数学系毕业论文.doc

09届分类号:
单位代码:10452
毕业论文
宁夏地区沙尘暴预测中的数学模型

姓名尹程娇
学号 200506130101
年级 2005
专业数学与应用数学
系(院) 数学系
指导教师张兆忠

2008年11月30日
摘要
结合宁夏中北部地区的特殊地理条件及近几十年的气候统计数据,对沙尘暴的发生机制进行全面讨论,建立相应的数学模型,分析沙尘暴的发生频率与各形成因素的关系,预测其风险程度,进而估计中国境内引起沙尘暴的重要沙源位置。
第一,根据影响沙尘暴发生频率的主要因素进行定性、定量分析,建立气候影响指数模型;第二,建立回归模型,据此估计出相应地区一定时间内沙尘暴的发生次数。
为了较准确地发出沙尘暴高风险预警信息,首先,根据沙尘天气气象等级的划分方法,将天气气象划分为A、B、C、D四个等级,然后,从概率角度出发,应用模型进行预测,所得结果与真实值误差较小。
结合上述所得结果,将中国内陆地区主要气象站点近20年沙尘暴发生的天数进行月份累加求和,对沙尘暴发生较多的地区进行筛选,剔除掉发生次数较少的站点,并反映在地图上,从而准确的估计了中国境内引起沙尘暴的重要沙源地位置,并结合第一个模型成功估计了沙尘暴的影响范围。
本模型囊括了沙尘暴形成的几大主要气候因素,科学合理的分析了各因素对沙尘暴形成的影响。为沙尘暴的预测及预防提供了一套科学实用、合理简便的方法。
关键词:气候影响指数模型;回归模型;模型
ABSTRACT
According to the special geography conditions of mid north part in NingXia and the climate statistical data of recent decades , we have made full discussion about the mechanism of occurrence of sandstorm established responded mathematical model .Aiming at estimating the risk extinction.
First, we have analyzed the occurrence frequency of its quality and quantity of sandstorm. Furthermore, we introduced the coefficient of wind and sand erosion,then established the index model of climate influence. After that we established the tropic model and established the occurrence time of sandstorm at responded place in some instant time.
From the angle of probability ,according to the separated method of atmosphere grade,the atmosphere grade were separated into four grades A ,B ,C ,D .Furthermore ,we predicted them by Markov model ,the consequence was little different from real value.
The number of occurring days of sandstorm were summed up by monthly ,witch were given by all stations in 20 years recently .We selected out the places which occur sandstorm more frequently ,excluded less frequently sand locations which induced sandstorm in china were estimated exactly .Combined with the first model ,we estimated the influence scope of sandstorm essfully.
This model included several main climate factors which form the sandstorm .A