云物理与人工影响天气研究进展

大气物理与人工影响天气
Atmospheric Physics and Weather Modif cation

云物理与人工影响天气研究进展

1 云物理观测研究

1.1 华北一次持续性重度雾霾天气的产生、演变与转化特征观测分析

2011年12月1—7日在华北地区发生了一次比较罕见、持续1周左右的低能见度重度雾霾天气。利用气象行业专项“京津地区低能见度雾霾天气监测与预报研究”观测试验资料，研究分析了此次持续性重度雾霾天气的气溶胶、云凝结核（CCN）、雾滴谱、含水量等微物理特征及大气能见度、边界层垂直结构特征，探讨了雾霾天气的产生、演变与转化特征及机理。结果表明，此次持续1周的雾霾天气过程发生在高压天气系统和静风条件下，暖平流和辐射降温形成的稳定逆温边界层结构有利于污染气溶胶的积累和雾霾的形成和发展，尤其是来自南方持续不断的湿平流使雾霾天气得以长时间持续和发展。整个雾霾天气期间能见度均小于2 km，最低能见度达到56 m，液态水含量在10-3g/m3量级，最大达到0.16 g/m3，气溶胶数浓度均在10000 cm-3以上，质量浓度范围为50～160 μg/m3。进一步的研究表明，此次长达1周的雾霾天气发生了3次强弱不同的霾气溶胶积累、霾雾转化和混合及减弱3个主要阶段。霾气溶胶积累阶段先后有爱根核模和积聚模气溶胶数浓度的积累和增加。霾向雾转化和混合阶段中，雾滴凝结释放的潜热和高浓度气溶胶环境使布朗碰并加剧，导致气溶胶尺度向粒径大的方向转移，从而提供了大量可形成云凝结核的气溶胶粒子，促进了雾的爆发性增强，浓雾过程中气溶胶向CCN活化率可达17%，而CCN向雾滴的转化效率可高达100%，此期间雾滴谱具有爆发性拓宽的特征；冷锋系统过境或辐射加热增强导致了雾霾过程的减弱和消散。（郭丽君，郭学良，方春刚，朱士超）

1.2 华北积层混合云中冰晶形态、分布与增长过程的飞机探测研究

利用国家科技支撑计划重点项目“环北京地区3架飞机联合云探测试验”数据，分析了2009年4月18日和5月1日2次积层混合云中冰晶形态、分布与增长过程。结果表明，飞机在0～16 ℃范围的云层内观测的冰晶形态主要包括板状、针柱状、柱帽状、辐枝状和不规则状。云中低层观测的冰晶形态受云顶温度影响，云顶温度不同，观测到的冰晶形态也不同，当云顶温度高于-8 ℃时，在云中低层观测到的冰晶形态以板状和针柱状为主；当云顶温度低于-13 ℃时，在云中低层可观测到辐枝状冰晶；当云顶温度低于-18 ℃时，在云中低层可观测到柱帽状冰晶。同时冰晶形态还受其所处云中位置的影响，在积层混合云的嵌入对流区和融化带中含有更多的凇附状冰晶；在融化层以上，冰晶的增长过程主要包括凝华、凇附和聚合过程，在垂直方向上，随着高度降低云中过冷水增多，冰晶的凇附增长也相应增强。积层混合云中的对流区和层云区粒子谱下落拓宽速率有明显差别，在4.8～4.2 km（-11.6～-8 ℃）高度层，对流区粒子谱拓宽速率为3 mm/km，而层云区为3.67 mm/km，层云中粒子拓宽增长的速率略高于对流区；而在4.2～3.6 km（-8～-5 ℃）高度层，对流区的粒子谱拓宽速率为6.67 mm/km，层云区为2.33 mm/km，对流区的粒子拓宽增长速率是层云区的近3倍，主要原因是嵌入对流层的低层含有较多过冷水。（朱士超，郭学良）

1.3 探测大气温湿廓线的35通道微波辐射计设计原理与特点

总结了自主研制的MWP967KV型地基35通道微波辐射计系统设计原理和主要特点。系统将K、V双频段宽带天线及接收机、宽带调频本振、温湿压计以及电源模块紧凑集成为一台整体设备。对各传感器的测量输出实时进行一体化综合处理，采用BP神经网络实时反演大气温度、适度廓线和汽、水总量。廓线的垂直覆盖范围为地表至顶空10 km，共划分为58层，辐射计样机于2012年秋冬季在北京地区开展了为期2个月的观测试验，利用这段时期内的69个探空资料样本对辐射计2个层次的实时观测输出都进行了对比检验，计算了水汽、氧气通道亮温和反演所得大气温湿廓线的平均偏差、均方差以及相关性。结果表明，该系统能够满足实时气象监测的需求，达到国际先进水平。（卢建平，黄建平，郭学良）

1.4 L波段探空判别云区方法的研究

利用2008 年1月到2009年12月的L 波段探空资料，以及与之时空匹配的Cloudsat云观测资料，分析云内和云外相对湿度的累积频率分布的结果显示，以75%作为相对湿度阈值判断云准确率可达81%。利用BS（Bias Score）和TS（Threat Score）评分方法对不同相对湿度阈值进行评分分析的结果显示，以81%作为相对湿度阈值TS 评分可达0.66，为最高。利用BS和TS评分方法分不同高度对相对湿度阈值进行评分分析，发现随高度的增加该高度上具有最好TS评分的相对湿度阈值在减小。利用这些阈值对云判断时，总的TS评分高于0.6，且准确率达到84%以上，比利用单一相对湿度阈值判断云准确率要高。对这些阈值进行优化，得到一套适合于我国L波段探空秒数据的云垂直结构的判别方法。（蔡淼，欧建军，周毓荃）

1.5 一次超级单体雹暴观测分析和成雹区识别研究

利用多普勒雷达资料，结合探空和常规资料，分析了2011年4月17 日一次超级单体雹暴的流场和回波结构演变特征。该雹暴是在条件性不稳定和垂直风切变较大的环境下产生的右移风暴。垂直剖面图显示雹云初生发展阶段，逐渐形成有组织的斜上升气流促进雹云发展。成熟降雹阶段，雹云内形成一支强的斜上升气流和深厚的中气旋，主上升气流对应雹云的弱回波区。雹云维持典型的弱回波区-悬挂回波-回波墙特征结构。根据雷达径向速度和雹云移速订正得出的“零线”演变发现，随着雹云的发展，“零线”逐渐向悬挂回波靠近，并穿过悬挂回波，“零线”的走向为上翘式，附近“穴道”的汇集力较强，有利于降雹。通过对“零线”位置的判断可分析有利成雹的区域。根据高低空两层强回波的水平错位，利用两高度强中心连线所作剖面能快速准确得出特征剖面，并将0℃层以上6 km 高度处降雹潜势达到100%的45 dBz的区域识别为成雹区，与降雹实况对比发现识别效果良好。（蔡淼，周毓荃）

1.6 一次西风槽过程过冷云水分布特征观测研究

过冷云水生消演变规律是云物理学和人工影响天气的重要研究领域。根据Hobbs 1974年提出的假定，利用飞机、卫星、雷达和雨量计等观测资料，对2012年9月21日河北一次西风槽天气过程进行观测研究，分析其过冷云水分布特征及演变规律。结果表明，槽前云系过冷水区宽厚并且过冷水含量较高，云滴浓度和均立方根直径较大并且均匀，冷云区厚而且没有分层，没有暖云配合；近槽云系中冷云区小粒子浓度降低但云滴直径增大，冷云区夹有干层，云系变厚出现暖云配合，冷暖云液态水含量较高，冷暖云区大粒子和降水粒子浓度和尺度增大，中尺度云团移动较快；槽后云系中云滴浓度最大，但云滴均立方根直径明显减小，过冷水区出现的高度下降、厚度很薄、过冷水含量较低，冷、暖云之间有干层，暖云对应的大粒子浓度和降水粒子浓度非常大，地面降水主要由暖云过程产生；云水（过冷水）含量峰值常出现在云内逆温层的上方；利用云粒子测量系统（PMS）资料分析过冷云水生消演变特征，其与卫星和雷达资料具有较高的一致性。（周毓荃，孙晶）

2 云降水物理与人工影响天气数值模拟研究

2.1 气溶胶对华北夏季对流云和降水影响的数值模拟研究

大气温室气体、气态前体物和颗粒物排放可以直接改变大气辐射收支，或间接改变云和降水过程，可能引起区域到全球尺度的气候和水循环变化。一些前期发表的大气排放对云和降水影响的定量评估研究结果并不一致。本研究利用MODIS卫星和WRF-CHEM模式，对2008年7月4日华北城市区一次对流性降水个例的气溶胶特性及其对降水的可能影响进行了分析。结果表明，研究区气溶胶光学厚度超过0.9，说明存在高浓度污染气溶胶。爱根指数大于1.0，说明研究区主要气溶胶粒子属于工业和生物质燃烧所产生，粒径尺度在0.25～0.5 μm。数值模拟研究表明，污染条件下模拟区域平均降水增加17%，但大于30 mm/h的降水强度出现增强，而小于30 mm/h的降水强度减弱。污染与清洁状况下的云微物理和动力差异表明，污染对风暴初始和消散阶段的冷暖云微物理、动力过程和上升气流有明显抑制作用，而对成熟期的风暴有明显增强作用。（郭学良）

2.2 减弱对流云降水的AgI催化原理的数值模拟研究

在对流云模式中增加了AgI两个预报量，耦合了考虑受水汽过饱度和温度影响的4种核化机制的AgI催化模块，使其具备了AgI 类催化剂的模拟能力，能够研究AgI 类催化剂对对流云系统的影响。利用此模式对一次华南对流云降水过程进行了AgI成冰剂催化数值模拟试验，对人工减缓对流云降水的可能性及原理进行了研究。模拟结果表明，在适当的时机对适当的部位进行大剂量的催化，可以减少总降水量，也可以减弱最大降水中心的雨强。当催化剂量达到2×108kg-1时，可以减少32%的降水量，具备有效减缓对流云降水成灾的可能性。大剂量催化后，大量的AgI粒子在冷区核化后消耗了大量的过冷水。催化后霰粒子的落速和雨水的落速减小。催化阶段由于霰融化成雨水减少而使降水减弱。催化结束后在霰融化成雨水增多的情况下，雨水的蒸发大幅增加，从而导致了降水量的持续减少。AgI在此次强对流云中主要以受过饱和度影响的凝结冻结和催化剂长时间作用的浸没冻结这两种方式成核。研究所用催化方法在外场作业中具有技术可行性。（楼小凤，孙晶，史月琴，张邢）

2.3 下垫面对雹云形成发展的影响

利用中尺度模式WRF对2005 年5 月31 日发生在北京地区的一次强冰雹天气过程进行了数值模拟研究，并与观测的雷达回波、冰雹云移动路径和冰雹落区进行比较，在此基础上探讨了城市和农田两种下垫面对雹云的影响。结果表明，由于“城市热岛”效应的作用，城市下垫面的地面感热通量显著增加，有利于雹云的发展增强和大冰雹的形成，使地面累积降雹量增加，但对雹云移动路径影响不大。农田下垫面具有较大的潜热通量，局地蒸发强，有利于大量小冰雹的形成，云中冰雹含量增加，但降雹强度较弱，地面累积降雹量小。（郭学良）

2.4 一次积层混合云降水不同尺度结构的数值模拟

利用中尺度数值模式WRF-ARW（V3.2）对2009年4月18—19日发生在张家口地区的一次积层混合云降水进行了模拟，并结合观测资料从不同尺度对这次降水过程进行了对比分析。结果表明，700 hPa西风槽、850 hPa低涡是影响这次降水的主要天气系统，来自南方的暖湿空气和西北内蒙古低涡带来的水汽是这次降水的主要水汽来源，两股水汽在张家口附近低层出现了大尺度辐合，有利于该地区云系的发展和降水的形成。降水云系呈东北—西南向带状分布，带长约1000 km，带宽300 km，在大片的云带中分布着很多个小的高值中心，中心区域一般在几十公里；结合雷达回波可以看到在均匀的回波层中镶嵌着柱状对流回波，具有典型的积层混合云降水回波特征；沿着雷达回波做剖面，发现云中云水含量分布无论是在水平方向还是垂直方向都是不均匀的，雨水的大值中心与上层的霰、雪的大值中心相对应，中心水平范围在10～20 km。（张微，周毓荃）

2.5 山西春季层状云系数值模拟及与飞机探测对比

采用中国气象科学研究院中尺度云参数化模式对2010年4月20日山西省一次春季层状降水云系的宏微观结构，特别是垂直方向上的微物理结构进行了数值模拟和分析。利用携带云粒子探测设备的飞机对该次层状云系进行了2次云物理探测飞行，并将飞机探测所获取的数据和图像资料与数值模拟结果进行了对比研究。模拟结果显示，该次降水过程以层状冷云降水为主，云中过冷水含量丰富，云系存在明显的3层结构，地面降水主要来自于云中高层冰晶、雪、霰等冰相粒子的融化和低层云水的转化。数值模拟与飞机探测对比分析显示，高空温度、湿度和高度的配置两者基本一致，数值模拟不同高度的云粒子相态、垂直方向云水比含水量与飞机探测获取的云粒子图像和云液态水含量的垂直结构基本吻合，但数值模拟的云中各种水成物粒子出现的高度较飞机探测偏高。（陶玥，史月琴）

3 人工影响天气关键技术研究

3.1 高炮、火箭和飞机催化扩散规律和作业设计

基于扩散计算的解析解提出了针对高炮、火箭和飞机等不同催化方式的点源、多线源和移动点源的数值计算方案，分别研究了不同催化方式催化剂扩散规律和有效范围，并利用卫星捕获的一次飞机播云实例检验了计算方案，同时研究了实现目标区充分催化的作业设计等问题。高炮作为点源催化、单个高炮作业，达到有效催化浓度的范围半径只有约0.5 km，应当采用多炮弹密集作业，比较有利于浓度和催化范围的维持，提高炮弹成核率能够明显提高高炮作业效果。火箭和飞机作为线源催化，1 h内达到有效催化浓度的宽度分别为7 km和6.6 km，此宽度可作为多线播撒作业飞行间距设计的参考依据；飞机单线播撒达不到充分催化的要求，而耕作式播撒，在风速作用下扩散区域会分散或重叠。根据风速大小设计的“8”字形来回播撒飞行路线，可使目标区得到充分播撒。在扩散计算方案研究基础上研发的各类催化扩散计算和作业设计软件系统，可方便准确地计算飞机、高炮和火箭实际作业时催化剂在云中扩散的范围、浓度及其随时间的演变，并可针对不同目标区进行充分播撒催化的作业设计，结果直观简明，为催化扩散计算的实际业务应用和作业设计提供了帮助。（周毓荃）

3.2 北京地区人工增雨效果和防雹经济效益评估

基于全市农业气象灾情统计资料，结合近年来北京地区开展的人工增雨、防雹作业情况，利用经典的区域历史回归统计方法，对2004—2010年人工增雨效果和防雹经济效益进行了客观定量评估。结果表明：（1）在5—9月的评估期，随着作业样本数逐年累加，人工增雨平均相对增雨率逐渐趋于稳定，并维持在20%左右，在所选目标区连续7年的人工增雨作业累计增加降水量约417.8 mm，增雨效果非常显著；（2）年平均人工防雹经济效益约2.48亿元，多年平均防雹投入产出比为1：16。人工防雹效益最高、最低年份分别为2009年和2005年，对应投入产出比分别为1：27和1：6。（李宏宇）

3.3 对流云人工增雨效果检验技术方法及应用

对流云降水时空变化较大，利用Woodley & Rosenfeld提出的建立在雷达资料基础上的移动目标单元法对对流云增雨作业进行效果评估。利用塘沽、北京及秦皇岛3部雷达资料，对其进行插值处理，确定移动目标单元识别和跟踪方法，然后在移动目标单元中确定催化单元和对比单元，记录每个单元的物理参量，利用Z-R关系反演降水量，对物理参量和反演降水量作统计分析，定量计算增雨效果的同时提供人工增雨的物理证据。应用该方法对2011年7月24日对流云人工增雨作业效果进行评估的结果表明，催化剂进入云中后使得最大回波强度增强、回波顶高增加，从物理角度证明了催化对增加降水起到了一定作用。利用降雨率对增雨作业定量效果分析的结果表明，该次作业相对增雨7.69%，显著度检验值为0.043。（李宏宇）

4 人工影响天气工程建设及业务工作进展

4.1 全国人工影响天气发展规划（2014—2020年）

为了避免这种情况的出现，在类比时要选择与目标相关的属性或关系。类比推理是有目的性的推理，目的性是类比推理的一个重要的约束。另外，概念聚类可以根据线索概念在概念网络中生成，围绕不同的线索概念可以形成不同的概念聚类，这也限制了类比的不合理扩展。在老子关于水的类比中，目标是用来说明善的，在概念网络中形成概念聚类，也是以具有水的正面意义的概念为线索的。这样就将水的负面特质或与善不相关的概念排除在概念网络之外了。

2014年12月，中国气象局人工影响天气中心牵头编制的《全国人工影响天气发展规划（2014—2020年）》（发改农经〔2014〕2864号）由国家发展改革委员会和中国气象局联合印发，该规划确定了全国人工影响天气的指导思想、发展目标、总体布局、主要任务、实施安排，提出了人工影响天气的组织管理体制和业务运行机制，是当前及今后一段时期全国人工影响天气发展的行动纲领，对全国人工影响天气现代化建设和科学发展具有重要指导意义。2014年10—11月，《全国人工影响天气业务发展指导意见》（气发〔2014〕95号文）、《人工影响天气专用技术装备管理办法》（气发〔2014〕106号文），相继由中国气象局正式印发颁布，标志着我国人工影响天气业务和装备管理步入规范发展的轨道。（陈添宇，周毓荃，房文）

4.2 东北人工影响天气工程建设

2014年是“东北区域人工影响天气能力建设”项目建设初见效益的重要一年。年度内，完成初步设计的修订与报批，首架新舟60 增雨机试飞成功并在第10届中国国际航空航天博览会上正式亮相，完成第3架高性能增雨飞机作业系统总体方案设计并选定了11套机载人工影响天气设备，启动区域飞机作业保障中心建设，作业指挥应用系统主体功能已在东北4省区安装部署；完成高性能作业飞机卫星通信系统、79部全球定位系统气象观测（GPS/MET）设备、3部X波段移动多普勒天气雷达、GPS/ MET数据处理中心软件系统以及效果检验外场试验区所有设备的采购，举办了人工影响天气前沿科学技术与飞机作业技术培训班。项目初步成果在东北区域春夏季抗旱增雨中发挥了重要作用。（李集明，陈卫红）

4.3 全国人工影响天气作业信息采集处理系统（V1.0版）投入业务运行

在多年业务工作的基础上，依托“中国气象局人工影响天气业务指挥平台”项目建设的全国人工影响天气作业信息采集处理系统（V1.0版）于5月21日通过专家组验收，成为2014年继人工影响天气预报模式系统后，第2个通过业务化验收的人工影响天气业务系统（气减函〔2014〕48号文）。

全国人工影响天气作业信息采集处理系统（V1.0版）由作业信息采集处理系统和实时上报系统2部分构成，依托全国气象业务宽带网，可实现全国人工影响天气作业信息的上报、采集、存储、监控、管理等功能；同时集成了站点信息、作业信息、人员信息、弹药信息等多种人工影响天气基础数据，为人工影响天气作业效果分析评估、联合作业指导、人工影响天气决策服务产品制作提供及时、可靠的信息来源。系统投入业务运行以来，有效地提高了地方人工影响天气部门作业信息上报效率，加强了国家级人工影响天气中心的业务指导能力和服务效益，为各地人工影响天气作业指挥和效果分析等业务的开展提供了有力支撑。（王飞，杨连英，李抗抗）

4.4 人工影响天气云降水特征参量静止卫星反演系统（CPPS-GSSL 2.0版）投入业务运行

该反演系统（CPPS-GSSL 2.0版），是基于我国FY-2系列静止气象卫星和L波段探空资料等实时反演生成云黑体亮温、云顶高度、云顶温度、过冷层厚度、云光学厚度、云粒子有效半径和液水路径等云特征参量反演产品，通过与MODIS反演参量的对比检验及与CloudSat云雷达、天气雷达、雨滴谱和地面降水等多种云降水观测进行物理合理性分析，检验了反演产品的准确性和可用性。反演产品在各省应用效果好，已为重点干旱地区及跨区域增雨作业、森林草原灭火增雨作业、重大社会活动消减雨作业等提供了强有力的技术支撑。（蔡淼，周毓荃）

4.5 2014年南京青奥会开、闭幕式人工消减雨取得明显效果

2014年8月16日和28日，第2届夏季青年奥林匹克运动会开、闭幕式分别于南京市奥体中心举行。为确保其顺利进行，组委会迫切要求开展人工消减雨试验和服务。江苏省气象局特邀中国气象局人工影响天气中心全程指导开展相关试验和服务工作，并取得明显消减雨效果。其中开幕式奥体中心场馆降水2 mm，场馆周边邻近站平均降水5 mm；闭幕式奥体中心场馆降水0.2 mm，场馆周边邻近站平均降水0.68 mm。确保了开、闭幕式的顺利进行。初步总结关键技术工作主要如下。

（1）在分析研究8月份南京天气和云降水特征基础上，提出并指导制定了南京青奥会人工影响天气服务技术方案，包括监测加密、通信指挥、作业防线布局和实施组织等多个分方案。

（2） 利用国家近年发展的人工影响天气作业条件业务数值预报模式，提前24 h给出催化原理、催化方案（包括催化区、催化时段、催化方式及催化量的预报）。并结合天气动力预报和实况监测，利用新建的人工影响天气远程会商平台，进行国家人工影响天气指挥中心同青奥会现场指挥中心的实时互动，滚动进行作业方案的实时会商和预报方案的及时修订，并达到预期催化效果。

（3）将中国气象局人工影响天气中心近年来研究发展的云降水精细分析系统（CPAS）移植开发，建立了青奥会消减雨作业指挥系统，实现基于卫星、雷达、探空及特种仪器等各类观测的云系宏微观结构和降水演变的实时精细分析、作业条件的预判识别、最佳的作业方案的实时设计滚动修正、现场飞机和地面多种催化的实时指挥等功能。

（4）利用移植的CPAS平台和作业指挥系统，有效组织飞机外围侦查探测预作业和临近区域高密度火箭催化作业，有效地抑制削弱了移近场馆的云团，证实了作业前的技术原理和设计，取得了较好的预期效果（图1 ）。（周毓荃，刘思瑶，濮梅娟，胡志晋）

4.6 国家级人工影响天气业务平台的建设及其在业务指导和服务中的作用

2014年人工影响天气中心自主研发建设完成国家级人工影响天气业务平台，该平台主要包括4部分功能。第1部分是信息传输、收集与存储管理功能，主要收集存储常规气象观测数据、人工影响天气特种观测、业务产品和飞机、地面人工影响天气作业数据，供实时业务使用，并处理形成典型个例库数据；第2部分是产品加工、检验和中试功能，主要对数据进行加工处理，综合分析形成各种人工影响天气特征量，用于对人工影响天气作业条件进行预报和监测预警，并对预报产品进行检验和新业务开发中试；第3部分是业务指导和服务功能，包括开展作业条件潜力预报、监测预警与专题会商、设计作业方案、开展飞机作业跟踪指挥和实时监控，以及作业后效果检验分析；第4部分是产品共享发布功能，将预报和监测产品通过网站进行发布，供相关业务单位使用。

平台建成后，针对我国各地出现的旱情和可能的作业天气过程，成功进行跨省（区）联合业务会商，在实时业务指导和服务中发挥重要作用。如在2014年4月，中国气象局人工影响天气中心联合黑龙江、吉林、辽宁、内蒙古4省（区）人工影响天气中心进行会商，对整个东北区域的云系结构、云带、过冷水、冰相粒子等的分布和演变情况进行综合分析，提出了适合开展作业的时间、地点和高度等方面的建议；东北人工影响天气中心根据东北区域作业需求和作业装备的布局进行了跨省（区）联合作业的部署，标志着跨省（区）联合作业步入逐级指导、联合作业的业务模式，提高作业的科技水平和效益（图2）。（周毓荃，史月琴，孙晶，蔡淼，刘卫国，陶玥，王飞）

4.7 优化空中云水资源评估

通过2011—2014年的不断探索和研究，中国气象局人工影响天气中心研发完善了空中云水资源监测评估方法（CWR-MEM）。该方法以大气水分收支平衡方程为基础，明确了包括水凝物在内的大气水物质概念，完善了各种水物质总量、降水效率、更新周期等概念和计算公式，提出了云水资源、空中云水资源总量和有效云水资源量等相关概念。

2014年，中国气象局人工影响天气中心组织专门技术力量，对该方案中三维云场和三维云水场的诊断识别等关键技术和评估时空尺度、复杂区域边界处理等评估方法进行了优化。根据云的气候特性，将中国按经纬度分为5个区域，利用2007—2008年的CloudSat云观测产品，分别统计得出各区域诊断云区的相对湿度阈值和云含水量典型值及其垂直分布，并将垂直分布随高度坐标改为温度坐标，云场物理意义更准确，明显改进优化了全国不同区域三维云场和三维云水场的诊断方案。对空中云水资源评估时，将评估区域细分为6个区域，并将各区域的边界处理成1°分辨率的闭合曲线，明显改进了对凝结和蒸发量的计算，提高了整体评估精度和计算准确率。

利用优化的CWR-MEM方案，对2008—2010年中国六大人工影响天气区域的空中云水资源进行了评估，完成了2014年空中云水资源监测评估报告。主要评估结果如下：2008—2010年，中国的水汽总量年平均值（GQv）约36.9×1012t，其中从各边界输入的水汽量年平均值约33.1×1012t，蒸发量年平均值约3.75×1012t；水凝物总量（GQh）年平均值约7.15×1012t，降水总量（GR）年平均值约5.02×1012t，云水资源总量年平均值（GCWR）约2.13×1012t，有效云水资源量年平均值（CWR）约1.23×1012t。水汽降水效率年平均值约为14%，水凝物降水效率年平均值约为70%，水汽更新周期年平均值约为10天，水凝物更新周期年平均值约为7 h。云水资源各特征量具有明显的时空分布差异。（周毓荃，蔡淼）

4.8 研发作业效果检验技术方法

在详细分析全国人工影响天气作业信息的基础上，揭示了全国不同区域的人工增雨作业需求；开发了4种非随机化人工增雨效果统计检验技术方法，研发了针对4种统计检验方案的显著性水平检验算法，并在江西、云南、河南、重庆、安徽5个试点省进行试验试用；研发了基于TITAN技术的播云多普勒雷达识别追踪及检验算法和基于常规雷达探测资料的人工增雨效果物理检验技术方法，并在试点省进行试验试用；对试点省2013年人工增雨作业典型个例进行了效果检验，给出了试点省人工增雨作业效果及其统计显著性水平；在试点省开展了基于历史降水资料的区域相关分析研究，为科学开展人工增雨作业和效果检验工作进行理论积累；通过分析影响试点省的主要天气系统和历史作业情况，结合试点省历史降水区域相关分析研究结果，给出试点省人工增雨主要作业影响区和对比区的区划设想；完成了2014年度全国人工增雨效果检验工作总结报告。（姚展予）

4.9 高效冷暖云催化剂的研制及新装备测试、考核和业务试用

中国气象局人工影响天气中心组织开展了WMC-IN-001、WMC-IN-002型2种冷云催化剂和WMCCN-001型吸湿性催化剂配方的调整、改进试验研究，并对催化剂的成核率进行检测。与目前业务用的焰剂类冷云催化剂成核率相比，新型冷云催化剂成核率高一个量级以上。播撒WMC-CN-001型吸湿性催化剂后，在多个速度下，大于2 μm的粒子浓度均可达到 101量级；冷暖云催化剂研究成果均通过了技术认定。研制的暖云催化剂已在福建、安徽开展地面燃烧炉的业务试用，在河北开展飞机播撒试用；对业务用机载烟条、烟弹和地面烟条等催化剂的成核率进行了统一检测，保障了催化剂的作业效率；组织了随州大方精密机电工程有限公司生产的“DF37 mm高射炮远程控制系统”和华云公司生产的“HY-1型机载焰条播撒系统”的产品定型和业务试用方案的评审。（房文，党娟，方春刚，苏正军，汪晓滨，刘汐敬）

图1 2014年8月28日闭幕式主要影响云带回波平均值及强回波（大于20 dBz）面积随时间的演变（多轮次作业后保障区，保障时段（20:15—22:08）回波减弱最明显）Fig. 1 August 28, 2014, the average echo of the statistical areas and the echo areas stronger than 20 dBz of the main inf uenceing cloud band during the closing ceremony (The most weakened echo effect time is 20:15–22:08 after the large operations)

图2 国家级人工影响天气业务平台总体结构Fig. 2 Structure of national weather modif cation operational platform

Advances in Cloud Physics and Weather Modif cation

1 Observational studies on cloud physics

1.1 Observation and analysis of characteristics of formation, evolution and transition of a longlasting severe fog and haze episode in North China

An unusual fog and haze event lasting for one week occurred during 1–7 December 2011 over North China. To investigate the characteristics and mechanism of formation, evolution and transition of the fog and haze event, the microphysical properties such as aerosol, cloud condensation nuclei (CCN), fog droplet spectrum and liquid water content (LWC), as well as horizontal visibility and boundary layer properties were studied by using the data collected in the project of Low-Visibility Weather Monitoring and Forecasting in the Beijing-Tianjin region. The results indicate that the long-lasting fog and haze event occurred in a high pressure weather system and calm wind condition. The stable boundary-layer structure resulting from temperature inversions caused by warm advection and radiation cooling provided a favorable condition for the accumulation of polluted aerosols, and the formation and development of the fog and haze event. In particular, the continuous southerly wet advection led to a long process. The horizontal visibility was almost below 2 km in the whole process, with the lowest being only 56 m. The average LWC was about 10-3g m-3, with the maximum reaching 0.16 g m-3. The aerosol number concentration was more than 10000 cm-3, with the mass concentration ranging from 50 to 160 μg m-3. The further study shows that the fog and haze event experienced three main different processes in intensity during the whole period, each process being divided into three main stages: aerosol accumulation, transition and mixture of aerosol and fog, and dissipation. Each stage had different physical features: the aerosol accumulation stage was characterized by the increase of aerosol number concentration in Aitken nuclei and accumulation mode sequentially. In the transition and mixing stage of fog and haze, the latent heating produced by the fog droplet condensation process and high aerosol number concentration condition intensif ed the Brownian coagulation process, which induced the small size of aerosols to become larger ones and enhanced the CCN activation process, thereby promoting the explosive development of the fog event. The ratio of aerosol activated to CCN reached 17%, and the ratio of CCN converted to fog droplets exceeded 100%, showing an explosive broadening of fog droplet spectrum. The decrease and dissipation of the fog were caused by an increased solar radiation heating or the passage of cold frontal system. (Guo Lijun, Guo Xueliang, Fang Chungang, Zhu Shichao)

1.2 Ice crystal habits, distribution and growth processes in stratiform clouds with embedded convection in North China: Aircraft measurements

Ice crystal habits, distribution and growth processes in two cases of stratiform clouds with embedded convection on 18 April and 1st May 2009 are analyzed with data observed during the Beijing Cloud Experiment (BCE). The results show that ice crystal habits in clouds with temperature between 0 – 16 °C were predominantly plate, needle-column, capped-column, dendrite and irregular. Ice crystal habits were affected by the cloud top temperature (CTT), which differed with the changing CTT. Plate and needle-column were predominant habits as CTT was warmer than -8 °C while dendritic and capped-column crystals were observed just as CTT was colder than -13 °C and -18 °C respectively. At the same time, ice crystal habits were also affected by their locations in cloud, since there were a lot of heavy rimed crystals in embedded convective regions. Above the melting layer, ice particle grew mainly by deposition, riming and aggregation processes. The riming process became more intense in lower cloud layer due to the increase of super-cooled liquid water content. The broadening rate of particle size distributions (PSDs) is obviously different between embedded convections and stratiform clouds in the vertical direction, at levels of 4.8–4.2 km (-11.6– -8 °C), the PSDs broadening rate in embedded convections is 3 mm km-1, smaller than 3.67 mm km-1in stratiform clouds, but at levels of 4.2–3.6 km (-8 – -5 °C), the PSDs broadening rate in embedded convections is 6.67 mm km-1, which was almost three times as fast as 2.33 mm km-1in stratiform clouds, which was mainly due to the fact that embedded convections had more super-cooled liquid water than stratiform clouds at levels of 4.2–3.6 km. (Zhu Shichao, Guo Xueliang)

1.3 A 35-channel microwave radiometer for prof ling atmospheric temperature and humidity

The design principles and main characteristics of the MWP967KV ground based 35 channel microwave prof ling radiometers are presented. The prototype radiometer is a compact integration of dual band (K and V) broadband radiometry antennas, two receivers, a synthesized local oscillator, a surface meteorological sensor, and a power supply in a cabinet. It has the capability of detecting down-welling atmospheric thermal emission continuously on a minute time scale. Several levels of observed data are composed and regulated. By using BP artif cial neural network retrieval algorithms, the radiometer is capable of retrieving the vertical distributions (profiles) of atmospheric temperature, water vapor, relative humidity, and other variables in real time. The retrieved prof les range from the surface up to 10 km in 58 layers. The radiometer was used in atmospheric observation in Beijing in autumn to winter of 2012 for about two months. The data of 69 radiosonde cases are gathered to evaluate the radiometer’s performance. The accuracies of dual band atmospheric bright temperature values are analyzed. The retrieved temperature and humidity profiles are analyzed as well, and the mean difference, root mean square difference, and correlation are calculated. The statistical results indicate that the radiometer has the ability to support real time weather surveillance, being internationally advanced. (Lu Jiangping, Huang Jiangping, Guo Xueliang)

1.4 Discriminating a cloud area by using L-band sounding data

L-band sounding data recorded from January 2008 to December 2009 and corresponding spatial and temporal CloudSat data are used to analyze the cumulative frequency distributions of relative humidity in and near clouds. It is determined that the accuracy of cloud discrimination can reach 81% against a relative humidity threshold set at 75%. In addition, various thresholds of relative humidity for discriminating clouds are evaluated on the bases of bias score (BS) and threat score (TS). By setting the relative humidity at 81%, the highest TS score of 0.66 is achieved. Moreover, relative humidity thresholds at various heights are also analyzed on the basis of BS and TS. The results show that the relative humidity threshold with the highest TS score at the same cloud height decreases when the height increases. The TS score of the discriminated cloud area with these thresholds for corresponding altitudes is higher than 0.6, and the accuracy is more than 84%, which is signif cantly better than that obtained by using a single relative humidity threshold for all heights. Finally, with these thresholds being optimized, a method of discriminating the cloud vertical structure is proposed by using L-band sounding data. (Cai Miao, Ou Jianjun, Zhou Yuquan)

1.5 Observation, analysis, and hail-forming area identif cation of a super-cell hailstorm

A detailed analysis on the evolution of stream fields and echo structures of a super-cell hailstorm that occurred on April 17, 2011, is conducted on the basis of Doppler radar data combined with radio sounding and surface observations. The main results are as follows: The hailstorm occurring in a conditional instability and signif cant vertical wind-shear environment was classif ed as a right-moving storm. A cross-section of the development stage shows that an organized updraft was formed gradually, which promoted the formation and development of the hail cloud. During the hail-forming stage, a strong, tilted updraft and deep meso-cyclone emerged in the hailstorm; the main updraft corresponded to the weak echo region. The hailstorm maintained a typical bounded weak echo region (BWER)-overhang echo-wall echo structure. According to the evolution of zero velocity line, which connects the radar radial velocity and the speed of hailstorm, the line approached the overhang echo zone with the developing hail cloud and crossed the overhang echo. The trend of zero velocity line was upturned, and the collection power of the cave channel near the line was suff ciently strong to form hail. The hail formation area can be analyzed through the determination of the zero velocity line. A method of identifying the characteristic structure of the hail-forming region is also presented in this study. According to the strong echo dislocation of high and low levels, the characteristic structure is determined quickly and accurately from the strong echo center section at two heights. Moreover, a 45 dBz region at a 6 km height above the 0 °C layer is identif ed as a hail-forming region, where the potential of hail is calculated to be 100%. The identif ed hail region is in good agreement with the actual hail observation. (Cai Miao, Zhou Yuquan)

1.6 Observational studies of distribution characteristics of supercooled cloud water during a westerly trough process

The growth and evolution of supercooled water are always a concern in the cloud physics and weather modification science. Based on the hypothesis proposed by Hobbs in 1974, a westerly trough in Hebei Province on 21 September 2012 is analyzed by using the airplane observation, satellite monitoring, radar monitoring, and other regular observation data. Results show that (1) a wide and thick area of supercooled water exists in front of the trough where the supercooled water is abundant, the concentration and root mean cube diameter of the forward scattering spectrometer probe (FSSP) are relatively of high value, and the cold cloud is thick without dry layers or warm cloud; (2) as the trough draws near, the cloud near the trough develops rapidly, the concentration and depth of the area of the supercooled water increase signif cantly, the cloud becomes thicker with dry layers, the liquid water content (LWC) in cold and warm cloud is abundant, meanwhile the concentration of 2DC and 2DP is of high value, and the mesoscale structures move quickly; (3) in the rear of the trough, the root mean cube diameter of the droplets and the amount of the supercooled water are remarkably small, and the height and width of the supercooled water decrease a lot, although the cloud concentration is still high, the cold cloud is very thin with a dry layer between warm cloud and cold cloud, and the warm cloud has several layers with a high value concentration of 2DC and 2DP. The precipitation is produced by the warm rain process. Usually the peak of the LWC stays over the temperature inversion layer. The results based on the analysis of the particle measurement system (PMS) data are well consistent with those based on the satellite and radar monitoring data.（Zhou Yuquan, Sun Jing）

2 Cloud physics and artif cial seeding simulation researches

2.1 A case study of aerosol impacts on summer convective clouds and precipitation over North China

The emissions of greenhouse gases, precursor gases and particulate matters may directly alter the Earth radiative budget or indirectly modify cloud and precipitation processes, and possibly induce changes in climate and the hydrological cycle at the regional to global scale. The previous publications reported a few quantitative assessments and inconsistent results on the effects of the emissions on cloud and precipitation. The aerosol properties and possible impacts on a convective precipitation case on 4 July 2008 over the urban region of North China are investigated based on the Moderate Resolution Imaging Spectroradiometer (MODIS) data and the Weather Research and Forecast (WRF) model coupled with Chemistry (WRF-Chem). Results show that the Aerosol Optical Depth (AOD) is over 0.9 in the study area, indicating a high concentration of aerosol pollution. The value of Angstrom exponent in the study area is larger than 1.0, indicating that the main particles in the area are industrial and biomass burning pollution aerosols with a radius of less than 0.25–0.5 μm. The modeling results show that the domain-averaged precipitation amount under polluted conditions can be increased up to 17% during the whole cloud lifetime. However, the maximum rainfall rate above 30 mm h-1is enhanced, whereas that below 30 mm h-1is suppressed in most cloud lifetime. The differences of cloud microphysics and dynamics between polluted and clean conditions indicate that both warm and ice microphysics and updraft are suppressed at the storm,s initial and dissipating stages, whereas those at the storm,s mature stage are obviously enhanced under polluted conditions. (Guo Xueliang)

2.2 Theoretical research on AgI seeding simulation of the decreased convective rainfall

After two prognostic variables are added, An AgI seeding scheme is coupled with a three-dimensional cloud model, considering four nucleation modes. A case of heavy convective rainfall is simulated using this model. Numerical seeding experiments of releasing AgI in cloud are simulated to study the possibility to decrease the heavy convective rainfall. Several tests of different locations and different concentrations of seeding particles are designed. Results show that over-seeding in an updraft area with supercooled water can not only reduce the amount of rainfall, but also reduce the maximum rainfall strength. With 2×108kg-1seeding concentration, rainfall amount can be decreased up to 32%, which greatly lowers the possibility of causing f ood. After seeding with large amounts of AgI, numerous AgI particles are nucleated, and these ice particles consume much supercooled water. The falling speeds of graupel and raindrops become weaker after seeding. The decrease of melting amount of graupel to rain in seeding cloud causes the decrease of rain amount, and later the much more evaporation of rain causes less rainfall amount. Results show that condensation freezing and immersion freezing are the dominant nucleation modes in this convective cloud. The over-seeding methods in this research are able to be used in a f eld operation. (Lou Xiaofeng, Sun Jing, Shi Yueqin, Zhang Xing)

2.3 Effects of underlying surface on the formation and evolution of hail cloud

A severe hailstorm in Beijing on 31 May 2005 was simulated using mesoscale model WRF and compared with the observed radar echo, hailstorm moving path and hail fall area. The effects of underlying surface of cities and farmland on hailstorm was investigated. The results show that due to the effect of Urban Heat Island （UHI）, the sensible heat f ux is obviously increased, which is favorable for the development of hail cloud and enhancement of vertical velocity and formation of larger-sized hailstones, and the increase of the surface accumulated hail fall. But the inf uence of urban surface on the moving path on hail cloud is smaller. The farmland surface has larger latent heat f ux and higher evaporation, which is favorable for the formation of a large amount of smaller-sized hailstones, and induces weak vertical velocity and small mean diameter of hailstones in the cloud. The surface accumulated hailfall decreases due to the weakening intensity of hail clouds for farmland surface. (Guo Xueliang)

2.4 Numerical simulation of a convective stratiform mixed cloud precipitation at different scales

The precipitation of a convective stratiform mixed cloud in Zhangjiakou during 18–19 April 2009 is simulated using the mesoscale numerical model WRF-ARW (V3.2) and comparatively analyzed with the observation data at different scales. Results show that the west wind trough at 700 hPa and the low vortex at 850 hPa are the main weather systems responsible for convective stratiform mixed cloud. The warm wet air from the southern China and the low vortex from northwest Inner Mongolia are main water vapor suppliers, which converge in Zhangjiakou region and thus are conducive to cloud system development and precipitation formation. The cloud system shows a NE-SW banded distribution, which is 1000 km long and 300 km wide, and has lots of cloud water centers, covering tens of kilometers. The cloud system has the echo characteristics of typical convective stratiform mixed cloud precipitation, such as columnar echo of cumulus cloud embedded in a uniform echo layer. The cross-section of radar echo shows that the cloud water content is heterogeneous either horizontally or vertically. The centers of rainwater are corresponding with the centers of graupel and snow in the upper layer, with a horizontal range of 10–20 km. (Zhang Wei, Zhou Yuquan)

2.5 Numerical simulation and f ight observation of stratiform precipitation clouds in spring in Shanxi Province

The CAMS meso-scale cloud model was introduced and operationally applied in Shanxi Province in 2009. The macro and micro structure of stratiform precipitation clouds, especially the vertical micro-physical structure are simulated and analyzed of a spring stratiform precipitation process in Shanxi Province on April 20th, 2010 by using this model. Two times of cloud physical detection flights are carried out by using a weather modif cation plane equipped with Droplet Measurement Technologies (DMT) in the same place during the same period of that day. The data and images from f ight detection and the results of numerical simulation are compared and studied. Simulation results show that the precipitation process mainly comes from cold stratiform cloud. The cloud contains a lot of supercooled water, and the thickness of the rich supercooled water layer is about 4000 meters. The temperature of the supercooled layer was 0– -40 °C, and the ratio content of the supercooled cloud water is 0.1–0.7 g kg-1with some ice crystals distributed unevenly. The structures of the stratus precipitation cloud can be roughly divided into three layers. The f rst layer (upper layer) is mainly composed of ice crystals; snow, sleet, and supercooled cloud water is mixed in the second layer (middle layer); and the third layer (lower layer) is mainly of liquid raindrops. The vertical distribution and the transformation of different hydrometers in different stages of the precipitation are analyzed. The precipitation mainly comes from the melting of the ice phase particles such as ice crystals, snow, sleet and the transformation of liquid cloud droplets. A comparison of the numerical simulation results and the plane observation shows that the relationship between temperature and altitude is in good agreement. The simulated vertical structure of the different cloud particle phase and the vertical distribution of the cloud liquid water ratio content are nearly the same as the vertical distribution of different cloud particle images and the cloud liquid water content of the f ight detection. The difference is that the simulated height where various hydrometeors appear is higher than the actual f ight detection. (Tao Yue, Shi Yueqin)

3 Research on technology of weather modif cation

3.1 Study of antiaircraft-gun, plane and rocket cloud seeding diffusion and operation designing

This article gave out the diffusion law of different seeding ways such as antiaircraft-gun, rocket and plane, based on the analytical solution of cloud seeding agent diffused in cloud, by the diffusion calculation model of point source, multi-line source and mobile point source. It studied the diffusion law and effective range of different seeding ways and examined the calculation scheme by using a f ight seeding track caught by a satellite, and discussed such problems as adequate seeding f ight designing. The main conclusions were as follows: As a point source, when using a single antiaircraft-gun for work, the operation range was only 0.5 km, it would be better to use multi-shell for keeping concentration and diffusion range, the work effect can be improved largely when nucleation rate was raised. The work of rockets and planes was calculated as a line source, the widths beyond threshold value 1 h after seeding were about 7 km and 6.6 km, which could be taken as a reference for the multi-line seeding f ight interval. Due to the effect of wind, the diffusion areas would disperse or overlap when using ‘S’ seeding way. The best f ight design which could make the target area get adequately seeded was a ‘8’shaped f ight route. The cloud seeding diffusion calculation and work designing software developed based on diffusion calculation model could calculate the diffusion range, concentration and evolution by time of agents released from a plane, an antiaircraft-gun and a rocket in real work, and could design the seeding ways for effective work in different target areas. The results, which were direct and clear, helped with the actual work application and seeding diffusion calculation as a guidance to weather modif cation in our country. ( Zhou Yuquan)

3.2 Evaluation of precipitation enhancement and hail suppression programs in Beijing region

Seeding effects investigation or evaluation is one of the most important parts of weather modif cation. It also acts as a crucial standard of assessing the scientific and technological level of weather modification activities, and plays an extremely important role in promoting the development in this connection. Taking into account the activities implemented in Beijing region in recent years, we assessed the seeding effects of precipitation enhancement and the economic benef ts of hail suppression between 2004 and 2010, based on the classical method of historical regional regression and the agricultural disaster data collected around the whole region. The results indicate that: (1) in the assessment period from May to September, the average ratio of precipitation enhancement efficiency tends to stand at about 20 percent with the sample numbers being accumulated year by year. In the target area selected, cloud seeding totally increased the precipitation amount by 417.8 mm during the 7 years. The statistical seeding effect is of high signif cance; and (2) the estimated average annual economic benef t of hail suppression is nearly 248 million yuan. The average cost-benef t ratio is about 1:16. The highest and the lowest economic benef t appeared in 2009 and 2005, with a corresponding cost-benef t ratio of 1:27 and 1:6, respectively. The methods studied for seeding effects evaluation and results help to strengthen the exploitation and utilization of cloud water resource in a scientific and technological sense in Beijing and its neighboring regions, which f rmly supports the approval of local disaster prevention and mitigation projects as well. (Li Hongyu)

3.3 Research on and application of a method to evaluate the effectiveness of convective cloud

precipitation enhancement

The reliability of convective cloud-seeding effectiveness evaluation is poor when a traditional statistical test method is used because of its large spatial and temporal variation. The f oating-target area method, a new one proposed by Woodley, is introduced, which is based on radar echoes. Some changes are made to this scheme taking into account Tianjin’s terrain and weather modification operation characteristics. The radar based data are used to determine the floating target cell recognition and tracking methods, then determine the catalytic units and control units in the floating target cells; the physical parameters and the retrieved precipitation of each unit are recorded, and the precipitation enhancement effect is calculated to provide physical evidence on artif cial rainfall. The method is used to evaluate the effectiveness of convective cloudseeding on 24 July 2011 in Tianjin, for example, and the objective evaluation results are obtained, which show that: the value of the maximum echo intensity and echo top height increased as the catalyst got into the clouds. It proves that artif cial catalysis takes effect in precipitation enhancement. The effectiveness of precipitation enhancement is 7.69% at a signif cance of 0.043. (Li Hongyu)

4 Progress in weather modif cation

4.1 National Weather Modif cation Development Plan (2014–2020)

In December 2014, National Weather Modif cation Development Plan (2014–2020), formulated by CMA Weather Modif cation Centre, was jointly issued by NDRC (National Development and Reform Commission) and CMA (China Meteorological Administration). The plan identif es the guidelines, goals, overall layout, main tasks and implementation arrangements of the nationwide weather modif cation prorgam, and also proposes an organization, management and operation mechanism for weather modification work. The plan serves as a program of action for nationwide weather modif cation at present and in the near future, and is of guiding signif cance to weather modif cation modernization and its scientif c development. From October to November of 2014, National Weather Modif cation Operations Development Guidance, Weather Modif cation Dedicated Technology and Equipment Management Regulations were formally issued by CMA, marking that China’s weather modif cation operations and equipment are managed by standards. (Chen Tianyu, Zhou Yuquan, Fang Wen)

4.2 Northeast Regional Weather Modif cation Capability Building project

The year 2014 showed signs of benefits in the project of Northeast Regional Weather Modification Capability Building. Within one year, primary design revision and approval were completed; the f rst Xinzhou 60 artif cial rainfall aircraft f nished its test f ight and made its debut in the 10th China International Aviation & Aerospace Exhibition; the third high performance artificial rainfall aircraft was completed in overall design, with 11 sets of airborne equipment having been selected; regional aircraft operation support center started its construction; main features of control system were deployed in the four northeastern provinces; the procurement was finished for high performance operation of aircraft satellite communications system, including 79 GPS/MET devices, 3 X-band Doppler weather radars, GPS/MET data processing center software system and all the devices for external field test areas; training classes were held for weather modification frontier technology & aircraft operations. The initial fruit of the project has played an important role in drought relief and rainfall enhancement efforts in the Northeast China region. (Li Jiming，Chen Weihong)

4.3 The Collection and Processing System of Weather Modif cation Operation Information OICPS V1.0 being in operational use

Based on years of professional work, the OICPS V1.0, part of Weather Modification Centre (WMC) Operational Control System project, was accepted by experts on 21th May. The OICPS V1.0 is the second operationally accepted system following the weather modif cation forecast model system. The OICPS V1.0 composes two parts, a real-time upload system and information acquisition & processing system. Relying on the national meteorological network, it makes it possible for the national weather modif cation operating information to be uploaded, collected, monitored, stored, displayed and managed. A variety of basic data, including information on stations, operations, practitioners and ammunitions, are integrated to offer timely and reliable information for effectiveness analysis and evaluation, joint guidance to an operation and production of decision services. Since the system’s running, the uploading of operation data has been effectively improved, the strength of WMC capability in guidance and service has been enhanced as a strong support to all other operators in control and evaluation. (Wang Fei, Yang Lianying, Li Kangkang)

4.4 Geostationary satellite-based retrieval system for cloud precipitation characteristics in weather modif cation (CPPS-GSSL 2.0) was put into operation

With many years of efforts, Weather Modif cation Centre of CMA developed the geostationary satellitebased cloud characteristics retrieval system (CPPS-GSSL 2.0), which was accepted in a technical review organized by the Department of Disaster Alleviation, CMA. The conclusion has been published and notif ed: the retrieved products are open to operational use.

The retrieval system (CPPS-GSSL 2.0) is based on FY-2 series geostationary meteorological-satellite and L-band sounding data and their real-time retrieved cloud characteristics related products such as Tbb, cloud top height, cloud top temperature, supercooled layer thickness, cloud optics thickness, cloud particle effective radius and liquid water path. By comparing with MODIS retrieval parameters along with a physical analysis of CloudSat cloud-radar, weather radar, raindrop size distribution and ground precipitation data, the accuracy and the usability of the system have been examined. The retrieval products have been used smoothly in all the provinces throughout China as a technical support to multi-regional cloud seeding, forest-grassland f re extinguishing and rain suppression for important social activities. (Cai Miao, Zhou Yuquan)

4.5 The successful weather modif cation for opening and closing ceremonies of the 2014 Second Summer Youth Olympic Games

On August 16 and 28, 2014, the opening and closing ceremonies of the Second Summer Youth Olympic Games were held in Nanjing Olympic Sports Center. In order to ensure the smooth ceremonies, the organizing committee raised the need to carry out cloud seeding tests and services. Meteorological Bureau of Jiangsu Province invited the Weather Modif cation Centre of the CMA (WMCMA) to guide the relevant tests and services for the whole operations, with rainfall obviously suppressed. In the opening ceremony, the precipitation at the stadium is about 2 mm, while the average precipitation around it is 5 mm. The numbers in the closing ceremony are 0.2 mm and 0.68 mm. The operations ensured the success of the ceremonies. The preliminary summary of the key technical work mainly includes:

(1) Based on the analysis of the characteristics of the cloud precipitation and the weather in Nanjing in August, the WMCMA put forward and guided the technical scheme for the weather modif cation for the ceremonies, including the intensive monitoring, the communication command, the layout design of operations, implementation organization and so on.

(2) Thanks to the numerical prediction model for the weather modification operation conditions the WMCMA developed, the catalytic principle and scheme were given 24 h in advance. Combined with the weather forecast and the monitoring of the actual situation, a real-time interaction between the WMCMA and Youth Olympic Command Center was maintained for the discussion on and the revision of the scheme and the estimation of the result.

(3) The Cloud and Precipitation Precision Analysis System (CPAS) developed by the WMCMA was transplanted to establish a command system of rain decreasing operation for the Youth Olympics. The realtime precision analysis of the macro and micro structures of the cloud and the evolution of the precipitation, recognition and discrimination of the operating conditions, the rolling correction of the optimal design for the operation, the real-time command of the multi-catalytic (plane and rocket) by satellite, radar, sounding and many other special instruments were realized.

(4) Thanks to the transplanted CPAS platform and operation command system, planes were used to do the periphery reconnaissance for the pre-operation and for the highly dense rocket based catalytic operation in the adjacent zones. The clouds that were moving towards the venue were successfully weakened, which proved the technical principle and the design before the operation, with expected effects being observed (Fig. 1). （Zhou Yuquan, Liu Siyao, Pu Meijuan, Hu Zhijin）

4.6 National weather modification (WM) operational platform plays an important role in WM guidance and service

National weather modif cation (WM) operational platform was developed by Weather Modif cation Center (WMC) in 2014. The platform mainly includes 4 parts. First part is to transfer, collect, store and manage information for real time use, such as meteorological observation data, WM special observation data, WM seeding data and ground operation data, based on which a database of case studies is developed. Second part is to process, verify and test products. By synthesizing various data, WM characteristic cloud and precipitation variables are produced to be used to forecast and warn seeding potential conditions. Third part is WM operational guidance and service, including forecasting seeding potential conditions, early warning, designing f eld seeding scheme, monitoring and commanding, and seeding effect evaluation and so on. The last part is to share various WM products by website to be used by relevant professionals.

The operational platform plays an important role in real time weather modif cation service. For example, a video consultation was held together by CMA-WMC, Northeast Regional-WMC, Heilongjiang Weather Modification Office, Jilin Weather Modification Office, Liaoning Weather Modification Office and Inner Mongolia Weather Modification Office in April 2014. In this consultation, the structure of cloud system and distribution of cloud band, supercooled water and ice particles in the northeast of China were analyzed. The seeding time, area, and height of rain enhancement were also discussed. The Northeast Regional-WMC arranged the inter-provincial joint operation according to rain enhancement demand. All of these marked the beginning of the operation model which features joint actions through a level-based guidance. As a result, weather modif cation is improved in science and in benef t (Fig. 2). (Zhou Yuquan, Shi Yueqin, Sun Jing, Cai Miao, Liu Weiguo, Tao Yue, Wang Fei）

4.7 Optimizing the evaluations of air cloud-water resources

As a result of continuous research and experiment during 2011–2014, Weather Modif cation Centre of CMA developed and improved the monitoring evaluation method for cloud water resources (CWR-MEM). The method is based on the atmospheric water vapor budgeting equation, clarifying the concept of atmospheric water substance including hydrometeor. It improved the calculation equation and concept of water substance mass, precipitation effectiveness and update period etc. It proposed such new concepts as cloud water resources, aggregation of cloud water resources and effective cloud water quantities.

In 2014, Weather Modif cation Centre of CMA organized the technical forces to optimize the evaluation methods of diagnosis and identification of three-dimensional water and cloud field, temporal-spatial scales and the processing of complex area boundaries. China was divided into f ve areas by longitude and latitude and by climate. 2007–2008 CloudSat’s observation data were used to count the relative humidity threshold, typical liquid water content values and their vertical distribution of each diagnosed cloud field. The height coordinate was changed into temperature coordinate, which made the cloud field concept more accurate, sharply optimizing the diagnosis scheme of three-dimensional cloud and water f eld in each area. To evaluate the cloud water resources, it is desirable to take six weather modification areas into consideration, before subdividing each area into six sub-areas, the borderline of which is made a loop curve with the resolution at 1°. This improves the calculation of condensation and evaporation values, including the integral resolution and accuracy.

The 2014’s cloud water resources monitoring report was prepared using the optimized CWR-MEM scheme with which the cloud water resources in six weather modification areas throughout China from 2008 to 2011 were evaluated. The results are as follows, from 2008 to 2010, the gross quantity of vapor in China was averaged around 36900 billion tons of which 33100 billion tons was input from the boundaries while evaporation was averaged around 3750 billion tons. The gross quantities of hydrometeor (GQh) were averaged at 7150 billion tons. The total precipitation volumes were averaged at approx. 5020 billion tons. Gross cloud water resources were averaged at 2130 billion tons whilst cloud water resources at 1230 billion tons. Annual water vapor precipitation effectiveness was averaged at around 14% while effectiveness of the hydrometeor precipitation was 70%. The update period for the vapor was averagely about 10 days and 7 hours for the hydrometeor. It can be concluded that the cloud water resources differ distinctly in temporal-spatial distribution. (Zhou Yuquan, Cai Miao)

4.8 Evaluation techniques and methods for cloud seeding effect

Based on the detailed analysis of the information from weather modification operations in the whole country, the specif c rain enhancement requirements in different regions are revealed. Four kinds of methods have been developed and integrated to evaluate the effect of nonrandomized rain enhancement operation, and the relevant testing algorithms of the signif cance level have been researched and developed as well. These algorithms have been applied in Jiangxi, Yunnan, Hainan, Chongqing and Anhui provinces. The Doppler radar identif cation, tracing and testing algorithms have been developed based on TITAN techniques and the physical evaluation methods based on regular radar data, which have been applied in the piloted provinces. Typical cloud seeding examples in 2013 in the piloted provinces have been analyzed and tested, and the evaluated effects as well as the statistical signif cance levels have been released. The regional correlation analysis has been made based on the historical rainfall data in the piloted provinces, which is useful for the theoretical accumulation in the f eld of rain enhancement operation and effect evaluation. According to the analysis of the synoptic systems and historical operations in the piloted provinces, as well as the regional correlation analysis, a designed mapping of the target areas and control areas for the cloud seeding in these provinces has been proposed. The summary report 2014 of rain enhancement effect evaluation in China has been prepared.（Yao Zhanyu）

4.9 The development of eff cient seeding agents for warm and cold cloud, and testing, assessment and trial of new devices

The Weather Modif cation Center (WMC) of CMA developed three types, WMC-IN-001, WMC-IN-002 and WMC-CN-001, of cloud seeding f are agents, tested their nucleation rate in cloud chamber, and compared them with those f are agents used in recent rain-enhancement operation. The result shows that the nucleation rates of WMC-IN-001 and WMC-IN-002, which are for cold cloud seeding, are higher by one order of magnitude at least than those used in operation. Under different wind speeds, the particle spectrum of WMCCN-001, which is hygroscopic type seeding agent, is tested in a wind tunnel. The result shows that the number concentration of particles whose diameter is more than 2 m is up to 101. The above three cloud seeding agents have been recognized by the Department of Science & Technology and Climate Change of CMA.

WMC carried out the trial use of hygroscopic f are for warm cloud in Fujian, Anhui and Hebei provinces, for ground smoke stove in Fujian and Anhui provinces, and for airborne flare in Hebei Province. Working jointly with Shanghai Material Management Division of CMA, WMC tested the nucleation rates of airborneand ground-flare, and flare bomb. A review of product design and operation oriented trial plan for “the remote control system for DF37 mm anti-aircraft guns”produced by Suizhou Dafang Precision Mechanical Engineering Co. Ltd. and “HY-1 type airborne f ame strip seeding system”produced by China cloud company was organized. (Fang Wen, Dang Juan, Fang Chungang, Su Zhengjun, Wang Xiaobin, Liu Xijing)