铼-锇同位素含量及其地质意义   总被引：2，自引：0，他引：2  

刘桂建  彭子成  杨刚  CHOU Chen-Lin 《地学前缘》2006,13(1):211-215

采用Carius管溶样方法,通过热电离质谱对淮北煤田煤中黄铁矿样品的Re、Os含量及其同位素进行了测定,得出黄铁矿样品中Re和Os含量分别为1·22~1·29ng/g和0·0046~0·0054ng/g。对两个样品同位素定年测定得出,其年龄值分别为(73·9±3·2)Ma和(33±9)Ma,两个样品的年龄相差约258~286Ma。含量和同位素年龄差值表明两个样品是不同时代形成的黄铁矿。Re-Os同位素体系比值揭示黄铁矿所赋存的地质体受到来自地壳物质的显著混染。另外,γOTs参数也证实了这一点。该参数分别为+17和+18,表明了有富含Re母体的地壳物质的加入,这为煤中Re-Os含量及地质理论研究提供了参考资料。  相似文献   

短期气候预测的现状 问题与出路(一)   总被引：4，自引：0，他引：4  

丑纪范 《沙漠与绿洲气象(新疆气象)》2003,26(1):1-4

从方法论上分析了短期气候预测的现状、问题与出路。着重指出：基础理论研究的欠缺又不甚得法是短期气候预测准确率提高缓慢的原因；应当将数值预报的提法从初值问题改为演变问题，进一步提为反问题；统计学方法与动力学方法要相互借鉴，取长补短，融合发展。  相似文献