江西省一次短历时暖区暴雨中尺度结构及发生维持机制分析   总被引：1，自引：0，他引：1       下载免费PDF全文

陈云辉  金米娜  许爱华 《气象与减灾研究》2015,38(3):26-34

利用地面和高空、卫星TBB、多普勒雷达和GFS(0.5°×0.5°)逐6 h再分析等资料,对2011年6月10日江西省西北部一次短历时暖区暴雨中尺度结构及发生维持机制进行分析。结果表明:1)此次过程是在有利的高、低空系统配置下发生在梅雨锋南侧的暖区暴雨,边界层急流和低空急流提供了充足的水汽条件,增强低层热力不稳定;高空分流区使大气动力不稳定发展,高低空急流的耦合作用为MCS维持提供了必备的不稳定机制;中低层热力不稳定,中高层对称不稳定,形成此次对流性强降水。2)地面中尺度辐合线、非锋性斜压带、能量锋的抬升作用为MCS生成和发展提够了启动机制。3)低层强盛的水汽输送、层结不稳定和地面持续而强的中尺度抬升使得多个雷暴单体在江西省西北部连续传播,形成"列车效应",降水强而集中。4)在水汽和不稳定条件具备的情况下,暖区对流性强降水发生在强低层辐合与强高层辐散相重迭的区域。  相似文献   

一次罕见黄渤海大风天气成因分析     

朱男男  刘一玮  孙密娜 《气象科技》2017,45(6):1070-1076

利用气象常规资料、风廓线资料和NCEP/NCAR 1°×1°再分析资料,对2015年10月1日黄渤海罕见大风天气成因进行分析。结果表明:较强冷空气与快速发展的入海气旋相互作用形成强气压梯度是导致此次海上强风的主要原因。对流层中低层强冷平流区与地面变压风大值区有较好的对应关系。上下相接的整层冷平流有利于地面形成强气压梯度和变压梯度。气压梯度在大风形成的初期起主导作用,变压梯度有利于强风的维持。本次过程出现明显动量下传现象,大风形成初期,500~1000m出现低空动量下传并影响地面风场,高空槽过境后,2000m以上的高空动量能够影响地面风场。风廓线观测到低层强风并伴有强的下沉运动,可以作为海上大风临近预警的指标之一。  相似文献   

Malaysia's Three Major Ethnic Group Preferences in Creating a Malaysian Garden Identity     

Mina Kaboudarahangi  Osman Mohd Tahir  Mustafa Kamal M.S. 《The Australian geographer》2013,44(2):197-213

Malaysia has a complex multiracial population, predominantly defined by three major ethnic groups: Malay, Chinese and Indian races, with diverse cultural backgrounds. Despite this, the country has a vision to be the most beautiful garden nation, and its National Landscape Policy (NLP) puts emphasis on creating a unique landscape and garden identity. Because of ethnic and cultural differences, there are differences between preferences for developing a garden identity for Malaysia. Hence, this study focused on the visual quality of gardens. Representative images of four well-established gardens of the world including Persian-Islamic, English, Japanese and Chinese gardens were presented to the study's respondents through preference photo surveys. Respondents from the three major ethnic groups in Malaysia were asked to rate their preferred garden types, elements and scenes that they would like to see in Malaysian gardens. The results pinpointed expectations of the visual quality of gardens. These highlighted some similarities and differences between the three major ethnic groups in their preferences for the scenes and elements that they sought in gardens. Diverse factors must be considered when creating Malaysian gardens that will be accepted by Malaysians of different ethnic groups. Garden development reveals preferences attached to visual qualities and emphasises cultural differences between garden users.  相似文献   

850hPa东高西低型低空环流与江西降水的关系     

王海  许爱华  金米娜 《气象与减灾研究》2012,(4):34-38

利用常规高空探测资料,分析了2000—2012年4—6月850 hPa层位势高度差异常(上海宝山或大陈岛站850 hPa层位势高度值比贵阳站大7 gpm或以上)形势下低空环流与江西降水的关系。结果表明,这种形势下,700 hPa高度层上均有西南低涡活动。近50%的个例江西省上空850 hPa层出现风速16 m/s以上的低空西南急流,约40%的个例有切变线活动;若去除850 hPa无切变线影响和切变线出现较晚的情形,江西省出现10站以上暴雨过程的比例为85.7%。  相似文献   

Evaluation of the effects of uncertainty on the predictions of landslide occurrences using the Shannon entropy theory and Dempster–Shafer theory     

Hosseinpoor Milaghardan  Amin  Ali Abbaspour  Rahim  Khalesian  Mina 《Natural Hazards》2020,100(1):49-67

Natural Hazards - One of the requirements for planning and decision-making to develop the infrastructures is to prepare the landslide occurrence hazard map. For this purpose, in this article, the...  相似文献   

Geophysical investigations in the El-Wad Cave,MT. Carmel,Israel     

Mina Weinstein-Evron  Yossi Mart  Alex Beck 《Geoarchaeology》1991,6(4):355-365

Measurements of the thickness of the sediment fill in the el-Wad Cave, Mt. Carmel, Israel were carried out using seismic refraction methods. The cave is one of the famous Mt. Carmel Caves, where finds of Mousterian to Natufian prehistoric cultures had been encountered. The survey discovered a series of karstic pits in several chambers in the cave, with good correlation between the dimension of the chambers and the thickness of the sediment fill. The deepest pit was found in the inner part of the cave, where the oldest archaeological material could be expected.  相似文献   

Further Documentary Evidence of Northern Hemispheric Coverage of the Great Dry Fog of 1783     

Gaston R. Demarée  Astrid E.J. Ogilvie  De'er Zhang 《Climatic change》1998,39(4):727-730

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Formation of pristane from α-tocopherol under simulated anoxic sedimentary conditions: A combination of biotic and abiotic degradative processes     

Jean-François Rontani  Mina Nassiry  Valérie Michotey  Sophie Guasco  Patricia Bonin 《Geochimica et cosmochimica acta》2010,74(1):252-14

Incubation of intact and oxidized α-tocopherol (vitamin E) in anaerobic sediment slurries allowed us to demonstrate that, as previously suggested by Goossens et al. (1984), the degradation of α-tocopherol in anoxic sediments results in the formation of pristane. The conversion of α-tocopherol to this isoprenoid alkane involves a combination of biotic and abiotic degradative processes, i.e. the anaerobic biodegradation (which seems to be mainly induced by denitrifying bacteria) of trimeric structures resulting from the abiotic oxidation of α-tocopherol. On the basis of the results obtained, it is proposed that in the marine environment most of the α-tocopherol present in phytoplanktonic cells should be quickly degraded within the water column and the oxic zone of sediments by way of aerobic biodegradation, photo- and autoxidation processes. Abiotic transformation of this compound mainly results in the production of trimeric oxidation products, sufficiently stable to be incorporated into anoxic sediments and whose subsequent anaerobic bacterial degradation affords pristane. These results confirm that the ratio pristane to phytane cannot be used as an indicator of the oxicity of the environment of deposition; in contrast, they support the use of PFI (Pristane Formation Index) as a proxy for the state of diagenesis of sedimentary organic matter.  相似文献   

The linear stability of dilute particulate rings     

Henrik N. Latter  Gordon I. Ogilvie 《Icarus》2006,184(2):498-516

Irregular structure in planetary rings is often attributed to the intrinsic instabilities of a homogeneous state undergoing Keplerian shear. Previously these have been analysed with simple hydrodynamic models. We instead employ a kinetic theory, in which we solve the linearised moment equations derived in Shu and Stewart 1985 for a dilute ring. This facilitates an examination of velocity anisotropy and non-Newtonian stress, and their effects on the viscous and viscous/gravitational instabilities thought to occur in Saturn's rings. Because we adopt a dilute gas model, the applicability of our results to the actual dense rings of Saturn are significantly curtailled. Nevertheless this study is a necessary preliminary before an attack on the difficult problem of dense ring dynamics. We find the Shu and Stewart formalism admits analytic stability criteria for the viscous overstability, viscous instability, and thermal instability. These criteria are compared with those of a hydrodynamic model incorporating the effective viscosity and cooling function computed from the kinetic steady state. We find the two agree in the ‘hydrodynamic limit’ (i.e., many collisions per orbit) but disagree when collisions are less frequent, when we expect the viscous stress to be increasingly non-Newtonian and the velocity distribution increasingly anisotropic. In particular, hydrodynamics predicts viscous overstability for a larger portion of parameter space. We also numerically solve the linearised equations of the more accurate Goldreich and Tremaine 1978 kinetic model and discover its linear stability to be qualitatively the same as that of Shu and Stewart's. Thus the simple collision operator adopted in the latter would appear to be an adequate approximation for dilute rings, at least in the linear regime.  相似文献   

Formation and evolution of dwarf elliptical galaxies – II. Spatially resolved star formation histories     

Mina Koleva  Sven De Rijcke  Philippe Prugniel  Werner W. Zeilinger  Dolf Michielsen 《Monthly notices of the Royal Astronomical Society》2009,396(4):2133-2151

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