咸阳市霜冻日期时空变化及气象因子分析

Spatial and Temporal Characteristics and Meteorological Factors of Frost Dates in Xianyang City

基于1971—2022年咸阳市11个国家气象站逐日地面观测资料,采用线性倾向估计、Mann-Kendall突变检验及相关统计分析等方法对霜冻的分布规律及气象因子进行分析。结果表明:咸阳各县(区)初霜日出现在10月中旬到11月上旬,终霜日出现在3月下旬至4月下旬,无霜期北部短、南部长,呈初霜日推迟、终霜日提前、无霜期显著延长趋势;初霜日、终霜日、无霜期突变点分别出现在2004、2007、2005年,突变后分别呈显著推迟、提前和延长趋势;初霜期以辐射霜冻最多,云量越少对应的霜冻日数越多,相对湿度和地面最低温度越小,出霜率越低。终霜期以混合霜冻为主,与天空云量关系不大,与初霜期相比湿度偏小,温度偏高,风速偏大。

Based on daily ground observation data from 11 national meteorological stations in Xianyang City from 1971 to 2022,the distribution pattern and meteorological factors of frost were analyzed using methods such as linear tendency estimation,Mann-Kendall mutation test and relevant statistical analysis.The results showed that the first frost days in all counties(districts)of Xianyang were from mid-October to early November,and the last frost days were from late March to late April,the frost-free period in the north was short and in the south was long,showing that the first frost day was delayed,the last frost day was advanced,and the frost-free period extended significantly.In 2004,2007 and 2005,the first frost date,the last frost date and the frost-free date were significantly delayed,advanced and prolonged respectively;the radiation frost was the most in the first frost period,the less cloud cover,the more frost days,the lower relative humidity and ground lowest temperature,the lower frost rate.The final frost period was mainly mixed frost,which had little relation with cloudiness.Compared with the first frost period,the humidity was lower,the temperature was higher and the wind speed was stronger.