关键词: 新郑大枣, 高温干旱, 有序样本聚类, 经验正交分解（EOF）, 信息扩散

Abstract:

The combination of heat and drought stress during the June-August period has become one of the agrometeorological disasters that are constraining the sustainable development of the jujube industry in Xinzheng city of Henan province, an important jujube production base in the Huang−Huai river basin. Based on the ground meteorological observation data from June to August in Xinzheng city from 1981 to 2022 and the high−resolution gridded real−time datasets from June to August in 2010 to 2022, this study used principal component analysis and ordered sample clustering methods to construct the jujube heat and drought index. A heat and drought disaster risk assessment model was developed by applying information diffusion theory to conduct a refined quantitative assessment of heat and drought disasters in the main jujube production area of Xinzheng. The results showed that the heat and drought index of Xinzheng jujube showed an upward trend from 1981 to 2022. The Mann−Kendall trend test showed a significant upward trend in the two periods from 1996 to 2007 and 2012 to 2022 (P<0.05). After the Empirical orthogonal function (EOF) decomposition of the Xinzheng jujube heat and drought index, the first mode accounted for 79.3% of the total variance contribution. Its spatial vector field displayed significant spatial consistency, indicating a consistent upward or downward trend of the heat and drought index across the entire area of Xinzheng city. The probability of mild, moderate and severe heat and drought risk occurring in Xinzheng city during June−August was 5%, 46% and 34%, respectively. Longhu town and the northern part of Mengzhuang town in the north of Xinzheng city, as well as Guanyinsi town and Lihe town in the south of Xinzheng city were high−probability areas for severe heat and drought risk. The probability of moderate heat and drought disaster risk was relatively high in Xindian town, Chengguan, Xinhua, Xinyan, Hezhuang town, Longwang town and Xuedian town in the central part of Xinzheng city, while the probability of mild heat and drought disaster risk was concentrated in Xindian town in the southern part of Xinzheng city. The high−risk areas in the main jujube planting areas of Xinzheng were mainly distributed in the northern part of Mengzhuang town, while the medium−risk areas were distributed in the southern part of Mengzhuang town, the northwest of Xuedian town, the northeast of Longwang town and the southern part of Hezhuang town. 

Key words: Xinzheng jujube, Heat and drought, Ordinal sample clustering, Empirical orthogonal function (EOF), Information diffusion