Identification

Title

Cloud-system resolving model simulations of aerosol indirect effects on tropical deep convection and its thermodynamic environment

Abstract

This paper presents results from 240-member ensemble simulations of aerosol indirect effects on tropical deep convection and its thermodynamic environment. Simulations using a two-dimensional cloud-system resolving model are run with pristine, polluted, or highly polluted aerosol conditions and large-scale forcing from a 6-day period of active monsoon conditions during the 2006 Tropical Warm Pool - International Cloud Experiment (TWP-ICE). Domain-mean surface precipitation is insensitive to aerosols primarily because the large-scale forcing is prescribed and dominates the water and static energy budgets. The spread of the top-of-atmosphere (TOA) shortwave and longwave radiative fluxes among different ensemble members for the same aerosol loading is surprisingly large, exceeding 25 W m⁻² even when averaged over the 6-day period. This variability is caused by random fluctuations in the strength and timing of individual deep convective events. The ensemble approach demonstrates a small weakening of convection averaged over the 6-day period in the polluted simulations compared to pristine. Despite this weakening, the cloud top heights and anvil ice mixing ratios are higher in polluted conditions. This occurs because of the larger concentrations of cloud droplets that freeze, leading directly to higher ice particle concentrations, smaller ice particle sizes, and smaller fall velocities compared to simulations with pristine aerosols. Weaker convection in polluted conditions is a direct result of the changes in anvil ice characteristics and subsequent upper-tropospheric radiative heating and weaker tropospheric destabilization. Such a conclusion offers a different interpretation of recent satellite observations of tropical deep convection in pristine and polluted environments compared to the hypothesis of aerosol-induced convective invigoration. Sensitivity tests using the ensemble approach with modified microphysical parameters or domain configuration (horizontal gridlength, domain size) produce results that are similar to baseline, although there are quantitative differences in estimates of aerosol impacts on TOA radiative fluxes.

Resource type

document

Resource locator

Unique resource identifier

code

http://n2t.net/ark:/85065/d7416xsg

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

2011-10-24T00:00:00Z

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