1990—2019年毕节春季霜冻气候特征及温度关系分析

春季霜冻是农业生产的主要气象灾害之一，该文利用毕节1990—2019年0 cm地温和气温资料，分析春季霜冻特征和霜期内不同天气现象下气温与0 cm地温关系。结果表明：近30 a毕节春季霜冻日数随时间呈显著减少趋势，特别在21世纪10年代减少速率跃增，终霜冻期随时间呈显著提早趋势。空间上春季霜冻日数自西向东递减，终霜冻期自东向西推迟，威宁大部和赫章西部高海拔山区是春季霜冻发生最频繁区域，且终霜冻在该区域显著偏晚。突变检验显示毕节春季霜冻日数的减少趋势呈现2个阶段性下降，在21世纪10年代后减少趋势显著，终霜冻提早明显，存在突变年。周期变化中春季霜冻日数存在准3 a和准8 a周期变化，其中3 a周期变化显著性最高。不同天气现象下春季霜冻期内日最低0 cm地温和日最低气温差异大，晴天辐射霜冻是毕节春季主要霜冻类型，期间日最低气温较日最低0 cm地温平均高出4.2℃,且存在月份差异。

Analysis of Climatic Characteristics of Spring Frost and Temperature Relationship in Bijie from 1990 to 2019

Spring frost is the main meteorological disaster of agricultural production. Based on the data of 0 cm ground temperature and temperature in Bijie from 1990 to 2019, the characteristics of spring frost and the relationship between temperature and 0 cm ground temperature under different weather phenomena during the frost period are analyzed. The results showed that the number of frost days in the spring of Bijie in the past 30 years showed a significant decreasing trend with time, especially in the 2010 s, the decrease rate increased sharply, and the final frost period showed a significant trend of coming earlier. Spatially, the number of spring frost days decreases from west to east, and the final frost period is postponed from east to west. Most of Weining and the high-altitude mountains in western Hezhang are the most frequent areas of spring frost, and the final frost is significantly later than other locations. The mutation test showed that the reduction trend of the number of frost days in the spring of Bijie showed a two-stage decrease, and the decrease trend was significant after the 2010 s. The final frost was obvious earlier and there was a year of mutation. There are quasi-3 a and quasi-8 a cyclical changes in the number of spring frost days in the cyclical changes, and the 3 a cyclical change is the most significant. Under different weather phenomena, there is a big difference between the daily minimum 0 cm ground temperature and daily minimum temperature during the spring frost period. Sunny radiation frost is the main type of frost in Bijie spring. During this period, the daily minimum temperature is 4.2℃ higher than the daily minimum 0 cm ground temperature on average, and there are monthly differences.