Humidity Effect and Its Influence on the Seasonal Distribution of Precipitation δ~(18)O in Monsoon Regions     

章新平  刘晶淼  何元庆  田立德  姚檀栋 《大气科学进展》2005,(2)

The humidity effect, namely the markedly positive correlation between the stable isotopic ratio in precipitation and the dew-point deficit ATd in the atmosphere, is put forward firstly and the relationships between the δ18O in precipitation and ATd are analyzed for the Urumqi and Kunming stations, which have completely different climatic characteristics. Although the seasonal variations in δ18O and △Td exhibit differences between the two stations, their humidity effect is notable. The correlation coefficient and its confidence level of the humidity effect are higher than those of the amount effect at Kunming, showing the marked influence of the humidity conditions in the atmosphere on stable isotopes in precipitation. Using a kinetic model for stable isotopic fractionation, and according to the seasonal distribution of mean monthly temperature at 500 hPa at Kunming, the variations of the δ18O in condensate in cloud are simulated. A very good agreement between the seasonal variations of the simulated  相似文献   

Sensitivity of Cyclone Tracks to the Initial Moisture Distribution:A Moist Potential Vorticity Perspective   总被引：1，自引：0，他引：1  

Zuohao CAQ*  Da-Lin ZHANG Meteorological Service of Canada  Ontario  Canada Department of Meteorology  University of Maryland  College Park  Maryland  USA 《大气科学进展》2005,(6)

1. IntroductionExtratropical cyclones are an important class ofsynoptic-scale weather systems. These systems playimportant roles not only in the long-term balances ofenergy, momentum, and water vapor in the climatesystem, but also in the regional weather …  相似文献   

An Improved Method for Doppler Wind and Thermo dynamic Retrievals     

刘舜  邱崇践  许秦  张芃菲  郜吉东  邵爱梅 《大气科学进展》2005,(1)

A variational method is developed to retrieve winds in the first step and then thermodynamic fields in the second step from Doppler radar observations. In the first step, wind fields are retrieved at two time levels: the beginning and ending times of the data assimilation period, simultaneously from two successive volume scans by  相似文献   

中纬度地区混合云中稳定同位素分馏的数学模拟—以乌鲁木齐降水为例(英)   总被引：8，自引：0，他引：8  

章新平  姚檀栋  田立德  刘晶淼  MasayoshiNAKAWO 《大气科学进展》2003,(2)

介绍的数学模型考虑了混合云中液、固态共存时以及冰面过饱和环境下稳定同位素的动力分馏效应。利用该数学模型,模拟了不同冷却条件下稳定同位素的温度效应。在相同的湿度条件下,湿绝热冷却过程中δ18O随温度的变化率小于等压冷却过程。冰面过饱和比Si的增大意味着动力分馏效应的增大。与平衡态相比,它的作用使得稳定同位素的综合分馏系数减小,从而使得降水中δ18O随温度的变化趋缓。模拟显示,湿绝热冷却过程中大气水线(MWL:=bδ18o+d)的斜率b和常数d均大于等压冷却过程。全球大气水线位于湿绝热冷却过程和等压冷却过程条件下分别模拟的两条大气水线之间。b和d的大小与Si呈正比。Si愈大,动力分馏效应愈强,b和d也愈大。反之亦然。然而,b和d的大小对云中含水量的变化具有低的敏感性。利用动力分馏模式模拟了乌鲁木齐降水中稳定同位素的变化。模拟的稳定同位素比率-温度以及δD-δ18O曲线分别与乌鲁木齐实测的稳定同位素比率-温度同归线以及大气水线有非常好的一致性。  相似文献   

线性热力学对大气系统的应用(I)大气系统的线性唯象关系和热力学性质(英文)     

胡隐樵 《大气科学进展》2002,(3)

从一般的热力学原理或其它自然原理对唯象关系所强加的限制,能够演绎出大气系统的一系列热力学性质。利用非平衡态线性热力学导出了湍流K闭合理论中湍流交换系数同唯象系数的关系,从理论上证明大气系统热量湍流输送同水汽之间存在交叉耦合,还导出了湍流强度同速度和位温梯度的关系,从而证明速度和位温空间分布的非均匀性是湍流之源。并证明湍流强度定理,不可压缩气体和各向同性湍流大气中,湍流强度正比于速度与位温梯度的标积。进而证明大气涡旋定理,位温的切变将导致涡旋运动或各种环流运动,速度涡度等于速度同位温相对梯度的矢积。展现了线性热力学在大气系统的应用前景。  相似文献   

Weather Yield Model for the Semi Tropical Region (Pakistan)     

Syed Faizan Haider  K.H.Asif  Amjad Hussain Gilani 《大气科学进展》1992,(3)

Weather models are essential tools for checking of the effect of the weather elements in terms of their effect on the production of the crop. This research is an attempt to see the effect of only two variables i.e., temperature and rainfall for the division Faisalabad (semitropical region of Pakistan).The model fitted is of the linear form:the values of a,b, c have been found. The expected yield has been calculated by using the aridity indices (X1 and X2 ) and the result in the form of coefficient of determination R2 has been found equal to 0.166. The significance of the regression coefficient has been tested, which shows that the contribution to the yield from aridity index at germination and that at ripening is significant.The wheat yields are the results of a wide variety of variables, most of which show varying degree of relationship with one another, some positive and some negative in terms of output. These variables may be technology, fertilizers, pesticides, epidemics, kinds of seeds used, market  相似文献   

Introduction of the Direct Method by Illustrating Schrdinger Equation and Its Application to Wave-Wave Striking Interaction     

高守亭  刘坤儒 《大气科学进展》1990,(2)

In this paper, both direct method and its application to wave-wave striking interaction are introduced by illustrating Schrodinger equation describing the amplitude evalution of some mesoscale systems.  相似文献   

The Synoptic Climatology of Monthly Mean Surface Temperature in Asia in Relation to the 700 hPa Circulation     

Runhua Yang  William H.Klein 《大气科学进展》1989,(2)

The synoptic climatology of monthly mean surface air temperature anomaly (MMATA) at 47 surface stations in Asia is assessed by two types of maps. The first consists of simple linear correlation coefficients between the MMATA at a station and the monthly mean 700 hPa height anomaly (MMHA) at 134 grid points in the Northern Hemisphere. In winter, these fields generally contain two equally important centers: a center of maximum positive correlation approximately 1300 km from the reference station and a negative center about 2800 km to its northwest. In summer, the positive center is located an average of 800 km from the reference station and strongly dominates the MMATA, while the negative center is no longer as important as in winter. The second kind of map is a special type of anomaly composite, constructed by multiplying the correlation coefficient at each grid point by the standard deviation of MMHA at the same point. This map shows the optimum distribution of height anomalies for abnormally warm (or c  相似文献   

THE INTERFACE EFFECT AND THE FORMATION OF A LOW-LEVEL JET ALONG THE EAST SIDE OF THE ROCKY MOUNTAINS     

周军  Walter K. Henry 《大气科学进展》1987,(2)

Based upon the analysis of several different causes for the low-level jet along the east side of the Rocky Mountains, the concept of "Interface Effect" is established. The basic mechanism for the formation of the low-level jet in North America has been found to be the compression and divergence, under the driving of ageostrophic winds, of the air columns between two surfaces-the ground and the bottom of inversion-which slope with different patterns in a cross-section normal to the jet stream. As a result, the air parcel is accelerated along the streamline and the anticyclonic shear of the current increased. Also, the diurnal variation of the jet is determined by the interface effect.  相似文献   

NUMERICAL STUDY OF LAKE-LAND BREEZE OVER LAKE VTTERN SWEDEN     

吴增茂 《大气科学进展》1987,(2)

This paper describes a two-dimensional lake breeze model with turbulent energy closure. The simulated results show that (1) the front of the lake breeze progresses inland faster in the late afternoon than at the fully developed stage; and (2) the lake breeze and land breeze have larger extension offshore than inland. The acceleration of the front in the declining phase of the lake breeze is explained in terms of the decreased turbulent friction acting on the head of the lake breeze. The larger extension offshore, probably, is attributed to the smaller roughness of water surface and to the offshore synoptic wind.  相似文献