We can also find a good relationship between frost-day temperature and mean temperature in the period, this may foreshow the variation of mean temperature is produced by frost-day temperature.

• 年霜冻日平均温度与年平均温度存在显著的正相关关系,而无霜冻日温度的年平均值与平均温度关系达不到信度检验。这预示着区域温度的增暖主要体现在霜冻日温度的变化。