黄淮海地区干热风灾害致灾因子时空特征分析

黄淮海地区是我国冬小麦主产区,也是干热风灾害危害最重、影响最广的地区,本研究利用黄淮海冬麦主产区81个站点1961-2017年的逐日气象数据和冬小麦生育期资料,分析了该地区小麦成熟期和干热风致灾因子的时空变化特征。在81个测站中,有23个成熟期提前趋势显著或极显著,但大部地区成熟期变化趋势不显著,有63%的站点未通过显著性检验。对干热风致灾因子达标日数和相似系数的分析表明,达到干热风灾害阈值的概率依次为14:00风速>14:00相对湿度>日最高气温,最高气温是形成干热风的主要限制因素,轻干热风的发生最高气温和相对湿度起主要作用,重干热风则是高温胁迫起决定作用,低湿条件使胁迫加重,风速只起辅助作用。揭示了该地区干热风危害总体减轻的气象条件基础,即干热风3要素表现为最高气温略降、14:00相对湿度略增、14:00风速明显减小的特征,3要素均向有利于减轻干热风发生的方向变化,对于冬小麦籽粒灌浆和产量形成是有利的。但灌浆成熟期内最低气温的显著升高,意味着气温日较差减小、小麦夜间呼吸消耗增大,对其干物质积累和产量形成带来潜在不利影响。

Spatial-temporal characteristics of dry-hot wind factors in Huang-Huai-Hai region

Frequently occurred extreme climate events and hazards had led agricultural system faced more uncertainty under the background of global warming.Huang-Huai-Hai region is the major winter wheat production area and the prevalent occurred and harder-hit area of dry-hot wind.It is important to research the spatial-temporal characteristics of dry-hot wind for the sustainable development of agriculture to face the challenge of climate change.By using daily meteorological data(daily maximum temperature,relative humidity at 14:00,wind speed at 14:00)and winter wheat growth data of 81 stations in Huang-Huai-Hai region from 1961 to 2017,the spatial-temporal characteristics of maturity date and dry-hot wind factors in the past 57 years was analyzed.There were 23 stations,of which the maturity date had advanced significantly or very significantly,while the change trend of maturity date was not significant in 51 stations.The analysis of the days of the three meteorological factors that met light and severe dry-hot wind indices and the analogous coefficient between the meteorological factors and dry-hot wind showed that,the possibility of wind speed at 14:00 that met the dry-hot wind indices was the largest,followed by the possibility of relative humidity at 14:00,while daily the maximum temperature had the minimum possibility.Daily maximum temperature was the limiting factor for the occurrence of dry-hot wind hazard.Daily maximum temperature and relative humidity played an important role for light dry-hot wind.High temperature stress played a decisive role for severe dry-hot wind and low air humidity aggravated the stress,while wind speed was supplementary factor for dry-hot wind.There were slightly decreasing trend of maximum temperature,slightly increasing trend of relative humidity and significantly decreasing trend of wind speed,separately,in most part of Huang-Huai-Hai region.The climatic trend of these three factors led to a decreasing trend of dry-hot wind hazard impact and was good for the grain filling of winter wheat.But the minimum temperature in this region had an obvious increasing trend and led to potential negative impact for dry matter accumulation and yield formation of winter wheat because the respiration consumption in the night would increase as a following consequence.