Cold stress seriously affects rice yield in Northeast China and, as a result of climate change, there are new trends in the characterization of cold damage. Accurate simulation of water temperature in paddy fields and assessment of cold damage hazard can contribute to improving the accuracy of agrometeorological disaster risk assessment in the context of climate change. Hence, in this study, first, we simulated the water temperature of paddy fields based on the paddy field energy-balance model and evaluated the simulation results. Subsequently, a composite cooling-degree-day (CCDD) indicator for rice fields was constructed based on water and air temperatures to characterize cold stress and identify cold damage events. Finally, a cold damage hazard-assessment model was constructed for rice based on the frequency and intensity of cold damage to assess cold damage hazard in Northeast China from 1979 to 2018. The results showed that the root-mean-square error between simulated and observed water temperatures of the rice field energy-balance model was 0.45, which means that the model accurately simulated the water temperature of the rice field on a large spatial scale. In 2004, cold damage to late-maturity rice accounted for 30% of the total study area, which was one of the years with most severe cold damage in late-maturity rice-growing areas thus far in the 21st century. Water temperature affected 76.4% of the area in 2004, and was related to radiation and saturated vapor pressure. The low-hazard areas accounted for more than 20% in 2009–2018, and the high-hazard areas were still higher than 10%, indicating that the threat of cold damage in the northeastern region of China remained severe as the climate has become increasingly warm.

中文翻译：

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基于能量平衡的稻田水稻冷害危害评估


冷胁迫严重影响东北地区水稻产量，气候变化导致冷害特征出现新趋势。准确模拟稻田水温和冷害危害评估，有助于提高气候变化背景下农业气象灾害风险评估的准确性。因此，本研究首先基于稻田能量平衡模型对稻田水温进行了模拟，并对模拟结果进行了评价。随后，基于水温和气温构建了稻田复合冷却度日（CCDD）指标，以表征冷胁迫并识别冷害事件。最后，基于冷害频率和强度，构建了水稻冷害危害评估模型，对1979年至2018年东北地区的冷害危害进行了评估。结果表明，模拟与实测的均方根误差稻田能量平衡模型的水温为0.45，这意味着该模型在大空间尺度上准确地模拟了稻田的水温。 2004年晚熟稻冷害占研究总面积的30%，是21世纪迄今为止晚熟稻产区冷害最严重的年份之一。 2004年水温影响面积达76.4%，与辐射、饱和水汽压有关。 2009-2018年低灾区占比超过20%，高灾区仍高于10%，表明随着气候变暖，东北地区冷害威胁依然严峻温暖的。