Importance of including ammonium sulfate ((NH4)2SO4) aerosols for ice cloud parameterization in GCMs

P. S BHATTACHARJEE; Y. C SUD; X LIU; G. K WALKER; R YANG; J WANG

doi:10.5194/angeo-28-621-2010

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Importance of including ammonium sulfate ((NH4)2SO4) aerosols for ice cloud parameterization in GCMs

Journal article

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Importance of including ammonium sulfate ((NH4)2SO4) aerosols for ice cloud parameterization in GCMs

P. S BHATTACHARJEE, Y. C SUD, X LIU, G. K WALKER, R YANG and J WANG

Annales geophysicae (1988), Vol.28(2), pp.621-631

2010

DOI: 10.5194/angeo-28-621-2010

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Abstract

A common deficiency of many cloud-physics parameterizations including the NASA's microphysics of clouds with aerosol-cloud interactions (hereafter called McRAS-AC) is that they simulate lesser (larger) than the observed ice cloud particle number (size). A single column model (SCM) of McRAS-AC physics of the GEOS4 Global Circulation Model (GCM) together with an adiabatic parcel model (APM) for ice-cloud nucleation (IN) of aerosols were used to systematically examine the influence of introducing ammonium sulfate (NH4)2SO 4 aerosols in McRAS-AC and its influence on the optical properties of both liquid and ice clouds. First an (NH4)2SO4 parameterization was included in the APM to assess its effect on clouds vis-á-vis that of the other aerosols. Subsequently, several evaluation tests were conducted over the ARM Southern Great Plain (SGP) and thirteen other locations (sorted into pristine and polluted conditions) distributed over marine and continental sites with the SCM. The statistics of the simulated cloud climatology were evaluated against the available ground and satellite data. The results showed that inclusion of (NH4)2SO4 into McRAS-AC of the SCM made a remarkable improvement in the simulated effective radius of ice cloud particulates. However, the corresponding ice-cloud optical thickness increased even more than the observed. This can be caused by lack of horizontal cloud advection not performed in the SCM. Adjusting the other tunable parameters such as precipitation efficiency can mitigate this deficiency. Inclusion of ice cloud particle splintering invoked empirically further reduced simulation biases. Overall, these changes make a substantial improvement in simulated cloud optical properties and cloud distribution particularly over the Intertropical Convergence Zone (ITCZ) in the GCM.

Earth, ocean, space

External geophysics

Physics of the ionosphere

Physics of the magnetosphere

Exact sciences and technology

Details

Title: Subtitle: Importance of including ammonium sulfate ((NH4)2SO4) aerosols for ice cloud parameterization in GCMs
Creators: P. S BHATTACHARJEE - Department of Geography and Geoinformation Science, George Mason University, Fairfax, VA, United States
Y. C SUD - Emeritus Meteorologist, Climate and Radiation Branch, Laboratory for Atmospheres Goddard Space Flight Center, Greenbelt, MD, United States
X LIU - Pacific Northwest National Laboratory, Richland, WA, United States
G. K WALKER - SAIC/General Sciences Operation, Beltsville, MD, United States
R YANG - Department of Geography and Geoinformation Science, George Mason University, Fairfax, VA, United States
J WANG - Department of Geosciences, University of Nebraska, Lincoln, NE, United States
Resource Type: Journal article
Publication Details: Annales geophysicae (1988), Vol.28(2), pp.621-631
DOI: 10.5194/angeo-28-621-2010
ISSN: 0992-7689
eISSN: 1432-0576
Publisher: Copernicus
Language: English
Date published: 2010
Academic Unit: Civil and Environmental Engineering; Physics and Astronomy; Chemical and Biochemical Engineering
Record Identifier: 9984104912202771

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