2015年锡林浩特市冬季光柱现象成因浅析

文章介绍了2015年冬季锡林浩特市出现的光柱现象,分析了此现象产生前后的气象要素变化特征和现象生成原因。结果表明:光柱现象产生于冬季降雪多、湿度大、气温低、风速小的大气环境中,一般出现在气温下降到-20℃,相对湿度达到80%,风速<2 m·s^(-1),前期有降雪的天气条件下,是由片状冰针反射和折射城市灯光产生。     

General circulation model simulation of mild nuclear winter effects

The climatic effects of an elevated uniform global layer of purely absorbing smoke of absorption optical depth 0.2 have been simulated using a version of the 9-level spectral model of McAvaney et al. (1978). The model was run at rhomboidal wave number 21 with convective adjustment, prognostic precipitation and soil hydrology, but fixed zonally averaged climatological cloud and fixed sea surface temperature, for constant January and July conditions with and without smoke absorption. Results show a reduction in convective rainfall in the tropics and monsoonal regions of the order of 50%, with diurnal average soil surface coolings of several degrees C except in those locations where the reduction in soil moisture is sufficient to effectively stop evaporation at the surface. In that case, small increases in temperature may occur. Results over Australia are consistent with the zonal mean picture. Run in a diurnal cycle mode, the model shows that daily maximum temperatures are more strongly affected, with soil surface coolings of the order of 2°–3° C in summer (with some local warmings) and 4°–6° C in winter. Overninght minimum temperatures cool by only 1°–2° C in both summer and winter. Possible effects of a lowering of sea surface temperature, variations in cloud cover, neglect of scattering by smoke, and infrared absorption and emission by the smoke are discussed.     

Whatever happened to nuclear winter? — An editorial

The National Center for Atmospheric Research is sponsored by the National Science Foundation.     

Initial uncertainties in ‘nuclear winter’: A proposed test based on the dresden firestorm

Conclusions An extinction optical depth of 20 is necessary for total darkness (NAS, 1985), although a considerably lower value than that can produce near-total darkness because scattered light does not generate shadows and contrast. It can be seen that the Dresden firestorm smoke cloud, calculated under the conditions usually assumed in nuclear winter calculations, should have resulted in total darkness over a vast area.Using the 500 mb chart, it can be retrodicted that the smoke plume, as part of the counterclockwise circulation about the low over southern Sweden, was over central Poland as dawn broke on the 14th. Indeed, at 9 AM (Table I), smoke from what had been Dresden should have been passing over what had been Warsaw. Depending upon the specific size of the plume at the time, anywhere from a few hundred thousand to over ten million people should have been plunged into darkness.It appears unlikely that such extensive darkening could have gone unreported (especially in the light of the heightened awareness resulting from wartime conditions, and the proximity of the Soviet/German front). This has direct implications for the aforementioned initial uncertainties in nuclear winter. Possible explanations include: (a) Very low smoke emission factors - perhaps even lower than 0.001 (Broyles, 1985); (b) Substantial removal of smoke in the black rain that followed the firestorm (Irving, 1963, p. 175). Values for prompt smoke removal reaching 90% are not out of the realm of possibility (Schneider et al., 1986; Penner, 1986).The present author is of the opinion that more effort should be expended by students of the nuclear winter phenomenon to learn from WWII mass urban fires. Many eyewitnesses to these events must still be living, and there must be at least some scientifically-useable material in archives. For example, there is a 122-m, 10-min motion film of the Dresden firestorm (Irving, 1963, p. 159). It is in the film archives of the Imperial War Museum. Perhaps some new details of firestorm genesis, spread, etc. could be learned from it. There must be other log books, such as the one of Kraus (1986), which could well yield scientificallyvaluable information.     

Different prediction skill for the East Asian winter monsoon in the early and late winter season

Climate Dynamics - The prediction skill for the East Asian winter monsoon (EAWM) in early (November–December, ND) and late winter (January–February, JF) is investigated based on the...     

一个适用于描述中国大陆冬季气温变化的东亚冬季风指数

利用1951年1月-2007年2月的NCEP V1格点资料和中国台站观测资料,定义了一个冬季风环流指数(IEAWM),并分析其与中国冬季气温和东亚大气环流变化的联系.结果表明该指数能够很好地反映东亚冬季风系统各成员的变化,兼顾北方和南方的环流状况和东西部热力差异的影响,改进了原有冬季风指数大多针对单一的冬季风环流成员及对中国冬季气温变化反映能力的不足,能够很好地反映中国冬季平均气温的异常变化.分析表明,当该指数为正值时东亚冬季风偏强,对应着地面西伯利亚高压和高空东亚大槽均偏强,东亚地区对流层中层的高-低纬度之间的纬向风经向切变加强,有利于中高纬度冷空气向南侵入,导致中国大陆地区气温偏低,反之亦然.IEAWM的年代际变化表明东亚冬季风在1985年之前偏强,1985年之后明显偏弱,这与1985年之后中国冬季变暖是一致的.     

欧亚冬季温带反气旋活动的气候特征

利用NCEP/NCAR再分析数据,通过判定和追踪温带反气旋的客观方法统计分析了1948-2013年欧亚地区冬季温带反气旋的生成、消亡、移动、生命史、强度等气候特征。结果表明,反气旋的主要源地位于蒙古高原、伊朗及其周边地区、地中海沿岸、中西伯利亚、波罗的海西北部、俄罗斯东北部等地,其中,蒙古高原和伊朗等地也是强反气旋最主要的源地。反气旋活动的大值分布区和反气旋生成的大值中心分布十分相似,主要活跃区对应低空平均经向温度梯度大值区和高空脊前。除源于蒙古高原和西伯利亚东北部的强、弱反气旋的移动距离差别不明显外,其他地区的反气旋移动距离与强度有密切关系。持续1-2 d的反气旋占总数的44.2%,而只有3.2%的反气旋生命史超过一周,且强反气旋比弱反气旋更易持续较长时间。      

浅析地面温度在零度以上时出现霜的现象

在多年的地面观测中,发现地面温度和气温在零摄氏度以上时,仍有霜出现,该文从地温表的安置、下垫面状况、地面辐射及物理属性4个方面对霜的形成原因进行了分析探讨,结果表明:气温在3～4℃,地面温度＞0℃时,水汽也能在青草面上凝结成霜。     

冬季北半球大气对秋冬季巴伦支海海冰异常的敏感性研究

基于ERA-Interim再分析资料,借助大气模式CAM4,分析了北半球冬季不同月份的平均大气对巴伦支海不同振幅及不同季节海冰扰动的敏感性,并考察了中高纬度典型大气模态的分布变化情况.结果表明,冬季巴伦支海海冰的减少,会导致湍流热通量异常向上、局地异常变暖及水汽含量的异常升高,且相关异常的强度和范围随着海冰减少幅度的减...     

湖震现象理论分析

本文用浅水波理论对湖震现象进行了分析，结果表明，湖震可以用驻波的概念解释。     

A mechanism to explain the spectrum of Hessdalen Lights phenomenon

In this work, we present a model to explain the apparently contradictory spectrum observed in Hessdalen Lights (HL) phenomenon. According to our model, its nearly flat spectrum on the top with steep sides is due to the effect of optical thickness on the bremsstrahlung spectrum. At low frequencies self-absorption modifies the spectrum to follow the Rayleigh–Jeans part of the blackbody curve. This spectrum is typical of dense ionized gas. Additionally, spectrum produced in the thermal bremsstrahlung process is flat up to a cutoff frequency, ν _cut, and falls off exponentially at higher frequencies. This sequence of events forms the typical spectrum of HL phenomenon when the atmosphere is clear, with no fog.     

ENSO 年冬季北半球平流层大气环流异常特征分析

利用1957-2002年欧洲中心的再分析资料和Hadley气候预测和研究中心的全球海表温度资料,对ENSO年冬季的平流层环流进行了合成分析,分别从暖事件和冷事件年的温度场、高度场和风场,分析研究了平流层大气环流的异常特征.分析结果表明,对应El Ni(n)o年冬季,在赤道东太平洋的温度场、高度场和纬向风场都有由大气低层的正距平转变为平流层负距平的特征;与之相反,在El Ni(n)a年冬季,赤道东太平洋大气低层的负距平到了高层变为正距平.同时,在纬向平均垂直剖面图中, El Ni(n)o年冬季北半球高纬地区从对流层顶到平流层温度场和高度场为正距平,而La Ni(n)na年出现相反的情况.在热带平流层,El Ni(n)o年冬季高空纬向风场在50 hPa到15 hPa左右为负距平,从15 hPa到1 hPa为正距平;而El Ni(n)a年则相反.在El Ni(n)o年冬季100 hPa以上的北半球高纬度地区存在一个类偶极子结构的异常高度场和风场,El Ni(n)o年在极区主要为正距平,El Ni(n)a年在极区主要为负距平.     

冬季审核地面气象资料的一些注意事项

对冬季较少出现的天气现象及其引伸的现象的资料处理情况进行概括,有助于台站处理审核原始资料。     

Measurements of arctic total ozone during the polar winter

Abstract

Ground‐based measurements of total ozone were made during the polar night from Arctic stations in the winters of 1987–88 and 1988–89. The measurements were made with automated Brewer ozone spectrophotometers using the moon as a light source. Data were obtained from Alert and Resolute in Canada for both winters and from Heiss Island, USSR, for the second winter. The method of measurement is briefly reviewed and data from the three stations are presented. The ground‐based total ozone measurements are compared with the integrated values derived from ozonesonde profiles.     

Chinooks and winter evaporation

Summary Chinooks are warm mountain winds which occur in the foothills of southern Alberta. They are often blamed for encouraging droughts in the western prairies because of the link believed to exist between them and excessive surface and subsurface evaporation. Measurements made over four winters show that evaporation rates during a chinook exceed the net radiation flux when there is water standing over the surface. However, the vapour flux fraction reduces to a level below the potential rate once the moisture content drops below saturation level within the upper subsurface layer no thicker than 2 mm. Meanwhile, the soil moisture reservoir below that layer remains virtually undepleted even in the face of persistently strong chinook events.With 6 Figures     

Circulation characteristics over the Himalayas during winter season

Summary ?During winter season, atmospheric systems, which traverse from west to east interact with the Himalayan massif and produce widespread rainfall over North India. In this study, we made an endeavor to examine the mean circulation features and large-scale budgets of kinetic energy, heat and moisture over Himalayas and the adjoining domain for winter season. The time-mean circulation is bifurcated into stable mean and transient eddy parts and examined the mean component of the circulation. The uninitialized daily analyses of European Centre for Medium range Weather Forecasts (ECMWF) for five winter seasons (1986–90) comprising December, January and February (DJF) have been used for the purpose. We noticed certain zones of strong activity over Iran, Afghanistan, and West China regions during winter season. These are characterized by intense vertical motions, cyclonic vorticity and adiabatic generation of kinetic energy. The features noticed over these zones include strong horizontal convergence of heat and moisture. These zones are further characterized by massive adiabatic conversion of available potential energy to kinetic energy. These features are conducive for the growth of atmospheric systems, which traverse over the zones and produce precipitation subsequently. Received November 16, 2000; revised February 5, 2002     

冬季北极涛动对西伯利亚高压、东亚冬季风以及海冰范围的可能影响

利用NCEP／NCAR月平均再分析资料（1958－1997），月平均海表面温度资料（1950－1992）以及月的海冰密集度资料（1953－1995），研究了冬季北极涛动与西伯利亚高压、东亚冬季风以及巴伦支海海冰范围之间的联系。研究结果表明，冬季北极涛动不仅影响北极和北大西洋区域气候变化，并且可能影响冬季西伯利亚高压，进而影响东亚冬季风。当冬季北极涛动处于正位相时，冬季西伯利亚高压和东亚冬季风都偏弱，在西伯利亚南部和东亚沿岸，包括中国东部、韩国和日本，从地表面到对流层中部气温偏高0.5-2℃。当冬季北极涛动处于负位相时，结果正相反。研究结果还表明，冬季西伯利亚高压对北极以及北大西洋区域气候变化没有显的影响，与北极涛动的影响相比，西伯利亚的影响强度和范围明显偏弱。研究进一步揭示了冬季北极涛动可能影响西伯利亚高压的可能机理。冬季西伯利亚高压与动力过程以及从地表面到对流层中部的气温变化有密切的关系。西伯利亚高压的西部变化主要依赖于动力过程，而其东部与气温变化更为密切。冬季西伯利亚高压的维持主要依赖于对流层中的下沉气流，这种下沉气流源于北大西洋区域，其变化受到北极涛动的影响。当冬季北极涛动处于正（负）位相时，气流的下沉运动明显减弱（增强），进而影响冬季西伯利亚高压。此处，冬季北极涛动对同时期的巴伦支海海冰范围有显的影响。