针对未配备气象传感器的全球卫星导航系统(GNSS)站缺乏实测气象参数,通常利用再分析数据、经验模型替代反演大气可降水量(PWV)的问题,定量分析地面气压(P)和加权平均温度(Tm)在反演PWV中的适用性:利用欧洲中期天气预报中心(ECMWF)发布...针对未配备气象传感器的全球卫星导航系统(GNSS)站缺乏实测气象参数,通常利用再分析数据、经验模型替代反演大气可降水量(PWV)的问题,定量分析地面气压(P)和加权平均温度(Tm)在反演PWV中的适用性:利用欧洲中期天气预报中心(ECMWF)发布的第五代再分析数据集(ERA5)、美国国家环境预报中心(NCEP)/国家大气研究中心(NCAR)再分析数据、第二代和第三代全球气压和温度模型(GPT2和GPT3)、全球格网非线性加权平均温度模型(GGNTm)计算P和Tm;然后以探空站实测气象数据为参考,评估不同P和Tm的精度及其对PWV反演的影响。结果表明:1)ERA5、NCEP、GPT2、GPT3获取P的偏差(bias)绝对值小于1 h Pa,均方根误差(RMSE)小于5.5 h Pa;2)在获取Tm方面,ERA5、NCEP、GGNTm、GPT3的bias绝对值小于2.5 K,RMSE小于5.5 K;3)将ERA5、NCEP、GPT2+GGNTm、GPT3获取的气象参数应用到PWV反演中,PWV偏差绝对值小于0.5 mm,RMSE小于3 mm。分析得出应用非实测气象参数反演的GNSS大气可降水量也可获得较高精度的结论。展开更多
The lifting technique is now the most popular tool for dealing with sampled-data controlsystems. However, for the robust stability problem the system norm is not preserved by the liftingas expected. And the result is ...The lifting technique is now the most popular tool for dealing with sampled-data controlsystems. However, for the robust stability problem the system norm is not preserved by the liftingas expected. And the result is generally conservative under the small gain condition. The reason forthe norm di?erence by the lifting is that the state transition operator in the lifted system is zero inthis case. A new approach to the robust stability analysis is proposed. It is to use an equivalentdiscrete-time uncertainty to replace the continuous-time uncertainty. Then the general discretizedmethod can be used for the robust stability problem, and it is not conservative. Examples are givenin the paper.展开更多
文摘针对未配备气象传感器的全球卫星导航系统(GNSS)站缺乏实测气象参数,通常利用再分析数据、经验模型替代反演大气可降水量(PWV)的问题,定量分析地面气压(P)和加权平均温度(Tm)在反演PWV中的适用性:利用欧洲中期天气预报中心(ECMWF)发布的第五代再分析数据集(ERA5)、美国国家环境预报中心(NCEP)/国家大气研究中心(NCAR)再分析数据、第二代和第三代全球气压和温度模型(GPT2和GPT3)、全球格网非线性加权平均温度模型(GGNTm)计算P和Tm;然后以探空站实测气象数据为参考,评估不同P和Tm的精度及其对PWV反演的影响。结果表明:1)ERA5、NCEP、GPT2、GPT3获取P的偏差(bias)绝对值小于1 h Pa,均方根误差(RMSE)小于5.5 h Pa;2)在获取Tm方面,ERA5、NCEP、GGNTm、GPT3的bias绝对值小于2.5 K,RMSE小于5.5 K;3)将ERA5、NCEP、GPT2+GGNTm、GPT3获取的气象参数应用到PWV反演中,PWV偏差绝对值小于0.5 mm,RMSE小于3 mm。分析得出应用非实测气象参数反演的GNSS大气可降水量也可获得较高精度的结论。
文摘The lifting technique is now the most popular tool for dealing with sampled-data controlsystems. However, for the robust stability problem the system norm is not preserved by the liftingas expected. And the result is generally conservative under the small gain condition. The reason forthe norm di?erence by the lifting is that the state transition operator in the lifted system is zero inthis case. A new approach to the robust stability analysis is proposed. It is to use an equivalentdiscrete-time uncertainty to replace the continuous-time uncertainty. Then the general discretizedmethod can be used for the robust stability problem, and it is not conservative. Examples are givenin the paper.
