双月刊

ISSN 1006-9895

CN 11-1768/O4

基于火箭和高炮真实催化轨迹的一次对流云消减雨的数值模拟
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中国气象科学研究院 中国气象局人工影响天气中心 北京,100081

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国家自然科学基金


Numerical simulation of a convective cloud rainfall reduction based on the realistic seeding trajectories of rocket and artillery
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    摘要:

    效果评估仍是人工影响天气研究面临的困难问题,数值模式在催化效果的评估方面有望发挥更大作用,建立能够模拟真实催化过程的数值模式是一条可行的途径。本文对一套三维中尺度催化模式进行了改进,采用了新的碘化银核化计算方案,并在模式中增加了人工冰晶预报量及相关微物理过程,实现了对地面火箭和高炮作业方式的仿真模拟。使用改进后的模式,采用500m的高水平分辨率,模拟了2019年9月1日华北中部一次对流云系的人工消减雨作业过程,对催化作业的消减雨效果进行了数值评估,并对碘化银在对流云中的核化特征及其催化作用机制进行了分析。结果表明:1)催化作业对目标云系的雷达回波强度产生了一些影响,催化导致更多降水粒子漂浮在高空,使得云体上部的回波强度略有增加,云体中下部的回波强度减弱,但催化作业并未改变目标云系雷达回波的自然演变趋势。2)催化作业达到了一定的消减雨效果,作业区下游出现大面积减雨区,降水总量减少,降水强度减弱,最大减雨量0.27mm,主要影响区的平均减雨率为5.1%。3)碘化银催化剂主要的核化方式为凝结冻结核化,其次为接触冻结核化。4)催化作业造成了过量播撒,人工冰晶的成长占据竞争优势,它抑制了过冷层中其他水成物的自然增长过程,人工冰晶的凝华增长是导致云中水汽和云水消耗量增加的主要原因,凝华潜热的释放最终也引起云中垂直气流发生变化。5)冷云降水是此次降水的主要物理机制,受催化的影响,暖层中霰融化过程(Mgr)的减弱导致雨滴总质量减少,这是降水减弱的主要原因,落入暖层下部的雨滴数量减少则是降水减弱的另一原因。

    Abstract:

    Effect evaluation is still a difficult issue in the weather modification field. Numerical models can play a greater role in the effect evaluation of cloud seeding. Developing numerical models with some more realistic simulation of cloud seeding process is a workable way. In this paper, a three-dimensional mesoscale seeding model has been improved through coupling a new AgI (silver iodide) nucleation calculation scheme. Artificial ice crystal predictand and its associated microphysical processes have been introduced into the model, and the realistic seeding operation modes of both ground-based rockets and artillery have can be simulated by the model. The artificial rainfall reduction operation of a convective cloud system in North China on September 1, 2019, was simulated using the above seeding model with a horizontal grid spacing of 500m. The seeding effect of rainfall reduction operation was evaluated, and the nucleation characteristics and working mechanism of AgI agents in convective clouds were analyzed. The results showed the following: 1) Cloud seeding had some impact on the radar echo intensity of the target cloud system. More precipitation particles stayed in the upper cloud region because of the cloud seeding operation, which slightly increased the echo intensity of the upper part of the cloud body and weakened the echo intensity of the middle and lower part of the cloud body. However, the natural evolution tendency of radar echoes of the target cloud system has not been changed by cloud seeding. 2) Cloud seeding achieved certain rainfall-reducing effects. A large-area rainfall-reducing zone appeared downstream of the operation area. The total rainfall amount was decreased, and the rainfall intensity was weakened. The greatest local value of rainfall amount reduction was 0.27mm, and the rainfall in the main affected area decreased by 5.1% on average. 3) Condensation-freezing nucleation was the main nucleation mode of the AgI agent, followed by contact-freezing nucleation mode. 4) Cloud seeding operation caused an overseeding effect. The growth of artificial ice crystals was in a dominant position during competition, and the natural growth processes of other hydrometeors in the supercooling cloud area were suppressed. The deposition growth of artificial ice crystals was the main reason for the increase in depletion of water vapor and cloud water, and deposition latent heat release eventually led to the change of vertical airflow velocity in the cloud. 5) The cold cloud precipitation process was the main physical mechanism of the rainfall. Due to the influence of cloud seeding, the weakening of the graupel melting process (Mgr) in the warm layer led to the decrease of the total mass of raindrops, which was the main reason for the weakening of rainfall, while the decrease in the number of raindrops falling into the lower part of the warm layer was another reason for the weakening of rainfall.

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  • 收稿日期:2021-05-07
  • 最后修改日期:2022-02-06
  • 录用日期:2022-02-18
  • 在线发布日期: 2022-02-21
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