长武塬区光合有效辐射的基本特征及气候学计算

Basic characteristics of photosynthetically active radiation and its climatological calculation on Changwu tableland

利用长武农业生态试验站2010年气象观测资料,分析了长武塬区光合有效辐射及其占太阳总辐射比例系数的日变化、季节变化特征和影响因素。结果表明：就日变化过程而言,光合有效辐射和总辐射趋势一致,晴天呈单峰型,起伏平滑;阴天的形状则不稳定,最大值出现在12∶30~15∶00之间。光合有效辐射具有明显的季节变化特征,春夏较大,秋季次之,冬季最小,从春到冬其平均日总量分别为6.32、7.23、5.63MJ/m2和3.58MJ/m2。光合有效辐射系数阴天大,晴天小;就月平均值而论,6月份最大,为0.423,1月份最小,为0.327。根据观测数据,论文给出了适合该地区的光合有效辐射计算的经验模型。

The diurnal and seasonal variation characteristics of the PAR and the ratio of the PAR to global radiation were studied by using the meteorological data from the Changwu Eco-agricultural Experimental Station in 2010.The results indicate that the diurnal variations of the PAR and global radiation on typical days have the same trend.The curve for sunny day shows a smooth unimodal feature,while the curve for cloudy day is not stable.The maximum values on both curves appear between 12∶30～15∶00.The PAR is characterized by the obvious seasonal variation and the mean total diurnal quantities of the PAR for the seasons are 6.32,7.23,5.63 MJ/（m2·d）,and 3.58 MJ/（m2·d） respectively,indicating that the total diurnal quantity is the maximum in spring and summer,the middle in autumn,and the minimum in winter.The ratio of PAR to global radiation in cloudy days is greater than that in sunny days.A maximum value of 0.423 is observed in June,and a minimum value of 0.327 in January.Accordingly,the calculation model of photosynthetically active radiation for the tableland is proposed.