NUMERICAL PREDICTION OF AN EXTREME RAINSTORM OVER THE PEARL RIVER DELTA REGION ON 7 MAY 2017 BASED ON WRF-ENKF

An ensemble Kalman filter based on the Weather Research and Forecasting Model (WRF-EnKF) is used to explore the effectiveness of the assimilation of surface observation data in an extreme local rainstorm over the Pearl River Delta region on 7 May 2017. Before the occurrence of rainstorm, the signals of weather forecasts in this case are too weak to be predicted by numerical weather model, but the surface temperature over the urban area are high. The results of this study show that the wind field, temperature, and water vapor are obviously adjusted by assimilating surface data of 10-m wind, 2-m temperature, and 2-m water vapor mixing ratio at 2300 BST 6 May, especially below the height of 2 km. The southerly wind over the Pearl River Delta region is enhanced, and the convergence of wind over the northern Guangzhou city is also enhanced. Additionally, temperature, water vapor mixing ratio and pseudoequivalent potential temperature are obviously increased over the urban region, providing favorable conditions for the occurrence of heavy precipitation. After assimilation, the predictions of 12-h rainfall amount, temperature, and relative humidity are significantly improved, and the rainfall intensity and distribution in this case can be successfully reproduced. Moreover, sensitivity tests suggest that the assimilation of 2-m temperature is the key to predict this extreme rainfall and just assimilating data of surface wind or water vapor is not workable, implying that urban heat island effect may be an important factor in this extreme rainstorm.     

气象因子对柏木种子品质影响初探

柏木是我国南方的主要用材树种之一,我县柏木栽培历史悠久,历年大量采集柏木种子,供自育和外销用。在生产过程中,我们对柏木种子品质进行了分析,就气象因子对柏木种子品质之一发芽率的影响进行探讨,使气象与林业部门密切配合起来,为提高柏木种子品质,建立优良采种林分提供依据和奠定良好的基础。     

徐湾—石头岗花岗闪长岩体对围岩的热影响

对徐海—石头岗花岗闪长岩体围岩中黑云母及有机质变质程度的研究发现:距岩体580m范围内的接触带岩石皆具有角岩化现象。黑云母含量受原岩成分影响,其鳞片粒径与岩体距离密切有关。围岩中镜质组反射率,(R_(mas))值与岩体距离之间有十分明显的规律。     

行业文摘

Z8928节油灵降低油耗效果显著在一定的使用条件下,把1‰的增效剂混入各种柴油机器的柴油中,便可节约8％左右的燃料,这是河南浚县科协实验化工厂生产的Z8928柴油节油灵所显示的效果。据不完全统计,我国每年消耗柴油约2000万吨,如能节约8％,其效益则非常可观。     

抗洪救灾遥感系统中河道防洪信息系统的试验研究

介绍了抗洪救灾遥感系统中河道防洪信息系统的试验研究.试验以微机作为基本硬件环境,通过对各种图形和遥感图像的输入、输出与处理方法的研究,采用以DBASE-Ⅲ为主,以FORTRAN、BASIC和C语言为辅的混合编程方法.建立了河道防洪信息系统.该系统具有数据更新、查询检索、统计报表、显示制图和对图形、图像的数据采集、编辑、存取、显示、输出与处理等功能.     

水库群优化调度函数的人工神经网络方法研究

提出了研究水库群优化调度函数的人工神经网络方法,并探讨了神经网络的训练参数、训练方法和训练样本的改变对网络训练和应用效果的影响。实例研究表明,模型及其算法是可行的、有效的。     

颗粒运动及其数理简析

根据大量的野外观测和沙(雪)颗粒运动动态摄影的资料,分析地球表面上气流带动的各种固体颗粒的主要运动形式——振动、滚动、滑移、跃移和悬移的物理图象中力的作用,给出其主要运动参数的表达式,建立各自简单的数学模型。特别对跃移运动还给出模拟轨迹方程。该模型与实际拍摄的轨迹相对比表明,较之以前风沙物理研究者模拟的跃移轨迹要好。文中首次提出的滑移概念,即振动、滚动和滑移三种颗粒运动形式代替以往分类的蠕移、跃移和悬移运动形式更准确和清晰。文中还明确回答了第一颗砂粒是怎样起跳的这一关键问题。