This study uses data provided by the National Meteorological Information Center of China, Japan Meteorological Agency (JMA) and National Oceanic Atmospheric Administration (NOAA) Physical Sciences Laboratory of the US...This study uses data provided by the National Meteorological Information Center of China, Japan Meteorological Agency (JMA) and National Oceanic Atmospheric Administration (NOAA) Physical Sciences Laboratory of the USA to analyze a cold air weather process at the beginning of January 2021. Synoptic analysis is mainly used to summarize synoptic laws or patterns based on observational data, and describe and infer weather processes. The main conclusions are as follows: The cold air travels south along the northwest path, affecting most of China. During the cold wave process, the first cold air is weak, which has a certain cooling effect on northern China. The second cold air was guided by the low vortex, the accumulation in the transverse groove of Mongolia was strengthened, and the cooling effect was significant. The southwest jet showed an increasing trend, and the water vapor transport conditions were good. However, due to the relatively gentle southern branch system, the warm and humid air flow was weak and the precipitation level was small. The purpose of this study is to better understand a large-scale cold air weather process in January 2021 in China.展开更多
为了实现一维频率扫描,设计了一个X波段的串馈频扫平面阵列天线。单个功分器采用四分支定向耦合器,并且引入低通滤波结构,在实现大功分比设计的同时还解决了两输出口间的相位偏移问题。采用低损耗空气带状线作为馈线,有效降低了串馈频...为了实现一维频率扫描,设计了一个X波段的串馈频扫平面阵列天线。单个功分器采用四分支定向耦合器,并且引入低通滤波结构,在实现大功分比设计的同时还解决了两输出口间的相位偏移问题。采用低损耗空气带状线作为馈线,有效降低了串馈频扫天线的损耗。馈电网络与天线阵列独立设计,降低了对计算机硬件的要求。实测结果表明,所设计阵列可实现-27°~30°的一维扫描,副瓣电平低于-22 d B。展开更多
文摘This study uses data provided by the National Meteorological Information Center of China, Japan Meteorological Agency (JMA) and National Oceanic Atmospheric Administration (NOAA) Physical Sciences Laboratory of the USA to analyze a cold air weather process at the beginning of January 2021. Synoptic analysis is mainly used to summarize synoptic laws or patterns based on observational data, and describe and infer weather processes. The main conclusions are as follows: The cold air travels south along the northwest path, affecting most of China. During the cold wave process, the first cold air is weak, which has a certain cooling effect on northern China. The second cold air was guided by the low vortex, the accumulation in the transverse groove of Mongolia was strengthened, and the cooling effect was significant. The southwest jet showed an increasing trend, and the water vapor transport conditions were good. However, due to the relatively gentle southern branch system, the warm and humid air flow was weak and the precipitation level was small. The purpose of this study is to better understand a large-scale cold air weather process in January 2021 in China.
文摘为了实现一维频率扫描,设计了一个X波段的串馈频扫平面阵列天线。单个功分器采用四分支定向耦合器,并且引入低通滤波结构,在实现大功分比设计的同时还解决了两输出口间的相位偏移问题。采用低损耗空气带状线作为馈线,有效降低了串馈频扫天线的损耗。馈电网络与天线阵列独立设计,降低了对计算机硬件的要求。实测结果表明,所设计阵列可实现-27°~30°的一维扫描,副瓣电平低于-22 d B。
