投影寻踪门限回归模型在年径流预测中的应用

为预测年径流这类同维复杂动力系统，提出了投影寻踪门限回归（PPTR）模型。构造了新的投影指标函数，用门限回归（TR）模型描述投影值与预测对象间的非线性关系，并用实码加速遗传算法优化投影指标指数函数和TR模型参数。实例的计算结果表明，用PPTR模型预测年径流是可行而有效的。PPRT模型简便、适用性强，克服了目前投影寻踪方法计算量大、编程实现困难的缺点，有利投影寻踪方法的推广应用，为解决高维非线性复杂预测问题提供了新途径。     

甘肃春小麦产量时空分布及其气候响应

利用近45 a甘肃省78县区春小麦实际产量生长期(3～6月)气温、降水和日照时数等资料,主要采用REOF和小波分析等方法,分析春小麦产量时空演变及气候响应。结果表明:1)甘肃春小麦产量由西向东、由北到南产量递减;2)存在河东、河西2个特别区域,春小麦在河西走廊地区高产而稳定,河东地区明显产量低且不稳定,陇中黄土高原地区最为突出;河西走廊区域产量变化与陇中反向,及河西产量偏高年份河东反而偏低,反之亦然。河东地区相关程度很高,产量变化与河西反向;3)河西走廊地区对气温响应敏感,甘肃黄土高原地区对干湿(降水)的变化敏感;4)响应最敏感区产量1991年之前变幅较小,之后变幅加大;丰欠年份相间,存在2～3 a的准振荡周期。     

DIAGNOSTIC ANALYSIS OF PERSISTENT DROUGHT/FLOOD EVENTS IN SUMMER OVER THE TWO-LAKE REGION OF CHINA

Based on the daily regional mean rainfall,the Z-index method is used to identify persistent flood and drought events lasting for at least 10 days over a region where Dongting Lake and Poyang Lake sit(referred to as the"two-lake region"hereafter).The National Centers for Environmental Prediction(NCEP)reanalysis data are then utilized to perform a preliminary diagnostic analysis on these events.The results indicate that the composite standardized geopotential height at 500 hPa presents two different meridional wave trains from north to south over the East Asian-Pacific region,i.e.,a"-+-"pattern for the droughts and a"+-+"pattern for the floods,respectively.The developing,maintaining and decaying phases in the drought and flood events are closely related to the intensity and location of a subtropical high and an extra-tropical blocking high.It is shown that the East Asian summer monsoon is strong(weak)with the occurrence of persistent drought(flood)events.Droughts(floods)are accompanied by a weak(strong)tropical convergent system and a strong(weak)subtropical convergent system.Furthermore,the persistent drought(flood)events are associated with a divergence(convergence)of vertically integrated water vapor flux.In the vertical profile of water vapor flux,divergence(convergence)in the mid-and lower-levels and convergence(divergence)in the higher levels are evident in the droughts(floods).Both the divergence in the droughts and the convergence in floods are strongest at 850 hPa.     

Composition and major sources of organic compounds in urban aerosols

Total suspended particles (TSP), collected during June 2002 to July 2003 in Guangzhou, a typical economically developed city in South China, were analyzed for the organic compound compositions using gas chromatography–mass spectrometry (GC/MS). Over 140 organic compounds were detected in the aerosols and grouped into different classes including n-alkanes, hopanoids, polycyclic aromatic hydrocarbons, alkanols, fatty acids, dicarboxylic acids excluding oxalic acid, polyols/polyacids, lignin products, phytosterols, phthalates and water-soluble sugars. The total amounts of the identified organic compounds including unresolved complex mixture (UCM) ranged from 3112 ng/m³ in spring to 5116 ng/m³ in winter, comprising on seasonal average 2.8% of TSP. Primary organic compounds peaked in winter although there are no heating systems burning fuels in Guangzhou. The highest saccharide levels occurred in fall due to agricultural activities. This study demonstrated that utilization of fossil fuels, biomass burning, soil resuspension and plastic/refuse burning are the major contributors to the identified organic compounds in the urban atmosphere of South China.     

DYNAMIC INFLUENCE OF QINGHAI-XIZANG PLATEAU AND ROCKY MOUNTAINS ON THE LEE CYCLONES

Using the operational model(B model)of Beijing Meteorological Center,we do some of numerical experi-ments of crossing and rounding mountains in all velocity adjustment scheme,and study dynamic effect ofQinghai-Xizang Plateau and Rocky Mountains on lee cyclones.The results show that due to air flow roundthe Qinghai-Xizang Plateau,divergence is distributed in the shape of confluence which matches cyclogenesisarea and cyclonic track in East Asia.In the downstream of the Qinghai-Xizang Plateau,convergence inthe upper troposphere restrains cyclone development in the east of China mainland.In North America,air flow primarily crosses over Rocky Mountains.Air is adiabatically cooled when it flows upward in thewest flank of Rocky Mountains,while air is warmed when it flows downward in the lee side.The fact isimportant for the lee cyclogenesis and the lee frontogenesis of Rocky Mountains.Air flow crossing over RockyMountains is also the main cause for forming dryline in the mid-west of United States.     

基于GIS的安徽省重大农业气象灾害测评系统

以安徽省重大农业气象灾害的气候规律分析及遥感监测方法的基础,利用地理信息系统技术,设计并建立了省级农业气象灾害测评系统。该系统运用结构化设计原理,根据用户需求及系统建设的基本目标,确定了系统结构及主要功能,以为主要支撑软件,建立了安徽省干旱,洪涝及低温冷害的基本数据库、灾害监测评估模型和应急反应及决策服务系统。     

T213数值预报产品在2003年宁夏首场透雨天气过程中的应用分析

2003年5月5～6日,宁夏出现了入春以来第一场透雨天气过程,本文利用常规天气资料和T213数值预报产品,对此次降水天气过程从主要影响系统和T213数值预报有关物理量预报场等方面进行分析发现,T213对我区降水有很好的预报能力和指示意义,并随着预报时效的缩短,其可信度在不断提高。     

北京及周边地区雷暴阵风锋特征统计分析

为全面和系统研究北京及周边地区阵风锋各方面特征,使用2006—2015年暖季(5—9月)北京多普勒雷达探测资料及北京、河北、天津自动气象站观测资料对北京及周边地区的阵风锋过程进行综合统计分析。结果表明,346次阵风锋过程有232次触发了对流,占总数的67%,表明阵风锋对雷暴具有较强的抬升触发能力。阵风锋在6—8月出现的日数占5—9月阵风锋总日数的85%;出现的时段主要是午后至傍晚(12—21时,北京时),维持时间0.5—3 h;阵风锋在北京东南方向生成的数量最多,且触发对流的次数也最多;其次为偏东和东北方向;偏南和西南方向生成阵风锋数量居中,而偏北、偏西和西北地区阵风锋个例相对较少,触发对流的比例也相对较低。产生阵风锋的母风暴中48%为孤立雷暴(包括孤立多单体和超级单体风暴),31%为雷暴群,21%为飑线;97%的母风暴最强回波在50 dBz以上,阵风锋的回波强度为10—25 dBz。91%的阵风锋移动速度集中在10—60 km/h,84%的阵风锋与母风暴的最大距离为1—60 km;在母风暴回波强度减弱到30 dBz以下时,80%的阵风锋能够继续维持的时间不超过2 h。阵风锋母风暴向东...     

掩星弯角资料同化在一次暴雨过程中的应用

使用GPS掩星弯角资料和NCEP预报场资料,采用GSI(Grid-point Statistical Interpolation)变分同化系统,对同化掩星弯角资料前后的分析场以及数值预报结果进行详细比较,分析了弯角资料同化对2012年7月21日北京特大暴雨预报结果的影响。结果表明,同化掩星弯角资料对初始场中的温度、湿度产生明显影响,500 hPa和700 hPa温度调整中心量值达到0.5℃和-0.6℃,700 hPa湿度调整中心最大量值达-0.14 kg·kg-1;同化过程改变了强降水发生前流场结构,明显提高了强降水中心位置、雨带走向及范围、降水强度的预报准确性;由降水TS评分可知,200 mm以上大暴雨模拟改善效果明显,但对弱降水预报效果较差。     

A GENERALIZED CANONICAL MIXED REGRESSION MODEL FOR ENSO PREDICTION WITH ITS EXPELMENT

A scheme is proposed for predicting NINO-region SST in terms of a generalized canonical mixedregression model based on principal component canonical correlation analysis(PC-CCA). and into the scheme are introduced such techniques as EEOF, PRESS criterion and consensus prediction. By optimizing physicalfactors and selecting optimal model parameters, experiments were made successful in predicting the LINO SST index for 1 to 4 seasons to follow. The scheme is shown to be stable in operation and its total technical level compares well with that of the model published in NOAA/NWS/NCEP CPC Climate Diagnostics Bulletin. butthe number of factors needed in our scheme is much fewer than that for the CPC's model in dealing with the sameproblems. This makes it possible to establish an operational ENSO monitoring system in China.