使用浙江省69个基准站2006—2015年5—9月以及同期杭州城区58个区域自动站小时降水资料,利用Gamma分布计算浙江省短时强降水的累积概率,同时综合其频率分布,揭示杭州市小时降水强度的分布特征。此外,以杭州市区为例,利用探空资料分析不...使用浙江省69个基准站2006—2015年5—9月以及同期杭州城区58个区域自动站小时降水资料,利用Gamma分布计算浙江省短时强降水的累积概率,同时综合其频率分布,揭示杭州市小时降水强度的分布特征。此外,以杭州市区为例,利用探空资料分析不同量级(≥50 mm·h-1、30~<50 mm·h-1、20~<30 mm·h-1、<20 mm·h-1)小时雨强出现的环境指标,并基于核密度估计方法提取预报指标。结果表明:杭州城区出现小于等于10 mm·h-1的降水概率高达98.4%,≥20 mm·h-1的概率仅0.05%;受杭州湾偏东气流影响,杭州市区发生短时强降水频率相对较高,尤其是余杭区的东部和西北山区;自2008年以来杭州市区每年短时强降水日数为18~28 d,其中大于等于50 mm·h-1的短时强降水日所占比例高达10%~20%(除2009年和2012年低于10%外);可用于预报杭州市区短时强降水的最佳环境因子依次为整层可降水量、K指数、最佳抬升指数、沙氏指数、925 h Pa露点温度和强天气威胁指数;在判断杭州市区短时强降水强度上表现最好的环境因子为整层可降水量,其次是850 h Pa垂直速度和925 h Pa散度。展开更多
The high level of safety demand of civil aviation requests local area augmentation system （LAAS） extremely high navigation integrity performance. A new LAAS pseudo-range error overbound method is proposed in this pa...The high level of safety demand of civil aviation requests local area augmentation system （LAAS） extremely high navigation integrity performance. A new LAAS pseudo-range error overbound method is proposed in this paper to improve the integrity of LAAS. Firstly, a more practical pseudo-range error distribution model is established. Then, by calculating the relationship between the statistical uncertainty of the model parameter and the integrity risk, a new method is proposed to calculate the pseudo-range error over-bound model. This method can effectively reduce the inflation factor and the resulting conservativeness of the over-bound model. Comparative experiments show that the method proposed in this paper performs better and satisfies the requirements of real applications.展开更多
文摘使用浙江省69个基准站2006—2015年5—9月以及同期杭州城区58个区域自动站小时降水资料,利用Gamma分布计算浙江省短时强降水的累积概率,同时综合其频率分布,揭示杭州市小时降水强度的分布特征。此外,以杭州市区为例,利用探空资料分析不同量级(≥50 mm·h-1、30~<50 mm·h-1、20~<30 mm·h-1、<20 mm·h-1)小时雨强出现的环境指标,并基于核密度估计方法提取预报指标。结果表明:杭州城区出现小于等于10 mm·h-1的降水概率高达98.4%,≥20 mm·h-1的概率仅0.05%;受杭州湾偏东气流影响,杭州市区发生短时强降水频率相对较高,尤其是余杭区的东部和西北山区;自2008年以来杭州市区每年短时强降水日数为18~28 d,其中大于等于50 mm·h-1的短时强降水日所占比例高达10%~20%(除2009年和2012年低于10%外);可用于预报杭州市区短时强降水的最佳环境因子依次为整层可降水量、K指数、最佳抬升指数、沙氏指数、925 h Pa露点温度和强天气威胁指数;在判断杭州市区短时强降水强度上表现最好的环境因子为整层可降水量,其次是850 h Pa垂直速度和925 h Pa散度。
基金the National Natural Science Foundation of China(61179054)the National Basic Research Program of China(2011CB707004)the National Key Technology R&D Program(2011BAH24B02)
文摘The high level of safety demand of civil aviation requests local area augmentation system （LAAS） extremely high navigation integrity performance. A new LAAS pseudo-range error overbound method is proposed in this paper to improve the integrity of LAAS. Firstly, a more practical pseudo-range error distribution model is established. Then, by calculating the relationship between the statistical uncertainty of the model parameter and the integrity risk, a new method is proposed to calculate the pseudo-range error over-bound model. This method can effectively reduce the inflation factor and the resulting conservativeness of the over-bound model. Comparative experiments show that the method proposed in this paper performs better and satisfies the requirements of real applications.
