27.3-day and 13.6-day atmospheric tide     

Li GuoQing  Zong HaiFeng 《中国科学D辑(英文版)》2007,50(9):1380-1395

An analysis of time variations in the earth's length of day (LOD) for 25 years (1973-1998) versus at- mospheric circulation changes and lunar phase is presented. It is found that, on the average, there is a 27.3-day and 13.6-day period oscillation in global zonal wind speed, atmospheric geopotential height, and LOD following alternating changes in lunar phase. Every 5-9 days (6.8 days on average), the fields of global atmospheric zonal wind and geopotential height and LOD undergo a sudden change in rela- tion to a change in lunar declination. The observed atmospheric oscillation with this time period may be viewed as a type of atmospheric tide. Ten atmospheric tidal cases have been analyzed by comparing changes in LOD, global zonal wind speed and atmospheric geopotential height versus change in lunar declination. Taken together these cases reveal prominent 27.3-day and 13.6-day tides. The lunar forcing on the earth's atmosphere is great and obvious changes occur in global fields of zonal wind speed and atmospheric geopotential height over the equatorial and low latitude areas. The driving force for the 27.3-day and 13.6-day atmospheric tides is the periodic change in lunar forcing during the moon's revolution around the earth. When the moon is located on the celestial equator the lunar declination equals zero and the lunar tidal forcing on the atmosphere reaches its maximum, at this time the global zonal wind speed increases and the earth's rotation rate decreases and LOD increases. Conversely, when the moon reaches its most northern or southern positions the lunar declination is maximized, lunar tidal forcing decreases, global zonal wind speed decreases, earth's rotation rate increases and LOD decreases. 27.3-day and 13.6-day period atmospheric tides deserve deeper study. Lunar tidal forcing should be considered in models of atmospheric circulation and in short and medium range weather forecasting.  相似文献   

Characteristics and Numerical Simulation of the Tropical Intraseasonal Oscillations under Global Warming          下载免费PDF全文

LIU Yunyun  YU Yongqiang  HE Jinhai  ZHANG Zhenguo 《Acta Meteorologica Sinica》2007,21(4):438-499

Using the ECMWF reanalysis daily 200-hPa wind data during the two 20-yr periods from 1958 to 1977 and from 1980 to 1999,the characteristics and changes of Intraseasonal Oscillations (ISO) in the two periods associated with global warming are analyzed and compared in this study.It is found that during the last 20 years,the ISO has weakened in the central equatorial Pacific Ocean,but becomes more active in the central Indian Ocean and the Bay of Bengal;under the background of the global warming,increase in the amplitude of ISO intensity suggests that the ISO has become more active than before,with an obvious seasonal cycle,i.e.,strong during winter and spring,but weak during summer and autumn;the energy of the upper tropospheric zonal winds has more concentrated in wave numbers 1-3,and the frequency of ISO tended to increase. Comparison between the results of control experiment and CO_2 increase (1% per year) experiment of FGOALS-1.0g (developed at LASG) with the first and second 20-yr observations,is also performed. respectively.The comparative results show that the spatial structure of the ISO was well reproduced,but the strength of ISO was underestimated.On the basis of space-time spectral analysis,it is found that the simulated ISO contains too much high frequency waves,leading to the underestimation of ISO intensity due to the dispersion of ISO energy.However,FGOALS-1.0g captured the salient features of ISO under the global warming background by two contrast experiments,such as the vitality and frequency-increasing of ISO in the central Indian Ocean and the Bay of Bengal.  相似文献   

国家级气象高性能计算机管理与应用网络平台设计   总被引：1，自引：3，他引：1       下载免费PDF全文

宗翔  王彬 《应用气象学报》2006,17(5):629-634

该文首先介绍了国家气象信息中心在高性能计算能力建设方面的成就及存在的一些问题, 阐述了计算网格的主要思想和技术特点, 并具体介绍了国家级气象高性能计算机管理与应用网络平台的架构和采用的主要技术路线和方法。  相似文献   

从中心投影影像制作正射影像的多种方法研究   总被引：1，自引：2，他引：1  

宣文玲  林宗坚 《测绘科学》2003,28(2):9-11

提出了由中心投影影像制作数字正射影像的三种新方法:(1)在具备立体像对的情况下,通过立体影像匹配求得视差值,直接利用视差值进行微分纠正,得到正射影像;(2)多中心影像不构成立体像对,但是各中心之间有一定的空间距离时,利用本文推导的一系列数学公式,可在影像匹配的基础上进行基于视差的微分纠正,从而得到正射影像;(3)直接利用地物稠密地区相应比例尺地形图的数字化成果,例如数字栅格地图(DRG)或数字线划地图(DLG),与单帧影像上提取的地物线划进行配准,从而实现正射影像纠正。还给出了影像上的特征线划与地图上的特征线划配准的新方法。  相似文献   

宁夏中部牛首山地区构造特征及其地质意义   总被引：2，自引：4，他引：2  

张进  马宗晋  任文军  雷永良 《大地构造与成矿学》2003,27(2):132-142

宁夏中部牛首山地区的古生代地层发育了许多具有逆冲构造特征的的变形构造,断层相关褶皱非常发育。通过分析这些构造及其相互关系,恢复了该地区中奥陶统米钵山组的变形过程,表明该套地层经历了(1)岩层受到水平挤压,顺层缩短阶段,(2)褶皱变形阶段,(3)逆冲变形阶段等三个阶段;这些构造是逆冲推覆构造发育不同阶段的产物。牛首山以及宁夏南部的大、小罗山是古逆冲构造带的前缘部分,宁夏中南部地区在中奥陶世至泥盆纪是作为北祁连造山带北侧的弧后前陆盆地靠大陆一侧而存在随着该弧后盆地的关闭,牛首山前缘构造带形成。而现今的牛首山以及宁夏中南部的奥陶系很可能都是无根的。  相似文献   

华北地区降雹时空分布特征   总被引：15，自引：2，他引：15  

杨贵名  马学款  宗志平 《气象》2003,29(8):31-34

应用1991—2000年华北地区基本站资料，统计分析了华北地区降雹的时空分布特征。结果表明：(1)与阴山山脉以及太行山脉有关的主要降雹高频区，组成了“T”型分布特征；(2)从旬或候雹日演变看，冰雹年变化具有三峰型；(3)降雹日变化有季节性特点。  相似文献   

新世纪地球科学视野中的新技术和新方法(代序)   总被引：4，自引：0，他引：4  

石耀霖  马宗晋  吴忠良 《地学前缘》2003,10(1):1-4

从科学发展战略的角度 ,讨论了新技术、新方法在地球科学中的应用。新世纪的地球科学在新技术、新方法的应用方面呈现出鲜明的时代特色 ,即观测范围的扩大与观测能力的增强 ,多学科观测的海量数据的积累与地球观测系统的整合 ,不断增强的挑战非线性复杂地球系统中的预测问题的能力。特别是 ,作为地球观测系统的整合的“数字地球”和作为地球过程的模拟工具的高效并行计算 ,将在地球系统科学的发展中发挥重要作用。从方法论的角度 ,文中特别指出 ,只有掌握新技术、新方法的人对新技术、新方法有正确的理解 ,并具有创新性的思维 ,新技术、新方法才能发挥其应有的效能。  相似文献   

A Historical Record of Coastal Floods in Britain: Frequencies and Associated Storm Tracks   总被引：1，自引：0，他引：1  

Zong  Yongqiang  Tooley  Michael J. 《Natural Hazards》2003,29(1):13-36

This paper examines flood frequencies in three coastal sectors of Britain and analyses the associated storm tracks and their principal pathways. The results indicate that the east coast of Britain has suffered most floods over the last 200 years. The frequencies of flood incidents in the south and southwest coast of Britain have increased, particularly during the 20th century, whereas on the west coast flood frequencies have declined. Three distinctive pathways of storm track are identified, related to flood incidents in each coastal sector. A southern pathway in a corridor along the 55° N parallel is associated with flood incidents recorded on the south and southwest coast, whilst storms that are associated with floods on the west coast concentrate along the 60° N parallel. The relationship between the frequencies of floods and climatic variations needs to be explored further. However, the development of coastal settlements has certainly increased vulnerability, and hence the risk of flood disasters.  相似文献   

海底火山喷发引发厄尔尼诺事件的数值模拟   总被引：8，自引：0，他引：8       下载免费PDF全文

刘厚赞  刘辉  俞永强 《Acta Meteorologica Sinica》1998,56(5):602-610

在东北太平洋海底火山实际位置,模仿实际火山喷发所产生的地热通量,对ＩＡＰ海－气耦合模式进行了强迫作用下积分试验。积分结果表明：海底火山溢流所产生的热能通过海洋对流影响表层海温,深层扩散极少;模拟出类似１９８６～１９８７年和１９９１～１９９２年厄尔尼诺事件形成发展的全过程。  相似文献   

低温敏不育系水稻“冷灌繁种”技术微气象效应的数值试验   总被引：2，自引：0，他引：2  

储长树  罗孝和 《南京气象学院学报》1998,21(1):95-103

在田间试验基础上,从系统生态学的观点出发,构建了水稻田冠层－水层温度场耦合模型。通过对模型的不同输入,模拟了不同天气条件,不同水稻群体结构以及不同灌溉方案下的冷灌效应,对低温敏水稻冷繁技术的生产实施具有指导意义。  相似文献