Climate change may induce severe frost damage to crops, and thus a reasonable assessment of frost risk, considering both crop phenology and meteorology, is required. Here, we introduced a new index of potential frost risk (F_risk) using thermal time (minimum air temperature below the threshold value) weighted by the percentage of budburst (P_bud). Moreover, we evaluated the spatiotemporal distributions of F_risk in tea fields within a 60 km×60 km area in east Japan from 1981-2020, using 1 km²-gridded meteorological data and a newly developed model of P_bud. The P_bud model considered three phenological phases (endodormancy, ecodormancy, and progress of budburst) and successfully represented changes in the P_bud of the tea buds for 15 years, with root mean square errors of 8.5 percentage points. The spatiotemporal distributions of F_risk over the past 40 years showed that potential frost risk significantly increased at elevations ranging from 50 m to 300 m because the budburst advanced at a faster rate than the temperature warming. These elevations corresponded to areas where tea plants were mainly cultivated, which indicates that tea cultivation is becoming vulnerable to frost, and the risk of economic losses due to the frost is increasing. The proposed assessment of frost risk could contribute to predicting frost damage and developing more reliable strategies for the operation of frost protection under the effects of future climate change.

中文翻译：

---

1981-2020年茶园冻害潜在风险时空分布：一种考虑物候和气象的建模方法

气候变化可能对作物造成严重的霜冻损害，因此需要考虑作物物候学和气象学对霜冻风险进行合理评估。在这里，我们引入了一个新的潜在霜冻风险指数 ( F _risk )，使用热时间（低于阈值的最低气温）按_萌芽百分比 ( P _bud )加权。此外，我们使用 1 km ²网格气象数据和新开发的P _bud模型评估了 1981-2020 年日本东部 60 km×60 km 区域内茶园F_风险的时空分布。在P_芽该模型考虑了三个物候阶段（内休眠、生态休眠和萌芽进展），成功地代表了茶芽P_芽15 年的变化，均方根误差为 8.5 个百分点。F_风险的时空分布过去 40 年的研究表明，在 50 m 至 300 m 的海拔高度范围内，潜在的霜冻风险显着增加，因为萌芽的推进速度快于温度升高。这些海拔高度对应茶树主要种植区，说明茶树种植易受霜冻影响，霜冻经济损失风险加大。拟议的霜冻风险评估有助于预测霜冻损害，并在未来气候变化的影响下为霜冻保护的运作制定更可靠的策略。