北方农牧交错带参考作物蒸散量时空变化与成因分析*6

利用北方农牧交错带46个气象站1961-2013年气象资料，采用Penman-Monteith公式法计算该地区参考作物蒸散量(ET0)、ET0对气象因子的敏感性系数、气象因子对ET0的贡献率，并通过趋势分析、GIS空间插值方法对这些指标的时空变化进行分析。结果表明：（1）北方农牧交错带年ET0平均值在839～1097mm，近53a来以0.21mm · a-1的速率减小。（2）空间分布上，ET0总体呈现“一高二低”的分布格局：陕北高原为高值区，大兴安岭北部高纬地区、青东农区及陇中片区为两大低值中心区。且陕北高原、陇中及青东农区61%的站点ET0平均以0.85mm·a-1（P＜0.05）的趋势递增，而吉林西部、科尔沁沙地、辽西地区则呈明显减小趋势。（3）气象因子对ET0的贡献受ET0对气象因子的敏感性和气象因子的相对变化共同影响，其中北方农牧交错带 ET0对相对湿度最敏感，其次为平均风速；但近53a 来风速呈极显著下降趋势，下降速率达0.0154m·s-1·a-1（P＜0.001），因此，综合分析结果表现为风速对ET0的贡献量最大，说明北方农牧交错带ET0下降主要归因于风速的降低。

Temporal and Spatial Change and Causes Analysis of the Reference Crop Evapotranspiration in Farming-Pastroral Ecotone of Northern China

Based on the FAO Penman-Monteith equation and the meteorological dataset in farming-pastroral ecotone of northern China during 1961 to 2013,ET0 and its sensitivity coefficients to meteorological factors were studied by using trend analysis and spatial interpolation methods.The results showed that the mean annual ET0 was 839-1097mm and decreased slightly at the rate of 0.21mm?y-1 during the study period. 61% meteorological stations in eastern Qinhai, mid-Gansu and the northern Shaanxi plateau showed an increasing trend of 0.85mm·y-1(P<0.05),while in Horqin sandy land and the western Liaoning the ET0 declined significantly. The meteorological factors’ contribution to ET0 was influenced by two aspects: the sensitivity coefficient and relative change rate of the meteorological factors. The sensitivity analysis showed the relative humidity was the most sensitive factor among the four main meteorological factors, followed by the wind speed, sunshine hours, mean temperature. But the wind speed decreased dramatically at the rate of 0.0154m?s-1?y-1(P<0.001)in recent 53 years, and the comprehensive result was that wind speed had the largest contribution to ET0, followed by relative humidity, which illustrating that the declination of ET0 wasdue to the deceleration of wind speed.