关键词: 中国西北科学考查团, 东亚寒潮侵袭, 台风生成, 半球间宏观系统, 气象灾害监测与预测

Abstract: The late Prof. Li Xianzhi (Dr.Sjan-zsi Li) was a professor with Peking University and a famous meteorologist in China. In his youth, he took part in The Scientific Expedition to China's Northwestern Provinces during 1927-1930. He observed the movement of a strong outbreak of cold air masses in late Oct. 1928, in Qinghai Province. This event had an important influence on Li Xianzhi's life. Between 1930 and 1936, he studied and then worked in Berlin University. He published his famous papers "A Study on the Outbreak of cold air in East Asia" and "A Study on Typhoon" in 1934 and 1936 respectively. He got a Doctor's Degree in 1934 and came back to his motherland in 1936. He devoted himself to the teaching of meteorological sciences in China's famous institutions of higher learning i.e., Tsinghua and Peking universitie, and to meteorological studies. He wrote quite a number of initiative works. He discovered that cold air coming from the North Pole region can sweep across the Equator and then reach the Southern Hemisphere, and lead to precipitation and drops in temperature over there. At the same time, he pointed out that the outbreak of cold air coming from Australasia can lead to the generation of typhoon in the northwestern Pacific when the cold air crosses the Equator and reaches the lower latitude regions of the Northern Hemisphere. In the later part of his life, Li Xianzhi presented a new concept of "Microscopical System between two Hemispheres". He pointed out that the heavy rainfall and flood disasters on the Chinese mainland are closely connected with the weather systems coming from the Southern Hemisphere. This theory points a new way to the monitoring and prediction of heavy rainfall and flood disasters in China. This paper presents a comprehensive study and comment on Prof. Li Xianzhi's principal research results and his viewpoint on the study of meteorological disasters, and shows his influence and his contribution.

Key words: Expedition to Northwestern Provinces of China, outbreak of cold air in East Asia, generation of typhoon, macroscopical system between two hemispheres, monitoring and prediction of meteorological disasters