摘要
Based on the method of rotated principal component (RPC) analysis and wavelet transforms, the winter precipitation from 36 stations over China for the period 1881-1993 is examined. The results show that the three leading space-time modes correspond, in sequence, to winter rainfall anomalies over the reaches of the Yangtze River, the bend of the Yellow River, and the northeastern region of China. The three modes exhibit interannual oscillations with quasi-biennial and 8-year periods as well as interdecadal oscillations with 16- and 32-year periods. The interannual oscillation (【 10 years) occurs in phase over the different areas, and its maximum amplitude migrates northward considerably with prominent interdecadal variations. However, the interdecadal oscillations (10-32 years) are out of phase over the different regions, and the amplitude variations have the characteristics of stationary waves. The rainfall anomalies appear to be closely related to the anti-phase changes of mean sea-level pressure (SLP) over the Asian mainland and the North Pacific. When the SLP rises over the North Pacific and decreases over the Asian mainland, the precipitation over East China increases noticeably. The linkage between the rainfall over China and the SLP anomalies apparently results from the strength of the East Asian winter monsoon and its associated temperature and moisture advection.
Based on the method of rotated principal component (RPC) analysis and wavelet transforms, the winter precipitation from 36 stations over China for the period 1881-1993 is examined. The results show that the three leading space-time modes correspond, in sequence, to winter rainfall anomalies over the reaches of the Yangtze River, the bend of the Yellow River, and the northeastern region of China. The three modes exhibit interannual oscillations with quasi-biennial and 8-year periods as well as interdecadal oscillations with 16- and 32-year periods. The interannual oscillation (< 10 years) occurs in phase over the different areas, and its maximum amplitude migrates northward considerably with prominent interdecadal variations. However, the interdecadal oscillations (10-32 years) are out of phase over the different regions, and the amplitude variations have the characteristics of stationary waves. The rainfall anomalies appear to be closely related to the anti-phase changes of mean sea-level pressure (SLP) over the Asian mainland and the North Pacific. When the SLP rises over the North Pacific and decreases over the Asian mainland, the precipitation over East China increases noticeably. The linkage between the rainfall over China and the SLP anomalies apparently results from the strength of the East Asian winter monsoon and its associated temperature and moisture advection.
