旱作春玉米农田Priestley-Taylor模式参数的变化

Priestley-Taylor(PT)参考作物蒸散(ET₀)估算模式系数(α)的本地化研究，对于确定水资源高效利用的半旱地农业生产措施及精准灌溉具有非常重要的意义。本文以FAO(1998)推荐的Penman-Monteith (PM)参考作物蒸散估算方法为标准，采用涡度相关技术并根据气象数据信息，监测半干旱气候条件下旱作春玉米农田尺度水、热交换传输过程，以分析Priestley-Taylor模式参数α的变化特征并确定其本地化估算参数值。结果表明，年时间尺度变化过程中高海拔半干旱气候条件下根据PT模式推荐系数α=1.26确定的参考作物蒸散量(ET_{0-PT 1.26})估算值，在11月至来年4月份非作物生长季期间平均偏低21.2%，在5月至9月份旱作春玉米生育期内平均高于PM模式的参考作物蒸散量(ET_0-PM)估算值5.5%，研究站点旱作春玉米生长季本地化适宜的PT模式系数α值为1.15±0.06。在季节变化过程中，旱作春玉米农田近正午时刻实际PT模式系数平均值呈单峰型变化趋势，春玉米抽雄抽穗开花期达到高峰，平均值为0.67±0.08，苗期最低，仅为0.26±0.13，全生育期平均值为0.50±0.21。若要在半干旱气候地区根据PT模式准确估算参考作物蒸散量，需进行PT模式参数的本地化研究。

Variation of Priestley-Taylor Model Parameter in Rain Fed Spring Maize Field

The study on Priestley-Taylor (PT) reference crop evapotranspiration model coefficient (α) in local area is of great significance in semi-arid agricultural water resources efficient use and precision irrigation in corn. Here, based on the FAO (1998)-recommended Penman-Monteith (PM) reference crop evapotranspiration as a standard method, we determined the water and heat exchange and its estimated parameters by the eddy covariance technique and Priestley-Taylor model under local climatic conditions. The results indicated that the estimated values of reference crop evapotranspiration (ET_{0-PT 1.26}) gained from PT model-recommended coefficient (α = 1.26) lowed by 21.2% on an average during non-growth stages (from November to April next year), and reached an average of 5.5% higher than those from PM model reference crop evapotranspiration (ET_0-PM) from May to September. The local PT model coefficient α value was 1.15 ± 0.06. The average PT model coefficient at noon during growth stages showed a single peak changing trend with the highest value of 0.67 ± 0.08 from tasseling to flowering stage and with the lowest value of 0.26 ± 0.13 at seedling stage. In conclusion, if the reference crop evapotranspiration is necissery to be estimated accurately by PT model in the semi-arid climate area, the local PT parameters should be studied firstly.