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1.
Zhaoyang CHAI He ZHANG Mulan ZHANG Xiao TANG Weipeng ZHENG Jiang ZHU Guangqing ZHOU Junji CAO Qingcun ZENG 《大气科学进展》2021,38(10):1611-1620
This article introduces "EarthLab ", a major new Earth system numerical simulation facility developed in China.EarthLab is a numerical simulation system for a physical climate system, an environmental system, an ecological system, a solid earth system, and a space weather system as a whole with a high-performance scientific computing platform.EarthLab consists of five key elements—namely: a global earth numerical simulation system, a regional high-precision simulation system, a supercomputing support and management system, a database, data assimilation and visualization system, and a high-performance computing system for earth sciences. EarthLab helps to study the atmosphere, hydrosphere,cryosphere, lithosphere, and biosphere, as well as their interactions, to improve the accuracy of predictions by integrating simulations and observations, and to provide a scientific foundation for major issues such as national disaster prevention and mitigation. The construction and operation of EarthLab will involve close cooperation with joint contributions and shared benefits. 相似文献
2.
T. Vrhovec 《Meteorology and Atmospheric Physics》1991,46(1-2):91-99
Summary A formation of a cold air lake in a basin is studied with a mesometeorological model.A dynamic Boussinesq hydrostatic mesoscale numerical model is developed in a staggered orthogonal grid with a horizontal resolution of 1 km and with a varying vertical grid. The topography is presented in a block shape so that computation levels are horizontal.The mesometeorological model is tested in three idealized topography cases (a valley, a single mountain, a basin) and test results are discussed.In an alpine basin surrounded by mountains and plateaus the air is supposed to be stagnant at the beginning of the night. Due to differences in radiation cooling an inversion layer is formed in the basin and local wind circulation is studied by model simulations.With 14 Figures 相似文献
3.
基于分拆数的角色访问控制模型的原理与实现 总被引：2，自引：0，他引：2
介绍了基于分拆数的权限管理策略的原理及其在角色访问控制模型中的应用，实现了一个结构简单、伸缩性好、功能强大的权限管理系统。提出了自然数按集合分拆的新概念，同时给出了一个自然数按某个有限集狭义分拆唯一的充分条件。 相似文献
4.
建立清代1644—1911年广东的旱涝指数序列,采用滑动t检验、完备总体经验模态函数分析了清代广东旱涝的突变特征和多时间尺度周期性特征。结果表明,清代广东旱涝指数整体较平稳,呈现先明显增加后减少、后略微增加的趋势。旱涝指数序列具有多个跃变点,且有年际尺度4.2 a和7.8 a,年代际尺度11.6 a、15.2 a、36.5 a和70.1 a,世纪尺度130.3 a左右的周期。发现广东旱涝有多个周期与太阳黑子相对数序列及东亚季风指数序列周期接近,故用交叉小波分析发现广东旱涝指数序列与太阳黑子相对数序列在0~6 a、7~8 a和11~16 a等多个时间尺度具有强凝聚性共振周期,与东亚夏季风指数序列在4~8 a和25~45 a等多个时间尺度具有强凝聚性共振周期。 相似文献
5.
This paper investigates why some La Niña events are followed by another La Niña and some others are not. We propose two preconditions that result in continuation of a La Niña. The first one is that La Niña must be a strong event (a major La Niña). This ensures that the reflected Rossby wave signal at the eastern boundary of the Pacific has a strong westward propagating cold ocean temperature anomaly over the off-equatorial region. The off-equator cold anomaly may not be conducive to the equatorial recharge process, and as a result, may favor the persistence of cold ocean subsurface temperature anomaly and prevent the transition from La Niña to El Niño. The second precondition is whether there are eastward propagating downwelling Kelvin waves during the decay phase of a major La Niña. Eastward propagating downwelling Kelvin waves could lead to demise for a tendency for a follow-up La Niña. The equatorial Kelvin wave activities are associated with fluctuations of surface wind in the equatorial far-western Pacific. The analysis suggests that both the surface wind in the equatorial far-western Pacific and the recharge/discharge of the equatorial Pacific are indicators for occurrence or no occurrence of a follow-up La Niña event. 相似文献
6.
The interplay between the North Atlantic Oscillation (NAO) and the large scale ocean circulation is inspected in a twentieth century simulation conducted with a state-of-the-art coupled general circulation model. Significant lead–lag covariance between oceanic and tropospheric variables suggests that the system supports a damped oscillatory mode involving an active ocean–atmosphere coupling, with a typical NAO-like space structure and a 5 years timescale, qualitatively consistent with a mid-latitude delayed oscillator paradigm. The two essential processes governing the oscillation are (1) a negative feedback between ocean gyre circulation and the high latitude SST meridional gradient and (2) a positive feedback between SST and the NAO. The atmospheric NAO pattern appears to have a weaker projection on the ocean meridional overturning, compared to the gyre circulation, which leads to a secondary role for the thermohaline circulation in driving the meridional heat transport, and thus the oscillatory mode. 相似文献
7.
We consider small non-divergent perturbations to a barotropic current flowing parallel to a straight coastline. Sufficient conditions for stability and a semi-circle theorem are established for general current profiles and topography. An asymptotic expansion for long waves is described. Some analytic solutions are obtained when the topography is piece-wise constant and the current is piece-wise linear. Two kinds of instability, a shear instability and a topographic instability, are identified. Our results are applied to a model of the East Australian current. 相似文献
8.
海门一次F1级龙卷的多普勒天气雷达特征分析 总被引：4，自引：4，他引：0
用多普勒天气雷达、常规观测和地面加密观测资料对2011年7月13日发生在江苏南通海门市树勋镇的龙卷风过程进行了详细分析。得出:较长时间的不稳定层结的存在,较低的抬升凝结高度,较强的水平和垂直风切变以及地面干线的存在为龙卷风的发生发展提供很好的动力条件;底层冷空气的切入,较强的风切变易使单体发展更加旺盛。强回波中心高度和垂直积分液态含水量的下降,径向速度风场中气旋性涡旋的迅速发展是对龙卷风提前警戒的很好指标。龙卷风进行过程中,此系统为低位质心的对流系统,产生的天气是龙卷,伴随大风,与冰雹的高位质心对流系统有明显的区别。中气旋高度,最大切变高度的骤降,中气旋尺度的急剧收缩预示着龙卷的发生,为我们今后的龙卷风预警提供有利的参考。 相似文献
9.
“15.7”广西超长持续性暴雨过程多尺度特征分析 总被引：5，自引：1，他引：5
利用多源气象资料,通过综合诊断分析方法,对2015年一次广西持续性暴雨过程进行多尺度特征分析。(1) 南亚高压经历了双体型构建,副热带长波槽有利于冷空气南下和高空急流的建立。El Ni?o状态下,副高强度偏强,位置偏西、偏南,有利于暖湿气流向广西输送。南亚高压过渡层与副高对峙,有利于冷暖空气在广西交汇。(2) 影响天气系统有高空槽、切变线、冷锋、低空急流、季风槽及低涡等多天气系统。降雨分为锋前暖区、锋面、高空槽加强、季风槽与低涡等四个阶段。(3) 中尺度特征为锋前暴雨发生在MCC云团形成到减弱期,雷达强回波呈弓型,对流性强;锋面暴雨发生在MCC减弱后云带,雷达强回波为弓型向直线型转换,对流性减弱;高空槽加强暴雨为直线型云系和雷达回波增强;季风槽与低涡暴雨为增强的涡旋型云系和雷达强回波。(4) 暴雨发生在总体地势为云贵高原下坡和地面喇叭口地形辐合的桂西北、海陆分布差异的沿海及山脉迎风坡的桂东南。可见,长时间持续性暴雨过程是一个多尺度和多天气系统相互作用的结果,暴雨发生在有利的大尺度环流背景和天气系统配置下的中小尺度系统频繁发生处,地形助推暴雨作用明显。深刻理解持续性暴雨发生的尺度特征可提高该类天气预报能力。 相似文献
10.
The carbon dioxide （CO2） concentrations and fluxes measured at a height of 17.5 m above the ground by a sonic anemometer and an open-path gas analyzer at an urban residential site in Seoul, Korea from February 2011 to January 2012 were analyzed. The annual mean CO2 concentration was found to be 750 mg m-3, with a maximum monthly mean concentration of 827 mg m-3 in January and a minimum value of 679 mg m-3 in August. Meanwhile, the annual mean CO2 flux was found to be 0.45 mg m-2 s-1, with a maximum monthly mean flux of 0.91 mg m-2 s-1 in January and a minimum value of 0.19 mg m-2 s-1 in June. The hourly mean CO2 concentration was found to show a significant diurnal variation; a maximum at 0700-0900 LST and a minimum at 1400-1600 LST, with a large diurnal range in winter and a small one in summer, mainly caused by diurnal changes in mixing height, CO2 flux, and surface complexity. The hourly mean CO2 flux was also found to show a significant diurnal variation, but it showed two maxima at 0700-0900 LST and 2100-2400 LST, and two minima at 1100-1500 LST and 0300-0500 LST, mainly caused by a diurnal pattern in CO2 emissions and sinks from road traffic, domestic heating and cooking by liquefied natural gas use, and the different horizontal distribution of CO2 sources and sinks near the site. Differential advection with respect to wind direction was also found to be a cause of diurnal variations in both the CO2 concentration and flux. 相似文献
11.
A numerical stochastic model is developed for the upcrossing rate across a specified threshold concentration. The model assumes that the concentration time series at a given spatial point within a dispersing plume can be approximated as a first-order Markovian process designed to be consistent with a given time-invariant concentration probability density function (pdf). The model requires only the specification of a concentration pdf with a given mean and variance and a concentration fluctuation integral time scale. Predicted upcrossing rates are compared with atmospheric plume concentration data obtained from a point source near the ground. For this data set, a log-normal pdf is found to give better estimates of the threshold crossing rate than a gamma pdf. 相似文献
12.
本文通过揭示雹暴发生前12小时降雹区出现湿柱与干暖盖的天气学事实,探讨其基本成因,利用有限区域细网格计算分析它们的物理结构,给出湿柱的概念模型。 相似文献
13.
Summary The surface low of a mature extra-tropical cyclone is often surmounted by a troposphere-spanning column of anomalously high
potential vorticity (PV). In this study the growth and decay of such a PV-tower is traced for one major North Atlantic frontal-wave
cyclone using the ECMWF analysis fields and adopting both Eulerian and Lagrangian frameworks.
A tower’s structure and composition relates intimately to the strength, scale and structure of the associated surface cyclone.
It is shown that the tower comprised a vertical superposition of three elements: (?) a quasi-seclusion of stratospheric air
extruded from an upper-level trough, (ℬ) a mid-tropospheric layer of intermingled air from diverse sources, but with a substantial
component originating from the system’s cold front, and (?) a low-tropospheric layer of diabatically-induced PV that was linked
to and originated from flow along a bent-back warm front.
An examination of the tower’s growth and decay helps identify the factors influencing the onset and rapidity of the cyclogenesis.
There was first an in-phase development of a surface baroclinic wave with the precursor of element (?), and also the emergence
of element (ℬ) in the form of a low-level elongated band of PV aligned along the cold front. Thereafter a short period of
rapid growth was marked by the appearance of a low-level band of PV along the warm front (element ?), and it co-spiraled with
and beneath the upper-level stratospheric intrusion (element ?). Demise of the tower followed a loss of amplitude of its central
portion and a loss of coherency aloft.
Evidence of the modulating as opposed to the dominating influence of diabatic processes upon the cyclone’s structure and strength
is derived from consideration of: the tower’s durable and ephemeral potential vorticity, the PV production along the warm
front, and sets of model simulations of the event that selectively suppress diabatic PV production.
Received July 9, 1999 Revised December 2, 1999 相似文献
14.
唐慧强 《南京气象学院学报》1998,21(1):80-84
利用集成硅气压传感器这种具有较大温度系数及非线性误差的典型传感器而设计一智能化的气压仪表,提出了较好地利用分段二次插值的方法,使非线性及温度误差降至完全可被忽略的程度,从而来提高仪表的精度;并提出了利用简易监视计数器等电路的设计来提高可靠性及合理的电路设计来降低功耗提高整机性能等一些完善而实用的方法。 相似文献
15.
16.
Knowledge on climate change impacts, adaptation, and vulnerability is fragmented, because it is found in disparate case studies which use inconsistent terminology and focus on distinct aspects relevant to adaptation. While large-scale syntheses such as the Assessment Reports of the Intergovernmental Panel on Climate Change provide a high level overview and are useful for international decision-making, there is a need for systematic and flexible access to this research-based knowledge in order to aid future adaptation research and decision-making. Against this background, we present a ‘conceptual’ meta-analysis, a novel approach to meta-analyse studies on climate change impacts, adaptation, and vulnerability in Europe. The meta-analysis results in a classification scheme for relating the diverse studies. This scheme consists of (i) a classification of studies according to the type of adaptation-relevant results they produce and (ii) a hierarchical classification of the regional and thematic context of studies. The implementation of this scheme, for example in the form of a database, overcomes some of the identified gaps of current adaptation knowledge representation. We furthermore present a quantitative analysis of the classified studies that exemplifies how the developed classification scheme can be applied to get a systematic and quantitative overview of the knowledge they contain. Thus, the conceptual meta-analysis and the classification scheme represent a first step towards a systematisation of knowledge on climate change impacts, adaptation, and vulnerability and may be seen as a useful complement to qualitative literature reviews. 相似文献
17.
Reduction of the thermocline feedback associated with mean SST bias in ENSO simulation 总被引：1，自引：1，他引：0
Baoqiang Xiang Bin Wang Qinghua Ding Fei–Fei Jin Xiouhua Fu Hyung-Jin Kim 《Climate Dynamics》2012,39(6):1413-1430
Associated with the double Inter-tropical convergence zone problem, a dipole SST bias pattern (cold in the equatorial central Pacific and warm in the southeast tropical Pacific) remains a common problem inherent in many contemporary coupled models. Based on a newly-developed coupled model, we performed a control run and two sensitivity runs, one is a coupled run with annual mean SST correction and the other is an ocean forced run. By comparison of these three runs, we demonstrated that a serious consequence of this SST bias is to severely suppress the thermocline feedback in a realistic simulation of the El Ni?o/Southern Oscillation. Firstly, the excessive cold tongue extension pushes the anomalous convection far westward from the equatorial central Pacific, prominently diminishing the convection-low level wind feedback and thus the air-sea coupling strength. Secondly, the equatorial surface wind anomaly exhibits a relatively uniform meridional structure with weak gradient, contributing to a weakened wind-thermocline feedback. Thirdly, the equatorial cold SST bias induces a weakened upper-ocean stratification and thus yields the underestimation of the thermocline-subsurface temperature feedback. Finally, the dipole SST bias underestimates the mean upwelling through (a) undermining equatorial mean easterly wind stress, and (b) enhancing convective mixing and thus reducing the upper ocean stratification, which weakens vertical shear of meridional currents and near-surface Ekman-divergence. 相似文献
18.
《Climate Policy》2013,13(2):216-231
Reducing emissions from deforestation and forest degradation (REDD) in developing countries has been at the centre of negotiations on a renewed international climate regime. Developing countries have made it clear that their ability to engage in REDD activities would depend on obtaining sufficient and stable funding. Two alternative REDD financing options are examined to find possible ways forward: financing through a future compliance market and financing through a non-offset fund. First, global demand for hypothetical REDD credits is estimated. The demand for REDD credits would be highest with a base year of 1990, using gross—net accounting. The key factors determining demand in this scenario are the emission reduction targets and the allowable cap. A proportion of emission reduction targets available for offsets lower than 15% would fail to generate a sufficient demand for REDD. Also examined is the option of financing REDD through a fund. Indirectly linking the replenishment of a REDD fund to the market is a promising mechanism, but its feasibility depends on political will. The example of overseas development assistance for global health indicates the conditions for possible REDD financing. The best financial approach for REDD would be a flexible REDD mechanism with two tracks: a market track serving as a mitigation option for developed countries, and a fund track serving as a mitigation option for developing countries. 相似文献
19.
利用SD型闪电频数识别高原雷雨云和冰雹云 总被引：10，自引：2，他引：10
分析了青海省西宁市和互助县两地的闪电频数资料，结果表明，在青海省人工防雹区山多，地形复杂的情况下，使用SD型闪电计数器可以识别饱点周围40km的雷雨云和冰雹云，当雷暴由山区向平地移动时，5min闪电频数不小于40次，可作为作用的指标，而雷暴从平面向山区移动时，作业指标不小于30次／(5min)，雷暴云闪电频数的升度大于10次（5min)也可以作为识别雷雨云和冰雹云的指标，但时效较短，利用ＳＤ型闪电频数识别高原雷雨云和冰雹云是一种简便，经济实用的手段，有助于没有雷达等观测设备的偏僻山区防雹作业。 相似文献
20.
The results of this study prove that there is significant troposphere biennial oscillation （TBO） in the South Asian climate, especially with the Indian summer monsoon rainfall. In order to explore the mechanism of TBO in the South Asian region, we defined a unified South Asian monsoon index to depict South Asian summer monsoon （SASM） and South Asian winter monsoon （SAWM） and the transition features between SASM and SAWM. Through further analysis, the connection between the abnormity of SASM and SAWM was discovered. Normally, a strong SAWM is beneficial for a weak SASM later, while a weak SAWM favors a strong SASM. Meanwhile, a strong SASM is favorable for a weak SAWM and a weak SAWM always happens after a weak SASM. Such results suggest the evolution of the South Asian monsoon, which may be an important mechanism to excite TBO in South Asia. 相似文献