Abstract:

Studying the occurrence patterns and causes of continuous rain during growth duration of rice in Chongqing could scientifically guide rice cultivation and prevent and mitigate disasters. Based on meteorological data from 1991 to 2020, rice growth period observations, and NCEP/NCAR reanalysis data in Chongqing, this study explores the climatic characteristics and atmospheric circulation patterns of continuous rain events across different rice planting regions and growth stages in Chongqing. The findings indicate a general decreasing trend in continuous rain events across all planting regions. Notably, in the central Chongqing it displayed the most significant decrease trend with a climate tendency rate of -0.33 per decade. Although in the southeastern region the proportion of stations with continuous rain was highest (1.18), it showed the weakest decreasing trend. Conversely, in the northeastern region the proportion of stations with continuous rain was lowest at 0.55, and the trend of decreasing continuous rain was most pronounced there. The frequency of continuous rain was highest during the vegetative growth stage and lowest during the reproductive stage. Spatially, the frequency of continuous rain was greatest in southeastern Chongqing, the maximum was 1.80, and lowest in northeastern Chongqing, the minimum was 0.27. The areas with higher frequencies were predominantly in the southern parts of Chongqing, varying slightly across different growth stages, while the lowest frequencies were consistently found in the northeastern parts. During the vegetative stage, continuous rain was most frequent. All regions were generally influenced by a negative geopotential height anomaly, which reduced the north-south geopostitial height gradient, making it easier for cold air to move south and result in continuous rain. In the southeastern Chongqing, water vapor originated from the Pacific Ocean and carried by the southeast periphery of the subtropical high. Compared to the seedling stage, the water vapor conveyor belt during the vegetative stage was further south, moving in a southwest direction.

Key words: rice, continuous rain event, climate characteristic, cause analysis

摘要：

为掌握重庆水稻生育期连阴雨的发生规律与成因，科学指导水稻生产防灾减灾，基于1991—2020年重庆市气象资料、水稻生育期观测资料及再分析资料，研究重庆水稻不同种植区及不同生育期的连阴雨气候特征和大气环流特征。结果表明，重庆各种植区全生育期的连阴雨均呈减少趋势，其中，中部减少趋势最明显，连阴雨发生站次比气候倾向率为-0.33·（10 a）^-1；东南部连阴雨发生站次比最高，达1.18，但减少趋势最弱；东北部连阴雨发生站次比最低，仅0.55，且预计阴雨灾害将进一步减少。水稻营养生长期的连阴雨发生频次最高，生殖生长期最低。空间分布上，水稻全生育期连阴雨发生频次东南部最高，单点最大值达1.80；东北部最低，单点最小值仅0.27；高值区分布在重庆偏南区域，不同生育期略有差异；而低值区始终位于东北部。连阴雨发生最为频繁的营养生长期，各地区均受负位势高度异常控制，南北位势高度梯度减小，冷空气南下易导致连阴雨发生。连阴雨发生频次最高的重庆东南部，水汽起源于太平洋，由副热带高压外围的东南暖湿气流提供。营养生长期的水汽输送带相比苗期更偏南，呈西南向分布。

关键词: 水稻, 连阴雨, 气候特征, 成因分析