气候变化背景下中国农业气候资源变化Ⅵ. 黑龙江省三江平原地区降水资源变化特征及其对春玉米生产的可能影响

利用黑龙江省三江平原地区1959—2007年降水资料和1983—2007年春玉米生育期资料，采用百分位法确定了各站点的极端降水阈值，结合极端降水频次、强度、最长连续（无）降水日数、极端降水贡献率等指标，分析了三江平原地区极端降水的年际间变化特征、不同等级的降水量变化以及春玉米各生育阶段极端降水的分配特征.结果表明：1959—2007年间，研究区域年降水量呈略微减少趋势，且年降水日数的减幅远大于降水量，年内降水量分布更趋于集中；极端降水频次和强度均呈减少趋势，极端降水频次的年际间波动大于极端降水强度；年极端降水量占全年降水量的比例略有减少，减少趋势不显著；年小雨日数极显著减少，而年中雨日数和年内大到暴雨日数的减少趋势不显著.三江平原地区春玉米各生育阶段的极端降水分配比例由高到低依次为生殖生长阶段、营养生长与生殖生长并存阶段、营养生长阶段和出苗前；春玉米生长季内降水量占年降水量的比例显著减少，导致春玉米生长季缺水的风险加大；春玉米生长季内最长连续无降水日数呈极显著增加趋势，增幅达1.1 d·(10 a) ^-1，而最长连续降水日数却呈极显著下降趋势，减幅为0.5 d·(10 a)^-1，说明研究区自然降水条件下春玉米生长季干旱风险有所加大.

Changes of China agricultural climate resources under the background of global climate change. Ⅵ. Change characteristics of precipitation resource and its possible effect on maize production in Sanjiang Plain of Heilongjinag Province.

Based on the 1959-2007 daily precipitation data and 1983-2007 spring maize phenologyical data, the thresholds of extreme precipitation at different places in Sanjiang Plain of Heilongjiang Province were calculated by percentile method, and, in combining with the indices involving the frequency and intensity ofextreme precipitation, longest consecutive wet (dry) days, and contribution rate of extreme precipitation, the annual change characteristics of extreme precipitation, quantitative change of different grade precipitation, and distribution characteristics of extreme precipitation at each growth stage of spring maize were analyzed. In 1959-2007, the annual precipitation in Sanjiang Plain showed a slight decreasing trend, and the decreasing amplitude of precipitation days was much larger than that of precipitation. Accordingly, the annual distribution of precipitation tended to be more concentrated. The frequency and intensity of extreme precipitation declined, and the annual fluctuation of the frequency was bigger than that of the intensity. There was a slight decrease in the proportion of annual extreme precipitation to annual precipitation, but the decreasing tendencywas not significant. The annual light rain days had a significant decreasing trend, but the annual moderate and heavy rain days didn’t have. During spring maize growth season, the distribution ratio of extreme precipitation from high to low was reproductive growth stage, coexistence stage of vegetative growth and reproductive growth, vegetative growth stage, and pre-mergence stage. There was a significant decrease in the proportion of the precipitation during spring maize growth season to annual precipitation, resulting in an increasing risk of precipitation scarcity during the growth season. The longest consecutive dry days during spring maize growth season showed a significant increasing trend, with the increment averaged 1.1 d·(10 a)^-1, while the longest consecutive wet days showed a significant decreasing trend, with the decrement averaged 0.5 d·(10 a)^-1. Under natural precipitation, the spring maize drought risk in the study region increased.