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1.
Conditional probability of icing in correlation with local weather elements, as well as with different macrocirculation types are investigated on the basis of 23 years of daily observations for two stations situated in the Pannonian Plain (Debrecen) and in mountainous region (Kékestetö, 1000 m above sea-level). Empirical histograms are calculated and a theoretical model of the distribution is elaborated. Ice is generally twice as frequent at night as during the day. Icing is 5–6 times as frequent on the top of the hill as on the plain, especially considering larger water-contents. Macrosynoptic conditions favourable for icing are essentially different in the two circumstances. At the higher altitude icing is more frequent in cyclonic situations. Considerable load is often accompanied with southwesterly, southerly currents. On the plain station however the anticyclonic situations are somewhat more frequently accompanied with ice formation. Wind speed is practically indifferent at the top of the hill, but on the plain ice formation prefers low wind speeds. These differences are in coincidence with the a priori information of the different nature of ice load. Namely, at the top of hill in-cloud icing is the predominant form, while on the plain fine rime and frozen precipitation represent the overwhelming majority of ice load events. No clear differences in probabilities of icing in any of the above relations appear, however, between the two perpendicular directions of measuring devices. From among the possible applications of the results, a local scenario on ice load changes assuming a 0.5 K global warming is presented. 相似文献
2.
A theoretical spongy spray icing model with surficial structure 总被引：1，自引：0，他引：1
In an attempt to improve the predictive capability of atmospheric icing models, we have developed a theoretical model of spongy ice formation, including the surficial morphology under a falling supercooled liquid film. A steady-state model of freshwater spongy spray icing for a stationary vertical cylinder is presented. A falling film submodel accounts for the flow of excess liquid on the icing surface. Traditional heat and mass balance equations at the outer surface of the falling film are formulated, along with heat and mass balances for the falling film and for the dendritic freezing zone. The rate of advance of the icing interface is calculated by analogy with the rate of advance of freely-growing ice crystals in bulk supercooled liquid. This allows, for the first time, the prediction of ice accretion flux and accretion sponginess, for a specific icing configuration and environmental conditions. An analysis of the model's sensitivity to spray temperature reveals that spray supercooling enhances both the rate of accretion and its sponginess. A comparison of the model's performance with experiments shows rather good agreement, and suggests that further research into the nature of the icing surface and its effect on the accreted ice is warranted. 相似文献
3.
利用2011年1月—2013年3月在贵州开展导线覆冰自动观测试验获取的观测资料,分析了覆冰过程演变及其气象条件变化特征,提出一次完整的导线覆冰过程包括覆冰开始、增长、维持、减弱、消融5个阶段,并得到覆冰过程的气象条件判别指标;基于导线覆冰理论模型的改进并结合气象条件判别,建立了基于过程判别的雨雾凇导线覆冰气象模式,应用该模式对观测获取的多个导线覆冰过程进行数值模拟检验。结果表明:模式能够模拟自然环境下覆冰的增长,并能够正确模拟出覆冰的减弱、消融,模拟过程覆冰质量变化的最大相对误差小于20%。该模式具有较完整的理论基础和计算方案,主要以常规气象观测要素为输入,能够计算输出覆冰全过程逐小时覆冰质量、覆冰厚度及覆冰密度变化,具有较大的应用前景。 相似文献
4.
Particulate contribution to extinction of visible radiation: Pollution, haze, and fog 总被引：2，自引：0，他引：2
Thierry Elias Martial Haeffelin Philippe Drobinski Laurent Gomes Jerome Rangognio Thierry Bergot Patrick Chazette Jean-Christophe Raut Michle Colomb 《Atmospheric Research》2009,92(4):443-454
A data set acquired by eight particle-dedicated instruments set up on the SIRTA (Site Instrumental de Recherche par Télédétection Atmosphérique, which is French for Instrumented Site for Atmospheric Remote Sensing Research) during the ParisFog field campaign are exploited to document microphysical properties of particles contributing to extinction of visible radiation in variable situations. The study focuses on a 48-hour period when atmospheric conditions are highly variable: relative humidity changes between 50 and 100%, visibility ranges between 65 and 35 000 m, the site is either downwind the Paris area either under maritime influence. A dense and homogeneous fog formed during the night by radiative cooling. In 6 h, visibility decreased down from 30 000 m in the clear-sky regime to 65 m within the fog, because of advected urban pollution (factor 3 to 4 in visibility reduction), aerosol hydration (factor 20) and aerosol activation (factor 6). Computations of aerosol optical properties, based on Mie theory, show that extinction in clear-sky regime is due equally to the ultrafine modes and to the accumulation mode. Extinction by haze is due to hydrated aerosol particles distributed in the accumulation mode, defined by a geometric mean diameter of 0.6 μm and a geometric standard deviation of 1.4. These hydrated aerosol particles still contribute by 20 ± 10% to extinction in the fog. The complementary extinction is due to fog droplets distributed around the geometric mean diameter of 3.2 μm with a geometric standard deviation of 1.5 during the first fog development stage. The study also shows that the experimental set-up could not count all fog droplets during the second and third fog development stages. 相似文献
5.
随着我国风电行业的快速发展，覆冰已经成为严重威胁风电场安全稳定运行的因素之一，针对这一问题，国内外学者陆续开展了相关研究。综合现有研究成果，从覆冰概况、研究方法分类、影响覆冰的因素、风机叶片覆冰期特点等方面做了总结。大量的研究成果显示：影响风机叶片覆冰的气象因素主要为环境温度、相对湿度、风速、液态水含量（Liquid Water Content,LWC）和体积中径（Median Volume Diameter,MVD）等。此外，冰风洞试验和数值仿真模拟方面已有很多成果，而覆冰模型法的研究还较少，后续研究的重点是开展对高分辨率数值预报产品的订正研究，构建适用于本地的风机叶片覆冰模型，为风电场提前预警覆冰期以采取融冰措施、合理安排生产等提供科学参考。 相似文献
6.
粤北地区导线覆冰气象特征与标准厚度推算 总被引：2，自引：0，他引：2
利用广东省乐昌高山气象站1972—1978年观冰资料和气候资料,分析了粤北地区导线覆冰的气象特征,建立了导线覆冰标准冰厚的气象推算模型。根据乐昌国家气象站的历史资料,对乐昌高山气象站的气候资料进行订正延长,构建了乐昌高山气象站覆冰年极值长年代序列,并推算出离地不同高度各重现期的标准冰厚值。结果表明,粤北地区导线覆冰主要发生在1月,其次为2月和12月,平均覆冰期在90天左右,最长覆冰期可达131天以上。主导风向、日最低气温、日降水量是影响导线覆冰厚度的主要气象因素。标准冰厚的年极值序列服从极值I型概率分布,历史上的最大导线覆冰值出现在2008年1月26日,2m高度标准冰厚达64.4mm,15m高度标准冰厚达92.7mm,与2008年冰灾实况调查的覆冰厚度(标准冰厚)115mm较为接近。 相似文献
7.
飞机积冰是影响飞行安全的重要危险天气,准确的积冰诊断对民航运行与安全具有重大意义,特别是对国产大飞机适航取证具有重要作用。本文参考改进的CIP(Current Icing Potential)指数,使用垂直速度和云中液态水含量对积冰潜势诊断指数进行优化得到SCIP(Simplified Current Icing Potential)指数,该指数直接基于大气层结资料给出较为准确地飞机积冰潜势,具有命中率高、实用性强的特点。用2021年2月28日至12月31日民航航空器报告对原CIP指数和SCIP指数进行对比验证评估,发现相比于原CIP指数,SCIP指数具有更优异的ROC曲线(Receiver Operating Characteristic Curve)和TSS评分(True Skill Score)。但是对于不同程度的积冰,原CIP指数和SCIP指数均表现出较一致诊断效果,表明SCIP指数对诊断飞机积冰潜势具有重要作用,但无法判断积冰强度。根据2020年3月16日陕西区域飞机结冰个例验证表明增加垂直速度和云中液态水含量的影响对飞机积冰的描述更加细致,对提升积冰潜势诊断效果具有重要意义... 相似文献
8.
2009年起,研究组开展了电线积冰野外观测试验及道路结冰规律的观测研究,将电线积冰观测研究从传统的积冰气象条件和积冰厚度观测提升到了积冰气象条件、积冰厚度加积冰天气云降水微物理综合观测研究的新高度,揭示了积冰发生的微物理机制,研究积冰增长率及其影响因子,建立的积冰增长模型较好地模拟了积冰增长过程。对沥青、水泥、土壤三种下垫面温度进行了观测研究,观测高速公路和桥梁不同路基深度的温度变化,并对桥面比路面更易结冰的现象从能量平衡方面做了理论解释。本文以作者团队取得的成果为主线,不求大而全,学习梳理相关的代表性研究成果,主要包括积冰发生频次的时空分布、积冰天气微物理特征、积冰增长率及其影响因子、积冰气象条件、积冰增长模型构建、道路结冰及积冰数值预报等几个方面,并对电线积冰未来的研究提出了建议。 相似文献
9.
Jean Laflamme 《Atmospheric Research》1995,36(3-4)
It is still a challenge today to get the statistical approach accepted by some transmission line engineers, namely for freezing rain icing loads. They see heavy icing storms as rare events and they still believe that in this case a sound engineering judgment is better than poor statistics. When they are convinced that statistics are good, such as for the flood problem, they do not hesitate to accept the probabilistic approach. Developing extreme values distributions of freezing-rain icing is however a difficult task. Because of the relatively small dimension of major freezing rain storms, freezing-rain icing is not a continuous “variate” at a particular site.One way of improving the statistics is to take simple icing measurements on a fine grid stations network. After only 17 years of measurements with Passive Ice Meters, good fit of extreme values is possible if we use “mesh”extreme values instead of “station” ones. Before pooling extreme values into a “mesh” or “region”distribution, some attention must be given to the homogeneity of the data within a given area. This has been done for four different regions of the province of Québec with very conclusive results. A mesh of about 50 km seems adequate with a temporal resolution of 12 h. Since transmission lines are spatial constructions, this finding can easily satisfy the need of the design engineers in defining icing loads. And, if some caution is given to identify special topographical features, a better knowledge of the spatial variation of icing makes also possible better line routing. 相似文献
10.
湖北省电线积冰微地形因子影响识别研究 总被引：2，自引：0，他引：2
电线积冰是影响电网正常运行的重要因素,研究电线积冰与微地形因子的关系对于电线积冰风险区划、电网建设可行性论证等具有重要指导意义。本文利用湖北省1：5万基础比例尺地形图数据和湖北省电网线路冰害故障调查统计数据,对电线积冰厚度与其对应的微地形因子进行相关性分析,识别对电线积冰有显著影响的微地形因子,分析电线积冰厚度与对其影响显著的微地形因子的定量关系,解析微地形因子对电线积冰敏感性等级。结果表明：地形起伏度、海拔高度、离水体远近程度、下垫面类型等是影响积冰厚度最显著的微地形因子;地形起伏度与积冰厚度呈乘幂函数关系,海拔高度与积冰厚度呈对数函数关系,离水体远近程度与积冰厚度呈分段函数关系,下垫面类型与积冰厚度无显式的函数关系,但积冰灾害发生点具有明显的随下垫面类型分布的特征;积冰厚度随地形起伏度、海拔高度的增加而增加,而其变化率和敏感性则逐渐减小;地形起伏度小于40 m时,其对积冰风险最敏感;海拔高度在25～100 m时,其对积冰风险最敏感;积冰厚度随离水体距离的增加呈先增后减的变化趋势,其变化率绝对值和敏感性也呈先增后减的变化趋势,当离开水体距离在2～2.7 km时,其对积冰风险最敏感;电线积冰灾害多发区域的下垫面主要为水体、林地,其次为农田和草地,水体对积冰风险的敏感性等级分别是林地、农田、草地的1.5、3.6和16.7倍。 相似文献
11.
在综合考虑雨凇和雾凇积冰增长以及热力融冰和升华脱冰的基础上,建立了一个基于常规气象资料的小时标准冰厚模型。模拟2008年和2013年浙江省两次严重电网覆冰灾害期间的标准冰厚,并用事故线路调查资料、电线积冰观测站和模拟导线拉力监测点的观测资料进行验证分析。结果显示:事故线路的最大标准冰厚观测值与模拟值相关关系达到0.01显著性水平,电线积冰观测站的日标准冰厚观测值与模拟值的平均绝对偏差小于0.6 mm,模拟导线拉力监测点的小时标准冰厚模拟值与观测值的决定系数为0.8093,均方根误差为0.8 mm。说明模型比较准确地描述了天气过程对电线积冰的影响,能够较好地反映标准冰厚的空间分布规律和时间变化特征。 相似文献
12.
利用2021年2月28日机载探测资料, 结合欧洲中期天气预报中心ERA5再分析资料、陕西省延安站探空资料, 分析飞机发生严重积冰的天气背景和云的宏微观结构特征。此次严重积冰天气是受高空槽、低空切变线、低空急流和地面冷锋共同影响的结果。ERA5再分析资料表明:过冷水大值区主要分布于锋区前部暖侧的700 hPa至600 hPa高度。探空资料表明:飞机探测区环境温度为-9~-3℃, 温度露点差为0℃, 具有发生严重积冰的温度和湿度条件。飞机遭遇严重积冰期间环境温度为-8~-5℃, 云粒子探头观测的液态水含量平均为0.35 g·m-3, 最大为0.7 g·m-3;总水含量仪观测的液态水含量平均为0.5 g·m-3, 最大为0.85 g·m-3, 有11 min大于0.45 g·m-3;云粒子中值体积直径平均为20.3 μm, 云粒子数浓度平均为149.3 cm-3;云粒子数浓度由低层到高层呈增大趋势, 而云粒子中值体积直径变化趋势与之相反。计算表明:国王350飞机在穿云作业时, 云中过冷水含量分别高于0.04 g·m-3, 0.15 g·m-3和0.45 g·m-3时可能遭遇轻度积冰、中度积冰和严重积冰。 相似文献
13.
电线积冰灾害是导致电力系统发生事故的重要自然灾害之一。基于已有研究成果,从电线积冰相关概念与分类出发,对电线积冰的影响与危害、时空分布、成因、影响因子、预报模型、风险评估以及预防措施等方面进行归纳。我国电线积冰灾害以雾凇型积冰和雨凇型积冰为主,主要环境成因包括准静止锋、大气垂直结构和逆温层,同时还受到地形、高度和导线自身特性等的影响。电线积冰灾害总体上呈现北方多雾凇而南方多雨凇的分布特征,20世纪80—90年代的积冰日数较多,90年代后呈下降趋势。为更好地实现电线积冰灾害的模拟与预测,预报模型也在不断完善,包括物理数值模型和统计预测模型;而对于电线积冰灾害风险评估的研究较少,主要集中在电线积冰灾害的危险性和线路的脆弱性。基于多学科指标构建的电线积冰综合性指标、基于灾变过程的综合风险评估及气候变化对电线积冰的影响将是今后重点研究方向。 相似文献
14.
N. P. Shakina I. A. Gorlach E. N. Skriptunova N. I. Komas’ko 《Russian Meteorology and Hydrology》2014,39(2):121-125
Analyzed is a serious flight accident with a Boeing-747 aircraft happened on July 31, 2013 during its flight from Moscow to Hong Kong. The plane entered the upper crystal part of the mesoscale convective complex (MCC) and got damaged the compressors of three engines. This is considered to be caused by the so called ice crystal icing in the areas with high concentration of ice crystals. Considered are meteorological conditions in the corresponding part of the flight route and available information about this type of icing. To prevent aircrafts from ice crystal icing, special attention should be paid to very short-range forecasting, now casting, and detection of zones of deep intense convection, especially of MCC along the flight route. 相似文献
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16.
2018年3月17日、27日,国产某型直升机在新疆五家渠地区成功完成2架次自然结冰试飞。利用NCEP/NCAR的1°×1°再分析资料、机测液态水含量资料结合常规气象资料,对2次结冰天气过程的天气环流形势、动力热力特征、液态水含量进行分析。结果表明:17日在高空冷涡、地面冷锋前的环流形势下,试飞高度层位于冷暖平流交汇处,温度为0～-4℃,比湿值为3～3.5 g/kg,处于强水汽辐合中心,并伴有弱上升运动,Ic积冰指数为20～30,云中液态水含量波动较大,飞机挂架上形成0.5 cm厚度的凇冰。27日在高空槽前和地面冷锋后的环流形势下,试飞高度层在弱冷平流中心附近,温度为0～-2℃,比湿值接近4.5 g/kg,处于弱水汽辐合中心边缘,伴有弱上升运动,Ic积冰指数为30～40,云中液态水含量稳定,飞机挂架上形成1～2 cm厚度的明冰。在气象保障中运用探空、云图、雷达、微波辐射计等资料有效预报了积冰区域及高度。 相似文献
17.
我国极度缺乏结冰气象条件中的云层数据，我国民用航空规章第25部附录C结冰条件只能复制于美国航空规章，对飞行探测得到的结冰云层数据进行附录C符合性分析的方法也少有研究。附录C结冰条件形成于20世纪40年代末，当时的探测手段与如今采用先进探测仪器所获取的数据形式有很大差异，因此首先明确附录C结冰条件参数的具体定义，根据当前探测仪器测量数据的高分辨率特性，对数据处理与分析方法进行研究。最后基于该方法对安庆结冰气象探测数据进行了分析，从分析结果看，该方法能够清晰呈现所探测结冰云层的结冰条件基本特征及其与附录C的符合性程度。 相似文献
18.
Tsoi-Ching Yip 《Atmospheric Research》1995,36(3-4)
The Chaine and Skeates icing model is a semi-empirical model. It is based on the formulations proposed by McKay and Thompson (1969). Horizontal ice accretion thickness is assumed to be the observed precipitation amount adjusted by the appropriate ice density. Clear ice density is assumed to be 900 kg/m3. Vertical ice accretion thickness is proportional to precipitation rate and wind speed. Ice accretion occurs only at temperatures near or below freezing. All impinging water is assumed to turn into ice. The freezing fraction is assumed to be one. Horizontal and vertical ice thicknesses are changed into equivalent radial thickness (Chaine and Castonguay, 1974). All parameters used in this model can be derived from routinely observed meteorological data. Icing amounts estimated by this model are very sensitive to wind speed and precipitation rate. Model simulated 30-year return period equivalent radial ice amounts for 20 Quebec locations are compared with collocated Passive Ice Meter data and the results are found to be reasonable. The variation of ice amount with height can be estimated by a log function proportional to 10 m icing amounts, except in British Columbia. Also the 30-year return period equivalent radial ice estimates due to freezing precipitations for 303 locations in Canada are calculated and an Ice Map is plotted. In the future, more work needs to be done to estimate ice amounts due to other forms of icing such as in-cloud rime icing and wet snow. These quantities should be added to the current amounts to make the ice map complete. Anecdotal ice information should be collected to validate the map. 相似文献
19.
采用Makkonen结冰增长模型镶嵌冰表面辐射融化模型建立适用于风机覆冰的预报模型，基于WRF耦合CALMET综合模式预测结果和风机性能参数驱动模型，进行风机覆冰开始和结束时间的预报。以湖北通山九宫山风电场为研究对象，对2012年12月至2013年12月期间监测到19次风机覆冰进行分析，分别采用提前1 d、提前2 d、提前3 d三种预报方案开展覆冰起止时间的预报，发现该模型对风机覆冰具有一定的提前预警能力，且越临近覆冰发生时间，预报准确性越高。 相似文献
20.
导线覆冰是在一定气象条件下发生的复杂的物理过程,贵州是我国南方导线覆冰最严重的受灾区,每年都会发生不同程度的覆冰灾害。本文利用地面观测资料、探空资料、NCEP再分析资料和覆冰资料,通过分析影响局地线路覆冰的大范围气候、天气背景及其变化特征,结合已有的覆冰灾害事件,侧重于气候背景的角度,分析总结了2008～2011年贵州产生覆冰的天气气候特征,气象要素条件以及地理环境因子与导线覆冰的关系,主要得出以下结论：贵州省导线覆冰与中高纬大气环流异常,西太平洋副高的北移,对流层下层逆温层的影响密不可分;贵州省地处云贵高原,北边小槽移动影响与南方来的暖湿空气汇集之地,容易形成冰冻天气,加之导线多分布于山上,则导线的材质与分布,导线所在环境的空气湿度,空气温度,风向风速,降水与天气状况等,决定了导线覆冰的厚度。 相似文献