基于无人机扰动的果园防霜试验研究

Experimental Study on Frost Prevention in Orchard Based on Unmanned Aerial Vehicle Intervention

为了探索一种“有效、快速、经济、安全”可移动的果园防霜技术,基于晚霜冻发生时伴随的近地面逆温现象,采用无人机扰动低空气流的方法,进行了果园防霜的试验研究。初步研究结果表明:①晚霜冻发生时(辐射型降温),在风速≤1.5 m/s情况下,近地面气温随高度升高且上升幅度较大,逆温较强(其中0.6 m至1.0 m逆温最强);风速>1.5 m/s时,各高度层温度骤升、温差变小,逆温强度减弱,但逆温一直存在。排除风速的影响,逆温在日落之前就已出现,之后逆温不断增强,至2122时前后达到最强,之后逆温缓慢减弱,黎明前又略有增强,之后迅速减弱直至消失。②无人机干预效果表明:自干预时起0.6 m和1.5 m高度温度升高,且0.6 m处增温更明显。③在无人机干预频率和干预风力足够的情况下,干预25 min时,增温效果达到最大(0.6 m可增温5.0℃左右,1.5 m可增温2.0~3.0℃),之后在无人机干预期间,干预效果维持最大水平,停止干预后,干预效果维持30 min后消失。

In order to explore an effective,fast,economical and safe mobile frost prevention technology,we carried out the frost prevention test by disturbing the air flow at low altitudes with unmanned aerial vehicle based on the near-ground temperature inversion phenomenon when late frost occurs.The preliminary results show that:(1)when the radiant frost comes,in the wind speed of≤1.5 m/s,the near-ground temperature increases greatly with height,and inversion is intense,especially from 0.6 m to 1.0 m.If the wind speed is>1.5 m/s,temperature at all heights rises sharply,and the temperature difference between the height levels becomes smaller,so the inversion is weakened,but it’s still there.Excluding the influence of wind speed,the inversion occurs before sunset and gets stronger and stronger,reaching the peak point around 21:0022:00 BT.Then the inversion slowly decreases,but slightly increases again before dawn.After that,it weakens quickly till disappearing.(2)The intervention effect of unmanned aerial vehicle(UAV)shows that both 0.6 m and 1.5 m temperatures increase from the beginning of intervention,especially at the 0.6 m height level.(3)If the intervention frequency and the intervention force of UAV are sufficient,the warming effect is greatest when the UAV intervenes for about 25 minutes.In such cases,the temperature at the 0.6 m height can increase about 5.0℃,and at 1.5 m height about 2.03.0℃,so the warming effect is obvious.During the UAV intervention,the intervention effect can be maintained at the maximum level.After the intervention is stopped,the intervention effect can keep about 30 min before gradually weakening and disappearing.