辽宁省玉米干旱的时空分布特征分析

辽宁省是东北重要的粮食主产地,干旱是造成该地区玉米产量不稳定的主要气象灾害。利用辽宁省45个气象站点1961-2015年的逐日气象观测数据和玉米发育期观测资料,计算作物水分亏缺指数(crop water deficit index, CWDI),根据玉米干旱等级标准计算各个生育期干旱的站次比、干旱频率,进而分析辽宁省玉米干旱的时空分布规律和玉米不同生育期干旱的分布情况。结果表明:经检验,CWDI能够较准确地反映辽宁省玉米的干旱情况,在辽宁省的适用性较好。辽宁省各生育期各等级干旱发生频率大致表现为径向分布,呈现出西部最高、中部次之、东部最低的空间分布规律。对于玉米各个生育期而言,发生干旱的频率随着玉米的生长体现为生育前期最高,生育中期次之,生育后期最低。辽宁地区45个站点的干旱站次比差异显著,在玉米生育期的各个阶段站次比处于波动变化的状态,没有明显的线性变化趋势。播种～出苗阶段是玉米干旱的易发时期,各个等级干旱站次比较其他阶段高,整体年际波动较小。轻度干旱和中度干旱是玉米整个生育期干旱情况的主要体现,本世纪以来,各生育期各等级玉米的干旱范围均有扩大趋势。

Analysis of Spatial and Temporal Distribution Characteristics of Maize Drought in Liaoning Province

Liaoning is an important grain production area in Northeast China,drought is the main meteorological disaster that causes the instability of maize yield in this area.The daily meteorological observation data from 45 meteorological stations in Liaoning province from 1961 to 2015and the observation data of maize development period were used to calculate the crop water deficit index (CWDI).According to the drought grading standard of maize,the ratio of drought occurring at stations and the frequency of drought in each growth period were calculated,and then,the spatial and temporal distribution of maize drought in Liaoning province and the distribution of maize drought in different growth periods were analyzed.The results showed that CWDI could accurately reflect the maize drought and had good applicability in Liaoning province.In Liaoning province,the frequency of drought at different grades in different growth periods presented a radial distribution,which was higher in the western area than that in the eastern area.For each growth stage of maize,the frequency of drought was the highest at the early growth stage,it was next at the middle growth stage and the lowest at the late growth stage.The ratios of maize drought occurring at 45 stations in Liaoning were significantly different,which also fluctuated in each stage of maize growth period,and there was no obvious linear change trend.During the period of seeding and seedling emergence,drought was easier to occur,and the ratios of drought occurring at stations of different grades were higher than other stages,and the overallinter-annual fluctuation was smaller.Light drought and moderate drought were the main manifestations of maize drought during the whole growth period.Since the beginning of this century,the extent of maize drought of all different grades in each growth period had tendency tobe severe.