亚热带东部丘陵山区作物气候生产力研究

本文根据1983年4月—1986年3月三年山区梯度观测资料，综合考虑山区光、热、水农业的气候资源匹配关系，建立不同山区、坡向、高度的作物气候生产力估算模式。模式中对山区温度、降水、日照等气象要素进行了修正。运用模式估算了不同山区、坡向、高度的水稻、玉米、冬小麦气候生产力。计算结果:亚热带东部丘陵山区单、双季稻、夏玉米气候生产力一般南坡大于北坡，西坡大于东坡；春玉米、冬小麦一般北坡大于南坡，东坡大于西坡。双季晚稻气候生产力大于双季早稻，夏玉米大于春玉米（神农架山区除外）。应该指出，目前高产典型水稻产量可达其气候生产力的60%以上，玉米和冬小麦仅达到30%—50%左右，表明山区农业气候资源可开发潜力很大。本文为合理开发山区气候资源、调整农业布局及提高单位面积产量提供了定量的科学依据。     

海南岛农业气候区划

本文依据农业气候适宜度进行海南岛农业气候区划,其方法是应用模糊数学扩展原理建立农业气候模型,得出各地可表示农业气候资源优劣的资源指数、表示它们之间配合程度的效能指数和表示可供挖掘的资源潜力的效能利用率;以它们为区划因子,通过模糊聚类分析和模糊相似优先比进行划区。全岛分为六个农业气候区。      

我国华南江南春季雷暴气候特征分析

基于我国华南江南地区274个基本地面气象观测站数据、全国闪电定位数据以及欧洲中心的全球大气再分析数据(ERA-Interim),对1981—2017年华南江南地区的春季雷暴日采用经验正交函数分解方法(EOF),并与气象要素场做回归分析。得出以下主要结论:(1)我国华南江南地区春季雷暴活动高发区主要在广西东部至广东西部;其高峰期在下午18:00和凌晨4:00左右,且大多数雷暴活动持续时间不超过3 h;山区雷暴活动主要在傍晚至夜间;平原雷暴活动主要在白天,高峰在17:00及06:00前后;(2)华南江南地区的雷暴活动存在着3~5年的短周期和16年左右的长周期变化;(3)雷暴日距平EOF分析的前3个主成分累计方差贡献达到72.3%。按其向量场的方差贡献分型,Ⅰ型表现为华南江南雷暴活跃特征呈现较统一的变化规律。深厚西南低涡槽前、上干下湿的水汽层结、上冷下暖的温度层结为华南江南地区发生大范围雷暴天气提供良好的动力、水汽和位势不稳定条件,是华南江南雷暴活跃异常的主要模态;Ⅱ型表现为从华南南部到江西与浙江南部有一条西南-东北向、下宽上窄的雷暴活跃正距平异常区,而两侧为负距平异常区。其环流特征表现为温度整层偏冷,水汽整层偏湿,而西南槽前动力抬升有利于水汽抬升凝结触发对流形成雷暴;Ⅲ型表现为华南和江南地区雷暴活跃特征呈南北反位相异常,其分界线在26 °N附近。其环流特征表现为较强的干冷空气南下与南方暖湿空气在南岭山区对峙形成异常的垂直环流圈。在其上升支,低层干冷空气被卷入中高层使得中高层暖湿空气凝结释放潜热形成对流,造成华南地区多雷暴发生,而江南地区处于垂直环流的下沉支,整层湿度偏干,造成江南地区雷暴相对偏少。      

COMPREHENSIVE ANALYSIS OF THE MACRO- AND MICRO-PHYSICAL CHARACTERISTICS OF DENSE FOG IN THE AREA SOUTH OF THE NANLING MOUNTAINS

Using the composite field observational data collected in the area south of the Nanling Mts. and numerical modeling, the seasonal features of dense fog and visibility, fog drop spectrum and physical concept of fog forming have been analyzed. The occurring frequency of low visibility（≤200 m） is very high with a mean of 24.7%, a maximum of 41.8% from the end of autumn to winter and next spring. The fog processes that occur in the area south of the Nanling Mts. in spring and winter result from the interactions of complicated micro-physical processes, the local terrain, water vapor transportation and the influencing weather system. The fog processes are arisen from advection or windward slope, which is much different from the radiation fog. Cooling condensation due to the air lifted by the local mountain plays an important role in fog formation. Windward slope of the mountain is favorable to the fog formation. Dense fog can occur at lower altitudes in the windward slope of mountain, resulting in the lower visibility. The fog is mainly of small-drop spectrum with smaller number-density than that of urban fog, and its drop spectrum has descending trend in the section of smaller diameter. The inverse relationship between fog water content and visibility is the best among several relationships of micro-variables. In addition to micro-physical processes of fog body itself, the motion of irregular climbing and crossing over hillside while the fog body is being transported by the wind are also important reasons for the fluctuation of micro-physical parameters such as fog water content.     

THE CALCULATION AND ANALYSIS OF SLOPE NET RADIATION IN CHINA*

By using the climatological calculating method for each component of slope surface net radiation proposed by the authors,calculations and analyses are done of the distribution features of slope net radiation in China with emphasis on the discussion of variations of slope net radiation in typical stations and sites with slope direction,slope,latitude and season.The distribution features of net radiation on the north and south slopes are,for the first time,mapped and discussed,revealing the great difference on the national basis,and thus acquiringa new interesting result that the negative-value area of winter net radiation on the north slope(20°)can reach Yunnan and Guizhou Provinces and middle and upper reaches of the Changjiang River.     

在一种寒潮情况下的水平温度场及冷锋构造

本文选择了一次大气物理过程比较简单的寒潮作为例子,讨论其温度场及冷锋的构造。事实看出,寒潮前沿的冷锋,在黄河流域时与在华南时,构造是不同的。本文对于锋的构造的改变进行了初步的讨论。再者,寒潮末期的高空温度场改变很大,作者试用锋生公式计算,结果指出,温度平流值的变化起着主导作用。     

METHODS CALCULATING THE SPATIAL DISTRIBUTION OF AGROCLIMATIC RESOURCES IN MOUNTAINOUS AREAS AND CLIMATIC EFFECTS OF MICROTOPOGRAPHY*

The methods calculating the spatial distribution of agroclimatic resources (temperature,humidity,precipitation,wind speed,etc.) in mountainous areas are presented.The linear model can be used for the mean temperature,accumulated temperature,and the occurrence date and duration of limiting temperature,but the nonlinear model for extreme temperature,humidity,precipitation and wind speed.The climatic effects of topography obtained from the application of these methods in the Shaxi River basin,Fujian Province,are also described.The results show that the methods proposed in this paper may effectively disclose the macro-and micro-variations of spatial distribution of agroclimatic resources in mountainous areas.     

THE EFFECTS OF THE PLATEAU'S TOPOGRAPHIC GRADIENT ON ROSSBY WAVES AND ITS NUMERICAL SIMULATION

By using barotropic model equations, this article analyzed the characteristics of Rossby waves, the propagation features of wave energy and the influence of dynamic and thermal effects of the Tibetan Plateau on Rossby waves, and the focus is on discussing the plateau's topographic gradient effects on atmospheric Rossby waves. Then based on the WRF3.2 and the NCEP/NCAR FNL reanalysis data, we devised comparative tests of changing the plateau's topographic gradient and simulated a process of persistent heavy rain that happened in May 2010 in South China. The results are shown as follows. The Tibetan Plateau’s topography is conducive to the formation of atmospheric Rossby waves. while the plateau's terrain, its friction and heating effects can all make the atmospheric Rossby waves develop into the planetary waves; The effects of plateau's north and south slopes on the Rossby wave’ phase velocity is opposite, and when the slope reached a certain value can the quasi-steady normal fluctuations be generated; Simultaneously, due to the plateau's topographic gradient, descending motion appears at the west side of the plateau while ascending motion appears at the east side, and the vertical movement increased with the amplification of topographic gradients. The plateau's topographic gradient also obviously amplified the precipitation in South China, and the rainfall area increased with the amplification of topographic gradients and gradually moved from south to north and from west to east, which is conducive to the occurrence and development of convective activities in the downstream areas of the Tibetan Plateau; Moreover, for the plateau’s dynamic and thermal effects, the Rossby wave’ propagation shows upstream effects of energy dispersion, so the plateau can then affect the weather in downstream areas. Moreover, the wave group velocity increased with the degree of topographic slope.     

坡面散射辐射的分布特征及其计算模式

本文应用安装在经纬仪上的天空辐射表所观测的坡面散射辐射资料,对散射辐射的各向异性问题作了较为详尽的分析。揭示出坡面散射辐射随坡向、坡度变化的基本规律。文中还对前人所提出的计算坡面散射辐射的各种模式进行了检验、评述。最终提出一种通用性较强的坡面散射辐射通量密度的计算模式。其物理意义和计算精度都较国外同类模式优越。