我区人工影响天气的设想及其初步进展

一、前言 广西地处我国南部低纬度地区,受东亚季风和南亚季风的双重影响。由于季风活动的不稳定性,常常带来旱、涝、风、雹、寒等自然灾害。特别是旱灾影响我区最烈,已是制约我区社会进步和经济发展的主要灾害。开展人工影响局部天气活动,改善广西生态条件,已成为区人民政府为民造福的重要决策之一。因而开展人工影响天气活动的科研工作,提高这一工作的效率,是振兴广西的迫切需要.     

大气准双周振荡的研究进展

大气准双周振荡(Quasi-Biweekly Oscillation,QBWO)主要是指时间尺度为10~20 d的振荡,它是大气中重要的低频系统之一,是在研究季风天气及其相联系的季风系统时被发现的。QBWO对大范围的长期天气变化及异常有着重要影响,且具有全球性和多季性。本文较系统总结了近年来QBWO的研究成果,主要对其结构、活动特征,以及它对天气气候的影响及其激发维持机制等进行了综述。在此基础上,对今后的一些研究重点进行了展望。     

东亚季风研究的进展

中国气象科学研究院曾长期组织和从事东亚季风及其对中国天气和旱涝影响的研究。该文对中国气象科学研究院在东亚季风研究方面取得成果进行综述, 并回顾了20世纪50年代以来国内有关季风的研究活动, 也回顾了影响我国天气气候、东亚季风环流系统的提出及其后续的有关东亚和印度季风系统的相互作用, 引发中国大陆暴雨生成的水汽输送, 表达中国大陆季风活动的季风指数设计等研究结果。综述了南海夏季风爆发、梅雨开始、中国雨季开始及传播等有关研究成果; 东亚季风系统中副热带地区低频振荡纬向和经向传播特征及与赤道地区不同之处, 东亚低频振荡对El Ni?o形成及夏季东亚热带和副热带季风爆发的可能影响, 东亚热带和副热带季风低频振荡对中国天气气候的影响等有关成果; 亚洲地区大气热源的计算及其分布, 青藏高原夏季热源对东亚夏季风及降水的可能影响, 青藏高原冬季冷源对El Ni?o生成的可能影响等有关成果; 东亚季风及降水的年际变化特征, 准4年年际振荡的分析及与ENSO形成间的相互作用, 极地对东亚夏季降水的影响及东亚季风年代际变化特征等成果。综述东亚季风系统形成的可能机制, 特别是亚洲大陆—西太平洋海陆热力差异及非洲、印度半岛、中南半岛及澳大利亚陆地与周围海洋对冬夏季风形成、印度和东亚季风系统形成、南海夏季风形成作用的结果。     

解读云贵 静止锋

贵州地处青藏高原东南侧、云贵高原东斜坡上,属中国亚热带高原季风湿润气候,且由于位于肯藏高原的东侧,受青藏高原大地形和中纬度季风天气影响,形成了一些独特的天气特点：比如雨凇（也有称雪凝、凝冻）,秋绵雨（华西秋雨的一部分）、秋风等,在影响这些天气的系统中,     

广西一次中层东风波强降雨过程诊断分析

通过对2014年7月08-09日广西东南地区强降雨天气过程分析,得出此次过程的主要影响系统为:中层东风波、季风槽前低层西南暖湿气流。此次东风波系统主要是受西太平洋副高和大陆副高之间的切变发展而成,东风波槽前和波轴上利于上升运动的出现,为强降雨提供了有利的动力条件。季风槽前低层西南气流为强降雨提供了充沛的水汽。     

南海西南季风异常与广东省汛期重要天气的关系

南海西南季风的活动直接影响广东省前、后汛期重要天气的异常,因此深入探索南海西南季风的活动规律及其与广东省各种重大天气异常的关系十分必要.利用合成分析和相关统计方法,探讨和分析了南海西南季风建立早晚、强弱与广东省前、后汛期降水量趋势,初、终台的早晚及登陆广东省的热带气旋个数等重要天气的关系.指出南海西南季风爆发早的年份,前汛期雨量以正常偏少为主、后汛期雨量以偏多为主、登陆广东热带气旋偏多;南海西南季风偏强的年份,后汛期雨量以偏多为主,登陆广东热带气旋以正常偏多为主.还分析了4～6月、7～9月以及前冬(12～2月)的海温场、500 hPa高度场与西南季风建立早晚、强弱的关系,初步探索了西南季风建立的早晚、强弱与广东省汛期重要天气气候异常的关系的一些机理,其结果可供短期气候业务预测参考.     

大理国家气候观象台发展之路

<正>大理国家气候观象台(以下简称大理观象台)成立于2006年5月。大理观象台位于青藏高原东缘,特有的地理环境和历史资源条件,成为其快速发展的天然优势。大理观象台对南支天气系统东移、对高原冷空气东移以及孟加拉湾风暴对我国中东部和西南、华南的影响等,是全国乃至东亚天气监测研究的最佳监测点。不仅如此,这里更是我国降水的主要空中水汽通道,大理处于东亚季风和西南季风的交汇处,对两支著名季风的监测作用十分突出。     

东亚热带季风与副热带季风降水特征研究的回顾与展望

东亚季风既包含热带季风又包含副热带季风,他们之间存在的相互作用直接影响我国大范围旱涝灾害。东亚热带季风和东亚副热带季风作为两种性质不同的季风,其形成原因及其主要天气系统截然不同,对应的热带季风降水和副热带季风降水在结构、性质上自然也存在很大的差异。简要回顾我国气象学家在东亚热带季风降水及东亚副热带季风降水方面的研究成果,概述最近关于东亚副热带季风研究的热点问题,引证了利用星载测雨雷达对南海地区降水性质的部分研究结果,并对进一步利用星载测雨雷达资料开展季风及其降水研究进行了展望。     

热带海洋变异对东亚季风的影响

季风主要是由于海陆热力差异随季节的变化所造成。热带海洋温度具有显著的年际异常，热带海温的变异不仅可以通过改变海陆热力差异，而且也通过热带地区强烈的海气相互作用，对季风系统产生重要影响，造成季风区天气和气候的异常。回顾了发生在热带东太平洋(ENSO现象)、热带西太平洋暖池和热带印度洋海温的变异对东亚季风的影响及其影响的物理过程，并指出东亚季风与这些热带区域的海温变异是一个有机的整体，只有对它们进行综合的研究，才能真正认识它们之中任一部分的变化。     

Revisiting the response of western North Pacific tropical cyclone intensity change to vertical wind shear in different directions

不同方向垂直风切变对热带气旋强度变化的影响存在明显差异,但对热带气旋无维强度变化的影响却差异较小.研究发现不同方向垂直风切变对无维强度变化的影响的细微差异与热带气旋周围的高层西风槽,倒槽,低层季风槽等天气系统配置有关.这一结果表明,在研究不同方向切变对热带气旋强度变化的影响时,除了下垫面热力作用外,还应考虑与切变相关的天气尺度系统的热,动力作用.     

An Overview of Research and Forecasting on Rainfall Associated with Landfalling Tropical Cyclones

The ability to forecast heavy rainfall associated with landfalling tropical cyclones (LTCs) can be improved with a better understanding of the mechanism of rainfall rates and distributions of LTCs. Research in the area of LTCs has shown that associated heavy rainfall is related closely to mechanisms such as moisture transport, extratropical transition (ET), interaction with monsoon surge, land surface processes or topographic effects, mesoscale convective system activities within the LTC, and boundary layer energy transfer etc.. LTCs interacting with environmental weather systems, especially the westerly trough and mei-yu front, could change the rainfall rate and distribution associated with these mid-latitude weather systems. Recently improved technologies have contributed to advancements within the areas of quantitative precipitation estimation (QPE) and quantitative precipitation forecasting (QPF). More specifically, progress has been due primarily to remote sensing observations and mesoscale numerical models which incorporate advanced assimilation techniques. Such progress may provide the tools necessary to improve rainfall forecasting techniques associated with LTCs in the future.     

新疆南部干旱区暴雨研究：科学认知与主要进展*

新疆南部(简称南疆)是典型的干旱区,地形和下垫面复杂,生态环境脆弱,对气候变化异常敏感。在全球变暖背景下,近年来南疆暴雨发生频率和强度明显增加,引起社会广泛关注。本文主要回顾了南疆干旱区暴雨的科学认知、研究进程和最新研究进展,南疆暴雨具有降水集中度高、相对强度大、极端性强、空间分布不均匀等特点。南疆暴雨研究经过了从大降水个例到多尺度相互作用机理和数值模拟发展应用的阶段,目前在南疆暴雨的重要影响天气系统和水汽输送等方面取得新的科学认识。最后,对干旱区暴雨科学研究的未来发展方向进行了简要的讨论和展望,以期承上启下,为未来新时期南疆暴雨研究提供创新基础。     

两次西行热带气旋影响云南降水对比分析

利用常规观测资料、中国气象局上海台风研究所(CMA-STI)热带气旋最佳路径数据和FY-2C卫星云图观测资料,以0608台风派比安和0809强热带风暴北冕两个西行热带气旋影响云南降水为例,通过其路径、降水量、移动速度、环境场和物理量场的对比分析,结果表明:两次台风源地、移动路径及登陆地点、影响时段、最大降水落区相同,但影响时间长度、影响范围和造成的灾害程度后者强于前者;西南季风与热带辐合带(ITCZ)较活跃,副热带高压西伸增强,并有低空急流、辐合区配合台风低压环流共同作用是热带气旋导致云南强降水的重要天气背景;云图中尺度分析发现,多种系统的共同作用,导致台风环流持久不消,进而易激发多个α-中尺度对流系统(MαCS)和β-中尺度对流系统(MβCS)云团生成并持久维持,是台风低压强降水发生的直接原因;物理量场的诊断分析表明,活跃的季风系统,使孟加拉湾和南海构成强大的水汽通道,伴随低空急流的建立和增强,致使大量不稳定能量和水汽向云南输送,在云南形成条件性对称不稳定(CSI)和深厚斜压性的正反馈机制,是导致云南强降水的重要物理机制。     

A review of Asian-Pacific monsoon

Research on the Asian-Pacific monsoon has a long history. This paper starts by summarizing field experiments investigating the Asian-Pacific monsoon. Since the 1960s, a number of international and regional monsoon projects and field experiments have been carried out, and substantial progress regarding research on the Asian-Pacific monsoon has been made. Second, the onset and the seasonal march of the Asian summer monsoon and the annual cycle of active and break periods of the monsoon, which are characterized by precipitation maxima and minima, are studied. Since the inter-tropical convergence zone （ITCZ or TCZ） is the dominating weather system and is the major birthplace of typhoons and tropical convective systems, the monsoonal rainfall and ITCZ are analyzed after the onset of the Asian monsoon. Finally, because the ITCZ has a close relationship with tropical convective systems and rainfall events in monsoon regions, analyses of the developments of deep convection and rainfall events are briefly introduced.     

Science and Prediction of Heavy Rainfall over China: Research Progress since the Reform and Opening-Up of New China

This paper reviews the major progress on development of the science and prediction of heavy rainfall over China since the beginning of the reform and opening-up of new China(roughly between 1980 and 2019). The progress of research on the physical mechanisms of heavy rainfall over China is summarized from three perspectives: 1) the relevant synoptic weather systems, 2) heavy rainfall in major sub-regions of China, and 3) heavy rainfall induced by typhoons. The development and application of forecasting techniques for heavy rainfall are summarized in terms of numerical weather prediction techniques and objective forecasting methods. Greatly aided by the rapid progress in meteorological observing technology and substantial improvement in electronic computing, studies of heavy rainfall in China have advanced to investigating the evolution of heavy-rain-producing storms and observational analysis of the cloud microphysical features. A deeper and more systematic understanding of the synoptic systems of importance to the production of heavy rainfall has also been developed. Operational forecast of heavy rainfall in China has changed from subjective weather event forecasts to a combination of both subjective and objective quantitative precipitation forecasts, and is now advancing toward probabilistic quantitative precipitation forecasts with the provision of forecast uncertainty information.     

A case study on a strong tropical disturbance and record heavy rainfall in Hat Yai, Thailand during the winter monsoon

The evolutionary process and structural characteristics of the atmospheric circulation and synoptic situation which caused the record heavy rainfall with a precipitation amount of 550 mm in Hat Yai,Thailand from 20 to 23 November 2000 is studied. In the study, the modern three dimensional observational data were collected as completely as possible, and detailed analyses were made. It is revealed that the colds urges of the Asian winter monsoon that originate from Siberia can arrive at the lower latitudes, including South Thailand, Malaysia, Indonesia, cause strong heavy rainfall there, and interact with weather systems in the near-equatorial regions of the Southern Hemisphere. This is strongly supported by Chinese scientist‘s original finding in 1930s. The strong convective cloud clusters in the above areas are generated by the direct influence of the cold surges, and are related with the South China Sea disturbances in the lowe rtroposphere. The maximum of the convergence of total moisture flux near South Thailand in the situation under study implies that the water vapour supply is abundant and very favorable to the occurrence of the heavy rainfall. The release of latent heat enhances the Hadley Circulation also. The feedback of the strong severe weather on climate indeed exists, and there are pronounced interactions between the multi-scale systems and between both hemispheres.     

Statistical Characteristics of Raindrop Size Distribution in the South China Monsoon Region (Guangdong Province)

While heavy rainfall frequently takes place in southern China during summer monsoon seasons,quantitative precipitation forecast skills are relatively poor.Therefore,detailed knowledge about the raindrop size distribution(DSD)is useful in improving the quantitative precipitation estimation and forecast.Based on the data during 2018-2022 from 86stations in a ground-based optical disdrometer measurement network,the characteristics of the DSD in Guangdong province are investigated in terms of the pa...     

Interannual variation of summer monsoon rainfall over Nepal and its relation to Southern Oscillation Index

Summary ?Nepal, lying in the southern periphery of the Tibetan Plateau receives about 80% of the total annual rainfall during summer monsoon (June–September). Rainfall analysis shows that summer monsoon is more active in the southern part of Nepal but in the high Himalayas and Trans-Himalayan region other weather systems like western disturbances are also as effective as monsoon in giving rainfall. The influence of Southern Oscillation (SO) in Nepal monsoon rainfall is found to be very significant. The years with significant negative (positive) Southern Oscillation Index (SOI) have less (more) rainfall in most of the cases during the 32-year period. This relationship is also found to vary with time. The years with deficient rainfall are associated most of the times with negative departure of SOI and the composite chart during these occasions shows about 95% area of Nepal experiencing below normal rainfall. Likewise at the time of positive departure of SOI, most of the region (94%) experienced above normal rainfall. There is a good relation between SOI and rainfall over Nepal during monsoon. The correlation coefficient between Nepal monsoon rainfall and monthly SOI shows a statistically significant in-phase relationship during and after monsoon but poor relation during the months prior to monsoon season. These results suggest that monsoon plays an active and effective role on the interannual variability including SOI. Received December 28, 1999/Revised May 22, 2000     

A verification of spatio-temporal monsoon rainfall variability across Indian region using NWP model output

Evaluation of weather forecasting systems and assessment of existing verification procedures are essential to achieve desirable seamless rainfall prediction. Prediction of wet and dry spells is quite useful in agriculture and hydrology but very few attempts have been made so far to resolve the issue using numerical model output. Performance of five state-of-the-art global atmospheric general circulation models and their ensemble mean has been examined in predicting the parameters of wet and dry spells (WSs/DSs) during monsoon period of 2008–2011 over seven subzones of the Indian region. The number of WSs across the region is found to be underestimated, while total duration and rainfall amount of WSs (DSs) overestimated (underestimated). Start of the first WS is late and ends of the last WS early in the model forecast. More uncertainty is noticed in the prediction of DS rainfall and its duration than that of the WS. The percentage area of India under wet conditions (rainfall amount over each grid is more than its daily mean monsoon rainfall) and rainwater over the wet area is overestimated by about 59 and 32 %, respectively, in all models.     

1998年7月长江流域特大洪水期间暴雨特征的分析研究

对１９９８年７月下旬发生于长江中下游的暴雨,即“二度梅”,进行了初步的分析研究,认为：（１）在这一时期由于副热带高压的向南撤退并稳定在偏南位置,为长江流域降水提供了重要的条件;（２）中纬度系统维持两脊一槽的形势有利于冷空气的南下,而夏季风在这一期间偏弱,前沿停留于长江流域,同时与中纬度的偏北气流形成一条沿长江流域东西走向的切变线;（３）在这条切变线附近不断有中尺度系统发生发展,其中一部分中尺度系统达到很强烈的程度,甚至引发了８８４ｍｍ／ｈ的强降水;（４）对流层上层,如２００ｈＰａ上的高压,其东侧的强烈的辐散区正好位于长江中下游地区,上下层系统的有利配合,对这次暴雨的发生十分有利。