Abstract: Based on the monthly data of air temperature and precipitation in the last 50 years from meteorological stations in the Songnen Plain, the climate variations and tendencies of the Songnen Plain were analysed by calculating climate trend coefficient and climate tendency ratio. The results showed that the annual mean air temperature increased by 0.3487℃ each ten year in the Songnen Plain in the last 50 years. The monthly air temperature showed an increased trend. The strong increase of air temperature in the winter and spring was observed by 0.5754℃ each ten year, while the air temperature in summer and autumn increased by 0.1868℃ each ten year as well. As the increase of the air temperature in the cold season was higher than that in the hot season, the year air temperature differences decreased. The temperature increase showed a regional difference. The tendency ratio of air temperature was highest with>0.45℃ each ten year in the Northwest of the Plain, while it was the lowest with<0.2℃ each ten year in the East of the Plain. The changes of the precipitation in the Songnen Plain were not significant, but with a weak decreased tendency. The tendency ratio of the yearly mean precipitation was -0.0783 mm each ten year. The decrease of precipitation in autumn was more obvious than that in other seasons.

Key words: Songnen Plain, Songnen Plain, Climate change, Climate tendency ratio, Air temperature, Precipitation