Directional Characteristics of Potentially Damaging Wind Gusts in the Southeast United States

Annual estimated storm damage in the United States is seven billion dollars. Much of that damage is caused by tree blowover that is induced by high wind gusts. The prevailing directions of these wind gusts dictate the zones around structures in which trees may potentially fall and cause damage. To gain a better understanding of hazardous wind gusts, this research examines the directional component of wind gusts in the Southeast United States. Regional patterns of wind gusts are identified and tied to atmospheric and terrestrial patterns. Results indicate the following: (1) gusts along the northeast coast of the study area are bidirectional, being from the northeast and southwest; (2) the southeast coast has a predominantly westerly component to the gusts with little impact from the east; (3) the Piedmont is strongly influenced by westerly gusts, but an easterly component increases gradually to the northeast; and (4) high gusts in the mountains demonstrate a strong relationship with the regional and local topographic characteristics.     

我国东南沿海午后短时降水极端峰值强度与湿度和地表气温的关联

利用中国东南沿海地区55个站点的逐时降水、日平均地面温湿场、低空气温露点差及OISST海表温度资料,对午后短时降水的极端峰值强度与湿度和地表气温的关联进行分析。结果表明,东南沿海地区午后短时降水极端峰值强度随气温的变化趋势存在明显变化,日最高气温低于29℃时,峰值强度随气温升高而上升;日最高气温高于29℃时,峰值强度随气温升高而下降。分析水汽条件作用发现,峰值强度在高温条件下随气温的升高而下降的现象与相对湿度变化有关,日最高气温较高时,相对湿度随气温的升高而大幅减小。初步分析可知,当陆地达到较高温度并进一步增温时,附近海域海表温度变化不大,使得洋面水汽含量增加较少。在陆地水汽主要来自于海洋的情况下,伴随陆地的进一步升温,地表相对湿度将减小。     

Study of temperature and precipitation variations in Italy based on surface instrumental observations

In this paper we present a study concerning the climatic behaviour of two principal observables, temperature and precipitation as obtained from the measurements carried out at 50 Italian meteorological stations, since 1961. Analyses of WMO Climate Normals (CliNo) from 1961 to 1990 have been performed dividing the 50 Italian stations in three different classes: mountain (11 stations), continental (17) and coastal areas (21).The comparison of the CliNo 1961–1990 with the trend of temperature and precipitation for the period 1991–2000 showed a sharp significant increase of summer temperatures over Italy starting from 1980. This phenomenon was particularly evident for mountain stations, where a significant temperature increase has been recorded also during the autumn. Moreover, the analysis of precipitation data permitted to point out that, starting from 1980, mountain stations have been affected by a significant increase of precipitation events during autumn and winter, while for the rest of the Italian territory a reduction of precipitations has been recorded during early spring.     

SOFTWARE REVIEWS

AMOS—Analysis of MOment Structures . James Arbuckle CLIMATEDATA–Summary of the Day . (Version 1.10). HYDRODATA–U.S.G.S. Daily Values (Version 2.0). The MAP SETS (includes EUROPEAN MAPSET, US MAPSET and WORLD MAPSET). James Taylor     

Analysis of gravity waves in the tropical middle atmosphere over La Reunion Island (21°S, 55°E) with lidar using wavelet techniques

The capabilities of the continuous wavelet transform (CWT) and the multiresolution analysis (MRA) are presented in this work to measure vertical gravity wave characteristics. Wave properties are extracted from the first data set of Rayleigh lidar obtained between heights of 30 km and 60 km over La Reunion Island (21°S, 55°E) during the Austral winter in 1994 under subtropical conditions. The altitude-wavelength representations deduced from these methods provide information on the time and spatial evolution of the wave parameters of the observed dominant modes in vertical profiles such as the vertical wavelengths, the vertical phase speeds, the amplitudes of temperature perturbations and the distribution of wave energy. The spectra derived from measurements show the presence of localized quasi-monochromatic structures with vertical wavelengths <10 km. Three methods based on the wavelet techniques show evidence of a downward phase progression. A first climatology of the dominant modes observed during the Austral winter period reveals a dominant night activity of 2 or 3 quasi-monochromatic structures with vertical wavelengths between 1/2 km from the stratopause, 3/4 km and 6/10 km observed between heights of 30 km and 60 km. In addition, it reveals a dominant activity of modes with a vertical phase speed of –0.3 m/s and observed periods peaking at 3/4 h and 9 h. The characteristics of averaged vertical wavelengths appear to be similar to those observed during winter in the southern equatorial region and in the Northern Hemisphere at mid-latitudes.     

乐山大佛佛脚平台改善工程的实践

乐山大佛佛脚原平台的稳定性问题使游客安全受到严重影响,开展佛脚平台改善工程非常必要。在大佛工程地质条件分析基础上,进行了佛身稳定性验算,为平台改善工程的设计提供了理论依据。工程设计在充分考虑结构稳定性的同时,坚持保护世界文化遗产,避免人为破坏文物现状及原有景观的设计原则和理念,采用了由贴坡混凝土墙、挑梁及现浇混凝土平台面板构成主体结构的设计方案,新建的平台结构与周围景观协调,维护了世界文化遗产的自然特性,实现了大佛、平台、山体及泯江四位一体的美学效果。     

TOPOGRAPHIC SHADING AND GEOGRAPHICAL PATTERNS OF DIRECT SOLAR RADIATION IN MOUNTAINOUS REGIONS*

Topographic shading curtails the period and complicates the geographic patterns of insolation in mountainous areas. Maps derived from oblique aerial photographs of shadow lines cast by the irregular, mountainous east horizon in Provo, Utah are used as a case study to illustrate an alternative to existing techniques of solar radiation data collection. For study areas of several hundred square kilometers, this method may be superior in resolution and at the same time more error free and economically feasible than other methods. Measurement of solar inputs received at sample stations scattered through the mapped area show that the phenomenon of topographically delayed sunrise has a distinct effect on daily totals of radiation in the manner suggested by the maps.     

NEW APPROACH TO ESTIMATING SOLAR RADIATION FROM SATELLITE IMAGERY*

A significantly less expensive but comparatively accurate means of estimating solar radiation from satellite imagery is demonstrated. Opaque cloud cover is visually extracted from nondigitized, photographic forms of GOES satellite imagery and solar radiation is estimated using this information as input into a relatively simple solar model. Daily root mean square, mean absolute and mean bias errors were 13.2, 8.6 and 1.1 percent, respectively. Maps of the spatial distribution of solar radiation for Arizona are included.     

皖南国际文化旅游示范区旅游经济差异分析研究

利用极差、标准差、变异系数、基尼系数、赫芬达尔系数、首位度等方法,以2000~2013年皖南国际文化旅游示范区各地市的国内旅游收入、国际旅游收入以及旅游总收入为分析对象,揭示皖南国际文化旅游示范区区域旅游经济差异的时空特征。结果表明：① 皖南国际文化旅游示范区旅游发展规模呈现不平衡态势,各地市间绝对差异较大,相对差异逐渐减小;② 示范区内各地市的国内旅游收入差异和旅游总收入差异小于国际旅游收入差异;③ 2000~2013年皖南国际文化旅游示范区国内旅游收入和旅游总收入的基尼系数介于0.30~0.41之间,处于相对合理区间,国际旅游收入的基尼系数介于0.50~0.67之间,差距较大,甚至很悬殊;④ 国内旅游收入和旅游总收入城市首位度指数始终介于1.2~2.2之间,相对较大,第1位城市对第2位城市形成稳定的规模优势,而国际旅游收入城市首位度指数大部分时间介于3.0~9.5之间,第1位城市对第2位城市形成绝对的压倒性的规模优势。通过对皖南国际文化旅游示范区旅游经济差异成因进行分析,表明区域旅游经济规模与旅游资源禀赋、旅游基础设施建设、交通区位条件好坏、政府政策支持以及经济发展水平高低之间的关系密不可分。     

Developing parallel procedures for line simplification

Abstract

This paper explores parallel programming issues that are relevant to the efficient implementation of spatial data handling procedures on current parallel computers through sample implementations of the Douglas line simplification procedure. Using source code-equivalent implementations of the Douglas procedure, this paper analyses the performance characteristics of two parallel implementations, compares their performance characteristics to those of a sequential implementation, and identifies critical components of the parallel implementations that enhance or inhibit their overall performance values. The results of this work show that the selection of appropriate interprocessor communication and load balancing strategies are crucial to obtaining large speedup values over comparable sequential implementations.