关键词: 作物水分亏缺距平指数, 游程理论, 柑橘干旱, 时空变化, 重庆

Abstract:

 Based on daily meteorological data from June to September (1971−2023) collected at 33 meteorological stations in Chongqing, this study calculated the crop water deficit index anomaly (CWDIa) on a ten−day scale. Using methods including runs theory, the Mann−Kendall test and wavelet analysis, the spatiotemporal variation characteristics of citrus drought during critical growth stages in Chongqing (June−September) were analyzed combiling the stations of citrus drought occurrence, drought duration, drought intensity and the centroid of citrus drought occurrence. This analysis aimed to provide a scientific reference for citrus drought resistance management in Chongqing. The results showed that: (1) from 1971 to 2023, the ten−day variation of stations of citrus drought occurrence during June−September exhibited an unimodal pattern, characterized by a "slow increase followed by a rapid decrease". The lowest value occurred in early June, peaked in late August, and decreased sharply from early to late September. (2) Interannually, the stations of citrus drought occurrence, the drought intensity and the drought duration during critical growth stages in Chongqing all exhibited non−significant decreasing trends from 1971 to 2023. Periodic variability was observed for all three indicators on time scales of 30y, 12−13y and 4y, with the scale of 30y showing relatively significant variability from 1971 to 2023. (3) From 1971 to 2023, the centroid of citrus drought occurrence during critical growth stages remained in central Chongqing. While compared to other periods in this intensity range, the 1981−1990 and 2021−2023 centroids moving significantly eastward and westward, respectively. (4) Spatially, the most of western Chongqing exhibited high drought frequency, high intensity and long duration during critical growth stages of citrus. In contrast, the southern part of southeastern Chongqing exhibited lower values across all three indicators.

Key words: Crop water deficit index anomaly, Runs theory, Citrus drought, Spatiotemporal variation characteristics, Chongqing