微观时间尺度气象因子影响露水量的通径分析

Path Analysis on Sensitivity of Meteorological Factors to Dew Amount in Micro-scale

露水量对微观尺度气象因子的敏感性是决定露水能否形成及露水量大小的关键。为研究半干旱区气象因子对梨枣树结露的影响,以黄土半干旱区2年生梨枣树为试验材料,对梨枣树冠层内的露水量以及影响因子:距地表2m高处风速μ、冠层相对湿度RH、冠层温度T、冠层温度露点差DPD、冠层饱和差VPD、土壤5cm处的温度T5进行了同步监测,并利用通径分析法在分和小时尺度上对相关因素进行了敏感性分析。结果表明,不同时间尺度条件下,不同因子对露水量敏感性存在差异。在分尺度上,敏感性显著的气象因子有4个,敏感性大小次序为:T>VPD>DPD>RH。在时尺度上,敏感性显著的气象因子有5个,敏感性大小次序为:RH>VPD>μ>DPD>T。无论在分还是时尺度上VPD对露水量具有较强的敏感性,其敏感性不会随时间尺度的变化而发生变化,其他因子的尺度效应会因时间尺度的变化而发生变化。

Sensitivity of meteorological factors to dew in micro-scale is the key to determine not only whether dew can form or not,but also dew amount.In order to clarify the influences of meteorological factors to dew condensation on the pear-jujube,2-year-old pear jujube trees growing in the loess plateau were used in this study,in addition,dew amount,relative humidity（RH）,temperature（T）,dew point-air temperature depression（DPD）and vapor pressure deficit（VPD）in the canopy,along with wind speed（μ,2m from the ground）and soil temperature（T5,in the depth of 5cm）were monitored synchronously.The results of path analysis on relevant factors in hours and minutes indicated that differences existed in sensitivities of different factors to dew amount in different time scales.In the scale of minutes,the order of significant factors in sensitivity was T 〉VPD〉 DPD〉 RH,while,in the scale of hours,it was RH 〉VPD〉μ 〉DPD 〉T.For VPDand DPD,no matter in the scale of minutes or hours,they had weak sensitivities on dew amount.But for other factors,there were obvious scale effect,so pushing up or pushingdown simply between scales are unreasonable.