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白素琴 《沙漠与绿洲气象(新疆气象)》2008,2(5):52-52
城市、农业和工业发展造成的富营养化的水促进了蓝藻的生长,就像促进有害的海藻生长一样。这些蓝藻的繁盛增加了水生生态系统的混乱状况。窒息了水生植物,抑制了无脊椎动物和鱼类的生活环境。一些蓝藻产生出能够引发严重的、偶然情况下致命的人类肝脏、消化系统、神经系统和皮肤疾病的毒素。蓝藻的繁盛威胁到水生生态系统,包括非洲的Victoria湖,北美洲的Erie湖,中国的太湖以及欧洲的波罗的海。 相似文献
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大气CO_2升高的一个重要的直接效应是促进植物生长。为了了解和预报自然物种及生态系统对CO_2增加的响应,需要有新的或修正的模式方法。由于在未来100年内,大气中CO_2将增加1倍,有效的模式将成为预报响应(如生产率的变化,植物群落组成的变化及分离的碳含量的变化)的重要手段。作为研究CO_2对植被直接影响的综合计划的一部分,对模拟植物和生态系统响应的要求进行了讨讨,主要的要求是(a)一种模式的复杂程度要与一般的生态知识相适应,主要是CO_2响应函数的处理;(b)建立预报植物、群落和生态系统对CO_2响应的模式;(c)评价由CO_2决定的模式参数的敏感性和不确定性,次要的要求是建立评价模式所需的资料条件的框架。 相似文献
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《大气和海洋科学快报》2021,(2)
受一次向东南方向移动蒙古气旋强风的影响,2020年4月18日甘肃省白银市的高压输电线路出现了严重的舞动,这造成了该地区的输电线路跳闸事故.基于0.5度逐小时分辨率的ERA5再分析数据,本文研究了这次蒙古气旋及其强风的形成机理.涡度收支的结果表明,辐合相关的垂直伸展以及垂直运动向上的正涡度输送是本次蒙古气旋形成的主因,而倾斜项的负涡度制造以及从气旋中心区域向外的正涡度输送在一定程度上不利于蒙古气旋的形成.动能收支的结果表明,蒙古气旋所伴随的风场主要由于气压梯度力的做功而迅速增强.与我国西北部其它的典型强风事件不同的是在本次事件中,未发现显著的来自于对流层高层的动量下传现象,垂直的动能输送在本次事件中仅对强风的形成有些许的促进作用.此外,水平风场对动能的输送作用使得蒙古气旋大风区的动能存在向外的净输出,这对蒙古气旋强风的生成有一定的延缓作用. 相似文献
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气象向量场的自然正交展开方法及其应用 总被引：8，自引：2，他引：8
王盘兴 《南京气象学院学报》1981,(1)
本文证明了一个包含n个空间点的风场的时间序列的自然正交展开,可以通过形式上包含2n个空间点的标量场的时间序列的自然正交展开来实现。据此,给出了求取风场的特征向量的方法。于是展开热带候平均风场的一个时间序列,求得了具有明显天气学意义的特征向量,其主要特征向量的时间系数的演变与此期间亚洲低纬主要环流系统的季节变化间存在良好的关系;由各层前两个特征向量给出的散度和垂直运动的空间分布及这种分布随时间的演变,形象地给出了季风降水的基本成因。 相似文献
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青藏高原对大气环流的影响 总被引：1，自引：0，他引：1
许多研究指出对于全球范围的大气环流,大地形的强迫作用(热力和动力的)和海陆的热力差异起着同等的重要作用,一切区域性的,尤其靠近地形附近地区的天气气候特点,则更多的或基本上决定于地形的影响。但是地形的影响是复杂的,过去作了许多的研究,离解决问题还存在较大的距离。本文主要通过青藏高原来具体讨论地形的影响。 一、青藏高原与全球大气环流 相似文献
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随着计算机网络的发展 ,特别是 Internet的迅猛的发展 ,传统的信息系统概念发生了巨大的变化 ,尤其是信息的存储、传递、发布以及获取方式。如何在更为广域和异构的计算机环境中获取所需要的信息 ,已成为亟待解决的问题。专业气象网站是这一技术发展的应用。专业气象网站竞争力 ,既取决于网站在气象资源信息利用方面的独特设想 ,又在于网站的技术含量 ,即网站开发人员的技术水平。1 网站运行系统的选择实现网站开发的软件有很多 ,一是动态页面的生成与显示 ;二是静态页面的生成与显示。对于动态页面的生成 ,可以使用许多方式 ,包括传统的C… 相似文献
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西北太平洋台风风场和波浪场特征 总被引：7，自引：1，他引：6
通过对西北太平洋１９８６～１９９６年７～１１月有代表性的西行及转向北上的３５个台风（热带低压、热带风暴、强热带风暴、强台风）发生时船舶气象报告中的气象和波浪场资料的统计分析,说明不同强度的台风和在不同的天气形势配置下,由台风引起的风场和波浪场的分布特征是有明显差异的。根据统计分析的结果给出了台风引起的风场和波浪场分布特征的统计模型。此模型对船舶有效的避离恶劣的台风天气和不利的海况,提供更好的海洋气象导航服务,有一定的实用价值 相似文献
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Storms that occur at the Bay of Bengal (BoB) are of a bimodal pattern, which is different from that of the other sea areas. By using the NCEP, SST and JTWC data, the causes of the bimodal pattern storm activity of the BoB are diagnosed and analyzed in this paper. The result shows that the seasonal variation of general atmosphere circulation in East Asia has a regulating and controlling impact on the BoB storm activity, and the “bimodal period” of the storm activity corresponds exactly to the seasonal conversion period of atmospheric circulation. The minor wind speed of shear spring and autumn contributed to the storm, which was a crucial factor for the generation and occurrence of the “bimodal pattern” storm activity in the BoB. The analysis on sea surface temperature (SST) shows that the SSTs of all the year around in the BoB area meet the conditions required for the generation of tropical cyclones (TCs). However, the SSTs in the central area of the bay are higher than that of the surrounding areas in spring and autumn, which facilitates the occurrence of a “two-peak” storm activity pattern. The genesis potential index (GPI) quantifies and reflects the environmental conditions for the generation of the BoB storms. For GPI, the intense low-level vortex disturbance in the troposphere and high-humidity atmosphere are the sufficient conditions for storms, while large maximum wind velocity of the ground vortex radius and small vertical wind shear are the necessary conditions of storms. 相似文献
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This paper reviews briefly advances in recent research on monsoon by Chinese scholars, including primarily： （1） the establishment of various monsoon indices. In particular, the standardized dynamic seasonal variability index of the monsoon can delimit the geographical distribution of global monsoon systems and determine quantitatively the date of abrupt change in circulation. （2） The provision of three driving forces for the generation of monsoon. （3） The revelation of the heating-pump action of the Tibetan Plateau, which strengthens southerlies in the southern and southeastern periphery of the Plateau and results in a strong rainfall center from the northern Bay of Bengal （BOB） to the Plateau itself. （4） Clarification of the initial onset of the Asian Summer Monsoon （ASM） in the BOB east of 90°E, Indochina Peninsula （ICP） and the South China Sea, of which the rapid northward progression of tropical convection in the Sumatra and the rapid westward movement of the South Asia High to the Indochina Peninsula are the earliest signs. （5） The provision of an integrated mechanism for the onset of the East Asian Summer Monsoon （EASM）, which emphasizes the integrated impact of sensible heat over Indian Peninsula, the warm advection of the Tibetan Plateau and the sensible heat and latent heat over the Indochina Peninsula on the one hand, and the seasonal phase-lock effect of the northward propagation of low frequency oscillation on the other. （6） The revelation of the ＂planetary-scale moisture transport large-value band＂ from the Southern Hemisphere through to the Asian monsoon region and into the North Pacific, which is converged by several large-scale moisture transport belts in the Asian-Australian monsoon regions and whose variation influences directly the temporal and spatial distribution of summer rainfall in China. （7） Presenting the features of the seasonal advance of the EASM, the propagation of intraseasonal oscillation, and their relationship with rainfall in Ch 相似文献
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The atmospheric and oceanic conditions before the onset of EP El Ni?o and CP El Ni?o in nearly 30 years are compared and analyzed by using 850 hPa wind, 20℃ isotherm depth, sea surface temperature and the Wheeler and Hendon index. The results are as follows: In the western equatorial Pacific, the occurrence of the anomalously strong westerly winds of the EP El Ni?o is earlier than that of the CP El Ni?o. Its intensity is far stronger than that of the CP El Ni?o. Two months before the El Ni?o, the anomaly westerly winds of the EP El Ni?o have extended to the eastern Pacific region, while the westerly wind anomaly of the CP El Ni?o can only extend to the west of the dateline three months before the El Ni?o and later stay there. Unlike the EP El Ni?o, the CP El Ni?o is always associated with easterly wind anomaly in the eastern equatorial Pacific before its onset. The thermocline depth anomaly of the EP El Ni?o can significantly move eastward and deepen. In addition, we also find that the evolution of thermocline is ahead of the development of the sea surface temperature for the EP El Ni?o. The strong MJO activity of the EP El Ni?o in the western and central Pacific is earlier than that of the CP El Ni?o. Measured by the standard deviation of the zonal wind square, the intensity of MJO activity of the EP El Ni?o is significantly greater than that of the CP El Ni?o before the onset of El Ni?o. 相似文献
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The Fe(II)/Fe(III)-partition in cloudwater samples collected during two field campaigns is evaluated. It turned out that the simultaneous occurrence of complexing and reducing substances in the atmosphere and the cloud processing increase the solubility of iron compounds present in aerosol particles. A correlation between the concentration of iron(II) in the liquid phase and the intensity of the solar irradiation was observed for most of the cloudwater samples. This could be due to the fact that both the photochemical reduction of the iron(III) complexes and the photochemical reductive dissolution of iron(III)(hydr)oxides are depending on the pH-value. Iron(II) seems to be oxidised back to iron(III) preferably by hydrogen peroxide during the night. Positive correlations were received e.g. between the concentration of dissolved iron and the concentration of oxalate and between the percentage of iron(III) and the concentration of hydrogen peroxide. A negative correlation was found e.g. between the concentration of dissolved iron and the pH-value. The uncertainty of the whole process of sampling and analysis was investigated and the conformity of the results was satisfying considering the sometimes difficult conditions during a field campaign. 相似文献
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A one-dimensional, time-dependent cloud model with parameterized microphysics is used to investigate the processes which control the rainout and washout of soluble gases from warm, precipitating stratiform clouds. Calculations are presented simulating the distributions of soluble species within and below the cloud layer and in the precipitating raindrops as a function of time and species' solubility. Our calculations indicate that for species with low solubility, wet removal processes are relatively slow and thus do not significantly affect the species' gas-phase abundance. As a result, the removal of low-solubility species by rainout and washout is controlled by thermodynamic processes with the concentration of the species in cloud and rainwater largely determined by the species' solubility. For highly soluble species on the other hand, dissolution into cloud droplets and removal in rain is quite rapid and the abundance of highly soluble species within and below the cloud falls rapidly as soon as the precipitation begins. Because of this rapid decrease in concentration, we find that for highly soluble species: concentrations in cloud droplets near the cloud base can exceed that of raindrops by factors of 2 to 10; washout can dominate over rainout as a removal mechanism; and that, after an extended period of rainfall, the rate of removal becomes independent of the microphysical properties and rainfall rate of the cloud and is controlled by the rate of transport of material into the precipitating column by horizontal advection. 相似文献
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Projected changes in summer precipitation characteristics in China during the 21st century are assessed using the monthly precipitation outputs of the ensemble of three “best” models under the Special Report on Emissions Scenarios (SRES) A1B, A2, and B1 scenarios. The excellent reproducibility of the models both in spatial and temporal patterns for the precipitation in China makes the projected summer precipitation change more believable for the future 100 years. All the three scenarios experiments indicate a consistent enhancement of summer precipitation in China in the 21st century. However, the projected summer precipitation in China demonstrates large variability between sub-regions. The projected increase in precipitation in South China is significant and persistent, as well as in North China. Meanwhile, in the early period of the 21st century, the region of Northeast China is projected to be much drier than the present. But, this situation changes and the precipitation intensifies later, with a precipitation anomaly increase of 12.4%–20.4%
at the end of the 21st century. The region of the Xinjiang Province probably undergoes a drying trend in the future 100 years, and is projected to decrease by 1.7%–3.6% at the end of the 21st century. There is no significant long-term change of the projected summer precipitation in the lower reaches of the Yangtze River valley. A high level of agreement of the ensemble of the regional precipitation change in some parts of China is found across scenarios but smaller changes are projected for the B1 scenario and slightly larger changes for the A2 scenario. 相似文献
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Hainan, an island province of China in the northern South China Sea, experienced two sustained rainstorms in October2010, which were the most severe autumn rainstorms of the past 60 years. From August to October 2010, the most dominant signal of Hainan rainfall was the 10–20-day oscillation. This paper examines the roles of the 10–20-day oscillation in the convective activity and atmospheric circulation during the rainstorms of October 2010 over Hainan. During both rainstorms,Hainan was near the center of convective activity and under the influence of a lower-troposphere cyclonic circulation. The convective center was initiated in the west-central tropical Indian Ocean several days prior to the rainstorm in Hainan. The convective center first propagated eastward to the maritime continent, accompanied by the cyclonic circulation, and then moved northward to the northern South China Sea and South China, causing the rainstorms over Hainan. In addition, the westward propagation of convection from the tropical western Pacific to the southern South China Sea, as well as the propagation farther northward, intensified the convective activity over the northern South China Sea and South China during the first rainstorm. 相似文献
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台风“彩虹”(1522)近海急剧加强的特征分析 总被引：13，自引：11，他引：2
采用多种大气和海洋资料对1522号台风"彩虹"近海急剧加强的特征进行了诊断分析。结果表明大气环流形势的变化、海洋环境的维持和台风内部结构的变化都有利于台风的近海加强。具体表现为:高层南亚高压西部型转东部型和中层西太平洋副热带高压加强西伸引起的环流形势的变化,使得台风区域高层辐散增强,中低层气旋性环流增强,低层台风东侧的水汽通量增强;低层北方弱冷空气侵入台风外围区域促进辐合抬升,环境风切变的减弱及弱切变的维持有利于台风加强,这些都是有利于台风增强的环流和动力条件。台风路径海域高海表温度和海洋暖涡的存在对台风急剧增强起了重要作用。此外,由于环流变化引起的潜热加热增大,导致了双中心位涡柱的形成和高层暖心的增加,台风内部结构的变化也有利于台风的进一步加强。 相似文献
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l. IntroductionModel simulation of soll physical properties is very 1mportant for climate studies becauseof the role they play in different interaction processes with the atmosphere. One of the mostwidespread studies is the implementation of soil models 1n General Circulation Models(GCMs); previous studies showed, in fact, that climate simulat1ons are sensitive to theparameterization of the energy and mass fluxes at the land surface (V1terbo, l995; Beljiaars etal., l996; Dolman et al., l997… 相似文献
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Various features of the atmospheric environment affect the number of migratory insects, besides their initial population. However, little is known about the impact of atmospheric low-frequency oscillation(10 to 90 days) on insect migration. A case study was conducted to ascertain the influence of low-frequency atmospheric oscillation on the immigration of brown planthopper, Nilaparvata lugens(Stl), in Hunan and Jiangxi provinces. The results showed the following:(1) The number of immigrating N. lugens from April to June of 2007 through 2016 mainly exhibited a periodic oscillation of 10 to 20 days.(2) The 10-20 d low-frequency number of immigrating N. lugens was significantly correlated with a low-frequency wind field and a geopotential height field at 850 h Pa.(3) During the peak phase of immigration, southwest or south winds served as a driving force and carried N. lugens populations northward, and when in the back of the trough and the front of the ridge, the downward airflow created a favorable condition for N. lugens to land in the study area. In conclusion, the northward migration of N. lugens was influenced by a low-frequency atmospheric circulation based on the analysis of dynamics. This study was the first research connecting atmospheric low-frequency oscillation to insect migration. 相似文献