Precipitation pulses and intraseasonal drought in Northeast China

30 years meteorological data were collected to analyze variations of precipitation amount, number of days, frequency and intervals using the Mann-Kendall (MK) and t test and relationships between rainfall patterns and climates over rainfed farmland. The results indicated that annual precipitation amount had a downward trend from 1989-2018. Whether in different years or months, small precipitation events(0<P ≤5 mm) are a dominating feature, significantly and positively related to annual total precipitation, which mainly occur in early or late growing seasons (May or September). The precipitation intervals decrease along with the category, and are longer in the drought years than in the humid years. Percent of intervals <6 days are more than 65%, the average dry days are 5. Short intervals(1-3 days) increase from May, get to the maximum in mid-growing season. Long intervals (>4 days) are opposite. While in growing seasons, the average dry days are <3 days.