摘要
本文是一年来从事夏季降水天气初步普查的简单报告。第一节首先指出所用分析方法与一般国内所通用者,稍有不同。高空等压面分析,取20米作为等高缐间隔,2℃作为等温缐间隔。代替40米及5℃的间隔,以适应夏半年较弱的温度场与气压形势场,在剖面分析中以等假相当位温缐代替位温缐,与等温缐配合以适应降水天气的凝结降水过程。第二节讨论了五种夏半年基本降水天气系统,即冷锋、阻塞高压与冷涡、季风热低压、暖锋及有风的结构,并简单地叙述了演变过程。第三节对某些天气概念提供一些批判性的讨论。根据现已增加的观测材料,论证季风与梅雨是多样性的,决定于大规模的温度场与流场特性,以高空湿度大小区分赤道气团与热带海洋气团,证明是不适当的,因为中国赤道锋降水区域以南,即在所谓南南季风的赤道气团中,中层大气仍是干燥的。降水区域内,中层对流层的大量水份,是由于辐合或抬升的作用,使潜势的对流不稳定性成为现实的不稳定性,而由下层空气上升带上去的。文中还论证了所谓西北槽槽缐前倾是将两个系统混作—个系统的不正确桔果。最后还讨论了切交缐及一般模型在天气分析预报中的应用与限制。
This is a brief report of a preliminary survey of certain rain-bearing systems over China in later spring and summer.In the first part,a general description of the methods of analysis used in this survey is given.As the temperature and wind fields are weak,and the precipitation is heavy,smaller intervals for the isotherms and contours in the constant pressure surface and pseudo-equivalent potential instead of potential temperature in the cross section analysis are used.In the second part,there are descriptions of the structure and development of five frequently observed rain-bearing systems i.e.cold front,blocking high and cold vortex,monsoon heat low,warm front and typhoon.The last part consists of discussions of some points of view in synoptic meteorology in China.It is stated that the monsoon precipitation is various in intensity and duration according the large-scale flow patterns.The difference of moisture content in the middle troposphere as a criterion for the identification of equatorial or tropical maritime air mass is proved to be missleading.It is shown that the upper air moist content is high only within the raining region near the polar or equatorial front.To the south of the equatorial front within the so-called equatorial air mass,the moist content in the middle troposphere is as low as within the tropical maritime air mass.It is the convergence and lifting of the tropical air mass which releases the convective instability and induces the surface moist air rising to the middle troposphere.The phenomenon of the forward-inclination of the so-called North-West Trough based on the time cross-section of wind is proved to be a mistake by combining two systems into one trough.The terminology of shear line,and the correct application of synoptic models in weather analysis and forecas-ting are also discussed.
作者
谢义炳
HSIEH YI-PING(Peking University)
出处
《气象学报》
1956年第1期1-23,共23页
Acta Meteorologica Sinica
