Identification

Title

Exploring impacts of size-dependent evaporation and entrainment in a global model

Abstract

While most observations indicate well-buffered clouds to aerosol perturbations, global models do not. Among the suggested mechanisms for this discrepancy is the models' lack of connections between cloud droplet size and two processes that can contribute to reduced cloudiness when droplets become more numerous and smaller: evaporation and entrainment. In this study, we explore different implementations of size-dependent evaporation and entrainment in the global atmospheric model CAM5.3-Oslo. We study their impact on the preindustrial-to-present day change in liquid water path (LWPPD-PI) and the corresponding aerosol indirect effect (AIE(PD-PI)). Impacts of the 2014-2015 fissure eruption in Holuhraun, Iceland, are also presented. Our entrainment modifications only have a moderate effect on AIE(PD-PI) (changes from -1.07 W m(-2) to -0.98 W m(-2)), and a small impact on the signal from the Holuhraun eruption compared to other suggested compensating mechanisms. Simulations with added size-dependent evaporation in the top of the stratiform clouds also show small evaporation differences between PI and PD. Moderate changes in AIE(PD-PI) were achieved when also including an entrainment feedback to the evaporation changes, mixing air between the cloudtop layer and the layer above. These changes were not associated with the size dependency, but changes in the cloud susceptibility to aerosols in both PI and PD when adding evaporation. We find that increased evaporation of smaller droplets at stratiform cloud tops can reduce LWP, but can increase LWP in some areas due to enhanced shallow convection caused by destabilization.

Resource type

document

Resource locator

Unique resource identifier

code

https://n2t.org/ark:/85065/d7rb77tq

codeSpace

Dataset language

eng

Spatial reference system

code identifying the spatial reference system

Classification of spatial data and services

Topic category

geoscientificInformation

Keywords

Keyword set

keyword value

Text

originating controlled vocabulary

title

Resource Type

reference date

date type

publication

effective date

2016-01-01T00:00:00Z

Geographic location

West bounding longitude

East bounding longitude

North bounding latitude

South bounding latitude

Temporal reference

Temporal extent

Begin position

End position

Dataset reference date

date type

publication

effective date

2020-02-27T00:00:00Z

Frequency of update

Quality and validity

Lineage

Conformity

Data format

name of format

version of format

Constraints related to access and use

Constraint set

Use constraints

Limitations on public access

None

Responsible organisations

Responsible party

contact position

OpenSky Support

organisation name

UCAR/NCAR - Library

full postal address

PO Box 3000

Boulder

80307-3000

email address

opensky@ucar.edu

web address

http://opensky.ucar.edu/

name: homepage

responsible party role

pointOfContact

Metadata on metadata

Metadata point of contact