摘要
云滴谱离散度(ε)作为衡量云滴粒子尺度分布以及离散程度的参数,在气溶胶-云-降水过程中有着重要作用。其中ε与云滴(N_(c))或背景气溶胶数浓度(N_(d))的相关关系是描述云内微物理和动力过程,以及量化气溶胶对云和降水影响的重要因子之一。很多气溶胶间接效应的研究中,未考虑云滴谱离散度带来的影响,这使得相关理论研究和模式模拟仍然具有一定的局限性。本文基于云滴谱离散度的概念,从多个方面回顾了近年来云滴谱离散度相关理论、观测和数值模拟研究进展,包括ε与N_(c)或N_(d)的相关性,云滴谱离散度对云中微物理参量和动力过程的影响机制,以及由云滴谱离散度引起的气溶胶间接效应的估算及其不确定性等。从过往研究来看,影响ε的因素很多,不仅是云滴数浓度,还包括云中的上升速度、液水含量等,甚至气溶胶的理化特性、云中的凝结、碰并、夹卷和蒸发等过程都会对ε产生不同的影响。背景气溶胶浓度的变化一定程度上会改变云滴尺度和浓度分布进而影响ε。受地区差异和云条件影响,ε与N_(c)或N_(d)的相关性存在很大差别,既有正相关也有负相关,甚至不相关。即使针对同一云团,在云的不同部位甚至云的不同发展阶段,ε可呈现出不同程度的变化。ε可通过改变暖云的云水-雨水转化效率从而对降水即第二间接效应产生影响;又可通过影响云滴有效半径从而改变云的光学特性来影响第一间接效应。不同的ε-N_(c)参数化关系会导致全球模式中间接效应的估算出现不同程度的抵消或增强,由此可导致地面气象场和降水分布发生改变。总之,ε与云中相关参量之间的关系以及对间接效应产生的影响还存在很大的不确定性,需要对背后的机理进行更加深入的研究。本文归纳总结了当前云滴谱离散度相关研究面临的问题和存在的挑战,对未来的研究重
As a key parameter to measure cloud droplet size distribution and dispersion characteristics,relative dispersion(ε)plays an important role in aerosol,cloud,and precipitation interactions.The correlation between ε and cloud droplet(N_(c))or ambient aerosol(N_(a))number concentrations is one of the important factors,not only for describing cloud microphysical and dynamic processes but also for quantifying the impact of aerosols on cloud and precipitation.The influence of ε was not well considered in previous studies on aerosol indirect effect,which makes the relevant theoretical research and numerical simulation still have certain limitations.Based on the concept of ε,this study reviews the theories,in-situ measurements,and modeling studies in recent years from the aspects of the correlation between ε and N_(c) or ambient N_(a),the mechanism of ε on cloud microphysical parameters and dynamical process,and the estimation of aerosol indirect effect caused by ε and its uncertainties.With the exception of N_(c),including updrafts,liquid water content,condensation,collision-coalescence,entrainment-mixing,evaporation in cloud,even aerosol physical or chemical properties can affect ε.The variation of N_(a) will partly change the concentration and size distribution of cloud droplet,then affect ε.Previous studies indicate that there is a direct dependence of ε on N_(c),but their correlation is complex and sensitive to many factors,such as aerosol loading and cloud conditions.Even for a same cloud parcel,ε varies considerably in different parts of cloud or at different evolutionary stages of cloud development.The ε-N_(c) correlation has been employed to evaluate the indirect effect in aerosol cloud interaction study.However,the diverse ε-N_(c) parameterizations may cause underestimation or overestimation of aerosol indirect effect in general circulation models.In addition,the occurrence and development of precipitation can be further affected through ε influencing the automatic transformation process of cloud w
作者
王飞
陆春松
WANG Fei;LU Chunsong(Key Laboratory for Cloud Physics,Chinese Academy of Meteorological Sciences,Beijing,100081,China;Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration,Nanjing University of Information Science&Technology,Nanjing 210044,Jiangsu,China)
出处
《高原气象》
CSCD
北大核心
2023年第4期809-820,共12页
Plateau Meteorology
基金
国家重点研发计划课题(2019YFC1510305)
国家自然科学基金项目(42175099)。
关键词
云滴谱离散度
气溶胶间接效应
参数化方案
Relative dispersion of cloud droplets
aerosol indirect effect
parameterization
