Vertical Variation of Cloud Microphysical Relationships and Their Implication on Entrainment and Mixing Processes in Stratocumulus Clouds Measured during the ACE-ENA Campaign
Abstract
Marine boundary layer clouds such as stratus and stratocumulus clouds play a critical role in the Earth's energy balance and hydrological cycle. Despite a simple shape of such clouds, complex interactions of cloud microphysical, dynamical, and thermodynamic processes occur in these clouds. Especially, mixing of cloudy air and entrained air from above cloud top is known to be an important process that can modulate cloud microphysical relationships differently depending on how mixing proceeds. Our recent studies on MASE and VOCALS stratocumulus clouds showed that mean volume diameter and liquid water content of cloud droplets were predominantly positively correlated in the data observed from horizontal penetrations through the middle of the clouds, which suggested homogeneous mixing (HM) trait. Meanwhile, correlation was vague for penetrations near cloud top, implying inhomogeneous mixing (IM). We speculated that such vertical variation of cloud microphysical relationships was due to vertical circulation of cloud parcels affected by entrainment and mixing. Here we make similar investigation on marine stratocumulus clouds observed during the Aerosol and Cloud Experiments in Eastern North Atlantic (ACE-ENA) Campaign. As expected, cloud microphysical relationships and mixing diagram analysis suggest IM near cloud top but as the altitude goes down, they show the trait of HM. Consistently the shape of droplet size distributions of undiluted and diluted sections is similar near cloud top but at lower altitudes droplets are clearly smaller in diluted sections. The relative dispersion tends to increase as liquid water content decreases but importantly such tendency is less pronounced at higher altitudes. These behaviors seem to be consistent with vertical circulation mixing hypothesis. More detailed results will be discussed at the conference.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.A11L2421Y
- Keywords:
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- 0305 Aerosols and particles;
- ATMOSPHERIC COMPOSITION AND STRUCTUREDE: 0320 Cloud physics and chemistry;
- ATMOSPHERIC COMPOSITION AND STRUCTUREDE: 0426 Biosphere/atmosphere interactions;
- BIOGEOSCIENCESDE: 4504 Air/sea interactions;
- OCEANOGRAPHY: PHYSICAL