Japan underwent a nationwide self-restraint of human activities in spring 2020 to prevent the spread of the COVID-19 infection. In order to evaluate the effect of suppressed human activities on temperature in the Tokyo Metropolitan area, a statistical analysis was made for temperature anomalies during the self-restraint period using hourly data on the AMeDAS network. The temperature anomaly was defined by the departure from the value that would have been observed without self-restraint, estimated from regression analysis for temperatures at surrounding non-urban stations. It was found that the temperature in central Tokyo (Kitanomaru Park) had a negative anomaly of −0.49°C with a 95% confidence range of ±0.19°C on the average over the strong self-restraint period from April to May. The anomaly was larger in the nighttime than in the daytime, and was found in an area spreading for several tens of kilometers, with a decreasing magnitude according to the distance from Tokyo. These facts indicate a possibility that the reduction of anthropogenic heat release during the self-restraint period resulted in substantial decrease of temperature in the Tokyo Metropolitan area.

日本于2020年春季在全国范围内对人类活动进行了自我控制，以防止COVID-19感染的蔓延。为了评估抑制的人类活动对东京都会区温度的影响，使用AMeDAS网络上的每小时数据对自我约束期间的温度异常进行了统计分析。温度异常的定义是偏离没有自我约束的情况下观测到的值，该值是通过对周围非城市站点的温度进行回归分析得出的。结果发现，在4月到5月的强烈自我约束期间，东京市中心（北丸丸公园）的温度具有-0.49°C的负异常，平均95％的置信区间为±0.19°C。夜间异常现象比白天大，并被发现在一个长达数十公里的区域，并且随着距东京的距离而减小。这些事实表明，自我约束期间人为热量释放的减少可能导致东京都会区的温度大幅下降。