Going beyond the traditional paradigm to improve understanding and parameterization of aerosol-cloud-interaction regimes

 

Authors

Yangang Liu — Brookhaven National Laboratory
Jingyi Chen — Stony Brook University
Chunsong Lu — Nanjing University of Information Science and Technology
Minghua Zhang — Stony Brook University

Category

Warm low clouds, including aerosol interactions

Description

It is well recognized that aerosol indirect effects depend on the regime of aerosol-cloud interactions, and thus improving understanding and parameterization of aerosol-cloud interaction regimes is essential to reducing the large uncertainty in model estimated aerosol indirect effects. However, our understanding of the regime dependence has been largely based on the dependence of droplet concentration on aerosol concentration and updraft velocity at the level of maximum supersaturation in adiabatic clouds. This study aims to extend/improve aerosol-cloud interaction regime charaterization by going beyond the traditional paradigm. Specifically, 1) We will show that relative dispersion of droplet size distribution exhibits a stronger regime dependence, first increasing with increasing aerosol loading in aerosol-limited regime, peaks in the transitional regime, and decreases with further increasing aerosol loading; the unique co-regime dependence of relative dispersion and droplet concentration on aerosols is expected to change our understanding of aerosol-cloud interactions. 2) We will investigate the change with height of the co-regime dependence. 3) We will examine the effect of entrainment-mixing processes on regime dependence using a new entraining parcel model. 4) We will explore a unified representation of aerosol-cloud interaction regime by examining the mutual relationships between aerosol properties and key cloud properties such as droplet concentration, relative dispersion and entrainment rate.