Abstract: Based on the Madden–Julian oscillation index, the outgoing long wave radiation (OLR) data, the daily NCEP/NCAR reanalysis data and precipitation data in the south of China, the relationship between Madden–Julian oscillation (MJO) and the snow disaster in 2008 in the south of China and the forming reason of snow disaster were discussed by a synthetic analysis method. The results show that the MJO has an obviously eastward phenomenon in the snow disaster process, namely, it spreads from the Western Pacific to the India Ocean. Accompanying with the eastward MJO, the precipitation intensity and its concentrating region also change. The MJO could modulate the snow disaster process to some extent. The analysis of OLR also suggests that four abnormal rainfall (snow) processes in the early of 2008 in the south of China are influenced by the two eastward MJO. The first eastward MJO leads to the strength of the western Pacific subtropical high continually, while the second one makes the south brand trough active. The southward wind in the west side of subtropical high and the active of the south trough make the warm wet airflow transporting continually to China, which provides water vapor condition for strong precipitation in the south of China.

Key words: Tropical region, Madden–Julian oscillation (MJO), Snow disaster, Outgoing long wave radiation (OLR)