河西走廊东部一次霜冻天气过程成因及其对农业的影响

Cause of a Frost Weather Process and the Impact on Agriculture in Eastern Hexi Corridor

2016年5月15日河西走廊东部发生区域性强霜冻天气,对农林业生产造成了严重灾害。利用实时MICAPS常规观测资料、物理量场和河西走廊东部区域内6个国家自动气象观测站和93个区域气象站观测资料,对这次霜冻天气进行了成因分析,并分析了霜冻对农业生产的影响。结果表明:高空中亚高压脊后有暖脊强烈发展,促使中亚脊向东北伸展,脊前强偏北急流引导冷空气向南爆发;晴朗、微风、干燥的地面环境场有利于辐射降温;深厚的冷平流、对流层中层强冷平流中心和高层冷平流向近地面传递是造成霜冻的主要原因;强冷暖平流快速交替,大温差加重了冻害影响程度。0cm地面温度和气温长时间持续≤0℃导致农林作物深度冻伤;前期气温偏高使得农林作物发育期提前,农林作物抵抗冻害能力明显下降,霜冻出现偏迟,冻害影响加重;冻害发生后,温度急剧上升,湿度迅速减小,作物水分强烈蒸腾,作物细胞严重受损,导致受灾程度加重。

Frost is one of the most universal meteorological disasters in China. The occurrence of regional strong frost affected agricultural and forestry production in the east of Hexi Corridor on May 15th, 2016. Based on the MICAPS general observation, physical quantity data and observation data from 6 automatic meteorological stations and 93 regional meteorological stations in the eastern part of Hexi Corridor, we analyzed the cause of the frost and its impact on agricultural and forestry production. The results showed that strongly developed warm ridge at Central Asia impelled Central Asia ridge extending to northeast, and leaded cold air erupting to southward. Breezy and dry ground environmental fields helped cool radiation. The main reasons which caused the frost were strong cold advection center of middle troposphere and high-rise cold advection transmitting to near ground and deep cold flow;alternated of strong cold and warm smooth flow increased temperature difference and aggravated the degree of frost damage;the depth of 0 cm ground temperature and air temperature below ≤ 0 ℃ caused deep freezing damage on agricultural and forestry crops. High temperature in the early stages made the growth period of agroforestry crops earlier and the ability of agroforestry crops to resist frost damage significantly decreased, which resulted the frost delayed and the frost damage aggravated. After the occurrence of frost, the temperature increased sharply, the humidity decreased rapidly, the crop moisture steamed strongly and the crop cells were damaged severely, which aggravated freezing damage.