风电场风资源测量与计算的精度控制

根据多个复杂地形风电场观测操作实践和大量观测数据的计算分析,提出了对观测数据和计算质量精度控制的主要措施,包括:复杂地形测风站布设的5个原则,仪器的合理选型和设置;对由于测风仪固有的系统误差和缺测数据的插补订正可能引起的计算误差进行了定量估算,通过对大量实测数据的对比计算显示:①目前普遍采用的进口风速计的相对偏差在1.6%～5.25%之间,由此可导致轮毂高度附近的年平均风功率密度误差在5%以上,最大达13.8%;②在季风气候区、复杂地形和风的年变率较大的地区,进行缺测数据插补订正时,应选取同季或同一主导风向的数据作为插补订正的基础数据,否则可能导致其平均风功率密度相对误差达20%～50%.     

VALIDATION OF NEAR-SURFACE WINDS OBTAINED BY A HYBRID WRF/CALMET MODELING SYSTEM OVER A COASTAL ISLAND WITH COMPLEX TERRAIN

The results from a hybrid approach that combines a mesoscale meteorological model with a diagnostic model to produce high-resolution wind fields in complex coastal topography are evaluated.The diagnostic wind model(California Meteorological Model,CALMET) with 100-m horizontal spacing was driven with outputs from the Weather Research and Forecasting(WRF) model to obtain near-surface winds for the 1-year period from 12 September 2003 to 11 September 2004.Results were compared with wind observations at four sites.Traditional statistical scores,including correlation coefficients,standard deviations(SDs) and mean absolute errors(MAEs),indicate that the wind estimates from the WRF/CALMET modeling system are produced reasonably well.The correlation coefficients are relatively large,ranging from 0.5 to 0.7 for the zonal wind component and from 0.75 to 0.85 for the meridional wind component.MAEs for wind speed range from 1.5 to 2.0 m s-1 at 10 meters above ground level(AGL) and from 2.0 to 2.5 m s-1 at 60 m AGL.MAEs for wind direction range from 30 to 40 degrees at both levels.A spectral decomposition of the time series of wind speed shows positive impacts of CALMET in improving the mesoscale winds.Moreover,combining the CALMET model with WRF significantly improves the spatial variability of the simulated wind fields.It can be concluded that the WRF/CALMET modeling system is capable of providing a detailed near-surface wind field,but the physics in the diagnostic CALMET model needs to be further improved.     

基于MODE对模式预报强风风场的检验分析

基于专业气象服务领域十分关注的模式强风预报性能的客观检验和致灾性强风预警服务效果的合理性判别问题,利用一次强风过程对电网专业气象预警服务效果的检验示范,探讨基于目标(面向对象)的诊断检验方法(Method for ObjectBased Diagnostic Evaluation,MODE)对强风事件检验的适用性。通过对强风空间检验的各个关键参数的选择确定、匹配分析,发现:(1)MODE检验的卷积半径、诊断量权重和匹配阈值等参数的选择,将影响检验目标的适度聚焦和误差表达的客观性,因此需要综合考虑预报和实况场的水平分辨率、用户对该类强天气预报误差的空间和时间冗余度等;(2)MODE检验可较好地量化给出模式预报的整体效果,包括:强风落区的范围大小和位置偏差、强风过程的时间相位差等,从而可量化判别出模式在各个时刻的空报和漏报区域以及对强风过程移动速度和生命周期长度的预报性能。     

登陆台风近地层湍流特征观测分析

在对多个登陆台风实地观测的基础上,选取出较有代表性的实验观测个例:“黄蜂”、“杜鹃”和“黑格比”3个登陆台风,分析探讨在登陆台风的中心、靠近中心位置的强烈影响区域和台风外围环流影响地区近地层湍流特征,以期对登陆台风的边界层湍流过程有所认识。观测资料分析显示,在登陆台风的中心及其强烈影响的区域:(1)风速和湍流强度均有强烈的变化;(2)水平湍流积分尺度明显增大,越靠近中心位置,增大越明显,而垂直方向没有明显变化;(3)在湍流谱的低频和高频区,湍能均可增大1~2个量级,其中垂直方向湍能增大的幅度略小于水平方向;(4)湍谱在惯性子区u,v,w3个方向的分布均不满足-5/3次方律,存在较大偏移,而在台风外围环流影响区和无台风影响时,则无上述的4个特征。     

广东省酸雨分布特征及其影响因素

根据广东省气象部门所属4个酸雨监测站10多年的资料,研究了广东省降水pH值、酸雨频率的时空分布特征及其影响因素.分析结果表明,广州、韶关和电白的酸雨频率都在56%以上,降水pH年均值小于4.9,汕头的酸雨虽然较轻,但降水pH年均值仍小于5.6,酸雨频率也达到31.7%.4个站均表现出春季降水pH值低、酸雨频率高的季节分布特征.近年来,广州、韶关、汕头的降水pH值变化不大,酸雨频率却呈上升趋势.广东酸雨的形成不仅与SO2排放量高、气溶胶酸化缓冲能力低有关,也与天气系统和气象条件有关.     

IEC的风机选型参数估算方法在中国的适用性研究

国际电工委员会编制的《风力发电机组设计要求》(IEC 61400-1)推荐了针对风电机组安全等级评估的极端风速和湍流强度特征值估算方法,因其简单便捷,在风电领域被广泛采用。利用全国风能资源专业观测网的193座测风塔观测数据,对IEC推荐的极端风速计算方法与我国规范推荐的基于极值I型概率分布方法进行比较,发现两种方法计算的193座塔70 m高度层50年一遇10 min平均最大风速,仅有7座测风塔较为一致,差异在±1%;IEC推荐方法的计算结果多数偏小,其中偏小10%以上的测风塔有121座,偏小30%以上的有44座测风塔,而偏大10%以上的只有9座测风塔;IEC方法计算的极值风速大幅度偏小的测风塔主要分布在台风影响的东南沿海地区,偏差较小的测风塔主要分布在西北和华北地形平缓区域,但同时偏大10%以上的测风塔也多分布在这一地区。以目前行业领域普遍采用的以15 m·s~(-1)风速的平均湍流强度作为风电机组选型指标,与严格按照规范,以15 m·s~(-1)风速段所有样本湍流强度的90%分位数处的值作为指标进行风电机组等级确定作对比,发现193座塔中有46座塔的选型是不安全的,甚至相差两个等级。     

广东韶关南华寺水松的年代及生境初步研究

通过树轮钻取样及查考历史资料,论证南华寺水松栽种年代分别为明代正德十四年、清代康熙初年及清代同治末年.取水样作化学分析及收集近数十年环境观测资料,分析水松荣枯的原因.认为环境污染及不恰当人为活动是多株水松枯萎的主要原因.     

Computation of Wave, Tide and Wind Current for the South China Sea Under Tropical Cyclones

Based on the third-generation oceanic wave prediction model (WAVEWATCH Ⅲ) ,the third-generation nearshore wave calculation model (SWAN) and the mathematical tide, tidal current and cyclone current model, which have been improved, interconnected and expanded, a coupled model of offshore wave, tide and sea current under tropical cyclone surges in the South China Sea has been established. The coupled model is driven by the tropical cyclone field containing the background wind field. In order to test the hindcasting effect of the mathematical model, a comparison has been made between the calculated results and the observational results of waves of 15 cyclone cases, water levels and current velocities of the of 7 cyclones. The results of verification indicate that the calculated and observed results are basically identical.     

Characteristics of Drag Coefficient in Different Coastal Regions of the South China Sea Under Tropical Cyclones–An Observational Study

To investigate the values of 10-m drag coefficient (CD) in different coastal areas under the influence of tropical cyclones, the present study used the observational data from four towers in different coastal areas of the South China Sea (SCS) during six tropical cyclone (TC) passages, and employed the eddy covariance method and the flux profile method. The analysis of footprint showed that the fluxes at Zhizai Island (ZZI), Sanjiao Island (SJI) and Donghai Island (DHI) were influenced basically by the ocean, and the flux at Shangyang Town (SYT) was influenced mainly by the land. The results showed that the dependence relationships of CD on 10-m wind speed (U10) in four different coastal areas under the influence of TCs were different. CD at ZZI and SJI initially increased and then decreased as U10 increased, similar to the pattern over the ocean. CD at ZZI and SJI represented the values over shallow water with seawater depths of ~7 m and ~2 m, respectively. Moreover, the critical wind speed at which CD peaked gradually decreased as the seawater depth became shallower in the coastal areas. CD at DHI and SYT decreased monotonously as U10 increased, similar to the pattern over the land. CD at DHI represented the value over the transition zone from shallow water to coastal land, and CD at SYT represented the value over the coastal land. Meanwhile, the eddy covariance method and the flux profile method were compared at ZZI and SYT during TC passages. It was found that their CD values obtained by the two methods were close. Finally, the parameterizations of observed u* and CD as a function of U10 over four different coastal areas were given under the influence of high winds. These parameterizations of observed C may be used in high-resolution numerical models for landfalling TC forecast.     

广东省风速极值Ⅰ型分布参数估计方法的比较

利用广东省86个气象站1951—2003年的年最大风速序列资料,应用极值Ⅰ型分布函数对各站的年极值风速进行了概率计算,计算过程中极值Ⅰ型分布函数分别采用了3种参数估计方法：矩法、耿贝尔法和极大似然法,结合3种表征参数估计优良性的指标,对不同的参数估计方法进行了比较,结果表明：大多数情况下采用耿贝尔法时拟合效果最好,即使在矩法或极大似然法为优的情况下,其拟合优良性指标与耿贝尔法也较为接近。