Find in Library

<p>Particle triboelectric charging, being ubiquitous in nature and industry, potentially plays a key role in dust events, including the lifting and transport of sand and dust particles. However, the properties of the electric field (<span class="inline-formula"><strong><em>E</em></strong></span> field) and its influences on saltation during dust storms remain obscure as the high complexity of dust storms and the existing numerical studies are mainly limited to the 1D <span class="inline-formula"><strong><em>E</em></strong></span> field. Here, we quantify the effects of the real 3D <span class="inline-formula"><strong><em>E</em></strong></span> field on saltation during dust storms through a combination of field observations and numerical modelling. The 3D <span class="inline-formula"><strong><em>E</em></strong></span> fields in the sub-metre layer from 0.05 to 0.7&thinsp;m above the ground during a dust storm are measured at the Qingtu Lake Observation Array site. The time-varying means of the <span class="inline-formula"><strong><em>E</em></strong></span> field series over a certain timescale are extracted by the discrete wavelet transform and ensemble empirical mode decomposition methods. The measured results show that each component of the 3D <span class="inline-formula"><strong><em>E</em></strong></span> field data roughly collapses on a single third-order polynomial curve when normalized. Such 3D <span class="inline-formula"><strong><em>E</em></strong></span> field data within a few centimetres of the ground have never been reported and formulated before. Using the discrete element method, we then develop a comprehensive saltation model in which the triboelectric charging between particle–particle midair collisions is explicitly accounted for, allowing us to evaluate the triboelectric charging in saltation during dust storms properly. By combining the results of measurements and modelling, we find that, although the vertical component of the <span class="inline-formula"><strong><em>E</em></strong></span> field (i.e. 1D <span class="inline-formula"><strong><em>E</em></strong></span> field) inhibits sand transport, the 3D <span class="inline-formula"><strong><em>E</em></strong></span> field enhances sand transport substantially. Furthermore, the model predicts that the 3D <span class="inline-formula"><strong><em>E</em></strong></span> field enhances the total mass flux and saltation height by up to 20&thinsp;% and 15&thinsp;%, respectively. This suggests that a 3D <span class="inline-formula"><strong><em>E</em></strong></span> field consideration is necessary if one is to explain precisely how the <span class="inline-formula"><strong><em>E</em></strong></span> field affects saltation during dust storms. These results further improve our understanding of particle triboelectric charging in saltation and help to provide more accurate characterizations of sand and dust transport during dust storms.</p>