Based on the extreme forecast index (EFI) of ECMWF, the “observed” EFI (OEFI) of observation is defined and the EFI is calibrated. Then the EFI equivalent percentile (EFIEP) and EFI equivalent quantile (EFIEQ) are d...Based on the extreme forecast index (EFI) of ECMWF, the “observed” EFI (OEFI) of observation is defined and the EFI is calibrated. Then the EFI equivalent percentile (EFIEP) and EFI equivalent quantile (EFIEQ) are designed to forecast the daily extreme precipitation quantitatively. The formulation indicates that the EFIEP is correlated not only to the EFI but also to the proportion of no precipitation. This characteristic is prominent as two areas with nearly same EFIs but different proportions of no precipitation. Cases study shows that the EFIEP can forecast reliable percentile of daily precipitation and 100% percentiles are forecasted for over max extreme events. The EFIEQ is a considerable tool for quantitative precipitation forecast (QPF). Compared to the probabilistic forecast of ensemble prediction system (EPS), it is quantitative and synthesizes the advantage of extreme precipitation location forecast of EPS. Using the observations of 2311 stations of China in 2016 to verify the EFIEP and EFIEQ, the results show that the forecast biases are around 1. The threat scores (TS) for 20 years return period events are about 0.21 and 0.07 for 36 and 180 hours lead times respectively. The equivalent threat scores (ETS) are all larger than 0 and nearly equal to the TS. The TS for heavy rainfall are 0.23 and 0.07 for 36 and 180 lead times respectively. The scores are better than those of high resolution deterministic model (HRDet) and show significant forecast skills for quantitative forecast of extreme daily precipitation.展开更多
为了进一步提高传统码索引调制(Code Index Modulation, CIM)的误码率性能和降低伪随机(Pseudo Noise, PN)码索引资源的耗费量,提出非正交分组-码索引调制(Nonorthogonal Grouping-Code Index Modulation, NG-CIM)方案。NG-CIM在发送端...为了进一步提高传统码索引调制(Code Index Modulation, CIM)的误码率性能和降低伪随机(Pseudo Noise, PN)码索引资源的耗费量,提出非正交分组-码索引调制(Nonorthogonal Grouping-Code Index Modulation, NG-CIM)方案。NG-CIM在发送端将每一个传输时隙并行分为调制块和映射块,调制块通过比特分组后映射成为多组调制符号,映射块为各组调制符号的正交分量和同相分量索引相同的PN码进行直接序列扩频传输。仿真结果表明,在加性高斯白噪声信道中,随着频谱效率的提升,NG-CIM的误码率性能较CIM有着约2~4dB的改善,同时PN码资源的耗费量也大大减少。展开更多
文摘Based on the extreme forecast index (EFI) of ECMWF, the “observed” EFI (OEFI) of observation is defined and the EFI is calibrated. Then the EFI equivalent percentile (EFIEP) and EFI equivalent quantile (EFIEQ) are designed to forecast the daily extreme precipitation quantitatively. The formulation indicates that the EFIEP is correlated not only to the EFI but also to the proportion of no precipitation. This characteristic is prominent as two areas with nearly same EFIs but different proportions of no precipitation. Cases study shows that the EFIEP can forecast reliable percentile of daily precipitation and 100% percentiles are forecasted for over max extreme events. The EFIEQ is a considerable tool for quantitative precipitation forecast (QPF). Compared to the probabilistic forecast of ensemble prediction system (EPS), it is quantitative and synthesizes the advantage of extreme precipitation location forecast of EPS. Using the observations of 2311 stations of China in 2016 to verify the EFIEP and EFIEQ, the results show that the forecast biases are around 1. The threat scores (TS) for 20 years return period events are about 0.21 and 0.07 for 36 and 180 hours lead times respectively. The equivalent threat scores (ETS) are all larger than 0 and nearly equal to the TS. The TS for heavy rainfall are 0.23 and 0.07 for 36 and 180 lead times respectively. The scores are better than those of high resolution deterministic model (HRDet) and show significant forecast skills for quantitative forecast of extreme daily precipitation.
文摘为了进一步提高传统码索引调制(Code Index Modulation, CIM)的误码率性能和降低伪随机(Pseudo Noise, PN)码索引资源的耗费量,提出非正交分组-码索引调制(Nonorthogonal Grouping-Code Index Modulation, NG-CIM)方案。NG-CIM在发送端将每一个传输时隙并行分为调制块和映射块,调制块通过比特分组后映射成为多组调制符号,映射块为各组调制符号的正交分量和同相分量索引相同的PN码进行直接序列扩频传输。仿真结果表明,在加性高斯白噪声信道中,随着频谱效率的提升,NG-CIM的误码率性能较CIM有着约2~4dB的改善,同时PN码资源的耗费量也大大减少。
