Advances of Theoretical， Observational， and Numerical Studies on Relative Dispersion of Cloud Droplet Spectra
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 （Nc） or ambient aerosol （Na） number concentrations is one of the...
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| Main Authors: | , |
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| Format: | Article |
| Language: | zho |
| Published: |
Science Press, PR China
2023-08-01
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| Series: | Gaoyuan qixiang |
| Subjects: | |
| Online Access: | http://www.gyqx.ac.cn/EN/10.7522/j.issn.1000-0534.2022.00067 |
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| Summary: | 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 （Nc） or ambient aerosol （Na） 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 Nc or ambient Na， 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 Nc， 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 Na 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 Nc， 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-Nc correlation has been employed to evaluate the indirect effect in aerosol cloud interaction study.However， the diverse ε-Nc 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 water to rain water in the model parameterization scheme， resulting in the variation of surface precipitation.Anyway， there is still great uncertainty in characterizing the correlation between ε and cloud parameters， and estimating its impact on aerosol indirect effect is very difficult.Therefore， the mechanisms behind them need to be further studied.The problems and challenges in the current research on ε are summarized.The comprehensive summary of the previous studies gives a perspective of further outlook.Some conclusions can provide references for further understanding the role of ε in aerosol cloud interaction. |
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| ISSN: | 1000-0534 |