While air temperature has been widely investigated to better understand the recent climate changes, the importance of soil temperature has been underestimated and rarely studied. Here, the long‐term soil temperature changes and the occurrence of extreme heats have been studied based on daily measurements in Jiangsu Province for 1970–2017. A general warming trend in soil temperature is observed at most stations, and these trends are more pronounced in the cold seasons than the warm seasons. Due to the asymmetric warming of maximum and minimum soil temperatures over the past 48 years, the diurnal range shows a long‐term decreasing trend with a rate of −0.34°C/10a. The occurrences of extreme soil temperatures have been analysed based on the probability density functions. It is found that the hot soil days have increased and cold soil days have decreased significantly, and these changes are particularly significant in the most recent decades.

中文翻译：

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基于江苏省地面测量的分层土壤温度的长期变化

为了更好地了解最近的气候变化，人们对空气温度进行了广泛的研究，但土壤温度的重要性却被低估了，很少进行研究。在此，根据江苏省1970-2017年的每日测量数据，研究了土壤长期温度变化和极热的发生。在大多数气象站都观察到土壤温度总体呈增温趋势，与冷季相比，这些趋势在寒冷季节更为明显。由于过去48年中最高和最低土壤温度的不对称变暖，昼夜范围呈长期下降趋势，速率为-0.34°C / 10a。根据概率密度函数分析了极端土壤温度的发生。