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利用 Ｐｅｎｍ ａｎ Ｍｏｎｔｅｉｔｈ 公式和 Ｎ Ｗ Ｓ Ｅ（非水分胁迫条件下作物腾发）模型及中国科学院禹城综合实验站的系列气象资料逐日模拟计算了冬小麦返青～收获期间的作物系数。分析表明：作物系数多年变化具有相对稳定性，当表土含水率为田间持水量的６０％ 时， Ｎ Ｗ Ｓ Ｅ 模型模拟计算作物系数多年均值与实验值较一致；同时，作物系数年际间的变化存在一定程度的变异性。 Ｎ Ｗ Ｓ Ｅ模型计算的作物系数的平均标准差为０１３，平均变差系数为０１２。气象因素对作物系数变异性的影响分析表明：太阳净辐射、风速和空气湿度的影响较显著，而气温波动的影响不明显；作物系数随风速增大或相对湿度、净辐射降低而增大。
The crop coefficients during winter wheat regreening ~ harvesting were calculated daily using Penm Monteith formula and N W S E (crop evapotranspiration under non-water stress) model and series of meteorological data from Yucheng Comprehensive Experimental Station, Chinese Academy of Sciences. The analysis shows that the coefficients of variation of crop coefficients are relatively stable over many years. When the moisture content of the topsoil is 60% of the field capacity, the multi-year mean values of N W S E model calculated by simulation are consistent with the experimental values; meanwhile, There is a degree of variability in change. The average standard deviation of crop coefficients calculated by N W S E model was 0.13 and the average coefficient of variation was 0.12. The analysis of the influence of meteorological factors on the variability of crop coefficients showed that the effects of net solar radiation, wind speed and air humidity were significant, while the influence of temperature fluctuation was not obvious. The crop coefficient increased with the increase of wind speed, relative humidity and net radiation .