基于有效雨量亏缺的吉林省玉米各级干旱发生频率地域变化

吉林省玉米生长季少雨干旱严重影响高产稳产。为了减轻干旱灾害影响，需弄清玉米生长季干旱发生的气象指标及其发生频率，明确各地干旱的气候风险。本文研究基于玉米生长阶段有效雨量盈亏指标和1961—2019年吉林省47个气象站的逐日降水量等数据，分析各地玉米不同生长阶段发生轻、中、重、特旱的频率，以及发生连续干旱的频率。结果表明：吉林省玉米生长季干旱划分为前期（4月21日—6月10日）、中期（6月11日—7月31日）和后期（8月1日—9月20日）干旱，玉米生长前期有效雨量较需水量亏缺28%、40%、55%左右和62%以上，中、后期亏缺32%、46%、60%左右和67%以上依次发生轻、中、重和特旱，严重和特重干旱玉米单产损失10%和15%以上。吉林省玉米干旱发生较频繁，且地理差异较大，西部干旱频繁且严重，东南部干旱较少且偏轻。各地玉米生长前期干旱频率最大，其次是后期，中期干旱频率较小。西部前、中、后期干旱频率在80%、50%和65%左右，重、特旱多发，发生2个阶段以上连续干旱的频率为25%左右；中部和东北部前、中、后期干旱频率在50%、25%和35%左右，以中旱为主，连旱频率在10%左右；东南部前、中、后期干旱频率均值在25%、10%和15%左右，以轻旱为主，连旱频率小于5%。干旱发生与否取决于农田水分亏缺，主要取决于生长阶段有效雨量和需水量。

Regional Changes of Maize Drought in Jilin Province Based on the Effective Rainfall Deficit

Drought and limited rainfall seriously affect high and stable yield of maize in the growing season in Jilin Province. To alleviate serious impact caused by drought, it is necessary to figure out the meteorological index and occurrence frequency of drought in maize growing season, and clarify the risk of drought in various parts of the province. Based on the index of rainfall deficit rate and the daily precipitation data of 47 meteorological stations in Jilin Province from 1961 to 2019, the occurrence frequency of light, medium, heavy and extreme drought in different maize growing periods, and the occurrence frequency of successive drought were analyzed. The results showed that the drought of maize growing season in Jilin Province was divided into three stages: the early stage (April 21 to June 10), the middle stage (June 11 to July 31) and the late stage (August 1 to September 20). Compared with water demand, when the effective rainfall deficit was about 28%, 40%, 55% and more than 62% in the early stage of maize growth, and the effective rainfall deficit was about 32%, 46%, 60% and more than 67% in the middle and late stages, there were light, medium, heavy and extreme drought, and the loss of maize yield per unit area was more than 10% and 15% respectively under heavy drought and extreme drought. The occurrence of drought in maize growing season was frequent, and had a geographical difference. It was more frequent and serious in the western part of the province, while it was less frequent and much lighter in the southeastern part. The drought frequency was the maximum in the early growing stage and lower in the late stage. The frequency was the lowest in the middle stage. The frequency of drought was about 80%, 50% and 65% in the early, middle and late stages in western part of the province, and about 25% of the drought was for successive stages. The frequency of drought was about 50%, 25% and 35% in the early, middle and late stages in the central and northeastern parts, mainly medium drought, and about 10% of the drought was for successive stages. The average frequency of drought was about 25%, 10% and 15% in the early, middle and late stages in southeastern part, mainly light drought, and less than 5% of the drought was for successive stages. The occurrence of drought was related to the water deficit in farmland, and mainly depended on the effective rainfall and water demand in maize growing season.