摘要
该文针对直接采用20世纪90年代初确定的中国主要作物的作物系数估算作物需水量存在的主要问题,分析了作物系数需要校正的原因:Penman修正式和Penman-Monteith公式在计算ET_0时差异较大,且对生育期较长的越冬作物的影响要高于生育期较短的夏季作物。同时利用河南省18站多年气象资料,分析了引起两公式差异的因素:辐射项处理的不同是引起两公式差异的主要原因。秋冬季,采用两公式计算的月ET_0、ET_rad值差异均高于春夏季,空气动力学项对ET_0值的影响与风速有关,较高的风速可能导致空气动力学项的影响高于辐射项;采用Penman-Monteith公式计算ET_rad值时,受季节、站点情况影响小,稳定性高,18站均表现为:平均气温对ET_rad的影响最小,1、11、12月相对湿度对ET_rad的影响较大,2-10月日照时数对ET_rad的影响较大。并根据2种不同的ET_0估算方法的关系,提出了基于Penman-Monteith公式的作物系数校正方法,对于提高作物需水量的估算精度有重要意义。
Aiming at the main problem that existed in estimating the crop water requirement through multiplying the crop coefficients of main crops determined in the early 1990s by ETo calculated using the Penman-Monteith equation, the reasons for crop coefficients which need to be revised were analyzed. There is a significant difference in ETo calculated by using the modified Penman equation and by Penman-Monteith equation, which affects overwintering crops with a longer growth period of greater than summer crops with a shorter growth period. The result showed that the monthly ETo and ETrad calculated by using Penman-Monteith equation were higher than that by modified Penman equation, and the difference between radiation terms was the main reason that caused the difference between the calculation results by using two equations based on the meteorological data of 18 stations in Henan province. The difference of monthly ETo and ETrad calculated by two equations in autumn and winter was higher than in spring and summer. The effect of aerodynamic term on ETo was related to wind speed, and the reason that the effect of aerodynamic term on ETo is higher than the radiation term maybe caused by high wind speed. Except for the relative humidity, average temperature and sunshine hours, radiation term was affected by the elevation of stations, as for the stations with a higher elevation, the impact of elevation on Penman-Monteith equation was greater than that on modified Penman equation. Using the sensitivity analysis method to evaluate the effect of average air temperature, relative humidity and sunshine hours on ETrad showed that Penman-Monteith equation was better than modified Penman model in calculating ET^ad. The ET~,d calculated through Penman-Monteith equation was little influenced by seasons and stations, and had a high stability. The results from 18 stations showed that the effect of average temperature on ET~,~d was the minimal, the impact of relative humidity in January, November and December on ET^ad was larger, and the influence of sunshine hours from February to October on ET^od was also greater. Therefore, ETo in Henan Province was calculated by Penman-Monteith equation instead of modified Penman equation, crop coefficients must be corrected, otherwise it caused the estimated values of crop water requirement to be higher, and its impact on overwintering crops with a longer growing period was greater than that on summer crops with a shorter growth period. Finally, according to the relationship between two difference methods of estimating ETo, the correction method of crop coefficient based on Penman-Monteith equation was proposed. This study has an important significance in improving the estimation precision of crop water requirement.
出处
《农业工程学报》
EI
CAS
CSCD
北大核心
2013年第19期88-97,共10页
Transactions of the Chinese Society of Agricultural Engineering
基金
"863"计划(2011AA100502)
国家公益性行业(农业)科研专项(201203077)
科技基础性工作专项(2007FY120100)
