陕西省基本风压的计算和研究

前言风压是建筑结构设计中基本的设计依据之一,它关系到各种建筑物及架空线路、广播、电视高塔及桥梁等工程的经济、适用、安全。因此,对基本风压的确定有着重要的现实意义,同时,考虑到现用荷截规范中所列陕西省风压值站点极少,且系一九七五年以前的风速资料计算结果,自记记录年代较短,站点又少,随着我省建筑事业的发展,这些风压值显得不足。因此,本文根据我省最大风速的基本情况,参照国内对风压问题的研究方法和经验,充分利用各县站的风速资料,参考灾情记载,对最大风速做了数理     

甘肃省的风压

风压是建筑结构设计中的基本依据之一。风压的大小不仪影响建筑物设计的合理性,而且影响工程的安全与经济效益。我们根据现行的《工业与民用建筑结构荷载规范》的要求,计算了全省的基本风压值,并结合极大风速给出了风压建议采用值,同时对全省风压的分布进行了分析,供有关部门使用参考。     

气象为工业生产服务

气象为厂房、楼房设计服务 工厂厂房,各种楼房设计,都必须考虑风压这个因素。 所谓风压,即大风在瞬时间对一平方米建筑物所产生的力。风压与风速成正比,风速越大,所产生的风压也就越大。在一定范围内,风速与地势高度成正比。一般说来,地势越高,风速就越大,风压也就越大。因此,在设计厂房、修建楼房时,必须对当地风压进行详细调查,采取必要的措施。不然,如果风压估计太小,一旦大风袭击,就要造成损失,甚至事故;如盲目地把风压估计大了,多用了许多钢材和人力,造成不必要的浪费。     

我区基本风压的分析

我区基本风压的分析单惠茹（内蒙古气候中心）风压是垂直于气流平面上所受到的风的压强，其单位为千牛顿／平方米，风压在建筑上称风荷载，风荷载直接影响着各种建筑工程的设计、施工和使用安全。所以，正确的计算和确定各地不同重现期的风压值，对各项建筑工程的抗风安全...     

也谈大风廓线的分布

风压是建筑物承受的主要自然荷载。由于各高度上的风压值是根据地面风速资料推算的,而风随高度变化的实测资料较少,所以究竟用什么方法来推算才比较符合实际,还有一些不同的看法。下面谈谈我们对这方面一些问题的看法。     

高层建筑顶部平均风速的推求

为了适应高耸建筑物的需要,工程设计迫切要求了解在强风情况下,风对建筑物影响的各种有关数据。为此,从1974年起,在广东省建委主持下,组织了共14个单位,在广州宾馆进行了风压、风振的实测研究工作,我台也参与了上述协作。 在探讨和研究风荷载对高层建筑物与构筑物的影响时,10分钟平均风速是风的一个重要统计特征,它的大小直接关系到建筑物的安全、经济和适用。例如:塘沽1966年8月28日瞬时风速虽大,达48.7米/秒,     

赣州风压计算的尝试

现在高层建筑越来越多,需要了解当地风压资料也越来越多。过去没有计算过本地风压,往往只提供了当地的风速资料。由于使用单位对风速资料的具体情况不太了解,可能计算出的风压资料有一定偏差。为了给建筑工程设计提供比较合理的风压值,以达到安全与经济的目的,笔者对赣州风压的计算作了一次尝试。对赣州基本风压公式与计算条件风压是在最大风速时,垂直于风向平面上所受到的压强,单位是kg,m。它可分为稳定风压（基本风压）和脉动风压（风振）。稳定风压是一般房屋设计应考虑的,而脉动风压是在设计高耸、柔性构筑物如烟囱、水塔和广…     

黑龙江省主要城市建筑风压计算与分析

了解一个城市最大风荷载是对高大建筑物和电信发射塔的安全保障之一。全国建筑设计大纲中给定的风压小于黑龙江省实际发生的最大风压。因此，在黑龙江省对于重点建设项目，具体地点应进行实地风压计算，以保证工程项目的安全。     

新疆建筑工程设计中风压研究及其应用

应用熵最大原理导出的概率模式研究了新疆建筑工程设计中最大风速的分布规律 ,并通过近100个气象观测站36年(1961～1996年)资料的分析 ,发现新疆最大风速若干规律性 ,在此基础上 ,建立了新疆风压系数预测模式为 :W。=0.0613e -0.0001h ,以预测模式和概率模式揭示了新疆风压分布特征。结果表明 :新疆大多数气象观测站的最大风速遵循Г分布 ;新疆风压系数随海拔高度的增加呈指数率减少 ;新疆风压分布特征为 :北疆大于南疆 ,西部、东部大于中部 ;高山和高原地区大于中低山区。风口、河谷风压值最大。塔里木油田地区风压特征为 :由东北向西南递减。这对于新疆建筑工程设计及相关的电力、公路等工程设计都具有重要的科学意义和使用价值。     

建筑物防雷设计容易忽视的问题

在现代社会中,由于经济的发展,特别是各种高灵敏度、精密电子电气设备进入家庭,人们逐渐认识到预防雷电的重要性。并对建筑物及其内部设备的防雷安全提出了更高的要求。然而,目前的防雷技术设计工作,还存在许多不容忽视的问题。 首先,有些建筑物防雷设计没有体现综合防雷的思想。过去和现在,许多建筑设计部门在对建筑物进行防雷设计的过程中,仅停留在外部防雷装置（ＬＰＳ）的设计上,认为只要安装了诸如避雷针（带、网）之类的防雷设施,就万事大吉了。但是,随着各种高档电子设备的出现,这种设计思维就引出新问题了,有许多建筑…     

北太平洋爆发性气旋的气候特征

利用1968—1987年的海平面天气图资料，分析了爆发性气旋的气候特点。主要内容有:爆发性气旋的发生频率，频率的时间分布，地理分布，大风强度及分布方位、气旋爆发前后的大风、中心气压、加深率等要素的变化。     

Evidence from the Historical Record to Support Projection of Future Wind Regimes: An Application to Canada

In the field of climate change impact analysis, bidirectional changes in projections of future wind regimes varying among studies, locations, and models have been described in the literature, which is understandable from a global perspective. However, we should attempt to find evidence in the historical record to support these projections. This paper attempts to address this issue by analyzing historical wind gust observations for up to 57 years (1953–2009) over Canada. Two wind gust analysis techniques were used: the speed of daily wind gust events ≥50?km?h^?1 was compared with (1) the climatological daily temperature anomaly and (2) the climatological daily sea level air pressure anomaly. In addition, the frequency of daily wind gust events ≥90?km?h^?1 was compared with both daily temperature and pressure anomalies. The results indicate that during the past five decades gust wind speed over Canada increased significantly as the daily temperature anomaly increased and the daily pressure anomaly decreased. About 50–60% of daily wind gust events ≥90?km?h^?1 occurred with positive daily temperature anomalies and negative daily pressure anomalies. One major conclusion is that the methods used in and results derived from this study might be applied to climate change impact analysis to support projections of future wind regimes.     

Observations of sea-breeze fronts near the shoreline

Results from an observational study of sea-breeze fronts as they cross a shoreline are presented. Two kinds of fronts are analyzed, one with an offshore regional wind and one without. Their structure is found to be substantially different, the former being steeper and having stronger gradients. Measurements of the profiles of the vertical component of the wind speed, its standard deviation and the structure parameter for temperature are presented along with time series of the structure parameters for water vapor pressure and wind speed. The vertical wind component, w, is found to be of the order of 1.0–1.5 ms^–1 in the front zone of the sharp front but only 5 as large in the weaker front. The usual height variation laws under convective conditions are found to apply for both the vertical velocity variance and the temperature structure parameter, which in conjunction with the appropriate spectra indicate that local equilibrium is re-established fairly quickly after the passage of the front. Substantial differences have also been noted in the values of the structure parameters before and after the front, especially in the water vapor pressure and wind speed, differences which are of dissimilar magnitude and sign for the two kinds of fronts.     

Mesoscale observations of surface fronts and low pressure centres in Canadian East Coast winter storms

The movements of surface cold and warm fronts and low pressure centres have been observed in several Atlantic Canada winter storms. Statistical aspects of the well-defined surface fronts (7 warm and 6 cold) are presented. Surface wind direction change was considered as the best indicator of the boundaries of the front; frontal zone widths ranged from 23 to 144 km. Average values of wind shifts were 107° for the cold fronts and 85° for warm fronts. Several case studies are presented, based primarily on surface MesoNet data (near Halifax, Nova Scotia and on Sable Island). In two of the cold fronts, there was a two-stage surface structure and rapid evolution as the front passed over the MesoNet. In some cases, both warm and cold, the wind shift and temperature change were coincident while in others they were not. In particular we observed that wind shifts often started 20–30 min ahead of the start of a temperature decrease in these cold frontal passages. A possible mechanism for this is discussed. We found little or no evidence of along-front structure in our data although other investigators have found considerable along-front variation on scales of 0(10 km). Observations of the passage of one low pressure centre are presented. In a second case, surface temperature changes indicated an apparent low pressure centre passage through the Sable Island MesoNet but closer inspection provides an alternative interpretation.     

暴雨系统数值预报初值中气象变量的相对重要性

修改初值中的某些变量,积分模式,与“对照过程”相比较,以确定在暴雨系统数值预报中一些变量的相对重要性问题。初始的水汽分布和边界层风场相对说来是不重要的。通过动力学上的联系,在积分6—12小时后能迅速的调整出和“对照过程”基本上一致的场。地面气压场是重要的。修改地面气压场后,预报的形势和降水量有根本性的改变。     

An analysis of six simultaneous wind records taken near Vancouver

Abstract

Hourly wind speeds and directions taken at six sites near Vancouver, Canada over a period of one year during 1971–1972 have been analyzed. Mean magnitude ratios obtained for different wind directions under high wind conditions vary from about 0.3 to 1.4 and can be explained qualitatively by local shelter effects, local terrain effects or anemometer heights. The mean magnitude ratio is in every case shown to be essentially identical to the ratio of mean wind magnitudes, for high wind conditions; this is justified by simple analysis. The standard deviation of the magnitude ratio lies between 0.24 and 0.69 of the mean ratio. Uncertainty in this mean ratio, which is an important link in wind engineering design, may have to be incorporated into statistical design procedures to avoid taking unknown risks in the estimation of design wind speeds.     

从单Doppler速度场反演风矢量场的VAP方法

从单Doppler速度场反演风矢量场的VAP(Velocity Azimuth Processing)方法是在假定相邻方位角的风矢量相等的前提下,从单部Doppler雷达所测得的各个距离圈上的径向速度随方位角分布的廓线推算风向和风速的方法。这个假定可以保证反演所得的风矢量场中仍保留次天气尺度的风场信息。 对VAP方法反演公式的误差分析表明,反演出的风向误差为20—30度,与常规测风的误差相近。风速误差一般为10~0m/s,但在某些特定的情况下可达到与风速相同的量级(10~1m/s)。 用VAP方法反演风矢量场前必须首先消除原始Doppler速度资料中的脉动。它可以通过简单的一维线性平滑实现。 文中给出了一个反演实例,从中可以分析出次天气尺度的切变线和辐合线。常规天气图和UHF雷达的风廓线观测表明,这些次天气尺度系统是存在的。它们与反射率因子分布的配置还表明这些次天气尺度系统是和降水相联系的。     

Two-point velocity statistics over Lake Ontario

Cross-spectra between wind speeds on several masts in Lake Ontario have been analyzed. As previously predicted, coherence over water (small intensity of turbulence) between wind speeds measured on masts lined up with the wind appears to be larger than over land, and increases with decreasing Richardson numbers. As a result, in cold air over warm water, wind speed fluctuations are well predictable from upstream measurements. For large angles between the anemometer line and wind, the difference between coherence over land and water disappears. Furthermore, there is no significant difference in vertical coherence between water and land. When the wind is parallel to the anemometer line, small eddies travel, in agreement with Taylor's hypothesis, with the local mean wind speed. Large eddies travel significantly faster. Vertical phase delay increases with increasing Richardson number.     

Mass transfer to bean leaves

A vapour of radio-lead (²¹²Pb) has been used to measure the Sherwood number, Sh, of model leaves at various angles of incidence,, to the airstream in a wind tunnel. The results for=0 are compared with Pohlhausen's formula and the results for 0, with Powell's experiments. The local values of Sh on the upwind and downwind sides of discs have been obtained. For leaves in the canopy, Sh was found to be about 25% greater than would be predicted by applying Pohlhausen's equation without correction for orientation.     

Lower Tropospheric Structure and Synoptic Scale Circulation Patterns During Prolonged Temperature Inversions over Athens, Greece

Summary In this paper an attempt is made to detect prolonged (of more than 24 hours duration) temperature inversions in the planetary boundary layer over Athens, to study their main characteristics and to find out the synoptic situations with which the inversions are associated. Given the close relationship between the synoptic-scale atmospheric circulation and the occurrence, maintainance and decay of temperature inversions, a simultaneous three category classification of presented inversions and their respective synoptic situations is presented. The classification relies mainly on the similarities and differences in the formation and the maintenance of prolonged temperature inversions. To provide a record of the structure of the lower troposphere and the synoptic conditions favourable to the formation of inversions, mean ascents of temperature and dew-point temperature and mean wind profiles for the years 1980–1994 were calculated for each category into which a total of 297 cases fell. The main element of this structure which strongly affects the pollution of the lower troposphere is the prolonged temperature inversion. Also, for each category, mean 500 and 850 hPa heights and temperature charts, 500 hPa height anomaly charts, mean sea level (MSL) pressure charts and MSL pressure anomaly charts were drawn. Received March 11, 1997 Revised October 6, 1997