冠层阻力对ET0计算公式影响的实验研究

his paper studies through testing surely for the rate of our country that ET0 of semi-arid climate reference crop ( alfalfa ), have revealed in ET0 calculation formula set condition the change law of Surface resistance rc, think: The value of rc in the growth period enters PM method calculation. The change tendency value of ET0 of calculated and the value of ET of actual measurement in PM formula is been close to fairly. Value of ET0 calculated about change range is larger than the value of actual measurement. The day of rc value of ET0 calculated and value of ET0 of actual measurement have no size. But value calculated overall change tendency is more close to value of actual measurement. Since rc calculates formula option, is different. Calculation is different as a result. Identical rc calculates formula , calculates value of ET0 for different time measure with the value of ET ( alfalfa ) of actual measurement contrast result also difference. Therefore in afterwards strict calculation, should calculate the condition of formula according to different area and different climate condition according to various rc, test result generation into different calculation formula lead revise surely, for the accurate calculation that has to suit the science of this area.