大气湍流间歇性对玉米花粉风扩散的潜在影响

Potential Impacts of Atmospheric Turbulences Intermittency on Wind Dispersal of Maize Pollen

现有研究成果已充分认识到大气湍流间歇性损耗将对大气边界层中颗粒物质的输送过程产生重要影响.然而,目前关于耗散间歇性对玉米花粉传播潜在影响的相关研究较为欠缺.基于拉格朗日随机模型,以耗散速率的时间变化为关键参量,定量地评估了大气湍流间歇性对玉米花粉传播的影响.数值分析结果表明,大气湍流间歇性能够增加花粉在花粉源附近及较远位置的分布几率;与稳定的大气条件相比,湍流间歇性对玉米花粉的传播,特别是对远距离传播能够产生更大的影响,且随着无量纲耗散率分布均方差的增加,长距离传播的统计物理量响应也将存在差异.研究表明,在复杂自然条件下,用一个特定的特征值或固定函数来描述玉米花粉的传播分布可能已不再适用,而需要找到一种更合理的描述方法.

It is gradually recognized that the dissipation intermittency(Dl)of turbulent wind has significant impacts on the transportation of particulate materials in the atmospheric boundary layer(ABL).However,the potential impact of DI on the wind dispersal of maize pollen is still not deeply investigated.Here,an improved Lagrangian Stochastic Model with temporal variations of the dissipation rate is employed as the key parameter to quantitatively evaluate the effects of atmospheric turbulences intermittency on wind dispersal of maize pollen.Numerical results show that the atmospheric turbulences intermittency leads to the increase of the distribution probability of pollen both near the pollen source and in the place very far from the pollen source.In comparison with atmospheric stability,the turbulence intermittency shows more significant impacts on the dispersal of maize pollen,especially for the long-distance dispersal.With the increase of the mean square error of the distribution of dimensionless dissipation rate,differences exist in the responding statistical physical quantities during the long-distance dispersal.The paper suggests that particularly under natural condition,a characteristic value or a fixed function may not be suitable for describing the distribution of maize pollen by wind dispersal.Therefore,a more appropriate way should be found to describe its distribution as soon as possible.