广西地面观测场四周障碍物影响分析

引入障碍物遮挡率和遮挡程度两种评定方法，对广西各站观测场四周障碍物进行分析，结果表明：广西地面观测场四周障碍物影响程度属于轻度或以下的台站占50％；属于中度影响占15％；达到重度占35％。     

气象观测环境变化对气象记录准确性的影响情况分析

揭阳市气象台观测场现已处于闹市中心 ,周围的楼房已越建越接近围栏 ,并越建越高。已对观测场形成包围态势 ,严重破坏了观测环境 ,对气象观测记录的准确性、代表性、比较性造成严重的影响。为了了解环境变坏对记录的影响情况 ,特对揭阳市气象台 46年的部分气象要素观测资料作一次粗浅的分析。1　观测场外周围环境介绍　　现在站在观测场向四周眺望 ,已见不到绿野。周围障碍物都是水泥楼房 ,障碍物最大仰角分别是 :方位 32 0～ 30°,仰角 36° ;30～ 1 5 0° ,仰角 2 9° ;1 5 0～ 2 2 5° ,仰角 32°;2 2 5～ 32 0°,仰角 5 1°。观测场外围…     

浅谈黔东南自治州气象探测环境

通过选取黔东南自治州16个县地面观测环境中不符合要求障碍物累计遮挡方位及遮挡面积、日出日落方向障碍物最大仰角、遮拦仪器感应面障碍物个数进行综合评定分析,结果表明:黔东南自治州有5个县市的地面气象探测环境表现出较差,综合评分在90分以上;只有4个县市气象探测环境相对较好,综合评分在90分以上。影响气象探测环境的主要因素是外部的影响和内部建设影响。     

台站遮挡对日照观测数据的一致性影响与订正方法研究

利用台站观测场周围360°遮挡仰角和云量观测数据,分析了台站遮挡对日照观测数据的一致性影响,从太阳高度角和遮挡物仰角的相对关系、云对遮挡比例的修正两个方面,建立了云天气象条件下台站遮挡日照时数的订正方法。以重庆巫山站为例,对2004—2013年期间有严重遮挡情况下的日照时数进行了遮挡计算和订正,通过遮挡期间及前、后两个未遮挡时段的纵向对比,以及与地形和气候条件相近的湖北建始站的同期横向对比,对订正效果进行了检验,结果表明:巫山站观测场周围遮挡物影响了日照时数观测,使观测数据前后产生明显的不一致;2004—2013年期间平均被遮挡的日照时数为218.0 h·a~(-1),遮挡比例达13.1%,受天气条件的对冲影响,夏半年遮挡影响可能高于冬半年;从纵向和横向两个方面的间接对比检验看,本文所建立的订正方法既计算了遮挡物自身的影响,又考虑了云天条件下对遮挡比例的修正,订正结果基本合理,可以相对准确地还原被遮挡的日照时数。     

利用Google earth调查气象台站环境

利用Google earth地图软件,可查看台站周围的环境,测定干扰源距地面观测场围栏的距离,并分析干扰源与观测状况。该软件可以帮助了解台站周围土地使用情况,登记周围障碍物,绘制台站和四周情况平面示意图。     

利用Google earth调查气象台站环境

利用Google earth地图软件,可查看台站周围的环境,测定干扰源距地面观测场围栏的距离,并分析干扰源与观测状况.该软件可以帮助了解台站周围土地使用情况,登记周围障碍物,绘制台站和四周情况平面示意图.     

观测场环境变化对五华气象观测记录的影响

通过对1957～2007年部分气象要素值的对比分析,发现五华气象站从建站至1996年观测场四周环境逐渐恶化,年平均气温,最高、最低气温同过去相比有所升高.由于建筑物对风场的阻尼作用,所测得的风力逐渐偏小,静风频率增加,大风出现天数也逐渐减少.能见度观测的目标物全被建筑物遮挡,影响能见度观测的准确性.     

鹤山市新气象观测场防雷工程设计与施工技术探讨

<正>1观测场的气象地理环境鹤山市位于广东省珠三角南部地区,地处北回归线以南,属于南亚热带季风区,鹤山市气象局新气象观测站属于国家一般气象站,位于鹤山市雅瑶镇陈山村旱坑山顶(22°44'14"N,112°58'52"E),海拔高度为47.2m,观测场周围的观测环境比较好,北面是水库,南面是农田,四周没有阻挡观测的建(构)筑物。2观测场的综合防雷工程设计2.1观测场的防雷地网和独立接闪杆设计     

地面气象探测环境与能见度目标物图绘制中的考虑事项

利用地面气象观测站探测环境调查结果,分析观测场四周障碍物分布变动情况,对于选取能见度目标物有指导意义。在此基础上,运用Google earth、GPS、数码照相、visio2003软件等技术手段配合制作出新的能见度目标物分布图,有助于提高台站能见度观测业务质量。     

探测环境变化对密云气象站地面风观测的影响

文章利用密云站、上甸子站1994-2013年的地面风观测资料,以上甸子站作为参考站,对比分析了密云站第二阶段与第一阶段风观测值的差异。结果表明:第二阶段风速平均值较第一阶段减小了0.5 m·s~(-1);2013年年平均风速受台站周围环境影响最大;观测场周围障碍物对不同季节、月平均风速影响程度为:春季最大,夏季最小;3月最大,8月最小;观测场周围环境对西南偏西风风速影响最大,对1~2 m·s~(-1)风速频率影响最大。第二阶段静风频率增加了5.5%;各季静风频率均有增加,冬季最大,春季最小,秋季大于夏季。     

A TWO-DIMENSIONAL NUMERICAL STUDY OF WIND SHELTERING EFFECTS OF SHELTERBELTS

Based on the dynamic and thermodynamic equations in the SBL,the protection characteristics and mech-anism of shelterbelts are numerically studied in this paper.The results are in consistent with those ob-served in fields and wind-tunnels.Research shows that the belts with a permeability of 0.3—0.4 have themaximum sheltering effects.The distance where wind speed reduces at least by 20% is at 18—19 times oftree height(H)behind belts.The protection distance reduces fast with the increase of the permeability andslowly with its decrease.The belts have weaker sheltering effects in upstream,generally beyond 6H infront of belts there are no sheltering effects.In addition,the belts with low permeability at top and highpermeability at bottom have much better sheltering effects than the belts with high permeability at top andlow permeability at bottom.The belts with 50% overall permeability reduce wind speed at least,by 20%at the distance of 5H on the leeward side and by 10% at 11H.When the air is unstable,the protectingeffects will be reduced.For the uniform belts with a permeability of 0.35,the distance where wind speedreduces at least by 20% is 15H under the unstable air and 13H under very unstable air.The belts reducethe turbulent diffusion coefficient at the bottom of belts,but increase it at the top.     

河南日照变化特征及成因分析

利用线性分析方法,根据河南31个站1954~2005年的日照资料分析了河南省及濮阳市的日照变化特征。结果表明,河南省年日照时数呈减少趋势,平均减少每10年74.2 h,东部平原地区年日照时数的递减幅度明显大于西部山区年日照时数的递减幅度。濮阳市年日照时数的递减幅度为每10年135 h,冬季与夏季日照的递减幅度大于春季和秋季日照递减幅度,日照时数减少时段主要发生在日出后和日落前太阳高度角较低的两段时间内。造成日照减少的气候原因主要是空气污染逐年加重,加之风速逐年减小,利于大气气溶胶在低空积聚,空气湿度增大,轻雾日数增多,造成大气透明度降低。非气候因素的影响主要是观测场周围障碍物高度角逐年增高,遮挡了部分阳光,使记录到的日照时数减少,气候因素对日照的影响大于非气候因素的影响。     

Trends of surface ozone concentrations in germany and their connections with changes in meteorological variables

Changes in daily mean and daily maximum surface ozone concentrations, temperature, and relative humidity are evaluated based on the data of long-term observations (from 11 to 16 years) carried out at eight German stations. For all stations the trends of daily mean surface ozone concentration are statistically significant and positive. The trend values are different and generally range from 0 to 10% per 10 years. The trends of the maximum daily concentration are, on average, approximately 1.5 times less. Noticeable part of trends of the surface ozone concentration is connected with the trends of meteorological variables: temperature, relative humidity, and air mass transport direction. After the account of the influence of the trends of meteorological variables, the trends of the surface ozone concentration at most stations substantially decrease. The highest trend values of daily mean and daily maximum surface ozone concentrations are observed in a cold season; in a warm season, the trend values are much lower, at some stations they are statistically insignificant. A conclusion is made that for a correct revealing of reasons of long-term changes in the surface ozone concentration one should take into account changes in meteorological factors influencing its formation.     

降水时间随机性对月总降水量的影响

降水量在时间分布上呈现较大的随机性,极端降水事件尤为如此。受此影响,月初(月末) 1～5 d之内的累积降水量很可能会超过当月总降水量的50%乃至更多。对1961—2017年中国2 400多站点资料统计分析结果发现,月初(月末) 1～5 d累积降水量对当月总降水量显著影响事件的出现频次,在季节和空间分布上都有鲜明特征。主要包括:1)月初累积降水量对秋冬季中各月的总降水量影响更大,月末累积降水量对1—4月的月总降水量影响较大。2)受月初累积降水量的影响,显著站点数在某些年份的某些月份出现极大值;受单次事件显著影响的站点数占全国总站点数的30%～50%,此即对应着一次全国大范围的极端降水事件。3)受月初(月末)累积降水量显著影响的站点空间分布随季节变化呈现出明显空间集聚特征。     

Sea-level response to atmospheric forcing along the north coast of Persian Gulf

Summary Data from tide gauges (1990–1999) at Bandar Abbas and Bushehr combined with atmospheric data at both stations are utilized to investigate the mean sea-level (MSL) response to meteorological forcing functions along the north coast of the Persian Gulf. The relations between MSL and forces due to air pressure, air temperature and local wind are examined. The characteristics of variability of each field are analyzed using the spectral analysis method. The annual cycle is dominant in the sea-level, atmospheric pressure, air temperature and wind spectra. The influence of local meteorological functions are quantified using forward stepwise regression techniques. The results suggest that 71.5% and 71.2% variations in the MSL of Bandar Abbas and Bushehr stations are due to meteorological forces at each stations. The model indicates that the most significant influence on the observed variation of MSL at Bandar Abbas is air pressure, while at Bushehr is air temperature. The results of multivariate and simple regression show that these parameters are highly intercorrelated. The sea-level is not significantly correlated with the monthly and winter NAO and Monsoon in the Persian Gulf. The remaining variations are due to density of sea water (steric effect), which has considerable influence on the sea-level variations, and coastal upwelling.     

太阳总辐射最佳倾角的时空分布

本文根据倾斜面上太阳总辐最佳倾角的角析表示式，利用平均太阳总辐射和直接辐月总量以及实际地表面反射率，计算分析了我国各月最佳倾角和最佳总辐射比的时空变化特征。同时对用天空散射辐射各同性模式计算倾斜面上总辐日总量的适用性问题亦作了简要讨论。     

AN ANALYTICAL ONE-DIMENSIONAL MODEL OF MOMENTUM TRANSFER BY VEGETATION OF ARBITRARY STRUCTURE

An analyticalone-dimensional model of momentum transferby vegetation with variable foliage distribution,sheltering and drag coefficientis developed. The model relies on a simpleparameterization of the ratio of theabove-canopy friction velocity, u*, to thewind speed at the top of the canopy,u(h), to predict vegetation roughness length(z0) and displacement height(d) as functions of canopy height (h) and dragarea index. Model predictionsof d/h and z/h compare very favorably withobserved values.A model sensitivity analysis suggests that shelteringeffects for momentum transfertend to make canopies with non-uniform foliagedistribution resemble canopies withmore uniform foliage distribution and that anyinfluence wind speed has on d/hand z0/h is more likely to be related to theinfluence that wind speed may haveon u*/u(h) rather than the influence windspeed may have on the foliage dragcoefficient. Model results indicate that z0/hand d/h are sensitive to uncertaintiesin the numerical values of the model parameters,foliage density and distribution,sheltering effects and variations in drag coefficientwithin the canopy. In additionz0/h is also shown to be sensitive to thepresence or absence of the roughnesssublayer. Given the simplicity of the model it issuggested that it may be of usefor land surface parameterizations in large scalemodels.     

城市化对华北地区最高, 最低气温和日较差变化趋势的影响

利用华北地区255个一般站和国家基本、 基准站1961\_2000年的实测资料, 经过质量检验和均一性订正后, 将所有台站根据人口和台站地理位置分为5个类别, 分析了这5个类别台站和国家基本、 基准站地面平均气温、 最高、 最低气温的年和季节变化趋势以及城市化影响。结果表明： 华北全部台站的年平均气温、 最高、 最低气温均呈增加趋势, 且以最低气温上升最为明显, 导致年平均日较差呈现明显下降。就城市化影响而言, 平均气温、 最低气温变化趋势中城市热岛效应加强因素的影响明显, 但城市化对最高气温趋势影响微弱, 个别台站和季节甚至可能造成降温。在国家基本、 基准站观测的年平均气温和年平均最低气温上升趋势中, 城市化造成的增温分别为0.11℃·(10a)-1和0.20℃·(10a)-1, 对全部增温的贡献率分别达39.3%和52.6%。各类台站的四季平均气温和最低气温序列中城市化影响均造成增温。城市化增温以冬季为最大, 夏季最小。城市化还导致乡村站以外的各类台站日较差减小, 近40年华北地区国家基本、 基准站年平均和秋、 冬季平均气温日较差明显下降均由城市化影响造成的。     

Intensified reduction in summertime light rainfall over mountains compared with plains in Eastern China

Based on daily rainfall data from 1960 to 2007, this study investigated the difference in rainfall trends between seven mountain stations and 21 nearby plain stations in eastern China for the months June–August. The amount and frequency of light rain (≤2.5 mm/day) over the mountain areas showed a greater decreasing trend than over the surrounding plain regions. The trend of light-rainfall frequency at mountain stations is ??4.8%/decade, approximately double that at plain stations (??2.3%/decade). The trend in light-rainfall amount at mountain stations is ??5.0%/decade, approximately three times that at plains station (??1.4%/decade). Reduced wind speed may explain the enhanced decrease in light rainfall over mountain areas through the weakened orographic lifting. Further study is needed to determine whether the precipitation difference between mountain and plain (urban) regions is exacerbated by air pollution in East China through its indirect effects and influence on regional air stability and wind speed.     

多种均一性检验方法比较研究

气候资料的均一性检验对气候观测及变化研究有着重要作用。本文从四川省160个台站近50年气温资料中,选取具有连续观测记录的站点105个,综合SNHT(标准正态均一性检验)、Buishand检验、Pettitt检验、MASH(均一性序列多元分析)、TPR(二位相回归检验)和von Neumann比率法,对该省年平均气温进行均一性检验。结果表明有42个台站存在序列间断点,占40%;而不均一台站中,因迁站导致的有29个,更换仪器引起的有19个。对气温序列分年代统计发现不均一台站数目有增加的趋势,其中20世纪60—70和80—90年代不均一性均由台站迁移所致。评估不同检验方法的敏感度和适用性,发现SNHT法与Buishand法、Pettitt法检验结果相符率为48.6%,TPR法与其他方法相符率偏低,但该法不涉及邻近站是否均一,在分析中可做补充判断。参考四川省地形特征分析,SNHT法在盆地及山地台站的断点显露率最高,分别为67.6%和57.1%,漏检和误判较少;高原地区SNHT法和Buishand法显露率较高,其中Buishand法漏检和误判率最低。鉴于减小对元数据依赖度的均一化检验思路,应采用多种检验方法综合,有助于气候资料在区域气候变化研究中的有效利用。