常用于分析降水、径流、气温等要素时间序列的趋势变化，其优点在于样本不需要遵循某一特定的分布，而且很少受到异常值的的干扰，计算简便。(It is often used to analyze the trend change of time series of factors such as precipitation, runoff and air temperature. Its advantage is that the sample does not need to follow a spe