利用常规气象资料模拟计算作物系数的探讨

Calculation of Crop Coefficient With Meteorological Data

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０１３，平均变差系数为０１２。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。

Crop coefficient was estimated with Penman Monteith formula and the NWSE (Non Water Stress Evapotranspiration) model driven with daily meteorological and crop data during reviving and harvest of winter wheat. The results showed that crop coefficient varies among years and remains a clear trend during growth season. When surface soil water content is set at 60% of field capacity approximately, the average crop coefficient of years estimated with NWSE model fits well with the experimental data. The average standard deviation and variation coefficient of crop coefficient estimated with NWSE model were 0 13 and 0 12 respectively. Analysis shows that the effect of net radiation, relative humidity and wind speed on crop coefficient variation is obvious, but the effect of temperature is negligible. Crop coefficient increases as wind speed increases, or net radiation or relative humidity declines.