Northern Hemisphere Teleconnection Patterns Associated with dominant Modes of Subseasonal Wintertime Precipitation in China

The singular vector decomposition (SVD) analysis is applied to investigate coupled patterns of subseasonal variability between the midlatitude 500-hPa height (Z500) from the NCEP-NCAR reanalysis and the pentad precipitation data in China during 38-yr Northern Hemisphere extended winter from November to March. The first two leading SVD modes together account for about 84.3% (35.7%) of the total covariance Z500 (precipitation). The first leading SVD mode (SVD1) reveals that both the Eurasian (EU) pattern and Pacific/North American (PNA) pattern wave trains are accompanied by a monopole structure of precipitation anomaly in the Southern China. The second leading SVD mode (SVD2) indicates that the West Pacific (WP) pattern circulation is associated with the dipole-like structure with the more or less precipitation changing alternatively between the lower reach of Yangtze River Basin and the South China.

Lagged regression are conducted to understand how the large atmospheric circulation evolves in association with the each dominant wintertime precipitation mode in China a few pentad in advance. The enhanced precipitation in Southern China in the SVD1 is found to closely related to a major blocking anticyclones centered over Scandinavia and western Russia, a weakened Aleutian Low and a cyclonic anomaly centered over the Tibetan Plateau which all strengthen gradually at lag=-3 to 0 pentad. The diploe-like precipitation over eastern China in SVD2 precipitation mode is associated with the weakened Siberia High and the northward movement of Aleutian low from at lag=-3 to 0 pentad. The wave train originated from both Atlantic and the tropical Pacific Ocean at lag=-3 pentad, and was enhanced by the tropical Pacific Ocean heating at lag=-2 pentad. The dipole convective structure with the enhanced convection over the Indian Ocean and the depressed convection in the tropical western Pacific and weakened Siberia High at lag=-3 pentads could be potential predictive precursor for the diploe-like precipitation mode in eastern China.