Types of weather system in Tumen River

Temperate continental monsoon climate. The basin belongs to temperate continental monsoon climate, with strong and dry spring wind, warm and rainy summer, cool and foggy autumn and long and cold winter. The annual and inter-annual distribution characteristics of precipitation are as follows.

1, mainly rain, with an annual precipitation of 500? 700 mm.

2. The distribution of precipitation in a year is extremely uneven. Winter is controlled by the dry and cold polar continental air mass, and the precipitation only accounts for 1% of the annual precipitation. 5%, of which the precipitation in June 5438+0 was less than that in the whole year, and most of it was snow. In spring, cyclone activity increases and precipitation increases, accounting for 10% of the whole year? 20%, of which April precipitation accounts for 3% of the annual precipitation? 6%。 Affected by the southeast monsoon in summer, the precipitation accounts for 50% of the annual precipitation? 70%, the maximum precipitation month appears in August.

3. The precipitation is obviously influenced by the topography in this area. In the upper reaches of the basin and the windward slope of the Hunchun River basin, the annual precipitation is 600? 700mm, belonging to the high precipitation area. The precipitation in Yanji basin and Helong basin on leeward slope is about 500mm, which is a low value area. In the northwest mountainous area, due to the uplift of the terrain, the precipitation has increased, generally 500? 600 mm. Generally speaking, the basin is rich in precipitation and water resources.

4. The interannual variation of precipitation is small. The maximum annual precipitation in the basin is 1 140mm, the minimum annual precipitation is 260.3mm, and the ratio of the maximum annual precipitation to the minimum annual precipitation is 4.4. This value is close to the vast rainy area south of Huaihe River in Qinling Mountains, but less than that in North China and the western part of Northeast China.