一次西南低涡过程的地面场中尺度分析

本文运用带通滤波分析方法,对四川省1981年7月由西南低涡等天气系统引起的大暴雨过程作了地面气象要素场的中尺度诊断分析。结果表明,带通滤波后的场具有明显的中尺度特征,其中一些物理量场的适当配置与6小时后的暴雨中心有较好的对应关系。说明了此带通滤波方法在实际业务预报中具有一定的使用价值。     

Numerical and experimental study of a flapping foil generator

The energy extraction performance of a flapping foil generator is studied through experiment and numerical simulation. A practical flapping foil generator has been proposed. The heave motion and the pitch motion of the foil are adjusted through a crankshaft-like structure. The heave and pitch motions of the foil are transferred to the rotational motion of the main shaft. A pair of gears is adopted to increase the pitch angle. A prototype with pitch amplitude θ₀ = 60^∘ has been built and the experiment is carried out in a tunnel. The overall performance of the mechanism has been analysed. Good agreement of numerical results and experiment data has been found. Further simulations with larger pitch amplitudes are carried out. It is found that higher efficiency can be achieved with larger pitch amplitude at medium frequency.     

一次典型高压型海雾过程中海上大气波导的数值模拟

2009年4月9—12日黄海海域发生了一次受高压系统影响的海雾过程。利用卫星观测与探空数据、WRF模式(Weather Research and Forecasting Model)对此次海雾过程及相伴的大气波导进行了观测分析与数值模拟。海雾与波导发展可分为3个阶段:(1)大气波导先于海雾存在于黄海海面;受高压下沉影响,黄海上空存在逆温层和较强的湿度梯度,表现为较强的贴海表面波导和非贴海表面波导。(2)海雾始于高压西部,并随高压系统逐渐东移减弱,向黄海北部扩展;辐射冷却虽然使雾顶附近逆温增强,但海雾的机械湍流使其顶部湿度梯度减小,雾顶附近对应弱悬空波导或波导消失。(3)高压系统影响使干空气下沉到雾区导致黄海海雾消散;雾顶附近逆温仍存在,同时湿度梯度增大,黄海上空逐渐变为非贴海表面波导。本研究结果表明:高压系统不仅极易为波导的发生提供有利条件,而且有利于海雾的生成,在海雾演变过程中主要是雾顶水汽梯度的变化导致了波导类型及强度的变化。     

成都市城市热岛特征初探

本文利用1986年夏季、1987年冬季市区观测资料和郊区气象站气候资料,分析了成都市热岛特征、热岛强度随时间的变化及绿化对城市小气候的影响。     

A Review of Radar- and Satellite-based Observational Studies and Nowcasting Techniques on Convection Initiation

Convection often produces severe weather which causes a great loss to human lives and properties. Precisely predicting the convection initiation process is crucial but challenging in operational convection nowcasting (0~2 h forecasting). Before the radar-defined CI occurring (e.g., the first occurrence of ≥35 dBZ echoes), observations at high spatial and temporal resolutions from weather radars and geostationary meteorological satellites can reveal precursor information such as the boundary-layer convergence lines and the rapid growth of newborn cumulus clouds. These radar- and satellite-observed precursor information are helpful for evaluating the pre-CI conditions and thus nowcasting the accurate CI timing and location. This paper reviewed the current status of radar- and satellite-based CI research and nowcasting techniques. The milestone works and the following studies in the last four decades were summarized to demonstrate how radar and satellite observations can be related to CI occurrence. The objectives and approaches of the CI research advance as the improvement in the capability of radars and were explained satellites. The research progress aids in the development of various CI nowcasting techniques. This paper introduced three well-established techniques that have been put into operational application, namely, ANC system, SATCAST algorithm, and UWCI algorithm. Some scientific issues with respect to radar- and satellite-based CI research and nowcasting were also presented.     

任意空间剖面图打印的实用程序

本文介绍了一个根据测站的经度(或纬度)打印任意空间剖面图的实用程序,通过自定义坐标,可打印在国家气象局制的6300号底图上。本程序采用BASIC语言,已在 Apple-Ⅱ上实现,对其中的部分语句修改后,也可以用于IBM-PC等其它微机上,用本程序制图,速度快,准确性高,可作为日常性的天气分析预报工具。     

一类“强降水构造”的观测研究

木文根据1966～1986年20年的观测研究,提出大气中存在一类“强降水构造”,它直观地表现为云区的组合。这类“组合”具有互补性、多尺度性、准静止性和阶段性、利用这些属性,有可能从常规地面图上(站距100-300公里)分析和预报出尺度为10~2公里的大～暴雨区;在省的加密地面图上(站距40～70公里)有可能分析出尺度为10~1公里的局地强对流雨。     

Analyses of the warm season rainfall climatology of the northeastern US using regional climate model simulations and radar rainfall fields

We examine the warm season (April-September) rainfall climatology of the northeastern US through analyses of high-resolution radar rainfall fields from the Hydro-NEXRAD system and regional climate model simulations using the weather research and forecasting (WRF) model. Analyses center on the 5-year period from 2003 to 2007 and the study area includes the New York-New Jersey metropolitan region covered by radar rainfall fields from the Fort Dix, NJ WSR-88D. The objective of this study is to develop and test tools for examining rainfall climatology, with a special focus on heavy rainfall. An additional emphasis is on rainfall climatology in regions of complex terrain, like the northeastern US, which is characterized by land-water boundaries, large heterogeneity in land use and cover, and mountainous terrain in the western portion of the region. We develop a 5-year record of warm season radar rainfall fields for the study region using the Hydro-NEXRAD system. We perform regional downscaling simulations for the 5-year study period using the WRF model. Radar rainfall fields are used to characterize the interannual, seasonal and diurnal variation of rainfall over the study region and to examine spatial heterogeneity of rainfall. Regional climate model simulations are characterized by a wet bias in the rainfall fields, with the largest bias in the high-elevation regions of the model domain. We show that model simulations capture broad features of the interannual, seasonal, and diurnal variation of rainfall. Model simulations do not capture spatial gradients in radar rainfall fields around the New York metropolitan region and land-water boundaries to the east. The model climatology of convective available potential energy (CAPE) is used to interpret the regional distribution of warm season rainfall and the seasonal and diurnal variability of rainfall. We use hydrologic and meteorological observations from July 2007 to examine the interactions of land surface processes and rainfall from a regional perspective.     

袁河流域强降水的天气背景与回波特征分析

为了更好地监测预警江西袁河流域强降水天气,使用江西雨量资料、欧洲中心格点（1°×1°）再分析资料和江西雷达回波等资料,对袁河流域5次大暴雨过程进行分析,结果表明：（1）袁河流域强降水天气形势场是925～700 hPa切变线、低层辐合高层辐散中心、西南气流达到12～18 m·s-1等因素影响;T-LnP图上整层水汽充沛,可降水量在75 mm以上;降水前低层累积不稳定能量CAPE（1000 J/Kg）和对流抑制能CIN（100 J/Kg）。（2）强降水回波的组合反射率CR在50 dBz左右,回波顶高在13 km左右,垂直积分液态水含量在12 kg·m2左右;40 dBz回波顶高在6～7 km,45 dBz回波顶高在6.5 km以下。（3）强降水和回波强度dBZ成正相关,随降水的增强,回波明显增强;当回波强度≤20 dBz时,雨强几乎不变;当回波强度在20～35 dBz之间,雨强随回波强度增加而缓慢加大;当回波强度在35～50 dBz之间,雨强随回波强度加大明显增加;而当回波强度≥50 dBz时,雨强反而趋于下降或维持。研究结果对袁河流域强降水的监测预警和预报服务有指导意义。     

Development of Artificial Intelligence Technology in Weather Forecast

Numerical weather prediction, which is the major basis of current weather forecast, has some shortcomings, such as the understanding of the law of atmospheric motion, the assimilation and application of observation data, the expression of model physics, etc., leading to the forecast error of weather. The rapid development of artificial intelligence technology in recent years provides a new possibility for the advancement and innovation of weather forecast. In this paper, the background of the development of artificial intelligence, the current situation of the application of artificial intelligence technology to weather forecast and the future development trend are mainly described to account for this possibility. After that, the idea for development of weather forecast technology based on the integration of artificial intelligence and numerical forecast is put forward. Particularly, this study stresses that, in order to advance the AI algorithm of weather forecast in the future, it is requested to focus on the nonlinear and chaotic characteristics of atmospheric motion leading to the uncertainty of forecast. Starting from the essence of mathematics and physics, we need to realize the hybrid modeling of mathematics and physics, not only to establish the framework of input-output mapping, but also to provide solutions to the bottleneck problems of weather forecast.