50年来湘中地区气候极值与农业气候指标动态变化趋势

利用湘中地区1961-2010年气象站逐日观测数据资料,选取与农作物密切相关的气候极值和农业气候指标,采用统计检验、趋势分析和Mann-Kendall突变检验等的方法,分析了湘中地区农业水热气候条件和气候极值,进而研究主要农业气候指标的变化倾向。研究发现：湘中地区近50年来,水热资源总体呈增加趋势；年强降水量呈增大趋势,尤其以夏季强降水量增加最为明显,表明夏季洪涝灾害的威胁加大；最高(低)气温阈值的变化表明极端高(低)温均呈缓解趋势,及其出现的天数在减少,说明由极端气候引起高温热害、低温冷害等气象灾害发生的可能性减小；≥0℃和≥10℃积温分别在1997年和2000年开始突变,上升趋势明显,表明湘中地区有效热量资源在增加；霜冻日数呈减小趋势,说明霜冻危害发生的风险在减小。这对确定合适的农业气候指标值和促进农业生产有重要的指导意义。

Climate Extremes and Agro-climatic Indicators: Dynamic Change Trends in Central Hunan During 1961-2010

Based on the daily observational data of meteorological stations in central regions of Hunan from 1961 to 2010, the climatic extremes and agricultural climatic indexes closely related to crops were selected, statistical analysis, trend analysis and Mann-Kendall mutation test were used to analyze the agricultural hydrothermal climatic conditions and climate extremes in central regions of Hunan, and the authors then studied the tendency of the main agricultural climate indexes. The results showed that: in the past 50 years, the agricultural hydrothermal climatic conditions in central regions of Hunan had an increasing trend; annual heavy precipitation was increasing, especially in summer, indicating that the threat of flood in summer was increasing; the change of the highest (lowest) temperature threshold indicated that the extreme high (low) temperature was mitigating trend, and the number of days was decreasing, which indicated that the possibility of occurrence of meteorological disasters such as high temperature and low temperature damage caused by extreme weather was reduced; ≥0℃ and ≥10℃ accumulated temperature began to change in 1997 and 2000, and the rising trend was obvious, indicating that the effective thermal resource in central regions of Hunan was increasing; frost days showed decreasing trend indicating that the risk of frost damage was decreasing. All this has important guiding significance for determining the appropriate agricultural climate index and promoting agricultural production.