中文摘要：

利用珠江流域42个观测站点的逐日气象数据对比分析了FAO56 Penman-Monteith（PM）、Priestley-Taylor、Hargreaves-Samani和Thornthwaite等4种蒸散发公式在珠江流域的适用性,并研究了在资料有限情况下PM公式的计算精度。PM公式由于详细考虑了空气动力与能量供给对蒸散发的影响,其在不同季节和地区的计算结果都较为稳定,并且与实际的观测接近,最适用于珠江流域的蒸散发计算。在蒸散发的计算中,日照时数的缺测对PM公式计算精度的影响最大,风速次之。通过设定修正系数后的PMT公式,计算精度得到了明显提高,在一定程度上可以满足对蒸散发计算的精度要求。因此,在其他资料缺失的情况下,只利用气温数据计算的PMT公式可成为一种理想的蒸散发计算公式。

英文摘要：

Based on the daily meteorological data from 42 stations in the Pearl River basin, different evapotranspiration methods including FAO56 Penman-Monteith（PM）, Priestley-Taylor, Hargreaves-Samani and Thornthwaite equations were compared to find out the most applicable one for calculating evapotranspiration in the basin. Then the calculation precision of PM formula under the conditions of limited data was analyzed. The results indicate that PM equation is the best one whose calculating result is stable for all seasons and districts and close to the observation data, and thus would be the most suitable formula for the evapotranspiration calculation in the Pearl River basin. To evaluate the influence of limited data on the calculation precision of PM formula, anyone of the data of relative humidity, sunshine duration, wind speed and pressure is assumed to be missing. Among the examined variables, sunshine duration is the most sensitive one to the calculating result, and wind speed follows. By setting a modified factor, the PM equation only based on the temperature data（PMT） still has a high calculation precision. As a result, PMT equation can be an ideal method for evapotranspiration calculation in the Pearl River basin when some variables of data are lacking.