Dependence of the effect of aerosols on cirrus clouds on background vertical velocity

doi:10.1016/j.atmosres.2012.03.003

Atmospheric Research

Volume 111, July 2012, Pages 79-89

https://doi.org/10.1016/j.atmosres.2012.03.003 Get rights and content

Abstract

Cirrus clouds cover approximately 20–25% of the globe and thus play an important role in the Earth's radiation budget. This important role in the radiation budget played by cirrus clouds indicates that aerosol effects on cirrus clouds can have a substantial impact on the variation of global radiative forcing if the ice–water path (IWP) changes. This study examines the aerosol indirect effect (AIE) through changes in the IWP for cirrus cloud cases. This study also examines the dependence of aerosol–cloud interactions in cirrus clouds on the large-scale vertical motion. We use a cloud-system resolving model (CSRM) coupled with a double-moment representation of cloud microphysics.

Intensified interactions among the cloud ice number concentration (CINC), deposition and dynamics play a critical role in the IWP increases due to aerosol increases from the preindustrial (PI) level to the present-day (PD) level with a low large-scale vertical velocity. Increased aerosols lead to an increased CINC, providing an increased surface area for water vapor deposition. The increased surface area leads to increased deposition despite decreased supersaturation with increasing aerosols. The increased deposition causes an increased depositional heating which produces stronger updrafts, and these stronger updrafts lead to the increased IWP. However, with a high large-scale vertical velocity, the effect of increased CINC on deposition was not able to offset the effect of decreasing supersaturation with increasing aerosols. The effect of decreasing supersaturation on deposition dominant over that of increasing CINC leads to smaller deposition and IWP at high aerosol with the PD aerosol than at low aerosol with the PI aerosol.

The conversion of ice crystals to aggregates through autoconversion and accretion plays a negligible role in the IWP responses to aerosols, as does the sedimentation of aggregates. The sedimentation of ice crystals plays a more important role in the IWP response to aerosol increases than the sedimentation of aggregates, but, not more important than the interactions among the CINC, supersaturation, deposition and dynamics. These interactions not only determine the effect of aerosols on IWP but also control how this effect varies with varying large-scale vertical velocities.

Highlights

► This study identifies mechanisms of aerosol-cloud interactions in cirrus clouds. ► Dependence of the mechanisms on background vertical velocity is examined. ► Aerosol-cloud interactions in cirrus clouds should consider background conditions.

Introduction

Cirrus clouds cover approximately 20–25% of the globe and as much as 70% over the tropics and, thus, can act as one of major modulators of global radiation budget (Liou, 1986, Liou, 2005). Hence, the effect of aerosols on cirrus clouds may have contributed to changing global radiation budget and to climate change since industrialization.

Lee et al. (2009) showed that aerosols can lead to significant changes at the top of the atmosphere (TOA) longwave radiation as well as shortwave radiation through their effects on cirrus clouds which have their origins in strong deep-convective vertical motions. About half of the large-scale cirrus clouds have their origins in the upper layers detrained from deep, precipitation cloud systems (Houze, 1993). The other half of cirrus clouds has their origins in large-scale vertical motion, much lower than vertical motion in deep convective clouds. Different dynamic intensities are likely to lead to different interactions between microphysics and dynamics by affecting the magnitude of deposition and sublimation. Hence, the properties of cirrus clouds and thus the effect of aerosols on them with the weak large-scale motion are likely to be different from those coupled with the strong deep-convective motion.

Starr and Cox (1985) investigated cirrus clouds developing with a large-scale vertical motion which was not associated with deep convective clouds. They reported that large-scale vertical motion significantly affected cirrus-cloud radiative and microphysical properties. This report implies that aerosol–cloud interactions are likely to depend on large-scale vertical motion. That a varying large-scale vertical motion is likely to accompany changing supersaturation and thus nucleation rate supports this implication (Starr and Cox, 1985). Supersaturation and nucleation rate basically determine an initial variation of cloud properties such as CINC and IWP (two most important estimates of the effect of aerosols on clouds) induced by an aerosol variation. Thus, different large-scale vertical motions are likely to lead to the different effects of aerosols on clouds.

In this study, the effect of aerosols on cirrus clouds developing with large-scale vertical motion (not associated with deep convective motions) is examined using a cloud-system resolving model (CSRM). Then, the dependence of this effect on large-scale vertical motion is examined using the CSRM.

Section snippets

Dynamics and turbulence

For numerical experiments, the Goddard Cumulus Ensemble (GCE) model (Tao et al., 2003) is used as a three-dimensional nonhydrostatic compressible model. The detailed equations of the dynamical core of the GCE model are described by Tao and Simpson (1993) and Simpson and Tao (1993).

The subgrid-scale turbulence used in the GCE model is based on work by Klemp and Wilhelmson (1978) and Soong and Ogura (1980). In their approach, one prognostic equation is solved for the subgrid-scale kinetic energy,

Case descriptions

A case of cirrus clouds located at (18° N, 30° W) off the coast of Western Africa is simulated here. A pair of simulations from 6 LST (local solar time) on July 1st to 18 LST on July 1st in 2002 is performed in which the aerosol concentration is varied from the PI level to the PD level. Henceforth, this case is referred to as “CONTROL” and the simulation with the PD (PI) level is referred to as the PD-aerosol (PI-aerosol) run, henceforth.

Reanalysis data from the European Centre for Medium-Range

Idealized cases

This study aims to isolate the varying role of aerosol–cloud interactions in the cloud-mass response to aerosols with varying large-scale vertical velocity. For the isolation, the simulations in CONTROL are repeated with differences only in large-scale vertical velocity. For the first of these idealized cases, the initial large-scale vertical velocity between 12 and 15 km in altitude in CONTROL, multiplied by a factor of 2, is applied. This idealized case is referred to as “W-M2”. For the other

Cloud properties

Fig. 4 shows the temporal evolution of the domain-averaged IWP. Clouds form earlier with larger background vertical velocity as shown in comparison among Fig. 4a, b, c, and d. Fig. 4 shows that the IWP in the PD-aerosol run is generally higher than that in the PI-aerosol run by 0.1–1.0 g m^− 2 during the time integration in CONTROL and W-M2. The time- and domain-averaged IWPs are 6.26 (6.01) and 8.32 (8.03) g m^− 2 for the PD (PI) aerosol case in CONTROL and W-M2, respectively. Unless otherwise

Summary and conclusion

Aerosol–cloud interactions in cirrus clouds developing with the large-scale vertical motion off the coast of Western Africa in the summer in 2002 were simulated using a CSRM coupled with a double-moment microphysics. Also, the dependence of these interactions on large-scale vertical motion is examined by varying the intensity of large-scale vertical motion.

Simulations showed that increasing aerosols increased IWP with a relatively low large-scale vertical motion (as shown in CONTROL and W-M2).

Acknowledgments

The authors wish to thank Dr. Wei-Kuo Tao and Derek Posselt for providing the GCE coupled with the double-moment microphysics used here and for valuable discussions.

References (38)

M.P. Meyers et al.
New RAMS cloud microphysics parameterization. Part II: the two-moment scheme
Atmos. Res.
(1997)
R.L. Walko et al.
New RAMS cloud microphysics parameterization: Part I. The single-moment scheme
Atmos. Res.
(1995)
B.A. Albrecht
Aerosols, cloud microphysics, and fractional cloudiness
Science
(1989)
N.A. Berezinskiy et al.
Altitude variation of relative ice-forming activity of natural aerosol
Sov. Meteorol. Hydrol.
(1986)
M.-D. Chou et al.
A shortwave radiation parameterization for atmospheric studies
M.-D. Chou et al.
Parameterizations for water vapor IR radiative transfer in both the middle and lower atmospheres
J. Atmos. Sci.
(1999)
C.C. Chuang et al.
An assessment of the radiative effects of anthropogenic sulfate
J. Geophys. Res.
(1997)
W.R. Cotton et al.
The Colorado State University three-dimensional cloud/mesoscale model. Part II: an ice phase parameterization
J. Rech. Atmos.
(1982)
P.J. DeMott et al.
Measurements of the concentration and composition of nuclei for cirrus formation
Proc. Natl. Acad. Sci. U. S. A.
(2003)
L.J. Donner et al.
Three-dimensional cloud-system modeling of GATE convection
J. Atmos. Sci.
(1999)

G. Feingold et al.

Evolution of raindrop spectra. Part I: solution to the stochastic collection/breakup equation using the method of moments

J. Atmos. Sci.

(1988)

G. Feingold et al.

The impact of giant cloud condensation nuclei on drizzle formation in stratocumulus: implications for cloud radiative properties

J. Atmos. Sci.

(1999)

H.W. Georgii et al.

Relations between the chemical composition of atmospheric aerosol particles and the concentration of natural ice nuclei

J. Rech. Atmos.

(1967)

W.W. Grabowski et al.

Cloud resolving modeling of tropical cloud systems during phase III of GATE. Part I: two-dimensional experiments

J. Atmos. Sci.

(1996)

J. Hallett et al.

Production of secondary ice particles during the riming process

Nature

(1974)

J.Y. Harrington et al.

Parameterization of ice crystal conversion processes due to vapor deposition for mesoscale models using double-moment basis functions. Part I: basic formulation and parcel model results

J. Atmos. Sci.

(1995)

R.A. Houze

Cloud Dynamics

(1993)

J.B. Klemp et al.

The simulation of three-dimensional convective storm dynamics

J. Atmos. Sci.

(1978)

T. Koop et al.

Water activity as the determinant for homogeneous ice nucleation in aqueous solutions

Nature

(2000)

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Dependence of the effect of aerosols on cirrus clouds on background vertical velocity

Abstract

Highlights

Introduction

Section snippets

Dynamics and turbulence

Case descriptions

Idealized cases

Cloud properties

Summary and conclusion

Acknowledgments

Atmos. Res.

Atmos. Res.

Aerosols, cloud microphysics, and fractional cloudiness

Science

Altitude variation of relative ice-forming activity of natural aerosol

Sov. Meteorol. Hydrol.

A shortwave radiation parameterization for atmospheric studies

Parameterizations for water vapor IR radiative transfer in both the middle and lower atmospheres

J. Atmos. Sci.

An assessment of the radiative effects of anthropogenic sulfate

J. Geophys. Res.

The Colorado State University three-dimensional cloud/mesoscale model. Part II: an ice phase parameterization

J. Rech. Atmos.

Measurements of the concentration and composition of nuclei for cirrus formation

Proc. Natl. Acad. Sci. U. S. A.

Three-dimensional cloud-system modeling of GATE convection

J. Atmos. Sci.

Evolution of raindrop spectra. Part I: solution to the stochastic collection/breakup equation using the method of moments

J. Atmos. Sci.

The impact of giant cloud condensation nuclei on drizzle formation in stratocumulus: implications for cloud radiative properties

J. Atmos. Sci.

Relations between the chemical composition of atmospheric aerosol particles and the concentration of natural ice nuclei

J. Rech. Atmos.

Cloud resolving modeling of tropical cloud systems during phase III of GATE. Part I: two-dimensional experiments

J. Atmos. Sci.

Production of secondary ice particles during the riming process

Nature

Parameterization of ice crystal conversion processes due to vapor deposition for mesoscale models using double-moment basis functions. Part I: basic formulation and parcel model results

J. Atmos. Sci.

Cloud Dynamics

The simulation of three-dimensional convective storm dynamics

J. Atmos. Sci.

Water activity as the determinant for homogeneous ice nucleation in aqueous solutions

Nature