EFFECT OF CIRCULATION LOW LATITUDES ON THE WEATHER OF MIDDLE LATITUDES——THE IDEA OF MID-RANGE AND SHORT-RANGE FORECASTS OF RAINSTORMS

There is a close relation between the circulations of the low latitudes over the ocean as well as their. variations and precipitation in China.Rainstorms and droughts which often cause disasters are two extreme cases of precipitation. Therefore it is practically and theoretically significant to forecast both of them. A series of analyses on the predominant rainstorms processes in mid-summer in North China were made from 1975 to 1977[1,2],and the method was used.As a consequence, a preliminary conclusion has been reached.     

有机锡对海洋微藻的生理效应

于１９９１年４月－１９９２年１月，分别用不同浓度的三苯基氯化锡和三丁基氯化锡培养扁藻和金藻，测定２４，４８和７２ｈ两种藻的净光合速率和生长速率。结果表明，ＴＢＴＣ对两种藻的毒性大于ＴＰＴＣ；ＴＰＴＣ和ＴＢＴＣ在浓度为０．２μｇ／Ｌ时，对两种藻的光合作用有轻微影响；浓度大于０．４μｇ／Ｌ，两种藻的光合作用不同程序地受到抑制。扁藻对有机锡的耐受力大于金藻：扁藻用两种锡处理后，第一天受害最严重，第二天和     

新一代水位测量系统—空气声学水位计

本文介绍了空气声学水位计的工作原理、技术指标及现场使用比测结果。结果证明用该仪器来更新水位测量系统是合适的。     

构造高差分析原理及其在地学研究中的应用

构造高差分析是构造解析及平衡剖面制作与恢复的基础.长期以来,构造高差并没有一个严格的定义,也缺乏原理性描述;构造高差分析也主要局限在构造地貌和地形高差的分析.本文在分析前人有关构造解析、地貌高差和构造高差研究的基础上,提出构造高程概念,将构造高差定义为构造高程之差,拓展了构造高差的内涵;并将构造高程定义为地质点所在构造...     

河套地区典型干线的形成及其在对流触发中的作用

利用高空、加密地面、EC-ERA5(0.25o×0.25o)再分析和FY-2系列静止气象卫星云图(可见光星下点分辨率1.25 km,红外5 km)等资料,对黄河河套地区3次典型干线的形成及其在对流触发中的作用进行了详细分析.结果表明:(1)3次干线触发对流出现在中高纬度高空槽东移诱发蒙古气旋发展的背景下,高低空系统配置...     

双排抗滑桩滑坡推力分配影响因素分析

以作用形式较为简单的双排悬臂抗滑桩(未带连梁)为模型并基于结构力学位移法得出的双排桩滑坡推力传递分配计算公式为基础,结合推力较大的红石包滑坡作为工程实例,分别分析了双排桩静排距,前后排桩的截面尺寸和桩间土弹性模量对推力传递分配的影响,得出了以下结论:(1)当增大后排桩的刚度或减小前排桩的刚度时,桩土相互挤压作用越小, A2/A1随之减小,反之A2/A1增大。(2)增大排距b时,A1减小,A2在b=3~10m时逐渐减小,但是变化幅度不大; 在b=10~21m时,不断增大。(3)当增大桩间土弹性模量时,A2增大。(4)随着前排桩截面高度的增大,A1、A2逐渐增大; 随着后排桩截面高度的增大,A1、A2逐渐减小。     

基于DEM的单位汇水面积尺度转换(英文)

Specific Catchment Area (SCA) is defined as the upstream catchment area of a unit contour. As one of the key terrain parameters, it is widely used in the modeling of hydrology, soil erosion and ecological environment. However, SCA value changes significantly at different DEM resolutions, which inevitably affect terrain analysis results. SCA can be described as the ratio of Catchment Area (CA) and DEM grid length. In this paper, the scale effect of CA is firstly investigated. With Jiuyuangou Gully, a watershed about 70 km2 in northern Shaanxi Province of China, as the test area, it is found that the impacts of DEM scale on CA are different in spatial distribution. CA value in upslope location becomes bigger with the decrease of the DEM resolution. When the location is close to downstream areas the impact of DEM scale on CA is gradually weakening. The scale effect of CA can be concluded as a mathematic trend of exponential decline. Then, a downscaling model of SCA is put forward by introducing the scale factor and the location factor. The scaling model can realize the conversion of SCA value from a coarse DEM resolution to a finer one at pixel level. Experiment results show that the downscaled SCA was well revised, and consistent with SCA at the target resolution with respect to the statistical indexes, histogram and spatial distribution. With the advantages of no empirical parameters, the scaling model could be considered as a simple and objective model for SCA scaling in a rugged drainage area.     

The impacts of permafrost change on NPP and implications: A case of the source regions of Yangtze and Yellow Rivers

This paper studies the relationship between net primary productivity (NPP) and annual average air temperature (GT) at 0cm above ground in permafrost regions by using revised Chikugo NPP model,cubic spline interpolating functions,and non-linear regression methods.The source regions of the Yangtze and Yellow Rivers were selected as the research areas.Results illustrate that:(1) There is significant non-linear relationship between NPP and GT in various typical years;(2) The maximum value of NPP is 6.17,5.87,7....     

青藏高原夏季500hPa纬向风的时空演变特征及其与我国降水的关系

本文利用NCEP/NCAR月平均再分析资料及中国160个测站月降水资料, 采用经验正交函数分解 (EOF)、相关分析、合成分析等方法, 对青藏高原夏季500 hPa纬向风近59年来的年际、 年代际变化趋势及其与我国降水的关系进行了分析。时空演变特征的分析结果表明: 自1950年以来, 青藏高原夏季500 hPa纬向风总体呈现减弱趋势, 其中在1950年代西风偏弱, 1960年代西风明显偏强, 1970年代至21世纪初西风一直处于偏弱阶段; 纬向风变化趋势的空间分布表现为高原大部分区域上空纬向风呈现减弱趋势, 其减弱趋势由东南向西北递增, 高原西北部及中部地区减弱趋势最为明显; 对高原夏季500 hPa纬向风距平时间序列作EOF分解, 得出第一特征向量的空间分布表现为整体减弱型, 其时间权重系数呈现长期正趋势; 时间系数的11年滑动平均分析表明1950年代后期到1960年代中后期纬向西风整体增强趋势比较明显, 1960年代末到21世纪初为西风减弱阶段, 且期间没有出现明显的上升或下降趋势; 时间系数的突变分析表明纬向风在1967年发生了一次较明显的减弱突变; 时间系数的小波分析表明其具有2~4年的周期, 这一周期成分在1950年代前期和1990年代末至21世纪初这两个时段比较显著。年际、 年代际尺度上高原夏季500 hPa纬向风减弱与我国降水关系的分析均表明: 高原纬向风减弱时长江中下游以北的我国部分地区降水偏少, 以东北和华北表现明显, 长江中下游以南地区降水明显偏多, 降水场与大气环流、 水汽通量散度场都有较好的配置关系。