2020年雾灵山人工低频强声波增雨和消雾试验

Rainfall Enhancement and Fog Dissipation Experiments in Wuling Mountain in 2020 Using Artificial Strong Sound Wave

为了研究人工低频强声波增雨和消雾作业手段的效果,使用最大声压级为155 dB的电声低频强声波装置原型机,于2020年8—9月在河北省雾灵山开展增雨和消雾外场作业观测试验。具有明显消雾效果的两个典型个例显示:作业开始后2~3 min内尺度小于10μm的雾滴减少,尺度大于10μm的雾滴增多;随后大部分尺度的雾滴明显减少,10 min内能见度可从小于100 m回升至最高1000 m。在风速、风向与消雾效果的关系方面,消雾效果明显的个例均发生在平均风速小于1.5 m·s^(-1)且风向可使雾能够途经声波装置影响范围近侧的条件下,而平均风速大于2m·s^(-1)的个例能见度几乎未出现趋势性变化。在一次地面平均风速为1.4 m·s^(-1)的对流云增雨作业中观测到符合试验预期的结果,开始作业后的3 min内地面雨强从0.3 mm·h^(-1)迅速增至7 mm·h^(-1)以上,并观测到出现迅速但维持时间较短的大雨滴。其他增雨个例在作业时段的平均风速均超过3 m·s^(-1),可能受风速偏大和观测点单一的影响,未能观测到明确且一致的增雨证据。

Low-frequency sound wave is a new type of operational approach that has the potential for enhancing rainfall and dissipating fog.To investigate the impact of this type of equipment,field operations and observational experiments are conducted in Wuling Mountain from August to September 2020.Wuling Mountain is located at Chengde of Hebei outside the northeastern boundary of Beijing.The main peak of the Yanshan Mountains is renowned for its foggy summers with an altitude of 2118 m.In the experiment,a prototype of an electronic acoustic low-frequency strong sound wave device is used.This device has a maximum sound pressure level of 155 dB.Meanwhile,observation instruments such as a disdrometer,visibility meter,fog droplet spectrometer,and automatic weather station with an ultrasonic anemometer are deployed.These instruments are used to obtain the background conditions and to monitor macro and micro changes during rainfall enhancement and fog dissipation operations for evaluating the effectiveness.In two typical cases with an obvious defogging effect,within 2 to 3 minutes after the start of the operation,the number of droplets smaller than 10μm decreased,while the number of droplets larger than 10μm increased.Subsequently,the size of the droplets on most scales decreased significantly,resulting in improved visibility.Within a span of 10 minutes,visibility could increase from less than 100 m to a maximum of 1000 m within 10 min.The relationship between wind speed,wind direction,and the dissipation effect of fog shows that cases with a noticeable defogging effect occur when the average wind speed is less than 1.5 m·s^(-1) and the wind direction causes the fog to pass through the near side of the influence range of the sound wave device,while cases with an average wind speed greater than 2 m·s^(-1) hardly show any change in visibility trends.Results,which align with the experimental expectations,are observed during an operation on a convective cloud precipitation when the surface mean wind speed is 1.4 m·s^(-1).In this case,the rainfall intensity increased rapidly from 0.3 mm·h^(-1) to more than 7 mm·h^(-1) within 3 min of operation,and large raindrops with rapid occurrence but short duration is observed.In other rainfall enhancement experimental cases,the average wind speed exceeded 3 m·s^(-1) during the operation period,and no clear and consistent evidence of increased rainfall is observed,which may be affected by the high wind speeds and only one single observation point.