Characteristics of spring consecutive dry days with different durations across China based on the objective zoning approach

• Published in: Atmospheric science letters 2021-07, Vol.22 (7), p.n/a
• Main Authors: Zeng, Zixuan, Sun, Jianqi
• Format: Article
• Language: English
• Subjects: Agricultural production; Atmospheric sciences; Climate; cluster; Cluster analysis; Clustering; consecutive dry days; Drought; Drought conditions; Dry periods; Duration; Empirical analysis; Methods; Orthogonal functions; Precipitation; Spring; Summer; Trends
• ISSN: 1530-261X; 1530-261X
• DOI: 10.1002/asl.1035

The duration of dry periods is closely related to drought conditions and is used to evaluate the degree of drought. In this article, using the rotated empirical orthogonal function (REOF) and K‐medoids clustering methods and considering the spatial continuity, 500 stations in China are divided into 10 clusters to analyze the variation characteristics of consecutive dry days (CDDs) with different durations in spring. In Clusters 1–5 over the middle and lower reaches of the Yangtze River, South China, North China, and eastern and western Southwest China, the contribution percentage of short‐duration CDDs to total dry days decreases, while that of medium‐ and/or long‐duration CDDs increases, which leads to an increase in the total dry days and the duration of CDDs. In Clusters 6–8, the total dry days decrease, which are mainly contributed by the decreases in medium‐duration CDDs (for Cluster 6 over southern Northeast China) or long‐duration CDDs (for Clusters 7–8 over northern Northeast China and southern Xinjiang). The total dry days change little in Clusters 9–10 over eastern Northwest China and northern Xinjiang, which is attributed to the offset among the changes in the three‐type duration CDDs. In Clusters 6–10, the duration of CDDs shortens overall. The decadal changes of spring dry days in China exhibit remarkable regional differences. The total day days and three‐type duration CDDs in some clusters (1, 4, and 8) all have significant decadal changes, but they have not in Cluster 7. And the decadal change times also exhibit regional differences. The investigation of different‐duration CDDs in this study provides more information on droughts at different time scales in China. Schematic diagram of the variations in total dry days and short‐, medium‐, and long‐duration CDDs in 10 clusters of China. Different (black) marks in China indicate the stations (central station) of each cluster. The (solid) arrows of ↑ and ↓ denote the (significant) increasing and decreasing trends, and the arrow of → represents almost no change. The values in the brackets denote the years when the significant decadal change occurs, and the marks of +/− indicate the increase/decrease decadal change.