午夜欧美大片免费观看,欧美激情综合五月色丁香,亚洲日本在线视频观看,午夜精品福利在线

Statistic methods are used to analyze the climate and anomaly characteristics of summer precipitation in Northeast China in recent 50 years.Results indicate that precipitation is unevenly distributed.Rains occurs mostly in July over most parts of Northeast China except the Sanjiang Plain.The occurrence probability of severe droughts is greater than that of severe floods,which indicates that drought disasters are more frequent than floods.Floods/droughts occur more frequently in the west part of Liaoning Province than in the other regions of Northeast China.Generally speaking,the wet/dry trend isn't obvious in recent 50 years,but there exists the alternative flood/drought variation feature with the interdecadal periods being about 27 and 11 years and the interannual periods being 3 to 6 years.Droughts occur more frequently in June;there often occur persistent droughts from June to July,and the regional severe floods are usually reported in July.Th opposite phase is found in the interdecadal scale variation between June and August.