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气溶胶辐射效应对河北山区一次对流云和降水过程的影响机理与阈值研究

Study on the Mechanism and Threshold of the Aerosol Radiative Effect on A Convective Cloud and Precipitation in the Mountain Area of Hebei Province

  • 摘要: 本文利用新一代中尺度天气研究和预报模式WRFv4.3对2017年5月22日河北西南部一次对流云和降水进行模拟。本研究采用卫星观测的气溶胶消光系数垂直廓线,分析了气溶胶辐射效应对云和降水影响。通过模拟试验,本研究量化了气溶胶辐射效应对本次降水率影响的气溶胶含量阈值,探讨了伴随辐射加热产生的微物理过程的潜热加热和平流加热等联动机制,并分析了辐射效应对温湿变量和热动力条件的影响。研究结果发现:(1)气溶胶光学厚度(AOD)从0.1增大至1.5,气溶胶辐射效应对降水峰值的影响先增大再减小,在AOD为1.0时增大效果最显著,对累计降水的影响先减小再增大,在AOD为1.0时的抑制作用最弱;(2)气溶胶辐射效应导致的辐射加热率的改变伴随着潜热加热率和总平流加热率的显著变化,总加热率的变化主要由后二者决定;(3)气溶胶辐射效应增强了对流成熟阶段的垂直上升运动,有利于更强对流和降水发生。

     

    Abstract: In this paper, a convective precipitation that took place in southwest Hebei Province on May 22, 2017, is simulated using the Weather Research and Forecasting (version 4.3). By applying the satellite-observed vertical profile of the aerosol extinction coefficient in the model, this study quantifies this study quantifies the response of precipitation rates to the aerosol loading represented by the aerosol optical depth (AOD) by the aerosol radiative effect (ARE). The relationship of latent heating of microphysical processes and total advective heating to radiative heating is discussed. The influences of the ARE on temperature, moisture, relative humidity, and thermodynamic conditions are examined. (1) Increasing the AOD from 0.1 to 1.5 results in an increase and then a decrease in the influence of the ARE on peak precipitation rates, and at an AOD of 1.0, the influence is the largest. Meanwhile, the impacts of ARE on cumulative precipitation rates decrease and then increase, and the inhibition effect is the weakest at an AOD of 1.0. (2) The change in radiative heating resulting from the ARE is accompanied by significant changes in the latent heating rate of microphysical processes and total advective heating rate. The change in total heating rate is primarily determined by the latter two. (3) The ARE enhances the vertical updraft in the mature stage of convection, which is conducive to stronger convection and precipitation.

     

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