| With the methods of EOF,REOF and Mahat wavelet analysis,the features of spatial anomaly and time evolution tendency of precipitation during the whole duration of spring wheat(MarchJuly) in the east of Yellow River in Gansu Province are studied,by using the precipitation data from 31 observational stations during 1958-2001.The results show that the main spatial anomaly structures are accordantly wet or dry in all areas.The precipitation anomaly region can be divided into four zones: the middle zone of Gansu,Longdong zone,Longnan zone,and the south zone of Gansu.The surging period of precipitation is discovered to be 13~14 years,3 years or so and 6~8 years. |