日光温室内气温观测的适宜频次初探

Study of Suitable Frequency of Temperature Observation in the Chinese Solar Greenhouse

根据河北省高邑县2008-2010年温室作物生长季的外界气温特征,将2008、2009和2010年度分别定为偏暖、偏冷和正常年型。以高邑县2008-2010年温室作物生长季采集周期为10min的小气候气温观测资料为基础,将一日内每10min的气温资料的算术平均值作为实际日平均气温,分别取每20min、30min、1h、2h、3h、4h的观测数据进行算术平均计算日平均气温,分析不同年型下计算结果与实际值之间的平均绝对误差MAE、标准差SD和积温相对误差R,并采用成对t检验进行显著性检验;以P<0.05作为显著性检验指标,确定日光温室气温观测的适宜方法和频次。将MAE、SD和R作为评价计算方法优劣的主要因子,MAE、SD和R越小,表示计算效果越好。结果表明:(1)当观测间隔小于4h时,所计算的日平均气温与实际值无显著差异,MAE≤0.19℃,SD≤0.24℃,R≤1.1%,观测数据能满足温室环境日平均气温的计算,且观测间隔时间越短,观测频次越高,检验效果越好;观测间隔达到4h时,计算结果的准确性存在一定风险;(2)6个每日4时次的组合所计算的日平均气温与实际值存在显著差异,观测试验中不宜采用;(3)用日极值法计算的日平均气温较实际值显著偏高,不能代表实际气温,观测试验中亦不宜采用;(4)采用改进后的7:00、10:00、13:00、16:00、19:00和23:00气温组合计算的日平均气温与实际值无显著差异,MAE≤0.24℃,SD≤0.30℃,R≤1.4%,计算结果可以代表实际气温,且减少了夜间观测次数,观测时间更符合工作生活习惯,能够在实际生产中应用。总体来讲,每日观测应不少于6次,所计算的日平均气温才可能代表实际日平均气温。

According to the external temperature characteristics of greenhouse crop growing season in Gaoyi County during 2008- 2010,2008,2009 and 2010 were defined as the warmer,the colder and the normal year type,respectively. Based on the microclimate temperature observation data per 10 min during the greenhouse crop growing season in Gaoyi County from 2008 to 2010,the arithmetic mean value calculated by every 10 min observation data in a day was regarded as the actual mean temperature. The arithmetic mean values calculated by every 20 min,30min,1hour,2 hours,3 hours,4 hours observation data respectively were regarded as the daily mean temperature. The mean absolute error（ MAE）,standard deviation（ SD） and the accumulated temperature relative error（ R） in the observation period between the arithmetic mean values calculated by every 20 min,30min,1 hour,2 hours,3 hours,4 hours observation data respectively and the actual daily mean temperature were analyzed and the significance was test by t-test. The suitable method and frequency of temperature observation in greenhouse was confirmed by the index of P〈0. 05. MAE,SD and R were applied for evaluating the calculation effect of these methods. The smaller was the MAE,SD and R,the better was the effect. The results showed,（ 1） when the observation interval was less than 4 hours,the daily average temperature calculated was not significantly different with the actual,MAE≤0. 19℃,SD≤0. 24℃,R≤1. 1%,so the method was suitable for greenhouse environment; Moreover,the shorter of the observation interval and the higher of the observation frequency,the better was the effect of the average temperature calculated. When the observation interval was 4 hours,the accuracy of the results has certain risks.（ 2） The daily mean temperature calculated by six compositions of four times observation data was significantly different with the actual,so the method should not be used in observation experiment.（ 3） The daily mean temperature calculated by the maximum and the minimum temperature was significantly higher than the actual value,therefore,the calculation method should not be used in observation experiment.（ 4） The daily mean temperature calculated by the improved method of using the 7： 00,10： 00,13： 00,16： 00,19： 00 and 23： 00 observation data was not significantly different with the actual,MAE≤0. 24℃,SD≤0. 30℃,R≤1. 4%,and the observation time in night was also reduced,therefore,the method can be used in the actual production.（ 5） Overall,at least six times in a day observation,the daily mean temperature calculated may be representative of the actual mean temperature.