long-term variation meaning in Chinese

长周期变异

In the long - term variation trend of heavy rain days and its intensity , most areas present increase tendency with the exception of the area of liaoning . there are positive correlation between heavy rain days and summer precipitation
东北地区不同区域大雨日数和大雨强度的长期变化趋势为辽宁地区大雨日数和强度变化趋势是减少趋势，东北中部大雨日数呈减少趋势，强度呈增加趋势。