New fast models of the Galactic tide     

M. Fouchard 《Monthly notices of the Royal Astronomical Society》2004,349(1):347-356

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Centaurs from the Oort cloud and the origin of Jupiter-family comets     

V. V. Emel'yanenko  D. J. Asher  M. E. Bailey 《Monthly notices of the Royal Astronomical Society》2005,361(4):1345-1351

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飞机探测云物理数据集的建立和应用   总被引：6，自引：3，他引：3       下载免费PDF全文

姚展予  濮江平  刘卫国  陈跃  汪晓滨  王柏忠 《应用气象学报》2004,15(Z1):68-74

通过收集大量历史和现今的飞机探测云物理资料,对所获取的资料进行必要的质量控制和检验,并进行统一整理、加工、规范和信息化处理,形成了具有规范格式和详细说明文档的"飞机探测云物理数据集"产品.该数据集产品具有分类查询、数据导出、格式说明等功能,可以按照时间属性、地理空间属性、数据种类等不同属性对该数据集中的各类数据进行多元化使用.借助于"气象科研数据共享平台","飞机探测云物理数据集"产品已在一定范围内得到广泛应用.在此应用基础上,包括国家科技攻关项目在内的许多科研或业务项目已经取得了许多可喜的成果.  相似文献   

Modelling the effect of an assumed cosmic ray-modulated global cloud cover on the terrestrial surface temperature     

J. Ramírez  B. Mendoza  V. Mendoza  J. Adem 《Journal of Atmospheric and Solar》2004,66(18):263

We have used the thermodynamic model of the climate to estimate the effect of variations in the oceanic cloud cover on the surface temperature of the Earth in the North Hemisphere (NH) during the period 1984–1990. We assume that the variations in the cloud cover are proportional to the variation of the cosmic ray flux measured during the same period. The results indicate that the effect in the temperature is slightly noticeable when we consider the surface hemispheric temperature on July 1987, finding an average temperature anomaly between −0.06°C and −0.14°C, along a latitudinal band between 20° and 40°. The surface temperature averaged globally in the NH presents a decrease of 0.01°C in average, which is almost the same for continents and oceans. However, these values are not significant when compared to the overall variability of the time series with and without forcing.  相似文献   

Nouvelles données sur le téphra de Sarliève et le téphra CF7, marqueurs chrono-stratigraphiques de Grande Limagne (Massif central,France)     

Didier Miallier  Serge Sanzelle  Thierry Pilleyre  Gérard Vernet  Sarah Brugière  Tohru Danhara 《Comptes Rendus Geoscience》2004,336(1):1-8

A trachytic tephra, discovered in the ancient lake of Sarliève, ‘Grande Limagne’, has been dated using the thermoluminescence technique. The obtained age, 16±4 ka ($\text{2}\text{σ}$), is older than that of the trachytic volcanoes of the Cha??ne des Puys, the ashes of which have already been locally recognised in the region. Its analysis confirms its originality. In the course of the comparisons made to search for its spring, it appears that the wide-dispersion tephra CF7, beforehand correlated by hypothesis to the Puy de Clierzou, probably originates from the Kilian crater or the Puy de Vasset. To cite this article: D. Miallier et al., C. R. Geoscience 336 (2004).  相似文献   

夏末华北低槽尾部雹云的生成环境和结构特征     

苏爱芳  银燕  蔡淼 《高原气象》2012,31(5):1376-1385

利用常规观测资料、多普勒雷达和卫星探测及反演资料、区域自动站资料及NCEP再分析资料,分析了2009年8月27日冀中南地区的突发性强风雹天气过程。结果表明,扩散南下的弱冷空气对强对流起触发作用,地面辐合线进一步促进了对流发展。雹云发展于上干下湿的环境场中,凝结潜热释放可能为雹云迅速发展提供了能量,中等偏强的深层垂直风切变为雹云的发展和维持提供了有利的动力条件。但08:00湿层低而浅薄、0℃层高度偏高(高于历史出雹的平均高度)和云顶亮温相对高等特征增加了预报难度,而相对高的云光学厚度可为午后强对流发展提供短临预报信息。雹云在雷达反射率产品上表现为线状排列的"超级单体族"特征,向东传播的多单体风暴使强风雹天气得以持续。  相似文献   

NCEP 全球预报系统在ARM SGP站点预报大气温度、湿度和云量的检验     

张寅  罗亚丽  管兆勇 《大气科学》2012,36(1):170-184

利用美国大气辐射测量项目(ARM)制作的“气候模拟最佳估计”(CMBE)观测数据集,检验美国环境预报中心(NCEP)全球预报系统(GFS)2001～2008年在ARM Southern Great Plains(SGP)站点预报的大气温度、相对湿度和云量的垂直分布,主要结论如下:(1)NCEP GFS较好地预报出了温度...  相似文献   

Characteristics of Solar Radiation and the Impact of Clouds at Yangbajing, Tibet          下载免费PDF全文

HUO Juan  LU Da-Ren 《大气和海洋科学快报》2012,5(3):235-239

Yangbajing (YBJ) is located in the Tibetan Plateau, China. The characteristics of solar radiation and its relationship with clouds at YBJ from April 2009 to April 2010 were analyzed in this paper. The annual mean solar radiation was 478.4 W m 2 , and the annual mean transmittance was 0.713. The atmospheric mean trans- mittance of clear skies reaches 0.828 when the solar elevation angle (SEA) is greater than 10 degrees. Comparisons with numerical simulations show that the atmosphere of YBJ is clean. Impacts from atmospheric conditions on solar radiation are similar for clear skies during the year because the standard deviation of transmittance in clear skies was less than 0.05 when the SEA was greater than 10 degrees. It is important to understand the impact of clouds on solar radiation without considering other impact factors. In the last part of this article, the authors analyzed and established a statistical quantitative relationship between surface solar radiation and cloud fraction.  相似文献   

Relationship between radar reflectivity and the time scale of warm rain formation in a global cloud-resolving model     

Kentaroh Suzuki  Graeme L. Stephens   《Atmospheric Research》2009,92(4):411-419

The connections between radar reflectivity and the time scale of warm rain formation are examined within a global cloud-resolving model. The parameterizations formulae of auto-conversion and accretion processes in the model reveal specific relationships between the time scale for auto-conversion and radar reflectivity of cloud water as well as between the time scale for accretion and radar reflectivity of rain water. The overall time scale for warm rain formation, determined by combined contributions from these processes, is found to relate with total radar reflectivity in the manner that varies with cloud-rain composition between auto-conversion and accretion limits. The global statistics from the model output reveals that the time scale is closely related with the total radar reflectivity, thus suggesting that the radar reflectivity is a gross measure of the warm rain time scale. The relationship developed is applied to both model-simulated and CloudSat-observed radar reflectivities to compare the time scales of warm rain formation between observation and the model. Comparison of the time scale so derived reveals significant differences between the model and CloudSat observations. These differences suggest that the simulated cloud-rain composition in the model is biased toward larger rain water contents and smaller content of cloud water compared to reality due to an accelerated cloud-to-rain water conversion in the model.  相似文献   

A comparison of MODIS-derived cloud amount with visual surface observations   总被引：6，自引：0，他引：6  

Andrzej Z. Kotarba   《Atmospheric Research》2009,92(4):522-530

Two main sources for global cloud climatologies are visual surface observations and observations made by spaceborne sensors. Satellite observations compared with surface data show in most cases differences ranging from − 15% up to − 1%, depending on sensor and observation conditions. These differences are partially controlled by sensors' cloud detection capabilities — a higher number of spectral bands and higher spatial resolution are believed to allow discrimination of clouds from land/ocean/snow background. A Moderate-Resolution Imaging Spectroradiometer (MODIS) produces images of the atmosphere in 36 spectral bands with a spatial resolution of 250–1000 m, thus having a capacity for cloud detection far more advanced than other operating sensors. In this study, instantaneous MODIS cloud observations were compared with surface data for Poland for January (winter) and July (summer) 2004. It was found that MODIS observed 4.38% greater cloud amount in summer conditions and 7.28% in winter conditions. Differences were greater at night (7–8%) than in daytime (0.5–7%) and correlations ranged between 0.577 (winter night) and 0.843 (winter day, summer day and night).  相似文献