静止卫星具有可连续高频率观测的特点,被广泛应用于数值天气预报中,以获得更精细、更真实的数值模式初始条件。基于WRF框架的陕西省区域数值模式系统,针对2022年7月陕西一次强降水过程,利用三维变分直接同化方法,协同常规观测资料,同化...静止卫星具有可连续高频率观测的特点,被广泛应用于数值天气预报中,以获得更精细、更真实的数值模式初始条件。基于WRF框架的陕西省区域数值模式系统,针对2022年7月陕西一次强降水过程,利用三维变分直接同化方法,协同常规观测资料,同化风云四号A星所探测的两个水汽通道辐射率资料。通过设计三组对比试验:(1)不同化任何资料的控制试验(CTRL);(2)仅同化常规观测资料的试验(CONV);(3)同化常规观测与AGRI水汽通道的试验(AGRI),系统评估了晴空区FY-4A卫星两个水汽通道辐射资料同化对降水预报的改进效果。结果表明,经过一系列的质量控制和偏差订正,通道9(10)同化前观测亮温和背景场亮温差值(observation minus background,简称OMB)的平均值由0.76(0.78)K减小到0.04(-0.02)K,同化后观测亮温和分析场亮温差值(observation minus analysis,简称OMA)的平均值进一步缩小为0.01(0.01)K;通道9(10)同化前观测亮温和背景场场亮温差OMB标准差为0.83(0.84)K,同化后观测亮温和分析场亮温差OMA的标准差为0.43(0.49)K,说明同化AGRI水汽通道辐射资料改善了模式的初始场。通过协同同化FY-4A AGRI水汽通道辐射率资料与常规观测资料,显著改善了降水预报性能,常规观测资料通过调整风场优化了天气系统配置,使降水落区与实况更加接近,AGRI水汽通道资料同化修正了中高层比湿场,使强降水中心的强度预报误差降低20%。展开更多
In this study, to investigate whether the variation of wind direction in the upper tropospheric monsoon over the central and eastern tropical Pacific shows similar characteristics to the classical monsoon region, the ...In this study, to investigate whether the variation of wind direction in the upper tropospheric monsoon over the central and eastern tropical Pacific shows similar characteristics to the classical monsoon region, the authors introduced a wind vector angle methodology that describes the size of the angle of the wind direction variation, as well as the directed rotary angle, which includes not only the size of the angle but also how the wind vector rotates. On this basis, the authors utilized and improved the directed rotary angle methodology to investigate the evolution of wind direction in detail, and the study confirmed the presence of the same four rotation features in the upper tropospheric monsoon region. Furthermore, the authors also identified the precise variation of wind direction in pentads with seasonal evolution, and found the onset time of the upper tropospheric monsoon may be earlier than the classical monsoon while the termination time may be later. The results further support and supplement the theory of global monsoons, which unifies the low-level and upper tropospheric monsoon as one monsoon system.展开更多
Considering the central and eastern tropical Pacific （CETP） has important climate impacts, and its seasonal variability is also thought to be important, the authors used the monsoon investigation method named ＇dyna...Considering the central and eastern tropical Pacific （CETP） has important climate impacts, and its seasonal variability is also thought to be important, the authors used the monsoon investigation method named ＇dynamical normalized seasonality＇, which can precisely describe the wind vector direction over time, to analyze the upper-tropospheric circulation over the region. The authors discovered that there is a clear reversal of seasonal changes between winter and summer wind, just like the classic monsoon. Accordingly, the authors propose the new concept of the upper- troposphere monsoon over the CETP. The results extend the classical lower-troposphere monsoon region into the upper troposphere.展开更多
文摘静止卫星具有可连续高频率观测的特点,被广泛应用于数值天气预报中,以获得更精细、更真实的数值模式初始条件。基于WRF框架的陕西省区域数值模式系统,针对2022年7月陕西一次强降水过程,利用三维变分直接同化方法,协同常规观测资料,同化风云四号A星所探测的两个水汽通道辐射率资料。通过设计三组对比试验:(1)不同化任何资料的控制试验(CTRL);(2)仅同化常规观测资料的试验(CONV);(3)同化常规观测与AGRI水汽通道的试验(AGRI),系统评估了晴空区FY-4A卫星两个水汽通道辐射资料同化对降水预报的改进效果。结果表明,经过一系列的质量控制和偏差订正,通道9(10)同化前观测亮温和背景场亮温差值(observation minus background,简称OMB)的平均值由0.76(0.78)K减小到0.04(-0.02)K,同化后观测亮温和分析场亮温差值(observation minus analysis,简称OMA)的平均值进一步缩小为0.01(0.01)K;通道9(10)同化前观测亮温和背景场场亮温差OMB标准差为0.83(0.84)K,同化后观测亮温和分析场亮温差OMA的标准差为0.43(0.49)K,说明同化AGRI水汽通道辐射资料改善了模式的初始场。通过协同同化FY-4A AGRI水汽通道辐射率资料与常规观测资料,显著改善了降水预报性能,常规观测资料通过调整风场优化了天气系统配置,使降水落区与实况更加接近,AGRI水汽通道资料同化修正了中高层比湿场,使强降水中心的强度预报误差降低20%。
基金supported by the National Natural Science Foundation of China Projects(41530424)SOA Program on Global Change and Air-Sea Interactions(GASI-IPOVAI-03)
文摘In this study, to investigate whether the variation of wind direction in the upper tropospheric monsoon over the central and eastern tropical Pacific shows similar characteristics to the classical monsoon region, the authors introduced a wind vector angle methodology that describes the size of the angle of the wind direction variation, as well as the directed rotary angle, which includes not only the size of the angle but also how the wind vector rotates. On this basis, the authors utilized and improved the directed rotary angle methodology to investigate the evolution of wind direction in detail, and the study confirmed the presence of the same four rotation features in the upper tropospheric monsoon region. Furthermore, the authors also identified the precise variation of wind direction in pentads with seasonal evolution, and found the onset time of the upper tropospheric monsoon may be earlier than the classical monsoon while the termination time may be later. The results further support and supplement the theory of global monsoons, which unifies the low-level and upper tropospheric monsoon as one monsoon system.
基金supported by the National Natural Science Foundation of China Projects(41530424)SOA Program on Global Change and Air-Sea Interactions(GASI-IPOVAI-03)
文摘Considering the central and eastern tropical Pacific （CETP） has important climate impacts, and its seasonal variability is also thought to be important, the authors used the monsoon investigation method named ＇dynamical normalized seasonality＇, which can precisely describe the wind vector direction over time, to analyze the upper-tropospheric circulation over the region. The authors discovered that there is a clear reversal of seasonal changes between winter and summer wind, just like the classic monsoon. Accordingly, the authors propose the new concept of the upper- troposphere monsoon over the CETP. The results extend the classical lower-troposphere monsoon region into the upper troposphere.
