首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   40篇
  免费   26篇
  国内免费   30篇
测绘学   1篇
大气科学   73篇
地质学   12篇
海洋学   6篇
天文学   1篇
综合类   1篇
自然地理   2篇
  2023年   2篇
  2022年   4篇
  2021年   6篇
  2020年   5篇
  2019年   5篇
  2018年   1篇
  2017年   1篇
  2016年   1篇
  2015年   3篇
  2014年   1篇
  2012年   1篇
  2011年   2篇
  2010年   1篇
  2009年   2篇
  2008年   3篇
  2005年   2篇
  2000年   1篇
  1999年   3篇
  1998年   9篇
  1997年   5篇
  1996年   2篇
  1995年   3篇
  1994年   7篇
  1993年   9篇
  1992年   5篇
  1991年   8篇
  1990年   3篇
  1979年   1篇
排序方式: 共有96条查询结果,搜索用时 187 毫秒
31.
Investigated statistically is the interrelation between East Asian winter monsoon(EAWM)and SST over sensitive areas of the Indian and Pacific Oceans.with focus on the relation of EAWMto strong ENSO signal area.i.e.,the equatorial eastern Pacific(EEP)SST.Evidence suggeststhat the EAWM variation is intimately associated not only with the EEP SST but with theequatorial western Pacific“warm pool”and equatorial Indian/northwestern Pacific Kuroshio SSTas well:the EAWM and ENSO interact strongly with each other on the interannual time scales,exhibiting pronounced interdecadal variation mainly under the joint effect of the monsoon QBO andthe monsoon/SST background field features on an interdecadal basis—when both fields are in thesame phase(anti-phase).strong EAWM contributes to EEP SST rise(drop)in the followingwinter,corresponding to a warm(cold)ENSO cycle;the EAWM QBO causes ENSO cycle to bestrong phase-locked with seasonal variation,making the EEP SST rise lasting from April—May toMay—June of the next year,which plays an important role in maintaining a warm ENSO phase.  相似文献   
32.
利用0.25°×0.25°分辨率的ERA5再分析资料,对201907号台风“韦帕”的环流形势、物理量场进行了诊断分析。结果表明,“韦帕”具有非对称结构,强度稳定,移速缓慢,路径复杂,降水量大,维持时间长,影响范围广的特点;副高减弱东撤、“双台风效应”与“韦帕”自身的不对称结构导致台风路径多次转折;西南季风带来的丰沛水汽使台风持续维持热带风暴级别,并给海南、广东、广西带来了强降水;水汽通量散度辐合和上升运动与降水落区有较好的对应关系,中心强度与同时段降水量级呈正相关。  相似文献   
33.
The study has shown that the shear component of the vertical integrated kinetic energy (Ks) over the box (40oE–100oE, 0o–20oN) can be used as a measure of the intensity of the South Asian summer monsoon (SASM). Based on its value averaged between June and August, the SASM can be divided into strong and weak monsoon episodes. Between 1958 and 2018, there existed 16 (16) strong (weak) monsoon episodes. Based on the calendar year, the relationship between the SASM and the ENSO episodes can be grouped into six patterns: weak monsoon - El Ni?o (WM-EN), normal monsoon - El Ni?o (NM-EN), weak monsoon - non ENSO (WM-NE), strong monsoon - La Ni?a (SM-LN), normal monsoon - La Ni?a (NM-LN) and strong monsoon - non ENSO (SM-NE). Previous studies have suggested that the WM-EN and SM-LN patterns reflect the correlated relationship between the SASM and El Ni?o/Southern Oscillation (ENSO) events. Therefore, we name these two strongly coupled categories WM-EN and SM-LN as the resonance effect. Two important circulations, Walker circulation (WC) and zonal Asian monsoon circulation (MC), in the vertical plane are found to be not always correlated. MC is controlled by thermal gradients between the Asian landmass and the tropical Indian Ocean, while the WC associated with the ENSO event is primarily the east-west thermal gradient between the tropical South Pacific and the tropical Indian Ocean. Furthermore, the gradient directions caused by different surface thermal conditions are different. The main factor for the resonance effect is the phenomenon that the symbols of SSTA in the tropical Indian Ocean and the equatorial eastern Pacific are the same, but are opposite to that of the SSTA near the maritime continent.  相似文献   
34.
35.
Using the Advanced Research WRF (ARW WRF) model and the Gridpoint Statistical Interpolation (GSI) three-dimensional variational analysis (3DVAR) system, the impact of assimilating ATOVS (Advanced TIROS Operational Vertical Sounder) radiance through the prototype Community Radiative Transfer Model (pCRTM) is evaluated on the forecasting of a heavy rainstorm occurring over the central Guangdong province in the southeast of China on 20-21 June 2005. A pair of comparison experiments (NODA and DA) for this case is conducted with multiple configurations, including nesting domains with 4-km and 12-km grid distances. The results showed that by changing the initial condition through data assimilation, a modified divergence and moisture field with the structure of dipoles has been added to the axis of the rainband with a southwest-northeast orientation. When more moisture carried by a southwesterly low level jet (LLJ) was converged into the northeast portion of the rainband around the observatory station of Longmen, the amplitude of moisture static energy (MSE) increased substantially at low levels much more than at middle levels, resulting in the enlarging of differences in MSE between 500 hPa and 850 hPa; the atmosphere became more unstable. Consequently, the convective rainfall increased in the northeast part of the province around the Longmen station, which was consistent with the observed distribution of rainfall.  相似文献   
36.
利用1982、1983年7—9月的欧洲中期天气预报中心(ECMWF)网格点资料,分析了北半球中高纬度以及热带地区500百帕高度场的30—50天周期振荡的遥相关结构及其演变特征。发现30—50天周期振荡的分布,在热带与对流活动中心相对应,在中高纬地区与主要的气压活动中心相配合。振荡的相关中心分布于15—70°N之间,并成大弧状排列,具有波列的结构特征,其路径具有显著的年际变化,其弧状排列的振荡中心具有纬向移动,移动方向与高度场振荡位相的纬向移动相一致,高度场振荡的纬向移动和波列的能量频散密切相关。  相似文献   
37.
38.
东半球跨赤道气流季节变化及其在EL NINO年的异常   总被引:2,自引:2,他引:2  
利用1979年1月到1987年12月美国国家气象中心六个层次的月平均风场资料,分析了东半球跨赤道气流的季节变化及其年际异常。得到冬、夏跨赤道气流的输送集中在对流层下部,冬季向南,夏季向北;春、秋跨赤道气流的输送集中在对流层上部,春季向北,秋季向南。低层跨赤道气流位置稳定,南北风方向转换时间为3月和11月;高层跨赤道气流位置变化较大,南北风转换时间为6月和1月。在El Nino年,跨赤道气流出现明显的异常,但表现形式不尽相同。ElNino年,夏季下层跨赤道气流稳定建立的时间比正常年推迟2—3候,且季内变化大,稳定维持时间短。  相似文献   
39.
针对煤层碎软、渗透性低、工作面瓦斯抽采难度大且效率低的问题,提出两端对接分段压裂顶板水平井组的工作面瓦斯抽采全覆盖模式。选取淮北煤田宿县矿区某矿井为例,依据研究区地应力与工作面展布特征,结合研究区内瓦斯地质条件及煤层力学性质分析,利用交叉偶极子声波测井方法优选水平井水平段布置方位,采用Fracpro PT的压裂模拟技术确定水平井水平段距离71煤层的范围,即布置在煤层顶板2 m以内;采用抽采模拟技术对研究区试验工程进行预测,结果显示,抽采3 a后工作面的瓦斯含量和压力都大幅度降低,达到了工作面瓦斯抽采全覆盖的要求。提出的抽采模式为国内类似地质条件煤矿地面瓦斯高效抽采提供一种手段。   相似文献   
40.
使用ECMWF1980—1986年7a格点资料对大气运动的正压模进行了分析。指出:对流层中大气正压运动流场显示的副热带高压带仅能反映出行星风带的季节性移动;与亚洲夏季风有关且反映季风局地性的则是副热带高压带南侧的东风带上的波状扰动;东风带上的经向风分量存在着纬向传播且传播方向和扰动幅度与印度、东亚季风子系统有关;随着北半球夏季的到来,亚洲季风区大气运动的斜压模有较大的增长且斜压运动动能占气柱内整层平均总动能的绝大部分,而在赤道附近的其他经度上则是正压运动动能的成分明显增长。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号