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41.
为了优化地面人工增雨作业技术,提出了区域多参量动态对比法(以下简称K值法),并使用该方法对2015—2017年选取的26次地面增雨作业,从不同参量、不同作业工具、不同作业剂量和不同作业方式等方面进行效果统计检验。结果表明:地面催化作业有较好的增雨效果,作业后3 h内的增雨率为14.4%,2 h时增雨效果最好;不同作业工具比较,火箭增雨速度快且增雨率大,增雨效果比高炮好;不同作业剂量比较,单次高炮作业剂量
42.
区域气候模式中云量参数化方案的研究 总被引:5,自引:1,他引:5
首先统计并分析了模式区域内夏季平均的云量分布状况,然后在一有限区域模式中,引进了云-辐射计算模式。比较了3种不同的云量参数化方案,最后提出了一种考虑了大气相对湿度、垂直运动速度的本模式的云量参数化方案,并简要介绍了模式引入不同方案后的模拟结果。模拟结果表明,本模式的方案模拟的云量分布及气候要素场都与实况最接近,说明这一机制反映了云在气候系统中的反馈作用。不同的区域模式宜用不同的云量参数化方案。云量 相似文献
43.
J. T. Wickramasinghe W. M. Napier 《Monthly notices of the Royal Astronomical Society》2008,387(1):153-157
We calculate the expected flux profile of comets into the planetary system from the Oort Cloud arising from Galactic tides and encounters with molecular clouds. We find that both periodic and sporadic bombardment episodes, with amplitudes an order of magnitude above background, occur on characteristic time-scales ∼25–35 Myr. Bombardment episodes occurring preferentially during spiral arm crossings may be responsible both for mass extinctions of life and the transfer of viable microorganisms from the bombarded Earth into the disturbing nebulae. Good agreement is found between the theoretical expectations and the age distribution of large, well-dated terrestrial impact craters of the past 250 Myr. A weak periodicity of ∼36 Myr in the cratering record is consistent with the Sun's recent passage through the Galactic plane, and implies a central plane density ∼0.15 M⊙ pc−3 . This leaves little room for a significant dark matter component in the disc. 相似文献
44.
By the use of the model of approaching drops (Arbel and Levin, 1977) the coalescence efficiencies of drops are computed. It is found that for interactions of drops at their terminal velocities the coalescence depends both on the size of the large drop and on the size ratio of the interacting drops in agreement with the experimental results of Whelpdale and List (1971) and Levin and Machnes (1977).The results were found to be sensitive to the assumption of the drops deformation and to the critical separation distance. This distance is defined as the distance at which the drops begin to merge. The variations of the coalescence efficiency with these parameters is discussed.Appendix: List of symbols
D
distance between the deformed surfaces of the drops
-
D
o
initial value ofD
-
D
s
stop distance, the distance at which the impact velocity vanishes
-
D
c
critical coalescence distance
-
E
collection efficiency
-
E
1
collision efficiency
-
E
2
coalescence efficiency
-
E
2R
coalescence efficiency for collisions with stationary targets
-
F
c
centrifugal force
-
p
ratio of the radii of the interacting drops
-
r
o
initial distance between drops' centers
-
R
L
radius of larger drop
-
R
s
radius of smaller drop
-
R
D
radius of deformation
-
v
approach velocity of two deformed surfaces
-
v
o
initial value ofv
-
V
i
impact velocity (given negative sign when drops approach each other)
-
V
c
critical impact velocity
-
W
i
velocity of the smaller drop at infinity for it to reachD
o with velocityv
o
-
x
i
impact distance, the distance between the trajectories of the two drops
-
x
c
critical impact distance for coalescence
-
average critical impact distance for coalescence
-
X
c
critical impact distance for collisions
-
coefficient of deformation given in equation 1
-
i
impact angle defined byWhelpdale andList (1971) given also inArbel andLevin (1977)
-
coefficient of deformation given in equation 2
-
viscosity of air
-
i
impact angle used inArbel andLevin (1977) and here
-
c
critical angle for coalescence
-
average critical angle for coalescence
On sabbatical leave (1976–77) from the Department of Geophysics and Planetary Sciences, Tel Aviv University, Ramat Aviv, Israel.The National Center for Atmospheric Research is sponsored by the National Science Foundation. 相似文献
45.
气候模式中云辐射反馈过程机理的评述 总被引:18,自引:0,他引:18
云对地气系统的辐射收支具有十分重要的作用,云辐射参数化是目前气候模式中不确定性的主要来源。云可以通过多种途径对辐射产生影响,形成不同符号、不同量值的反馈机制。研究表明,模式气候对不同的云辐射参数化方案十分敏感。预报云水含量方案的引入,改进了对云辐射过程的模拟,但与观测资料相比仍有差距。一般说来,模式中引入云水的相变和相互作用的云粒子大小产生负反馈,而光学厚度和云量产生的是正反馈。云辐射反馈的净作用其大小和符号因模式而异。云辐射与大尺度天气气候背景之间有着紧密的联系,尤其是海温对辐射平衡有显著影响。最后总结了当前云辐射研究中存在的主要问题,并提出了改进的途径。 相似文献
46.
智慧地质是充分运用新一代信息技术,发现和总结地质演化的时空规律,判断和预测未来发展趋势,集海量专家认知于一体,认识水平可最大程度的符合或逼近地质自然规律,从而使地质成果以智慧的方式服务于人、造福于人。其意义在于以人为本、服务于人,具体内涵表现为实现地质调查监测工作流程的信息化、地质信息资源互联互通的统一化、地质数据分析应用的智能化、地质成果产品服务的精准化。北京市通过不断创新城市地质工作发展理念、搭建由感知到服务的全流程信息化基础,已经基本具备智慧地质的雏形。智慧地质的建设是一个循序渐进的过程,科学谋划、做好顶层设计、夯实地质理论基础、做好信息平台基础搭建是智慧地质当前发展的首要任务。 相似文献
47.
Peng Wang Lei Liu Xichuan Liu Shuai Hu Shijun Zhao Wenming Ji Taichang Gao 《地球科学进展》1986,35(7):704-714
The accurate observation of the microphysical structure of cloud and precipitation plays an important role in understanding the formation of clouds and precipitation. In-situ measurement using measuring instruments carried by meteorological balloons is an effective way to obtain the microphysical properties of cloud and precipitation particles, which is a supplementary means for aircraft to observe cloud and precipitation particles. This observation method plays a more and more important role in in-situ measurement. According to the difference of the working principle of the existing balloon-borne cloud and precipitation particles probes, the detectors can be divided into particle impact-sampling sensors, particle imaging sensors, light-scattering sensors, light intensity attenuation sensors and charge measurement sensors. The working principles, key technologies and main advantages and disadvantages of typical instruments were summarized, and their applications to detailed cloud structure acquisition, cloud remote sensing method establishment, cloud and precipitation physical process research and parameterization, and scientific observation of thunderstorm clouds were briefly introduced. Finally, the development trend of balloon-borne cloud precipitation particle detectors was prospected, which will provide reference for related technical research and equipment development. 相似文献
48.
ESTIMATION OF ARTIFICIAL PRECIPITATION ENHANCEMENT RESOURCE CONDITION AND CLOUD SEEDING POTENTIAL BY GROUND-BASED REMOTE SENSING DATA* 下载免费PDF全文
Duan Ying 《Acta Meteorologica Sinica》1999,13(1):103-114
In this paper,the data of continuous atmospheric vertical integral vapour and liquid water content during April-June of 1992-1994 obtained by a ground-based dual-channel microwave radiometer are used to analyse the statistical characteristics of atmospheric vapour and liquid water content,and the relative distribution characteristics of vapour and liquid water content in cloudy atmosphere,the correlative relation of integral liquid water content L and ground precipitation intensity I.and precipitation transform rate of precipitation system.Finally,the weather modification condition of precipitus stratiform clouds and seeding potential is analyzed and discussed. 相似文献
49.
50.