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101.
Xi-Yun Hou Hai-Hong Wang Lin Liu Department of Astronomy Nanjing University Nanjing : Institute of Space Environment Astronautics Nanjing University Nanjing 《中国天文和天体物理学报》2006,6(3):372-378
Collinear libration points play an important role in deep space exploration because of their special positions and dynamical characteristics. Since motion around them is unstable, we need to control the spacecraft if we wish to keep them around such a libration point for a long time. Here we propose a continuous low-thrust control strategy, illustrated with numerical simulations combined with the orbit design and control of the World Space Observatory/UltraViolet (WSO/UV). 相似文献
102.
利用吉林省业务运行的WRF模式,计算了与紫外线指数相关的气温、湿度、云量、风速等常规气象要素和地表向下的短波辐射通量、地面热通量、反照率等非常规气象要素,利用长春市紫外线观测资料,分析了紫外线辐射与常规和非常规气象要素的相关性。基于长春市紫外线观测实况,以常规气象要素、非常规气象要素、混合气象要素为因子,利用相同的统计建模方法,分别建立紫外线预报模型。结果表明:大气短波辐射等非常规气象要素与紫外线指数的相关性,明显高于气温、云量、比湿、风速等常规气象要素;应用非常规气象要素和混合气象要素的紫外线预报方程,显著优于常规气象要素;基于混合气象要素的紫外线预报方程,与基于非常规气象要素的预报方程比较,预报性能差异不大。此外,应用常规气象要素建立的分季节紫外线预报方程,其预报效果明显优于全年预报方程。应用非常规气象要素建立的分季节紫外线预报方程,与全年预报方程相比,预报效果差异不大。 相似文献
103.
The flexible global ocean-atmosphere-land system model, Grid-point Version 2: FGOALS-g2 总被引:3,自引:0,他引:3
李立娟 林鹏飞 俞永强 王斌 周天军 刘利 刘骥平 包庆 徐世明 黄文誉 夏坤 普业 董理 申思 刘屹岷 胡宁 刘咪咪 孙文奇 史湘军 郑伟鹏 吴波 宋米荣 刘海龙 张学洪 吴国雄 薛巍 黄小猛 杨广文 宋振亚 乔方利 《大气科学进展》2013,30(3):543-560
This study mainly introduces the development of the Flexible Global Ocean-Atmosphere-Land System Model: Grid-point Version 2 (FGOALS-g2) and the preliminary evaluations of its performances based on results from the pre-industrial control run and four members of historical runs according to the fifth phase of the Coupled Model Intercomparison Project (CMIP5) experiment design. The results suggest that many obvious improvements have been achieved by the FGOALS-g2 compared with the previous version,FGOALS-g1, including its climatological mean states, climate variability, and 20th century surface temperature evolution. For example,FGOALS-g2 better simulates the frequency of tropical land precipitation, East Asian Monsoon precipitation and its seasonal cycle, MJO and ENSO, which are closely related to the updated cumulus parameterization scheme, as well as the alleviation of uncertainties in some key parameters in shallow and deep convection schemes, cloud fraction, cloud macro/microphysical processes and the boundary layer scheme in its atmospheric model. The annual cycle of sea surface temperature along the equator in the Pacific is significantly improved in the new version. The sea ice salinity simulation is one of the unique characteristics of FGOALS-g2, although it is somehow inconsistent with empirical observations in the Antarctic. 相似文献
104.
K. V. S. Badarinath Shailesh Kumar Kharol V. Krishna Prasad Anu Rani Sharma E. U. B. Reddi H. D. Kambezidis D. G. Kaskaoutis 《Journal of Atmospheric Chemistry》2008,59(3):219-236
Measurements of total ozone column and solar UV radiation under different atmospheric conditions are needed to define variations
of both UV and ozone and to study the impact of ozone depletion at the Earth’s surface. In this study, spectral and broadband
measurements of UV-B irradiance were obtained along with total ozone observations and aerosol optical depth measurements in
the tropical urban region of Hyderabad, south India. We specifically used an Ultra-Violet Multifilter Rotating Shadow band
Radiometer (UVMFR-SR), to measure UV irradiance in time and space. To assess the aerosol and O3 effects on ground-reaching UV irradiance, we used measurements from a Microtops II sun photometer in addition to the Tropospheric
Ultraviolet Visible radiation (TUV) model. We also assessed the Defense Meteorological Satellite Program – Operational Line
Scanner (DMSP-OLS) night time satellite data for inferring biomass burning fires during the study period. Results clearly
suggested a negative correlation between the DMSP-OLS satellite derived fire count data and UVMFR-SR data suggesting that
aerosols from biomass burning are directly attenuating UV irradiance in the study region. Also, correlation analysis between
UV index and ozone measurements from sun photometer and TOMS-Ozone Mapping Instrument (OMI) indicated a clear decrease in
ground reaching UV-B irradiance during higher ozone conditions. The higher levels are attributed to photochemical production
of O3 during the oxidation of trace gases emitted from biomass burning. Results also suggested a relatively high attenuation in
UV irradiance (~6% higher) from smoke particles than dust. We also found a relatively good agreement between the modeled (TUV)
and measured UV irradiance spectra for different atmospheric conditions. Our results highlight the factors affecting UV irradiance
in a tropical urban environment, south India. 相似文献
105.
The degradation reactions of two monoazo pigments, namely, Red 53:1 and Red 48:2, by Fenton, photo‐Fenton and UV/H2O2 systems have been studied. The efficiencies of the Fenton reactions increased with temperature, but the formation of solid agglomerates was observed when the reactions were carried out above 50°C indicating a coagulant action of Fe+2 or Fe+3. Photo‐Fenton reactions irradiated by sunlight presented the best rate constants for cleavage of the azo bond and the naphthalene rings. The UV/H2O2 system exhibited the highest efficiency with respect to the consumption of H2O2. The presence of a carbonyl group in the ortho position of the naphthol ring hampered the oxidation of pigment Red 48:2 by hydroxyl radicals. This finding may be explained in terms of the acceptor character of the COOH group, and suggests the formation of a complex containing two six‐membered rings between Fe+3 and the pigment molecule. 相似文献
106.
The reflectance of Saturn’s moon Enceladus has been measured at far ultraviolet (FUV) wavelengths (115-190 nm) by Cassini’s Ultraviolet Imaging Spectrograph (UVIS). At visible and near infrared (VNIR) wavelengths Enceladus’ reflectance spectrum is very bright, consistent with a surface composed primarily of H2O ice. At FUV wavelengths, however, Enceladus is surprisingly dark - darker than would be expected for pure water ice. Previous analyses have focused on the VNIR spectrum, comparing it to pure water ice (Cruikshank, D.P., Owen, T.C., Dalle Ore, C., Geballe, T.R., Roush, T.L., de Bergh, C., Sandford, S.A., Poulet, F., Benedix, G.K., Emery, J.P. [2005] Icarus, 175, 268-283) or pure water ice plus a small amount of NH3 (Emery, J.P., Burr, D.M., Cruikshank, D.P., Brown, R.H., Dalton, J.B. [2005] Astron. Astrophys., 435, 353-362) or NH3 hydrate (Verbiscer, A.J., Peterson, D.E., Skrutskie, M.F., Cushing, M., Helfenstein, P., Nelson, M.J., Smith, J.D., Wilson, J.C. [2006] Icarus, 182, 211-223). We compare Enceladus’ FUV spectrum to existing laboratory measurements of the reflectance spectra of candidate species, and to spectral models. We find that the low FUV reflectance of Enceladus can be explained by the presence of a small amount of NH3 and a small amount of a tholin in addition to H2O ice on the surface. The presence of these three species (H2O, NH3, and a tholin) appears to satisfy not only the low FUV reflectance and spectral shape, but also the middle-ultraviolet to visible wavelength brightness and spectral shape. We expect that ammonia in the Enceladus plume is transported across the surface to provide a global coating. 相似文献
107.
利用自动经验基线校正方法,分析2013年4月20日芦山MS7.0级地震13个近场强震动台的观测资料,以估算同震位移场分布,并据此反演了震源滑动模型.经与GPS结果比较,两种不同方法给出的芦山7级地震的水平近场同震位移场幅度都不超过cm级,均显示为典型的逆冲型地震(兼有少量左旋走滑错动).强震最大水平和垂直永久位移分别为4.9 cm和4.4 cm,分别出现在51YAM台和51QLY 台.两种资料反演的震源滑动模型虽显示多事件特征,但主要滑动均集中在第一次事件,即初始滑动点两侧的走向长约30 km、倾向长约25 km的相对集中的较小范围内,强震和GPS模型的最大滑动量分别为1.14 m和1.09 m,较为一致.其余子事件滑动量小且分布零散,不能排除其数值效应的因素.反演矩震级均在Mw6.7左右,地表破裂应该不明显.文章还讨论了目前在我国利用近场强震动记录估计Mw6~7级地震同震位移场存在的困难和问题,为今后类似工作提供参考. 相似文献
108.
109.
中国20年一遇气温和降水极值变化的高分辨率模拟 总被引:1,自引:0,他引:1
基于25 km高分辨率区域气候模式(RegCM3)嵌套MIROC3.2_hires全球气候模式结果,进行IPCC SRES A1B情景下21世纪气候变化的模拟,分析中国区域未来气温和降水极值重现期的变化。首先检验模式对当代(1981-2000年)极端事件重现期的模拟能力,结果表明,模式能够较好地再现中国地区20年一遇极端事件的基本分布型,但所模拟的数值与观测相比还有一定偏差,特别是在极端降水方面。21世纪中期(2041-2060年)和末期(2081-2100年)20年一遇的高温极值在整个区域内均将升高,东北地区增幅最大;低温极值将增大,中心位于内蒙古、新疆及青藏高原南麓;降水极值也将普遍增大。气温和降水极值在21世纪末期的增加幅度均比中期要大。在未来全球变暖背景下,中国地区极端高温事件将明显增多,面积增大;极端低温事件将大幅度减少,面积减少;强降水事件也将增多,面积不断扩大。 相似文献
110.
基于测量结构水下光纤应变获取冰力的方法首次应用于渤海JZ20-2NW加锥导管架平台,该方法方便进行零点标定,可获取结构总冰力的绝对信息(包括均值和波动值)。首先介绍了JZ20-2NW平台的现场监测系统,主要包括结构水下应变响应记录冰力信息,甲板上部视频记录同步冰情(冰厚、冰速和来冰方向)信息和拾振器记录结构冰振响应;重点分析了由测点应变向结构总冰力的转化方法,并对总冰力进行了初步分析。将无量纲化实测冰力与5种典型冰力计算模型进行了比较,分析结果表明,锥体宽度与海冰厚度比值(简称"宽厚比")对冰力大小及变化起决定作用。 相似文献