2003年江淮流域强降水过程与30—70d天低频振荡的联系   总被引：9，自引：1，他引：8  

夏芸  管兆勇  王黎娟 《南京气象学院学报》2008,31(1):33-41

利用NCEP／NCAR再分析和地面观测站的逐日降水资料,研究了2003年夏季江淮流域强降水过程与低频振荡的联系。结果显示,主周期为30～70d的低频振荡对2003年江淮流域暴雨的形成具有重要贡献：低频涡旋在江淮地区降水期的对流层高、低层呈负、正配置,具有斜压结构,利于降水发生;850hPa上正涡度系统的传播具有明显的北传和西传特征;存在于西太平洋、西北太平洋及其以东地区的低频波列（P—J）的活动过程影响了我国2003年江淮低频强降水的形成;整层低频水汽通量显示来自副热带高压外围的西南季风对水汽输送的贡献较显著,且2003年江淮地区30-70d时间尺度上降水的水汽来源为南海而非孟加拉湾或西太平洋。  相似文献   

沈阳冬夏季可吸入颗粒物浓度及尺度谱分布特征   总被引：15，自引：0，他引：15       下载免费PDF全文

严文莲  周德平  王扬峰  杨军  李子华 《应用气象学报》2008,19(4):435-443

利用沈阳大气成分监测站颗粒物监测仪 (Grimm 180) 连续测得的夏季 (2006年8月)、冬季 (2006年12月和2007年1月) 可吸入颗粒物的数浓度和质量浓度数据, 分析了沈阳市可吸入颗粒物浓度日变化、谱分布及污染特征, 在此基础上结合沈阳市常规气象资料, 分析了气象要素和颗粒物污染之间的关系。结果表明:沈阳市冬、夏季部分时段可吸入颗粒物浓度存在明显的日变化和日际变化; 谱分布较好地符合Junge分布; 沈阳冬季PM₁₀超标日数占冬季观测总天数的77%, PM_2.5超标日数 (按美国EPA日均标准) 占冬季观测总天数的87%, PM₁₀平均数浓度为6668.7个/cm3, 平均质量浓度达252.8μg/m3, 分别是夏季的3.0和2.4倍; 冬、夏季PM_2.5/PM₁₀平均质量分数分别为0.647和0.603, PM_2.5占可吸入颗粒物总数量的99%以上; 浓度变化在很大程度上受到各种气象要素的影响, 与温度、风速负相关, 与湿度正相关, 降雨、降雪过程使得颗粒物浓度明显降低, 近地层逆温和雾是颗粒物增多的一个重要因素。颗粒物污染对城市能见度影响较大。  相似文献   

An Observational Study of Black Carbon Aerosol in Northwest China in the Spring of 2006     

GAO Run-xiang  NIU Sheng-jie  ZHANG Hua  XIN Jin-yuan  GUO Jun  XU Mei 《南京气象学院学报》2008,31(5)

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离岸型背景风和海陆风对珠江三角洲地区灰霾天气的影响   总被引：18，自引：0，他引：18  

陈训来  冯业荣  范绍佳 《大气科学》2008,32(3):530-542

不同类型的背景场和海陆风对珠江三角洲地区大气灰霾有不同的影响。作者主要利用空气质量模式系统Models-3 (MM5/SMOKE/CMAQ)研究离岸型背景风和海陆风对珠江三角洲一次灰霾天气的影响, 结果表明, 中尺度气象模式MM5对珠江三角洲地区这次灰霾天气的气象模拟, 较好地模拟了风速和风向的变化。多尺度空气质量模式CMAQ模拟出了PM10浓度的变化, 与观测值比较一致。在这次灰霾天气过程中, 由于离岸型背景风与陆风风向一致, 在陆风维持的情况下, 内陆源区的PM10被输送到沿海地区, 导致沿海城市和海面上PM10浓度比较高; 而在海风维持的情况下, 海风与离岸型背景风方向相反, 造成海风较小, 致使整个珠江三角洲地区灰霾天气都比较严重。敏感性试验结果表明离岸背景风和海陆风的相互作用对灰霾天气的生成与分布有重大的影响。  相似文献   

Investigating the age and structure of the infrared old open clusters LK 1, LK 10, FSR 1521 and FSR 1555     

C. Bonatto  E. Bica 《Monthly notices of the Royal Astronomical Society》2009,392(1):483-496

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The topology and polarization of subbeams associated with the 'drifting' subpulse emission of pulsar B0943+10 – V. A new look at the low-frequency burst-mode emission     

Svetlana A. Suleymanova  Joanna M. Rankin 《Monthly notices of the Royal Astronomical Society》2009,396(2):870-877

This paper reports new observations of pulsar B0943+10 carried out at the Pushchino Radio Astronomy Observatory (PRAO) at the low radio frequencies of 42, 62 and 112 MHz. B0943+10 is well known for its exquisitely regular burst-mode (B-mode) drifting subpulses as well as its weaker and chaotic quiescent mode. Earlier Arecibo investigations at 327 MHz have identified remarkable, continuous changes in its B-mode subpulse drift rate and integrated-profile shape with durations of several hours. These PRAO observations reveal that the changes in profile shape during the B-mode lifetime are strongly frequency dependent – namely the measured changes in the component amplitude ratio are more dramatic at 327 and 112 MHz as compared with those at 62 and 42 MHz. The differences, however, are most marked during the first several tens of minutes after B-mode onset; after an hour or so the profile shape changes tend to be more similar at all four frequencies. We also have found that the linear polarization of the integrated profile increases continuously throughout the lifetime of the B mode, going from hardly 10 per cent just after onset to some 40–50 per cent after several hours. Pulsar B0943+10's B mode thus provides a unique new opportunity to investigate continuous systematic changes in the plasma flow within the polar flux tube. While refraction in the pulsar's magnetosphere may well play some role, we find that the various frequency-dependent effects, both between and within the two modes, can largely be understood geometrically. If the modes and B-mode decay reflect systematic variations in the carousel-'spark' radius and emission height then a specific set of profile and linear polarization changes would be expected.  相似文献   

The silicate and carbon-rich models of CoRoT-7b, Kepler-9d and Kepler-10b     

Yan-Xiang Gong  Ji-Lin Zhou 《天体物理学报》2012,(6):678-692

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Acoustic-Gravity Waves from Bolide Sources     

Douglas O. ReVelle 《Earth, Moon, and Planets》2008,102(1-4):345-356

We have developed a new approach to modeling the acoustic-gravity wave (AGW) radiation from bolide sources. This first effort involves entry modeling of bolide sources that have available satellite data through procedures developed in ReVelle (Earth Moon Planets 95, 441–476, 2004a; in: A. Milani, G. Valsecchi, D. Vokrouhlicky (eds) NEO Fireball Diversity: Energetics-based Entry Modeling and Analysis Techniques, Near-earth Objects: Our Celestial Neighbors (IAU S236), 2007b). Results from the entry modeling are directly coupled to AGW production through line source blast wave theory for the initial wave amplitude and period at (at 10 blast wave radii and perpendicular to the trajectory). The second effort involves the prediction of the formation and or dominance of the propagation of the atmospheric Lamb, edge-wave composite mode in a viscous fluid (Pierce, J. Acoust. Soc. Amer. 35, 1798–1807, 1963) as a function of the source energy, horizontal range and source altitude using the Lamb wave frequency that was deduced directly during the entry modeling and that is used as a surrogate for the source energy. We have also determined that Lamb wave production by bolides at close range decreases dramatically as either the source energy decreases or the source altitude increases. Finally using procedures in Gill (Atmospheric-Ocean Dynamics, 1982) and in Tolstoy (Wave Propagation, 1973), we have analyzed two simple dispersion relationships and have calculated the expected dispersion for the Lamb edge-wave mode and for the excited, propagating internal acoustic waves. Finally, we have used the above formalism to fully evaluate these techniques for four large bolides, namely: the Tunguska bolide of June 30, 1908; the Revelstoke bolide of March 31, 1965; the Crete bolide of June 6, 2002 and the Antarctic bolide of September 3, 2004. Due to page limitations, we will only present results in detail for the Revelstoke bolide.  相似文献   

Late Quaternary glaciations in the Cogarbu valley,Bhutanese Himalaya   总被引：1，自引：0，他引：1  

Xu Peng  Yixin Chen  Gengnian Liu  Beibei Liu  Yingkui Li  Qing Liu  Yesong Han  Weilin Yang  Zhijiu Cui 《第四纪科学杂志》2019,34(1):40-50

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冀中饶阳凹陷西柳10断块古近系沙三段-沙二段层序地层及沉积演化          下载免费PDF全文

王旭旭  张廷山  张喜  孙文钊 《沉积与特提斯地质》2019,39(4):27-37

为了探讨饶阳凹陷蠡县斜坡北东缘西柳10断块古近系沙河街组沙三段-沙二段(Es~3-Es~2)层序地层特征及其沉积特征,依据高分辨率层序地层学理论,结合岩心、测井等资料,对研究区沙三段-沙二段层序地层进行划分,对其沉积特征、相带展布及其演化规律进行研究。研究结果表明,沙河街组沙三段-沙二段可划分为4个III级旋回,11个IV级旋回,32个V级旋回。沉积物岩性以细砂岩、粉砂岩及泥岩为主,沉积环境主要为辫状河三角洲平原和三角洲前缘,划分出7种沉积微相。结合研究区区域构造演化及沉积背景,认为沙三段-沙二段沉积时期,主要经历湖退到湖进的演变过程。  相似文献